Laboratory assays were conducted to determine the effect of temperature on head capsule width of L. botrana (Lepidoptera: Tortricidae). One nonconstant and six constant temperatures were assayed. Temperature significantly affected head capsule size. Head capsules were larger at low temperatures (15–21°C) and smaller at high temperatures (24 and 30°C). Nonconstant temperature and 27°C also produced insects with larger head capsules similar to those ones collected at low temperatures. Five instars were recorded at all temperatures, and no overlap was found between mean head capsule widths; however, an overlap of the ranges of head capsule widths was found between L2 and L3 in larvae reared at 24°C. Growth ratios were also relatively constant. Head capsule growth followed Dyar′s rule. Head capsule width–instar relationship was better described by a second-degree polynomial regression equation.

Piophila casei L. or cheese skipper is a well-known fly with a controversial role: it is considered harmful in the food industries but important in nature as a detritivore and useful for studies in forensic entomology. The temperature response of P. casei was studied at five constant temperatures: 15, 19, 25, 28, and 32°C. The lowest mortality percentage of eggs was recorded at 15°C and the highest at 32°C. Conversely, less mortality was observed for maggots at higher temperatures. The developmental time from first instar to adult decreased with temperature reaching the lowest value at 32°C (13.7 d). Adult longevity was strongly affected by temperature, decreasing from 20.5 d at 15°C to 6.6 d at 32°C. Mean total fecundity per female was higher at 25°C and lower at 15 and 19°C, whereas the best performance in mean daily total fecundity per female was recorded at 32°C. Male longevity followed a similar trend to the one observed for females. The net reproductive rate (R₀) was greatest at 25°C, whereas the highest r_m was recorded at 32°C. At this latter temperature, the highest mean generation time (T) and doubling time (D) were also observed. The finite rate of increase (λ) was augmented slightly with higher temperatures.

The effects of nitrogen concentration on the reproduction and development of citrus mealybug, Planococcus citri, were studied on two colors of coleus, Solenostemon scutellarioides. Green and red-variegated coleus plants were supplied with varying applied nitrogen concentrations (0, 25, 50, 100, 200, and 400 ppm) for 32 d before being artificially inoculated with citrus mealybugs. Female citrus mealybug life history parameters including eggs contained within the egg mass and respective body cavity, body length (mm), and developmental time (d) were measured. A modified micro-Kjeldahl digestion procedure followed by colormetric assay was conducted twice throughout the study to assess leaf nitrogen concentration. The results of this study show that the citrus mealybug life history parameters were influenced by the applied nitrogen concentrations (ppm), leaf nitrogen concentration (%), and total moisture content (g). Citrus mealybugs feeding on both green and red-variegated coleus, receiving the high nitrogen fertilizer concentrations (200 and 400 ppm) had the greatest egg loads, were larger in size, and had the shortest developmental times. Leaf nitrogen concentration also affected the citrus mealybug life history parameters with those mealybugs feeding on plants containing the highest leaf nitrogen contents having the greatest egg loads, larger in size, and the shortest developmental times. In addition, total plant moisture content impacted the citrus mealybug life history parameters similar to leaf nitrogen concentration. However, this was based on plant architecture whereas percent plant moisture content for both green- and red-variegated coleus was comparatively similar for all nitrogen concentrations. The life history parameters measured were more pronounced on green coleus compared with red-variegated coleus, perhaps because of nitrogen allocation differences between the two coleus colors. Thus, higher nitrogen concentrations, in the form of supplemental fertilizers used in greenhouse production systems, leads to an increase in the performance of citrus mealybugs as defined by increased egg loads, larger mature females, and shorter developmental times on coleus plants. These results indicate that the implementation of proper fertilizer practices may lessen the likelihood of dealing with extensive insect outbreaks, thus potentially reducing insecticide use.

The effect of temperature on the development of immature stages of the predator Iphiseius degenerans (Berlese) was studied at 15, 20, 25, 27.5, 30, and 32.5°C with 60% RH and photoperiod of 16:8 (L:D) h when feeding on Tetranychus urticae. The data obtained were used for the estimation of the thermal requirements of this predator by a linear and nonlinear model (Lactin 2-model). Developmental thresholds that were estimated by the linear model for immature stages of egg, protonymph, and deutonymph were approximately the same and found to be 11.71, 10.11, and 11.28°C, respectively, whereas that of the larval stage was found to be lower (7°C). The Lactin-2 model was also applied, and lower values were estimated for all immature stages than those by the linear model. Biological characteristics and life table parameters of the predator were also studied at 15, 20, 25, 30, and 32.5°C. Preoviposition period was shortest at high temperatures of 30 and 32.5°C (1.18 and 1.08 d, respectively), whereas fecundity was highest at 30°C. Longevity of adults and mean generation time was longest at 15°C. The intrinsic rate of increase was highest at 25 and 30°C (0.22 and 0.23 d⁻¹, respectively), whereas doubling time was found to be shortest at 30°C. The results show that this predator develops effectively at a broad range of temperatures. Moreover, it can increase at relatively high temperatures and is well adapted to the high temperatures that occur in Mediterranean region.

Soybean aphid populations have been hypothesized to respond to nutrient availability in soybean plants. We examined how soil potassium (K) deficiency affects soybean aphid population at both regional and field level scales. First, we measured soil and leaf nutrient levels and monitored soybean aphid populations in 34 production soybean fields throughout Wisconsin. A principle component analysis (PCA) was used to examine the relationship between soil and leaf nutrients and soybean aphid population growth. Results showed that aphid population growth rate was negatively correlated with soil K and P and leaf K, N, P, and S, whereas peak aphid densities were positively correlated with the same suite of soil and leaf nutrients. In a manipulative field experiment, we established low, medium, and high K fertility soybean plots and determined life table parameters of soybean aphids. Aphids developing within clip-cages showed a significantly greater intrinsic rate of population increase and net reproductive rate in the low K treatments in comparison with the medium and high K treatments. In these same plots, naturally colonizing populations of soybean aphids also had significantly higher peak abundance and rate of population increase in the low K treatment compared with medium and high K treatments. In general, these findings indicate that soil K availability and leaf K levels affect plant quality and may play an important role in soybean aphid population dynamics.

Parasitoids exposed to low temperatures may suffer from extreme physiological conditions inducing direct or indirect chill injuries. Under long cold exposure (which also includes starvation), individuals face a great challenge in maintaining both water balance and energy reserves. Key parameters associated with individual fitness and physiological parameters related to cold-hardiness were analyzed. One-day-old mummies of the aphid parasitoid Aphidius colemani Viereck (Hymenoptera: Aphidiinae) were exposed to cold (2 and 4°C) for various periods (1–3 wk) under a high relative humidity (75 ± 5% RH) and darkness. High mortality and shortened adult longevity occurred with increasing duration of exposure at low temperatures. Individual parasitoid mass loss increased with cold storage duration and was associated to a marked decrease in dry mass caused by lipid reserve depletion. Water content (water mass/dry mass) slightly increased with cold exposure duration because of starvation. Similar patterns were observed for both temperatures tested. This study emphasizes (1) how energetic reserves may be critical to survive at low temperatures and (2) that the survival and longevity are related, at least in part, to the depletion of energy reserves during starvation.

