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Adults of Fannia canicularis (L.) and F. femoralis (Stein) were given a choice of poultry manure of 25, 35, 45, 55, and 65% moisture for oviposition. Adult F. canicularis laid most eggs on 55 and 65% moisture manure, whereas adults of F. femoralis laid most eggs on 65% moisture manure. Few eggs of either species were laid on manure ≤45% moisture. Larval development trials were conducted at 33, 40, 47, 52, and 56% manure moisture, noting number emerged, time required for emergence, and adult size. Neonate larvae of F. canicularis developed well at moisture levels ≥47%, some developed slowly and into smaller adults at 40%, whereas 33% moisture was lethal. Manure moisture of 40–47% depressed emergence and slowed development of neonate F. femoralis larvae. Early third instars of Fannia spp. were more resistant than neonate larvae to low moisture conditions. Some third-instar F. canicularis could survive and emerge at 33% moisture, whereas some third-instar F. femoralis could emerge at moisture levels of ≥40%. Overall, F. canicularis tended to use drier manure for oviposition and could develop in lower moisture conditions relative to F. femoralis. Implications of these moisture requirements for management are discussed.

Plant growth and yield responses to carbon dioxide (CO₂) enrichment are well established. Much less is known of the response of arthropod pests to CO₂ enrichment. Reproductive response of twospotted spider mites (Tetranychus urticae Koch) on white clover (Trifolium repens L.) to a range of CO₂ concentrations was measured. The CO₂ treatments were applied for 24 h d⁻¹ at ≈395, 484, 570, 657, and 748 μLL⁻¹ on the 14 d before and 26–27 d after infestation with mites. Eggs, larvae, nymphs, and adult mites were removed from leaves and counted 27–29 d after infestation. Leaf area and weight were measured, and leaves were analyzed to measure structural and nonstructural carbohydrates, N, amino acids and digestibility. Carbon dioxide enrichment caused linear increases in plant growth and foliar nonstructural carbohydrates, but caused linear decreases in foliar N. Carbon dioxide enrichment significantly increased the rate of mite reproduction on both clover clones. Correlations between mite population increase were significantly positive for foliar nonstructural carbohydrates and significantly negative for foliar N. Concentrations of ambient CO₂ expected in the 21st century may increase the risk of mite population damage on some plant species.

Mass trapping to control the Chinese tortrix Cydia trasias (Meyrick) by removal of males using sex pheromone traps was evaluated in three plots of Chinese scholar-trees Sophora japonica L. in Beijing, China, in 2000. The traps, baited with 0.25 mg C. trasias synthetic sex pheromone (60% E8, E10-dodecadienyl acetate (E8, E10–12:Ac) and 40% E8, E10-dodecadien-1-ol (E8, E10–12:OH), were deployed in the trapping plots at a density of one trap per two trees. The trees in all plots were planted ≈4.5 m apart along pedestrian paths. In the trapping plot on Zhichun Road, the mating rates of caged virgin females were reduced by 70.65% and 66.48% when compared with the control plots during the overwintering- and second-generation moth flight-period, respectively. Population densities of hibernating larvae on tree trunks during the third generation were significantly lower than those of the overwintered generation (the third generation of the previous year). Tunneled petioles caused by first- and second-generation larvae were reduced by 47–79% and 62–81%, respectively. Bored seed pods caused by third-generation larvae were reduced by 87–96%. Higher initial populations in the trapping plot on North Shuangyushu Road may have led to the higher observed petiole and seed pod injuries than in the other two plots during the second and third generations. Thus, male removal using sex pheromone traps is a promising means of effectively controlling C. trasias on street-planted Chinese scholar-trees.

Eggs from field-collected Glyptotendipes paripes Edwards were hatched and the immature life stages individually reared under 11 constant temperatures between 10.0 and 35.0°C (2.5°C increments) in the laboratory. No egg hatch was observed at 10.0°C for up to 30 d. At 35.0°C, egg hatch was normal but the larvae did not survive to second instar. The developmental zero growth was estimated at 9.0°C. Degree-day requirement for G. paripes development from egg to adult was estimated at 717 DD above 9.0°C. No significant difference between development time of males and females was noted and the sex ratio was near 1:1.