The developmental biology and fitness of the carob moth, Ectomyelois ceratoniae (Zeller), is highly variable and depends on many environmental factors. This study was conducted to determine the impact of fruit moisture content on carob moth mortality, development, and fitness. We found a significant relationship between fruit moisture content and carob moth mortality and development. Only 1 of 61 carob moths completed larval development within 85 d in fruit having <5.0% moisture content, and no larvae survived at moisture contents <3.5%, close to the predicted minimum of 3.2% moisture content; 75% of the larval mortality occurred below 7.3% fruit moisture. Of the 32 larvae that were still developing on day 85, 75% were below 13.2% fruit moisture. Average female development ranged from 49.3 ± 4.2 d at 21.8 ± 0.7% fruit moisture to 81.0 d at 5.0% fruit moisture, and average male development ranged from 47.7 ± 4.8 d at 21.8 ± 0.7% fruit moisture to 75.5 ± 4.5 d at 5.1 ± 0.3% fruit moisture content. Maximum predicted development occurred at 19.6 and 20.4% fruit moisture content for females and males, respectively. Female fitness was more adversely affected at low fruit moistures than was male fitness as indicated by a greater decrease in adult emergence weight and greater increase in developmental time. Adult longevity of both sexes was not influenced by the fruit moisture at which they were reared as larvae. The average number of eggs laid by females was linearly related to the fruit moisture at which they were reared as larvae. Population fitness as estimated by the population doubling times was negatively affected by low fruit moisture content, and times ranged from 9.9 to 210.4 d over the range of conditions in this study. Future studies aimed at testing fitness parameters of the carob moth should control fruit moisture content to make valid inferences concerning the impact of environmental factors on development and fitness of this species.

Periodical cicadas (Magicicada spp.) are insects with a 13- or 17-yr life cycle that spend most of this time underground feeding on xylem from plant roots. In the 13th or 17th year of the life cycle, typically millions of cicadas emerge from the soil within a given area in near perfect synchrony. Factors controlling emergence, whether exogenous or endogenous, remain a mystery. By removing 13-yr periodical cicadas [Magicicada cassini (Fisher 1851)] from their natural environment in northwest Arkansas and controlling most exogenous factors in the laboratory, this study examined deviations or similarities in life cycle patterns compared with those occurring in nature. In a series of replicated experiments starting 9 mo before natural emergence in environmental chambers with constant light and temperature, we found that 14 of 60 nymphs associated with soybean (Glycine max L.) plants or cedar trees (Juniperus virginiana L.) successfully emerged in May 1998 in synchrony with the natural population from which they were removed. Seven of 10 nymphs feeding on a control cedar tree for 9 mo at the field study site also emerged in May 1998. It seemed that all nymphs surviving 9 mo under laboratory conditions emerged during the period of natural emergence. Whether this represents endogenous control of emergence remains to be critically tested, but from data collected in this study, the internal timing of emergence seems to be set at least 9 mo before emergence.

The newly invasive soybean aphid, Aphis glycines Matsumura, has seriously threatened soybean production in North America, after having spread to >20 states in the United States and several southern provinces of Canada. Control of A. glycines has focused on applications of insecticides, which are not a long-term solution to soybean aphid pest management. In autumn, soybean aphids start producing alate females (gynoparae) that search for their overwintering host plants, the common buckthorn, Rhamnus cathartica. The gynoparae then produce pheromone-emitting wingless female offspring (oviparae) that attract male aphids. In this study, we report the chemical identification of the soybean aphid sex pheromone using gas chromatography–electroantennogram, gas chromatography–mass spectrometry, and nuclear magnetic resonance spectroscopy. Behavioral activities of males and gynoparous females in the field were also characterized. The potential applications using formulations containing specific soybean aphid pheromone compositions for reducing overwintering populations are discussed.

Volatile compounds from apple trees (variety Golden Smothee) were collected in the field from attached apple branches enclosed in plastic bags in the morning and at dusk and during three growth periods (after petal fall [APF], immature fruit [IF], and close-to-full ripening [CFR]). Collections were analyzed by gas chromatography–mass spectrometry (GC-MS) and gas chromatography–electroantennographic detection (GC-EAD) using the antennae of Cydia pomonella males as biological detectors. Forty-four compounds were detected in the volatile collections. The most abundant compound in all treatments was (Z)-3-hexenyl acetate, a common green leaf volatile. Other abundant compounds were (Z)-3-hexenol, (E,E)-α-farnesene, hexyl acetate, 4,8-dimethyl-1,3,7-nonatriene, hexyl hexanoate, and germacrene D. Most of the compounds that showed significant differences between periods were emitted in greater amounts in the APF and/or IF periods than in the CFR period. (E)-β-caryophyllene and an unidentified compound were significantly more abundant during the day, whereas 2-hexanone, octanal, and (Z)-3-hexenol were significantly more abundant at dusk. GC-EAD responses were very weak and significantly higher than background noise only to hexyl acetate, 4,8-dimethyl-1,3,7-nonatriene, nonanal, (Z)-3-hexenol, hexyl butanoate, and (E,E)-α-farnesene. In further electroantennographic (EAG) assays with synthetic compounds, high responses by the antennae of both males and females were recorded to many of the compounds identified. Males showed a response equal to or higher than females to all compounds except β-myrcene.

Captures of male dogwood borer, Synanthedon scitula (Harris), in traps baited with trinary and binary blends of the female sex pheromone components were compared with those in traps baited with the most effective commercially available lure in apple orchards in West Virginia, Virginia, and North Carolina. Traps baited with the trinary blend [88:6:6 vol:vol:vol (Z,Z)-3,13 octadecadienyl acetate (ODDA):(E,Z)-2,13-ODDA:(Z,E)-3,13-ODDA] and the binary blend [96:4 (Z,Z)-3,13-ODDA:(E,Z)-2,13-ODDA] captured significantly more male dogwood borers than traps baited with the best commercial lure. Although the trinary blend captured the most males, there was no significant difference in captures with the binary blend at all six field sites. Chemical analysis revealed that the commercial lure contained 91.5% (Z,Z)-3,13-ODDA, 7.3% (Z,E)-3,13-ODDA, and 1.2% (E,Z)-3,13-ODDA, a potent behavioral antagonist of dogwood borer. Species specificity of the trinary and binary blends was very high; >97% of all moths captured were dogwood borer compared with 6–74.4% for the commercial lure. Male dogwood borer showed a concentration-dependent response to traps baited with different source concentrations of the trinary blend at all locations and of the binary blend at most locations. Between 4 and 113 times more male dogwood borers were captured in traps baited with the trinary blend within commercial orchards than within adjacent woodland habitats.

In field tests of floral chemicals dispensed singly, alfalfa looper moths, Autographa californica (Speyer), were captured in traps baited with phenylacetaldehyde, β-myrcene, or benzyl acetate. Cabbage looper moths, Trichoplusia ni (Hübner) were also captured in traps baited with phenylacetaldehyde, methyl salicylate, or methyl-2-methoxy benzoate. In evaluations of binary blends of those same compounds, generally more alfalfa looper moths were trapped when β-myrcene was presented with phenylacetaldehyde or with benzyl acetate compared with phenylacetaldehyde alone or benzyl acetate alone. Similarly, more cabbage looper moths were trapped with β-myrcene with phenylacetaldehyde compared with phenylacetaldehyde alone. These findings provide new chemical blends for luring and trapping both sexes of alfalfa looper and cabbage looper moths and suggest differences in preferences of these two moth species for floral odorants.

During the dry season in the humid forest zone of Cameroon, maize is the most important off-season cash crop grown in hydromorphic inland valleys (IVs), which may also be reservoirs for pests such as the stemborer Busseola fusca Fuller and its natural enemies. Pest and parasitoids were monitored in IVs and close-by upland maize fields from January 2002 through December 2004. Trap catches and oviposition data showed that B. fusca was active throughout the dry season and long and short rainy seasons of 2004. Egg batch densities were considerably lower in the dry than in the rainy seasons. Important natural enemies were the scelionid egg parasitoids Telenomus busseolae Gahan and T. isis Polaszek. B. fusca was the predominant borer species in all seasons in maize in IVs as well as in upland fields, followed by Sesamia calamistis Hampson and Eldana saccharina Walker. B. fusca larval densities were lowest in the IVs and increased in the course of the year in the upland fields. In contrast, S. calamistis densities were higher in IVs than in upland maize fields. At harvest of the IV maize, B. fusca and E. saccharina larval densities were 47.3 and 15.5 times higher, respectively, than on old maize stubbles in upland fields planted during the previous year. Grain yields as well as the marketable ear index were 1.1–2 times higher in the dry season than in the long and short rainy seasons, indicating the importance of IVs for dry season maize production in Cameroon.

Predation is an important factor in the dynamics of gypsy moth (Lymantria dispar L.) populations, yet predation rates can be difficult to estimate accurately in the field. Biased estimates can result from spatial heterogeneity in risk or from artifacts associated with deploying prey. Here we compare predation rates on freeze-dried gypsy moth pupae affixed with beeswax to pieces of burlap with predation rates on naturally occurring live pupae in the same sites. Daily predation rates, primarily by small mammals, were two to eight times greater for freeze-dried deployed pupae than natural pupae, depending on the year. These results indicate apparent predation rates can be substantially biased by artifacts associated with deployed prey, such as human scent, artificial substrates, or freeze drying. Results from studies using similar methods may provide qualitative comparisons of relative predation risk, but their estimates of absolute predation rates should be interpreted with caution, and attempts should be made to quantify and correct for any resulting bias.

The purpose of this study was to investigate spider assemblages of the Italian vineyards of Langa Astigiana (northwest Italy). Pitfall trapping and standardized hand collecting were combined to have an overall idea of the spider fauna living in this agroecosystem. A total of 138 samples for pitfall sampling and 92 for hand collecting sites were collected at 23 different times over a period of 2 yr (2003 and 2004). The vineyards differ mainly from agricultural practices (certified organic production, production according to EEC’s Council Regulation 2092/91 on biological agriculture and intensive production) and for the heterogeneity of landscape matrix surrounding them. We studied the influence of these two factors on spider assemblages applying canonical correspondence analysis and multiresponse permutation procedures (MRPPs). Significant results of MRPP were analyzed in terms of hunting strategies. Significant differences are found among groups according to both landscape heterogeneity and agricultural practices, the first resulting more significantly. Analyzed in terms of hunting strategies, an increase in landscape heterogeneity seems to provide an increase in ambush spiders and specialized predators, whereas an increase in sheet web weavers seems to be related to homogeneous landscapes.

The relationship between habitat structural composition, presence of Ixodes scapularis Say (I. dammini Spielman, Clifford, Piesman, and Corwin), and the prevalence of Borrelia burgdorferi infection in small mammal populations was studied at 12 4-ha study sites selected within two perpendicular transects spanning New York State. Species-adjusted small mammal infection rates (SARs) were calculated to enable comparison of B. burgdorferi infection rates among sites with differing small mammal species composition and were used as the outcome variable in a predictive model. Sites with high SARs were characterized by lower overstory tree canopy height and basal area, increased understory coverage, substantial understory shrub coverage, decreased presence of surface water or saturated soil, high dominance values for I. scapularis, and higher tick burdens on small mammals. These differences were statistically significant from sites with moderate or low SAR values. Understory foliage height profiles were created for each study site, and significant differences in vegetation structural composition between high SAR sites and those with low or moderate SAR were documented. High SAR sites had increased density of herbaceous foliage at 0 and 25 cm, and higher shrub density at 0, 25, and 50 cm measurements above the ground, associated with I. scapularis questing success, and lower densities of sapling trees at 25, 50, and 75 cm. The structural composition of understory vegetation may dictate vector density and predict B. burgdorferi infection rates in small mammals in New York State.

We describe and compare the distributions of three species of riparian tiger beetle in the floodplains of the Tedori River System in Japan. To explain the species distributions, we considered both environmental factors and interspecific interactions, especially the intense competition for food, among the three species. First, we characterized the topography and sand content of the floodplains selected by each species. Cylindera elisae was found on floodplains downstream and those with fine-grained deposits, whereas Cicindela gemmata inhabited only upstream floodplains in mountainous areas with fine-grained deposits trapped by sand-trap dams. Cicindela transbaicalica was distributed widely along the river. Second, we compared mandible size among the species. Interspecific overlap in mandible length was very limited, which suggests that competition for food is weak among these species. These results suggest that environmental factors may be important determinants of the distribution of riparian tiger beetles along the Tedori River.

We hypothesized that the elaiosomes of seeds of the invasive plant, Centaurea maculosa (spotted knapweed), elicit seed-dispersing behavior by native ants (myrmecochory), potentially providing a mechanism enhancing its invasiveness into native plant communities. Elaiosomes are small nutrient-rich nodes produced on seeds of some plants. Ants collect and disperse elaiosome-bearing seeds, later consuming the elaiosome, but usually discarding the seed intact away from the parent plant. The seeds of C. maculosa possess elaiosomes, suggesting that the dispersal of its seeds and its ability to rapidly spread into native habitats may be enhanced by myrmecochory. We tested for myrmecochory at two Palouse prairie sites in Montana by presenting seeds of C. maculosa and two native dominants, Balsamorhiza sagittata (a forb) and Psuedoroegneria spicata (a bunchgrass). Seeds were presented in choice (seeds of all three plants) and no choice (seeds of only one plant) treatments. At both study sites, ants readily dispersed the seeds of the invasive plant, C. maculosa, while ignoring seeds of the native plants, B. sagittata and P. spicata. In addition, myrmecochory was not influenced when all three seed types were presented together. Different ant species were observed removing seeds from stations at each site, indicating that myrmecochory of C. maculosa seeds is not restricted to one ant species but rather may be a generalized response across ant communities. Our results indicate that myrmecochory may enhance dispersal of C. maculosa and facilitate its invasion into native plant communities.

North American grapevine yellows is a destructive, phloem-limited disease of winegrapes in the mid-Atlantic and northeastern regions of the United States caused by at least two phytoplasmas (aster yellows and X-disease Candidatus phytoplasma spp.). Because insects have been identified as vectors of grapevine yellows in several countries, one or more insect vectors are suspected of transmitting the phytoplasmas in North American vineyards. Adding to evidence in support of insect transmission of North American grapevine yellows were observations that diseased vines often occurred in clusters frequently near vineyard edges that bordered woodland vegetation, suggesting movement of insect vectors into vineyards. The spatial distribution of North American grapevine yellows-affected vines was annually assessed in two northern Virginia vineyards over an 8-yr period. Spatial analysis indicated that diseased vines were significantly clustered, or their distribution was nonrandom, in both vineyards. Clustering was observed more frequently in the larger of the two vineyards. In addition, we surveyed the abundance of leafhoppers and planthoppers in and around three North American grapevine yellows-affected Chardonnay vineyards. The relative abundance of captured candidate vector species in and around North American grapevine yellows-infected vineyards differed among sampling methods. Agallia constricta was the most commonly captured leafhopper in sweep sampling in all years. Several species known to transmit phytoplasma were also captured, including Scaphoideus titanus, a grapevine yellows vector in Europe, Graminella nigrifrons, and Deltocephalus flavicosta. Three leafhopper species, S. titanus, Osbornellus auronitens, and Jikradia olitorius, exhibited seasonal movement into the vineyard that may account for the observed clustering of diseased vines.