Studies on sub-Antarctic insects have suggested that species inhabiting the epilithic biotope (cryptogam-dominated habitats) exhibit higher habitat specificity than those species of the vegetated biotope (habitats dominated by vascular plants), and that this is partially the consequence of recolonization of the latter by migration from the former, which acted as glacial refugia during the Neogene. Here, the Acari is used to independently test this idea. To do so, 17 different habitats belonging to both the epilithic and vegetated biotopes were quantitatively sampled on sub-Antarctic Marion Island. These habitats included those on a rocky shore zone, in lowland vegetation, and in a mid-altitude fellfield. Thirty-nine morphospecies/taxa from 27 families were recorded, with a maximum abundance exceeding 300,000 individuals/m⁻². Mite assemblages differed significantly between all habitats, although the most pronounced differences were between the rocky shore, fellfield epilithic, and vegetated biotope habitats. Major differences between the rocky shore and fellfield habitats indicated that a clear distinction must be drawn between these two groups of habitats, although both were previously considered part of the epilithic biotope. It seems likely that the mite fauna of the vegetated biotope was derived mostly from fellfield habitats following deglaciation. Habitat specificity was also more pronounced in the epilithic (rocky shore and fellfield epilithic) species than in those from the vegetated biotope. Thus, the Acari provide support for the hypothesis of reduced habitat specificity in vegetated biotopes, possibly as a consequence of recent recolonization.

Insect herbivores have been assumed to be more abundant in agricultural habitats than in native habitats; however, this hypothesis is rarely tested explicitly by comparing field populations of domesticated plants and their wild ancestors. This study examined the abundance of the sunflower moth, Homoeosoma electellum (Hulst), and its parasitism by natural enemies in agricultural and native sunflower habitats. Nutrient levels and plant population factors in the two habitat types were measured to identify factors associated with the patterns of herbivory and parasitism. Adult male and larval H. electellum were consistently more abundant in agricultural habitats. In contrast, parasitism of H. electellum was 6–10 times higher in native sunflower habitats than in agricultural habitats. Also, fewer parasitoid species were found in agricultural habitats, and parasitism by individual parasitoid species was reduced by 90%. Larval densities per flower head were higher on agricultural plants, but parasitoids failed to respond to the higher densities. The relationship between flower age and larval infestation differed between agricultural and wild flowers; larval age tracked agricultural flower age, but on wild flowers, larvae moved from older to younger flowers. Among the three nutrients sampled, only nitrogen was positively correlated with habitat differences. These results indicate that patterns of trophic interactions varied by habitat type and were related to plant phenotypic changes and environmental habitat factors such as crop domestication, nitrogen fertilization, and plant phenology.

Larval population distributions of Chironomidae (Diptera), Glyptotendipes paripes Edwards in particular, were examined over a 2-yr period in two central Florida lakes (Dora and Yale), and for 1 yr in Lake Wauburg in relation to selected water and sediment physicochemical properties. The nutrient status of the study lakes varied from transitional mesotrophic/eutrophic to hypereutrophic. Glyptotendipes paripes larvae were the most common in Lake Wauburg, while Cladotanytarsus spp. were numerically the most abundant in Lakes Dora and Yale. Mean density of G. paripes in Lake Dora declined sharply during the study period to very low levels and remained low through the remainder of the investigation. Glyptotendipes paripes densities in Lake Wauburg remained high during the entire study period. Populations of G. paripes in Lake Yale generally peaked during summer and fall and decreased considerably during the winter. Estimated G. paripes annual productivity ranged widely from 0.2 g/m² (Lake Dora) to 156.9 g/m² (Lake Wauburg). Canonical correspondence analyses indicated that the primary influences on distributions of chironomid larvae in the study lakes were water depth, dry weight of sediment, and the presence of sand, muck or vegetation. Although G. paripes larval distributions tended to be associated with shallower, sandy substrates in Lakes Dora and Wauburg, these larvae were distributed over or in the muck bottom areas of Lake Yale.