The suitability of Myzus lythri (Schrank) (Homoptera: Aphididae) and Galerucella calmariensis L. (Coleoptera: Chrysomelidae), herbivores of purple loosestrife, for preimaginal development and survival of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), Coleomegilla maculata (DeGeer) (Coleoptera: Coccinellidae), and Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) was quantified to provide a more complete understanding of predator–prey relationships in the purple loosestrife (Lythrum salicaria L.) system. Individual first- or second-instar predators were assigned to one of four diets: (1) a control diet, Acyrthosiphon pisum (Harris) (Homoptera: Aphididae) or a combination of A. pisum and Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs; (2) M. lythri nymphs and adults; (3) G. calmariensis eggs; or (4) G. calmariensis larvae. Preimaginal survival of C. carnea was similar for all diets and ranged from 61 to 76% on G. calmariensis larvae, M. lythri, and the control diet. Preimaginal survival of H. axyridis ranged from 27% on G. calmariensis larvae to >80% on M. lythri and the control diet. Preimaginal survival of C. maculata was >90% on M. lythri and the control diet. H. axyridis larvae reared on G. calmariensis eggs and C. maculata larvae reared on G. calmariensis eggs or larvae did not survive to the adult stage. Preimaginal development times of the three predatory species were 2–5 d longer on G. calmariensis larvae and M. lythri than on the control diets. Adult weights for the three predatory species were significantly reduced when reared on M. lythri and for H. axyridis when reared on G. calmariensis larvae. Myzus lythri is suitable prey for preimaginal survival of the three predatory species. G. calmariensis larvae are highly suitable for development and survival of second-instar to adult C. carnea and less suitable for H. axyridis.

The pea leafminer, Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae), is an important pest of leafy greens in the Holland Marsh, Bradford, Ontario, and was first discovered in this area in 1998. A 2-yr study was undertaken to document the parasitoid complex of this recent addition to leafminer guild in Ontario and examine endoparasitoids reared from pea leafminer pupae collected from eight host plants: celery (Apium graveolens L.), spinach (Spinacia oleracea L.), lettuce (Lactuca sativa L.), mustard greens (Brassica juncea L.), pea (Pisum sativum L.), potato (Solanum tuberosum L.), and gai lan (Brassica alboglabra L.). Members of three families of Hymenopteran parasitoids were identified: Chrysocharis oscinidis Ashmead (Eulophidae), Halticoptera circulus (Walker) (Pteromalidae), and three species in the Braconidae, including two unidentified Dacnusa spp. and one unidentified Opius sp. Mortality and parasitism rates of pea leafminer pupae were higher in 2002 than 2003 and varied according to host plant. Parasitism rates ranged from 4 to 27% in 2002 and 4% to 13% in 2003. The parasitoid complex differed among host plants, and there were differences in the range of host plants on which parasitoids were found to parasitize pea leafminers.

The lesser peachtree borer, Synanthedon pictipes (Grote and Robinson), is an important pest of Prunus spp. We determined the susceptibility of S. pictipes to six entomopathogenic nematode species: Heterorhabditis bacteriophora Poinar, H. indica Poinar, Karunakar and David, H. marelatus Liu and Berry, Steinernema carpocapsae (Weiser), S. feltiae (Filipjev), and S. riobrave Cabanillas, Poinar and Raulston. Nematode virulence in S. pictipes was compared with virulence in two known susceptible hosts, Galleria mellonella L. and Tenebrio molitor L. In S. pictipes, the steinernematids were more virulent than the heterorhabditids, the virulence of S. carpocapsae was greater than S. riobrave, with S. feltiae being intermediate between the two, and no differences in virulence were detected among the heterorhabditids. Each nematode exhibited similar or greater virulence to S. pictipes than to T. molitor, and the steinernematids’ virulence to S. pictipes was greater or similar to H. bacteriophora or H. marelatus virulence in G. mellonella. A quadratic dose-response relationship was detected between S. carpocapsae and S. pictipes, and an LC₅₀ was estimated to be 7.99. Comparisons of steinernematid reproductive potential per host, or per milligram host, generally indicated the highest production in G. mellonella; production in S. pictipes was similar or greater than in T. molitor. In S. pictipes, no differences in reproduction were detected among nematode species. Based on our findings and other studies on related insect species, we conclude that the prospects for controlling S. pictipes with entomopathogenic nematodes are promising (particularly with S. carpocapsae and S. feltiae), and field testing is warranted.

We studied the influence of herbivory by two introduced insect herbivores on the survival and performance of seedlings of Melaleuca quinquenervia (Cav.) Blake (Myrtaceae), an invasive tree that threatens the Florida Everglades ecosystem. Boreioglycaspis melaleucae (Moore) (Homoptera: Psyllidae) nymphs and Oxyops vitiosa (Pascoe) (Coleoptera: Curculionidae) larvae were transferred onto Melaleuca seedlings within replicated 0.25-m² caged plots in Palm Beach County, FL. The treatments included three densities of Boreioglycaspis first instars at 1, 15, and 50 nymphs per seedling, one treatment of a single first Oxyops larval instar per seedling, another treatment of both one Oxyops larva and one Boreioglycaspis nymph per seedling, and caged and uncaged controls. Herbivory by Oxyops did not affect Melaleuca seedling height, leaf number, or survival. Feeding by Boreioglycaspis decreased survival, height, and leaf number, with these measures of plant performance ≈50% lower in the high and medium densities compared with controls. In a field plot adjacent to the experimental area, we measured growth, survival, and naturally occurring insect density and damage on 1,100 seedlings. Although insect densities were on average lower in the field plot than in the experiment, mortality and growth rates of the seedlings were comparable with those in the experiment. The results indicate that, above a threshold density, Boreioglycaspis herbivory may be effective in reducing growth and survival of Melaleuca at the potentially critical seedling life stage. It also seemed that effects of the insects were independent rather than antagonistic or synergistic.

Field studies were conducted in 2001 through 2004 to assess the compatibility of two herbicides, 2,4-D (2,4-dichlorophenoxyacetic acid) and clopyralid (3,6-dichloropicolinic acid), with two root insects, Cyphocleonus achates (Fahraeus), and Agapeta zoegana L., introduced for biological control of spotted knapweed, Centaurea stoebe Lamarck subsp. micranthos (formerly C. maculosa) in Montana. Both herbicides were applied at the fall and spring rosette stage. In 2003, both herbicides reduced knapweed canopy cover by ≈98% compared with ≈85% in 2004. The number of live larvae of both insect species was significantly lower in treated plots than in controls in 2003. In 2004, the number of live C. achates larvae was significantly lower in treated plots than in controls at the fall application, but larval numbers were not different at the spring application. Larval numbers of C. achates were not different between application times in 2003 but were significantly lower in fall-treated plots than in spring-treated plots in 2004. Numbers of A. zoegana larvae were not different between treated plots and controls in 2004. Larval numbers of A. zoegana were significantly lower in fall-treated plots than in spring-treated plots in 2003, but there was no difference between application times in 2004. Larval numbers of each insect species were similar between herbicides in both years. We conclude that fall applications of both herbicides are not compatible with the two insects. Spring applications of the two herbicides may be compatible with both insect species if delayed until late spring.