We sampled phytoseiid mites (densities, diversity, and age structure) on several plants located in four uncultivated areas surrounding vineyards over 3 yr to determine how leaf structure affects populations. The plant composition of these areas greatly influenced the numbers and species of phytoseiids present. The relationships between leaf structure (trichome, pollen densities, number, and structure of domatia, leaf surface) and Kampimodromus aberrans (Oudemans) densities also were studied. The frequency of occurrence and the abundance of K. aberrans per cm² were correlated to high trichome densities. A complex phylloplane (many hairs and shelters or domatia) could confer a competitive advantage to K. aberrans over other phytoseiid mite species. The number and the rating of domatia were important to K aberrans development; high proportions of immatures were observed only on plants with these structures. Pollen densities were significantly correlated to trichome densities; domatia structure had only a somewhat lesser effect. Our study shows that dense trichome and pollen levels are favorable to the development of K. aberrans populations and add perspective on the influence of domatia on this important predaceous mite.

The effect of temperature on the duration of embryonic and nymphal development as well as on the preoviposition period of the polyphagous predator Macrolophus pygmaeus Rambur was studied in the presence and in the absence of prey on eggplant, pepper-plant, and tomato at 15, 20, 25, 27.5, 30, and 35°C, with 65 ± 5% RH and photoperiod of 16:8 (L:D) h. The aphid Myzus persicae (Sulzer) was used as prey on eggplant and pepper-plant and the whitefly Trialeurodes vaporariorum (Westwood) on tomato. The data obtained were used for the estimation of the thermal requirements of this predator. The temperature threshold for egg development was found as 7.61 and 6.92°C, for nymphal development in the presence 8.74 and 9.19°C and in the absence of prey 8.21 and 9.29°C, for preimaginal development 8.68 and 8.79°C, for preoviposition 7.58 and 6.96°C, and finally for egg-to-egg development 8.48 and 8.51°C on eggplant with M. persicae and on tomato with T. vaporariorum, respectively. On pepper-plant the temperature threshold for nymphal development was 8.26 and 8.23°C in the presence and in the absence of prey, respectively. The values of temperature threshold for development of the various nymphal stages were similar. It was also found that the slopes of the linear regressions between the rate of nymphal development and temperature were not significantly different among the different host plants in the presence and in the absence of prey. Also, the slopes of the linear regressions concerning the development of each nymphal stage with temperature were not found to differ significantly among the host plants in the presence and in the absence of prey. The thermal constant for egg development was estimated as 177 and 182, that for nymphal development in the presence 269 and 253 and in the absence of prey 332 and 306, for preimaginal development 439 and 431, for preoviposition 100 and 98 and finally that of egg-to-egg development 541 and 533 degree-days when fed on M. persicae on eggplant and on T. vaporariorum on tomato, respectively. On pepper-plant the degree-days for nymphal development was 280 and 361, in the presence and in the absence of prey, respectively. The temperature threshold for development was not found to differ among the host plants in the presence and in the absence of prey. However, the degree-days were significantly different between the presence and absence of prey on each host plant; the thermal constant in the absence of prey was estimated as an average of 1.21 times of that in the presence of prey. The results show that M. pygmaeus can establish, develop, and oviposit even in the absence of prey in relatively low temperatures and hence it can be released early in the season for an earlier and more effective control of whiteflies and aphids on vegetables.

The predation potential of small mammals, in particular mice, Peromyscus spp., and invertebrates, was evaluated from 1992 to 1995 near the leading edge of gypsy moth, Lymantria dispar (L.), spread into the southeastern United States. Two study sites were established in each of three geographic areas: the coastal plain, Piedmont, and mountains. All sites were mixed hardwood stands with varying amounts of oak, Quercus spp., and all were classified for gypsy moth susceptibility. Small mammal density was estimated using Sherman live-traps and pitfall traps within these 4.68-ha sites in early and late summer. Each site contained 75 trapping stations located on a 25-m grid. Predation was measured by offering freeze-dried gypsy moth pupae near trapping stations at four heights (0, 0.25, 1.0, and 2.0 m) on different tree boles. Pupal predation was monitored for three consecutive nights. Vertebrate predation was positively correlated with good mast production in the previous autumn. Predation data showed that when mice were at high densities they were the major source of pupal predation. However, within these southern sites, when densities of Peromyscus spp. were low, predation by invertebrates was occasionally greater than predation by vertebrates. These data suggest that in some years invertebrates may retard gypsy moth buildup when small mammals are scarce due to mast crop failures.