A functional response study of the eight most common arthropod predators of cotton bollworm, Helicoverpa zea (Boddie), eggs was conducted in the laboratory. Predators were starved for 24 h, and single predators were exposed to different prey density treatments. Predation response was observed at 6, 12, and 24 h after feeding trials began. At the highest prey density (150 eggs per predator), Hippodamia convergens Guerin-Meneville and Collops quadrimaculatus (F.) adults and Chrysopa oculata Say larvae showed the highest consumption rates (116, 85, and 119 eggs/24 h, respectively), followed by H. convergens larvae (51 eggs/24 h), adult Geocoris punctipes (Say) (45 eggs/24 h), and adult Scymnus loewii Mulsant, Orius insidiosus (Say), Notoxus spp., and Nabis capsiformis Germar (1, 1, 10, and 12 eggs/24 h, respectively). Adult Notoxus spp., N. capsiformis, and O. insidiosus showed type 1 functional response, whereas adult C. quadrimaculatus, G. punctipes, H. convergens, and larval H. convergens and C. oculata showed type 2 response. All predators consumed the highest number of bollworm eggs at 35°C and the lowest numbers at 15°C; predation rate at 35°C was four times higher than that at 15°C. The prey density–dependent behavior of predators and effect of temperature on their predation behavior are discussed.

Plant glandular trichomes can confer protection from herbivores, but may also affect natural enemies. We studied time allocation of activities (inactive, moving, probing, feeding, and grooming) of nymphs of the predatory bugs Macrolophus pygmaeus and Orius niger on the upper surface of tomato leaflets from the cultivars Dombito, Elxis, and H30. In H30, which had the highest density of type VI glandular trichomes on the upper surface, both insects spent more time in grooming their tarsi and rostrum than the other two cultivars. In Dombito and Elxis, which have trichome densities that didn’t differ much, no significant differences were observed in time allocation of activities for both insects. When averaged across cultivars, younger instars of M. pygmaeus spent less time on probing and more time on grooming, whereas for O. niger, the nymphs of first stage spent more time on grooming and less on movement than the nymphs of older stages. Between species, O. niger first instars groomed more and walked less than M. pygmaeus, whereas there were no detected differences between the other instars tested.

The use of insectary plants in agroecosystems to provide floral resources for enhancing natural enemy activity is an increasingly used practice, but candidate flowering plant species are not always screened for their attractiveness to key arthropods in the system being studied. In the work presented here, the relative attractiveness of four species of insectary plants to beneficial and pest insect species was assessed by observing the relative frequencies of flower visits to replicated blocks of the insectary flowers in two Oregon broccoli fields. The four plant species tested were alyssum (Lobularia maritima L. Desv.), coriander (Coriandrum sativa L.), buckwheat (Fagopyrum esculentum Moench), and phacelia (Phacelia tanacetifolia Benth.). Predatory hoverflies (Syrphidae) were identified to species, where possible, because of their previously observed importance as aphid predators in broccoli fields in the study area. The other beneficial insect groups observed were in the families Apidae, Coccinellidae, Tachinidae, and Vespidae, and the three main pest species were western tarnished plant bug (Lygus hesperus Knight), western spotted cucumber beetle (Diabrotica undecimpunctata undecimpunctata Mannerheim), and imported cabbageworm (Pieris rapae L.). The Syrphidae visited mostly coriander, but this “preference” was probably influenced by competition from other foragers. Bumblebees and the three pest species visited mostly phacelia, and other species groups were less consistent in their flower choices. The different insect preferences for flowers are discussed in terms of the key influencing factors that should be considered when assessing the relative attractiveness of insectary plants in the field.

Individual larval movement was studied in the laboratory to determine whether or not Ctenocephalides felis (Bouché) larvae display differences in the time spent in food patches of varying quality. Both early and late instars were tested. Young instars exhibited marked differences in their response to food patch quality. When no food was present, the mean time these larvae remained at the site was 24.5 h. When food patches contained feces only, eggs only, or equal amounts of feces and eggs, the time spent before leaving increased to 62.6, 120.5, and 192.3 h, respectively. The response by older instars was less dramatic. No differences were observed between food patches with only feces or eggs. Older larvae also remained longer in patches containing both feces and eggs (201.9 h). Our data suggest that C. felis larvae do not respond randomly to food patches of varying quality and that particular dietary components have an influence on movement behavior according to developmental stage. Obtaining all of the essential dietary components seems more critical in the early stages of development.

Attack rates, progeny production, sex ratios, and host use efficiency of Muscidufurax raptor Girualt and Sanders, Spalangia cameroni Perkins, S. endius (Walker), S. nigroaenea Curtis, S. gemina Boucek (Hymenoptera: Pteromalidae), and Dirhinus himalayanus (Hymenoptera: Chalcididae) were evaluated in laboratory bioassays with five dipteran hosts: house fly (Musca domestica L.), stable fly (Stomoxys calcitrans L.), horn fly (Hematobia irritans L.), black dump fly [Hydrotaea aenescens (Weidemann)] (Diptera: Muscidae), and a flesh fly (Sarcophaga bullata Parker) (Diptera: Sarcophagidae). M. raptor, S.cameroni, and S. endius readily attacked and produced progeny on all five host species, with substantially lower production from S. bullata than from the muscid hosts. Rates of host attacks by S. nigroaenea and S. gemina were similar on house fly, stable fly, and black dump fly hosts, with lower rates on horn fly; almost no progeny were produced by S. nigroaenea on S. bullata hosts. D. himalayanus, a large-bodied chalcidid parasitoid, had highest rates of host attacks and progeny production on S. bullata and H. aenescens, followed by stable fly and house fly hosts; very few progeny were produced by this species on horn fly hosts. Overall differences among different geographic strains of parasitoids (from Russia, Kazkhstan, and Florida) were generally small, although the Florida strain of M. raptor was superior to the two Eurasian strains.

We studied, over a 6-yr period, temporal dynamics of plum curculio, Conotrachelus nenuphar (Herbst.), immigration into an unsprayed section of a commercial apple orchard with the main aim of establishing the relationships between the timing of immigration, weather factors, and phenological tree stage. By using panel and pyramid traps baited with attractive synthetic odor and deployed near woods adjacent to orchard trees, we exploited the chemical cues potentially directing the spring immigration by plum curculios. On each of the 6 yr, traps were inspected on a daily basis over the entire period of plum curculio immigration, which ranged from 51 to 85 d. Across all 6 yr, most immigrant plum curculios (on average 57% of the total) potentially colonizing host trees were captured by traps by the time of petal fall. Based on our combined trapping and weather data, we propose the occurrence of pre- and postpetal fall periods of plum curculio immigration, each of which is influenced to a different extent by temperatures prevailing in spring. Only during the prepetal fall period, but not afterward, was there a strong influence of air temperature on captures by both panel and pyramid traps. Thermal constants (expressed in degree days) estimated reflected more accurately onset of plum curculio immigration than tree phenology. Our combined results indicate that the odor-baited traps evaluated can be used to predict initiation of plum curculio immigration using thermal constants and also to monitor accurately the magnitude of plum curculio immigration into orchard blocks. Findings are discussed with respect to the ecology and management of plum curculio.