The population dynamics and population genetics of two bivoltine species of corn borers are modeled in a hypothetical region of irrigated transgenic and nontransgenic corn. European corn borer, Ostrinia nubilalis (Hübner), adults were assumed to disperse throughout the landscape for both mating and oviposition. Southwestern corn borer, Diatraea grandiosella Dyar, adults were assumed to have very localized dispersal behaviors. Resistance developed quickly in both species when the allele for resistance to the transgenic toxin was dominant. When the allele for resistance was not dominant and few or none of the heterozygous larvae survived the toxin, the behaviors of adult insects determined the speed of resistance development. With block refuges of 10–40% the European corn borer developed resistance within 15–38 yr, but the southwestern corn borer never developed resistance within the 100 yr simulated. A row-strip refuge configuration did not change the time for resistance to develop in the European corn borer; however, row-strip refuges cannot be recommended for the southwestern corn borer. Uncertainty about adult behaviors in irrigated corn led us to examine the potential impact of behavior on resistance development. Adult behaviors influenced resistance development more than refuge size. For instance, if the first flight of moths exhibit random mating and uniform oviposition throughout the landscape and the second flight exhibits localized mating and oviposition, resistance developed at least five times faster in the southwestern corn borer population and three times slower in the European corn borer population compared with our standard assumptions. We discuss the implications of adult behavior, refuge configuration, refuge placement within the landscape and year-to-year relocation on resistance management plans.

Egg and larval survivorship of Carposina sasakii Matsumura in fruits was investigated, and its effects on adult population dynamics was examined by comparing the seasonal adult population trends in apple and peach orchards. Egg survivorship was relatively high and did not differ among fruits, cultivars, and seasons. However, larval survivorship in fruits was very low according to fruits, cultivars, and seasons. In late apple (‘Fuji’), no larvae survived inside fruits during mid- to late June, and larval survivorship in mid-July was very low (2.0%). In early apple (‘Tsugaru’) and early peach (‘Kurakatawase’), larval survival was 18.1 and 43.7% during mid- to late June, respectively. However, in late peach (‘Hakuto’), it was much lower (4.5%). The mean numbers of degree-days between the first and the last adult flight peaks were significantly different among different orchard systems. Significantly more degree-days occurred in apple (1029.8 DD) and apple-peach adjacent orchards (939.2 DD) than in peach orchards (681.0 DD). This could have been caused by high larval mortality in apples during the early season, and a mixture of both multivoltine and univoltine components contributing to C. sasakii overall population dynamics. Implications for management of C. sasakii in diverse fruit systems are discussed.

The phenology, spatial distribution, and reproductive ecology of Anthonomus palmeri Jones & Burke and Anthonomus townsendi Jones & Burke (Anthonomus grandis species group; Coleoptera: Curculionidae) were studied over a period of 2 yr on three species of Hampea (Malvaceae: Gossypieae) in southern Mexico. These weevil species are closely related to the cotton pest Anthonomus grandis Boheman, and Hampea is the probable ancestral host of the group. The three species of Hampea studied, H. montebellensis Fryxell, H. longipes Miranda, and H. mexicana Fryxell, are small to medium sized, dioecious trees that occur in montane habitats above 500 m in elevation in the central portion of the state of Chiapas, Mexico. All three species had limited reproductive periods, with flowering beginning with the rains during June and ended during August for H. longipes and H. mexicana and mid-September for H. montebellensis. Only male flower buds were found infested with weevils. Infestation levels of male flower buds were relatively low (<30%) for all species and years except for H. longipes during 1990. During that year, >90% of the buds of H. longipes were infested. Weevil populations on each of the Hampea species had specific and distinct size preferences in the flower buds chosen for ovipostion. No flower buds were found with multiple oviposition punctures, indicating that female weevils were able to distinguish previously infested flower buds and avoided ovipositing in them. Weevils were aggregated on branches with the greatest number of buds. The ecology of the species of Anthonomus studied is compared with their close relative, the cotton boll weevil when on cotton and wild hosts, and the factors that may have lead this one species to be a pest of cotton are discussed.