We evaluated the potential effect of phenological differences in maize, Zea mays L., and soybeans, Glycine max L. Merr., on adult densities and oviposition of the western corn rootworm, Diabrotica virgifera virgifera LeConte. Maize and soybean varieties were planted at various planting dates in Urbana-Champaign (east central Illinois) and Monmouth (northwestern Illinois) during 2000 and 2001. Historically, maize is grown in rotation with soybean in east central Illinois and is not rotated (continuous maize) in northwestern Illinois. Results from our research in the Urbana-Champaign phenology trial indicated that adult captures increased in soybean plots after the maize developed past the R2 stage of development. Significantly more D. v. virgifera eggs were deposited in the soil of soybean plots than in early planted maize plots. However, maize was not abandoned as an egg-laying site. In fact, the soil in late-planted maize plots was a competitive sink for D. v. virgifera eggs compared with soybean treatments. Results from our research in the Monmouth phenology trial indicated adult captures increased in late-planted maize after the R2 stage of development. Significantly more D. v. virgifera eggs were deposited in late-planted and early planted maize as compared with soybean. Soybean plots were not an egg-laying target at the Monmouth experimental site. We believe this documents different field level responses in ovipositional behavior of D. v. virgifera populations that inhabit east central and northwestern Illinois. We also hypothesize the intensive selection pressure that resulted from decades of crop rotation in east central Illinois resulted in a variant D. v. virgifera that responds to the phenology of maize by expanding its ovipositional range of crops, most notably to include soybeans.

The emergence and premating reproductive behaviors of adult dogwood borer moths, Synanthedon scitula Harris (Lepidoptera: Sesiidae), were examined under controlled conditions in the laboratory and in apple orchards in Virginia. The diel periodicity of male response to pheromone sources was recorded using traps baited with commercial pheromone lures and with a recently identified, trinary blend of dogwood borer sex pheromone components. An earlier study reporting a significant effect of pheromone trap height on the capture of male dogwood borer was revisited, using commercial lures and the new pheromone. Under a 16:8 (L:D)-h photo regimen, the emergence of male and female moths showed a diel periodicity, peaking at 0600 hours. Sexual receptivity of female moths, indicated by the onset of calling behavior, occurred in most individuals on the day after emergence and was observed only during the crepuscular period just before and after sunset. Similarly, the capture of male dogwood borer in traps deployed in July and baited with virgin female moths or pheromone lures coincided with the period of female calling behavior, peaking sharply between 2000 and 2100 hours. When pheromone-baited traps were deployed in September, the peak capture of male dogwood borer occurred earlier, between 1900 and 2000 hours. Traps baited with a commercial lure captured significantly more male dogwood borer at 1.8 m (6 ft), whereas those baited with the trinary dogwood borer sex pheromone captured similar numbers of males at elevations ranging from 1.2 to 2.4 m (4–8 ft). Use of the new dogwood borer sex pheromone has tremendously increased the precision of trapping data and has yielded reliable measurements of the behavior and abundance of male moths that pertain directly to improved monitoring and management capabilities.

In the Ozark National forests of Arkansas and Missouri, an outbreak of a native cerambycid beetle, the red oak borer, Enaphalodes rufulus (Haldeman), seems responsible for widespread oak mortality. The underlying reasons for this outbreak are being studied. Historically, a small portion of within-tree red oak borer mortality has been attributed to natural enemies (woodpeckers and nitidulid larvae), but the majority of mortality is from unknown factors. In four experiments, phloem sandwiches were used to observe inter- and intraspecific predation on red oak borer larvae. Our studies revealed that red oak borer was cannibalistic and that this behavior resulted in statistically significant weight gain. Observations were also made on predaceous behavior by associated insect larvae, specifically carpenterworms, elaterids, and nitidulids. We found that carpenterworms and elaterids will eat red oak borer larvae, but nitidulids exhibited no predaceous behavior. These observed behaviors may have important implications for red oak borer population dynamics because they identify potential mortality factors to red oak borer larvae.

Although adult female embiids (Order Embiidina) superficially lack morphological diversity, their variety of habitats may impose distinct selective pressures on behavior, such as their use of silk and their tendency to aggregate. For example, where silk serves as a primary defense from environmental threats, coloniality might be adaptive. The cost of production or spinning might also prompt them to share silk. These ideas were tested in laboratory trials involving three species of embiids with different lifestyles: an arboreal species (Antipaluria urichi (Saussure) from a neotropical rain forest, a species (Notoligotoma hardyi (Frederichs) that dwells on surfaces of granite outcrops in Australia, and another Australian species (Australembia incompta Ross) that stitches leaf litter together. The cost of spinning silk was analyzed by recording CO₂ output in the short term during spinning and by measuring performance in long-term trials where embiids were forced to repeatedly replace their silk. Their subsequent development or reproductive output was scored. Overall, the cost of spinning was relatively low. However, the tendencies to spin and to aggregate varied in a manner related to how silk is used in the field. As such, the more exposed the embiid is to the elements, as for the two species that spin on surfaces, the more silk they spun and the more likely they settled near a neighbor. In contrast, the embiid that used dead leaves (not silk) as walls for their abodes produced scant silk and showed little tendency to aggregate.

We evaluated the potential management of oriental beetle, Anomala orientalis (Waterhouse), in cranberry by disruption of communication between the sexes through application of the female sex pheromone deployed from wax disks in 2003 and 2004. Mean weekly catch of males in pheromone traps on each untreated bog minus that on each pheromone-treated bog was significantly greater than zero throughout the male flight period for both years of the experiment. Captures of males in traps placed on the edge of pheromone-treated bogs were intermediate between those on control and treated sites; thus, disruption may be limited a short distance from pheromone-treated plots, and treatment of surrounding areas that harbor beetles may be necessary. We deployed a limited number of tethered virgin females in the field for two nights in 2003; when returned to the laboratory, only females on control sites laid fertile eggs. In 2004, we assessed whether delayed mating occurred in the field by deploying tethered females within soil-filled pots and estimated mating rates over five nights by the presence or absence of fertile eggs within soil samples. Only one female among the treated sites laid fertile eggs, whereas the cumulative percentage of females laying fertile eggs in control sites rose steadily over five nights to 96%. The results of this study suggest the strong potential of mating disruption of oriental beetle in cranberry using retrievable, high-dose, point-source dispensers of pheromone.

Field research was conducted to describe and characterize spring emergence and seasonal flight activity of the cabbage maggot, Delia radicum L. (Diptera: Anthomyiidae), in relationship to degree-day accumulations. Turnip and rutabaga fields were monitored in the northern Willamette Valley in western Oregon from 2001 through 2004. Spring emergence from overwintering puparia was monitored using emergence cages. A bimodal spring emergence pattern was observed, with ≈70% of the spring population emerging in an early peak in late March, 2 mo before a later peak near the end of May. The mean degree-day accumulations at 10, 50, and 95% of spring emergence using a lower and upper developmental threshold of 4.3 and 30°C beginning 1 January had corresponding degree-day values of 200 ± 50.2 (8 March), 330 ± 22.2 (4 April), and 762 ± 60.1 (28 May), respectively. Seasonal flight activity was monitored using yellow water traps. Spring flight patterns mirrored the bimodal emergence patterns but with a delay of 3 d to 5 wk between emergence and detection of flies in the water traps. The mean degree-day accumulations recorded from the beginning to the end of spring flight had corresponding degree-day values of 303 ± 61.5 (31 March) to 839 ± 51.9 (4 June). Fly activity was lower over the summer from the beginning of June until the end of August (2,138 ± 82.3 DD). A fall flush of activity was observed each year beginning in late August to early September and extending through October (2,860 ± 170.6 DD).