Reproductive tactics of some insects are affected by photoperiod because daylength is a reliable cue indicating seasonal change in environmental suitability. We tested the hypothesis that late-season (short-day) photoperiod affects the length of the oviposition cycle of the eastern lubber grasshopper, which is from a subtropical area with a winter dry season. We predicted that oviposition would occur sooner in short-day (11.5:12.5 [L:D] h) than in long-day (13.75:10.25 [L:D] h) individuals, and that costs associated with earlier oviposition would be expressed as smaller eggs or fewer eggs per female under the short-day photoperiod. Two diets (low and high food quantity) were tested at each photoperiod. Although MANOVA yielded no significant main effect of photoperiod on the timing of oviposition, number of eggs, and mean egg dry mass, there was a significant multivariate interaction between photoperiod and food for these variables. In the low food treatment, the short-day animals produced fewer, smaller eggs than did the long-day animals, but this multivariate difference between short-day and long-day animals was absent in the high-food treatment. Photoperiod and its interaction with food did not affect timing of oviposition in either multivariate or univariate analyses. The absence of the predicted change in timing of reproduction in an autumn photoperiod suggests that seasonal constraints on reproduction do not exert a strong influence on reproductive timing of this population. Our alternative hypothesis is that the combination of short days and low food availability serve as a cue to lubber grasshoppers of an oncoming dry season with potentially limiting food, and that they respond to this cue by reducing the mass of reproductive output but not by accelerating reproductive timing. Thus, we propose that these subtropical grasshoppers adjust reproductive investment in response to seasonal changes in resource availability.

We studied pupal diapause maintenance and termination in Endopiza viteana, a pest of commercially grown grapes. We observed considerable variation in diapause intensity, which ranged from 5.5 to 10 mo under natural temperatures and photoperiods. Adult males tended to emerge from diapause slightly earlier than females, suggesting that E. viteana may be protandrous. In the field, low temperatures maintained diapause in overwintering pupae, and adult emergence began at ≈148 degree-days accumulated from 1 January. Photoperiod did not influence diapause termination in E. viteana. Overall, most adults emerged in spring at roughly the same time, regardless of the date at which pupae entered diapause; however, emergence was extended over a 6-wk period. Moreover, eggs oviposited by late-emerging females may experience photoperiods that would lead to diapause in pupae. Under natural conditions, extended adult emergence may result in overlapping generations; accordingly, coordinating the timing of control tactics with peak oviposition is very difficult for this insect pest.

This study addressed whether prior damage to black mustard, Brassica nigra (L.) Koch, would reduce growth, herbivory, or mortality of two specialist herbivores on new leaves. Plants received either no initial damage or 12 h of feeding by two third instars of Pieris rapae (L.) or 50 adult Phyllotreta cruciferae (Goeze) when plants had four leaves. Later, the seventh leaf of plants was either harvested for measurement of trichome density and glucosinolate concentration or enclosed in a mesh cage containing two neonate P. rapae or 10 adult P. cruciferae. Caged herbivores were measured for mass gain, leaf consumption, and mortality after 1 wk. Damage by P. rapae caused substantial increases in trichome density and sinigrin concentration, whereas damage by P. cruciferae had no effect. Larvae of P. rapae grew 30% more slowly on plants initially damaged by conspecifics than on control plants. Percent herbivory by P. rapae was 33% lower on plants initially damaged by either P. rapae or P. cruciferae than on control plants. Growth rate and percent herbivory by P. cruciferae were not generally affected by prior plant damage. However, mortality of P. cruciferae was 84% higher on plants previously damaged by conspecifics than on control plants. Together, the data demonstrate that induction responses negatively affected both Pieris and Phyllotreta and suggest that trichomes may be relatively important in the increased resistance. Test herbivores generally performed similarly on plants damaged by either herbivore, suggesting a low specificity of effect for the induction response.