Some currently used tree-scale sampling techniques targeting saproxylic insects capture individuals that are attracted to or landing on specific potential hosts. The success of such techniques is entirely dependent on strong primary attraction in targeted insects. However, up to this point, field experiments testing the primary attraction hypothesis have produced contradictory results. To test the efficiency of such techniques, and consequently, the strength of primary attraction for saproxylic Coleoptera, we sampled insects landing on contrasting snag types including new and old snags of five different tree species using sticky traps in a single mixed 135-yr-old boreal stand in Western Quebec, Canada. Ordination analyses showed homogenous assemblages among the different snag types and stovepipe controls, when considering either all species captured or only targeted functional groups, and very few species showed strong affinities to specific snag types. Species composition of assemblages was in several cases correlated with the species and status of trees neighboring the sampling units, which suggest that prelanding host selection mechanisms do not allow insects to single out a potential host while in flight. Our results suggest that primary attraction may play a role at larger spatial scales and help insects identify potential habitat patches, while selection of a single host at the local scale is done by trial-and-error through random landing. In such a context, future studies aiming at describing precise host-use patterns of saproxylic insects should rely on methods targeting larvae or emerging adults such as wood dissection and rearing.

Population densities of highly aggregated insect species in complex and variable habitats can be difficult to estimate efficiently, accurately, and with minimal variance. Aphis pomi DeGeer exemplifies this situation, in that its infestations typically are found near the tips of vigorously growing shoots of apple, Malus domestica Borkh, which vary in number and distribution throughout the growing season. Because A. pomi populations are permanently confined to vigorous shoots, randomly selecting shoots to sample is inefficient and unnecessarily increases the variance in population estimates. Previous workers resolved many difficulties in sampling A. pomi by recommending the use of the number of aphids on the most infested leaf as a reliable predictor for the number of aphids on the shoot. While this sampling protocol has been widely adopted, it is most applicable early in the growing season or in other unusual situations when tree vigor is high and randomly selected shoots are likely to be infested. In this paper, we confirm that the most infested leaf is still a reliable predictor for the number of aphids on a shoot throughout the growing season, even when A. pomi densities are very low. However, we also suggest that the efficiency and performance of the most infested leaf as a predictor can be improved by using preliminary sampling to determine the proportion of vigorous shoots in the orchard or block of interest and sampling for A. pomi only from those vigorous shoots.

Gaining a better understanding of the spatial variation of pests is a key to their more effective mapping to improve our knowledge of their overall population dynamics and optimize our control strategies. Geostatistical methods were used in this study to characterize spatial variability in Lobesia botrana Denis and Schiffermüller (Lepidoptera: Tortricidae) larval infestation, injury, and damage patterns in six locations over 2 yr. Regression was used to detect and separate macroscale trends from the microscale variation. The presence of macroscale variation indicated a significant edge effect with insect population moving into vineyards and ovipositing mainly along the field edges. Similarities in the patterns of spatial variability occur between the second and third generations and also between infestation, injury, and damage in all fields. The microscale variation was studied using semivariograms for all fields. Semivariograms strongly indicate that the spatial structures of L. botrana larvae were aggregated with dependency down a row of vineyards differing from that across rows of the crop, leading to anisotropy. The average range across the vine rows was consistently shorter than along rows, suggesting that migration occurs more easily down rows than across them. The anisotropic analysis further indicates that sampling programs can deploy sample locations at greater distances along the rows than across them, and interpolation algorithms that use this information may produce better map estimates. These results have implications for developing sampling plans for management of L. botrana and for site-specific agriculture.

The development of cost-effective management and sampling techniques for western flower thrips, Frankliniella occidentalis (Pergande), on garden impatiens, Impatiens wallerana (Hook. f.), requires that information about the within-plant distribution and diurnal patterns of thrips abundance be known. Impatiens flower bud development was divided into five arbitrary stages, representing tightly closed buds through fully opened flowers. Numbers of immature and adult thrips associated with these flower stages were determined at six times daily (0000, 0200, 0600, 0800, 1400, and 2000 hours). In addition, thrips distribution was determined among flowers with and without pollen, and on budless foliage, at two times daily (0800 and 0000 hours). Each successive stage of flower bud development contained significantly more adult female and immature thrips than the previous stage. The oldest flowers contained significantly fewer immature thrips than penultimate stage buds. There was no effect of sampling time on thrips density across flower bud stages. Flowers with pollen had significantly more adult female thrips compared with flowers without pollen, but numbers of adult male and immature thrips were not affected by presence of pollen. Foliage consistently contained the fewest of all life stages of thrips. There was a significant effect of time on female thrips abundance within the fully opened flower with pollen category and no effect of time on immature thrips abundance.

Early detection and precision targeting are key elements in a successful management strategy of stored product pests so that actions can be implemented while the population density is still low and controllable. The overall purpose of pheromone trapping is not to catch as many insect pests as possible, but to obtain monitoring data that provide as much information as possible about the spatio-temporal dynamics of the pest population. We placed 30 pheromone-baited traps in a grid with traps being 3–4 m apart in a relatively small trapping space with (1) no food, (2) no human activity, (3) all traps placed at the same height, and (4) no presence of Plodia interpunctella females (except when used as lures). Male moths were released from single locations, and the purposes of this study were to (1) evaluate the trapping efficiency (number of male P. interpunctella caught) when using different (Z,E)-9,12-tetradecadienyl acetate (Z9,E12–14:Oac) (ZETA) concentrations in lures, (2) release male P. interpunctella individuals from single locations and determine the relationship between pheromone-baited trap captures and distance from the release site, and (3) describe the spatial distribution pattern of pheromone-baited trap captures. The main conclusions were that (1) total trap captures of male P. interpunctella individuals were similar when deploying ZETA concentrations in lures ranging from 1 to 2,000 μg, (2) there was a significant exponential negative relationship between trap captures and distance from release sites when using live P. interpunctella females, 50 μg, or 500 μg as attractants, (3) the location of trap capture centroids was similar for trials with random and aggregated spatial distributions, (4) independently of pheromone concentration, most trap capture centroids were located within 3 m from the release site, and (5) even in a highly simplified environment, there was considerable difference in the spatial trends from three different release sites.

Plagiodera versicolora Laicharting (Coleoptera: Chrysomelidae) stops reproduction in mid-August at Ishikari, Hokkaido, Japan, despite the fact that the degree-days required for complete development predict an additional generation late in the season. We examined whether the life cycle of P. versicolora was constrained by the seasonal decline in quality of its host plant, Salix sachalinensis Fr. Schmidt (Salicaciae). P. versicolora was maintained for three successive generations throughout a season under constant laboratory conditions and fed host leaves obtained from the field site. Larval and adult performance declined in the generations that were produced later in the season. Developmental time in the last generation was significantly longer than in the first generation, although larval survivorship did not differ significantly between generations. Preoviposition periods were significantly longer and the number of eggs laid from the first oviposition to the 10th day of oviposition was significantly fewer in the last two generations compared with the first generation. In addition, reproductively inactive females that laid no eggs were significantly more frequent in the last two generations. This reproductive inactivity in female adults in late generations may be caused by diapause, which can prevent P. versicolora from producing an additional generation on poor-quality host plants. However, the physiological condition of the reproductively inactive females was different from that induced by short photoperiod in diapausing females because feeding was observed in the former females but not in the latter ones.

Field experiments were conducted in Stoneville, MS, to determine the impact of soybean planting date and maturity group on stink bug (Heteroptera: Pentatomidae) populations. Maturity group IV and V soybeans were planted on three planting dates in 2003 and 2004. Planting dates were late March-early April, late April-early May, and late May-early June. Plots were sampled weekly with a standard 38.1-cm-diameter sweep net. Planting date and maturity group each had a significant effect on stink bug populations. In general, the earliest planting date had the lowest densities of stink bugs, whereas the latest planting date had the highest densities of stink bugs. Over the 2-yr period, cumulative numbers of stink bugs (SE) ranged from 17.9 (6.25) per 25 sweeps for the first planting to 190.9 (20.03) per 25 sweeps for the third planting date when averaged across maturity groups. Additionally, stink bug populations were generally lower on maturity group IV soybeans than on maturity group V soybeans. Cumulative numbers of stink bugs on maturity group IV soybeans averaged 52.4 (26.23) and 25.2 (6.93) in 2003 and 2004, respectively. On maturity group V soybeans, cumulative numbers of stink bugs averaged 96.9 (28.05) and 85.7 (40.84) in 2003 and 2004, respectively. These data provide valuable information about the population dynamics of stink bugs and indicate that early plantings of maturity group IV soybeans in the mid-South will escape heavy stink bug densities.

Recent studies have revealed that natural enemies can influence reproductive success of plants by eliminating their herbivores, thereby reducing damage to photosynthetic or reproductive tissues. Some plant species apparently have evolved “indirect defenses” in response to such top-down selective pressures, producing volatile compounds that are used as cues by natural enemies searching for their herbivorous hosts. The research summarized in this article evaluates the potential for such top-down influences on plant fitness in an endemic prairie system and the role of plant volatiles in location of hosts by parasitoids. The study system was comprised of the prairie perennial Silphium laciniatum L. (Asteraceae), the gall wasp Antistrophus rufus Gillette (Hymenoptera: Cynipidae), and its parasitoid Eurytoma lutea Bugbee (Hymenoptera: Eurytomidae). In common garden experiments, we assessed the impact of gall wasp herbivory on growth and reproduction of S. laciniatum and the mediating influence of the parasitoid using three treatments: plants caged with gall wasps, plants caged with gall wasps and parasitoids, and control plants caged without gall wasps. Despite technical difficulties in excluding wild gall wasps and parasitoids, plants caged with gall wasps flowered later than control plants and had reduced reproductive output, producing shorter flowering stems and fewer and smaller seeds of lower viability. The parasitoid apparently “rescued” plant reproduction by killing gall wasp larvae, resulting in larger seeds that were more likely to germinate. Parasitoid females responded more strongly to volatiles produced by galled plants compared with ungalled plants in field olfactometry bioassays. This seems to be the first evidence in an endemic community of a plant species gaining a fitness advantage by producing volatile compounds that attract natural enemies of herbivorous insects.

Hairy nightshade, Solanum sarrachoides (Sendtner), is one of the preferred host plants for the green peach aphid, Myzus persicae (Sulzer), the most efficient vector of potato leafroll virus. Recent studies have also shown the ability of S. sarrachoides to act as a reservoir of potato leafroll virus. Our previous field studies have revealed a greater number of winged and wingless green peach aphids on S. sarrachoides than on adjacent potato, Solanum tuberosum (Linnaeus), plants indicating a preference for S. sarrachoides. This apparent preference for S. sarrachoides was further studied in the laboratory through a series of settling and emigration bioassays. The settling bioassays were conducted under light and dark conditions to study the influence of visual cues on green peach aphid host-plant preference. Settling bioassays with both winged and wingless green peach aphid revealed a preference for S. sarrachoides over potato and for potato leafroll virus–infected plants over noninfected plants of both species. Settling patterns of green peach aphid remained the same under both light and dark conditions, indicating that visual cues were not required for the observed response, and other cues like gustatory, tactile, and olfactory could be involved. To explore the involvement of olfactory cues on the preference of green peach aphid, emigration bioassays with wingless green peach aphid were conducted in the absence of visual, tactile, and gustatory cues. Emigration rates of wingless green peach aphid were lower from the vicinity of leaflets of S. sarrachoides than those of potato and lower from the vicinity of leaflets of potato leafroll virus–infected plants than leaflets of noninfected plants of both species. The results suggest that olfactory cues attract and/or arrest green peach aphid, thereby influencing its preference for S. sarrachoides over potato and potato leafroll virus–infected over noninfected plants.

A 3-yr study (2001–2003) was conducted to determine if the cultivation of Bt maize (Mon810, cultivar Novelis), compared with an isogenic maize line (cultivar Nobilis) with and without an insecticide treatment, has unintended effects on nontarget organisms of the arthropod community in maize fields. Furthermore, suitable monitoring organisms and appropriate methods should be selected. Maize ear samples were taken in Bt maize, an isogenic maize variety, and an isogenic maize variety with insecticide treatment. The community of arthropods was monitored and evaluated. In the first year of the study, the abundance of the mycetophagous/saprophagous beetle species Cortinicara gibbosa was significantly higher in Bt maize than in the isogenic control. These differences in arthropod communities between Bt maize and the isogenic control were not reproducible in the following years. No other significant differences in arthropod communities between Bt maize and the control were observed. Several significant differences between the insecticide-treated plots and the other treatments were detected. The abundance of the aphid Rhopalosiphum padi was significantly higher in the insecticide-treated plots than in the Bt maize or control plots over all 3 yr. The same was observed for the ladybird Coccinella septempunctata in 2003. Thrips populations were influenced negatively by the application of insecticide in 2002 and 2003. Sampling of maize ears is a suitable method in detecting changes of arthropod abundance on the community level.

Fall armyworm is a significant agricultural pest in the United States, affecting most notably sweet corn and turfgrass. Two morphologically identical strains, rice strain (R-strain) and corn strain (C-strain), exist that differ physiologically and behaviorally and can be identified by mitochondrial haplotyping. Recent studies of overwintering populations in Florida indicate that the mitochondrial lineage associated with the R-strain itself consists of two genetically distinct subgroups, with one having molecular markers consistent with interstrain hybridization between R-strain females and C-strain males. To test this possibility and examine the ramifications of interstrain mating on population behavior and strain fidelity, larvae and adult males were tested for genetic marker combinations representative of the host strains and potential hybrids. These studies showed a sexually dimorphic distribution pattern for a sex-linked marker that is a predicted result of interstrain mating. Despite evidence of substantial interbreeding in the overwintering sites, both FR and the strain-diagnostic mitochondrial markers still showed the plant host and habitat biases associated with the host strains, indicating that strain integrity was largely maintained. However, there is evidence that the two R-strain subpopulations differ in habitat distribution in a manner suggestive of the “hybrid” genotype being less specific in its plant host preference. The existence of a genetically distinct hybrid subpopulation must be taken into account when evaluating fall armyworm population dynamics and infestation patterns in overwintering areas.

We studied the phylogeography and genetic diversity of the pine sawyer Monochamus alternatus (Hope) (Coleoptera: Cerambycidae) to understand its colonization dynamics, potential for further invasion, and potential species divergence. This species is the main vector of the pine wood nematode Bursaphelenchus xylophilus (Steiner and Buhrer), which is the causative agent of pine wilt disease in Japan. The genetic structure was studied using sequences of mitochondrial DNA and microsatellites. The phylogenetic analysis revealed two distinct lineages within M. alternatus. There is no clear boundary between haplotypic distributions of the two clades. Coalescence should have been extended by population subdivision. There might also be a fusion of the two distinct populations, and both are completely saturated. Analysis of the microsatellite genotypes of populations in Japan showed a complex genetic structure. Estimates of overall population differentiation (F_ST) were significantly different from zero. The populations are thought to be at demographical nonequilibrium or to show restricted gene flow among prefectures. Although neighboring populations often had similar genetic compositions, significant isolation by distance in the total population was not detected. It is suggested that population expansion may have occurred not only by natural dispersal on a small scale, but also by long-distance dispersal likely enhanced by the relocation, (by humans) of infested wood. Our data suggest that M. alternatus is a species capable of dispersing over a large area, and therefore, multiple invasions of M. alternatus from distant areas is a possibility.