Under controlled conditions we exposed eggs of 17 potential host taxa representing five orders and 14 families to females of Trichogramma platneri Nagarkatti, an egg parasitoid used as an inundative biological control agent against codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae). Trichogramma platneri successfully parasitized species from five lepidopteran families (Gelechiidae, Noctuidae, Pyralidae, Sphingidae, Tortricidae) and the green lacewing, Chrysoperla carnea Stephens (Neuroptera: Chrysopidae). Female wasps spent more time on heavier host eggs and the probability of successful parasitism was related to the structural integrity of the chorion of the host egg. We observed oviposition attempts on all other lepidopteran hosts offered and on eggs of Geocoris punctipes Say (Hemiptera: Lygaeidae) and Nezara viridula L. (Hemiptera: Pentatomidae). Dipteran and coleopteran eggs were not attacked. Sentinel eggs of the six physiologically acceptable hosts were exposed in a walnut orchard in California during inundative releases of T. platneri and all hosts were attacked equally. Parasitoids were also equally active at all heights from 1.5 to 6.5 m within the orchard canopy. Inundative releases of T. platneri may impact naturally occurring populations of green lacewings within walnut orchards, and have the potential to impact nontarget lepidopteran populations within the release area.

Tachinaephagus zealandicus Ashmead is a gregarious endoparasitoid that attacks third instars of muscoid flies, including house flies, Musca domestica L. A colony of this parasitoid was established from samples collected from a poultry farm in Santa Cruz da Conceição, São Paulo, Brazil. The objective of this study was to evaluate the influence of feeding treatment, host density and temperature on attack rates on T. zealandicus. Parasitoids that were given honey as adults attacked two to three times as many house fly larvae (25 host attacks/female/d) as parasitoids that were given only water or nothing. Host attacks and progeny production by T. zealandicus on house fly and Chrysomyia putoria increased over the range of host:parasitoid ratios tested, reaching a maximum of 21–22 hosts killed and 13 progeny produced/female/d at the highest host density of 32 larvae/female. Host attacks were higher at 22°C than at the other temperatures studied (20–29°C), but differences in attack rates were small over the range of 20–27°C (10–13 host attacks/female). Comparatively few hosts (6.3) were attacked at 29°C. Higher rates of progeny production also were observed among parasitoids tested at lower temperatures (9–11 progeny produced/female at 20–22°C) than at 29°C (1.8 progeny/female). Females of T. zealandicus that were stored at 15°C after emergence had highest rates of host attacks (58–62 hosts killed per group of five female parasitoids) and progeny production (174–261 progeny) after 6–12 d of storage at this temperature; relatively few hosts were attacked or parasitized (6–9 host attacks and progeny/group) after 0 or 1 d at 15°C.

Emergence patterns and cold tolerance of adult Bathyplectes curculionis (Thomson) were studied in relation to weather conditions that are typical during fall and winter in the Southern Great Plains. Laboratory studies were conducted to confirm that daylength and environmental temperatures prevailing during fall and winter are conducive to termination of diapause, pupal development, and emergence of B. curculionis adults. Mean Julian dates for first detection of the parasite in larvae of Hypera postica (Gyllenhal) were 69 and 72 for two field research sites in Oklahoma. These dates indicate that adults of B. curculionis emerge during winter and are frequently subjected to freezing temperatures as they begin parasitizing the first larvae of H. postica to infest alfalfa, Medicago sativa L., each year. Both laboratory and field studies demonstrate that >80% of adult parasites can survive repeated exposures to daily low temperatures ranging from 0 to −9°C. This level of cold tolerance indicates that the adults can survive during February and March when mean low temperatures are −1 and 3°C, respectively, in central Oklahoma. Although some adults of B. curculionis do emerge during fall and winter in the Southern Great Plains when there are no hosts available, this potential disadvantage to effective biological control is offset somewhat by the cold tolerance of adults, which allows survival during late winter and spring when they parasitize the first larvae of H. postica to infest alfalfa annually.

The red imported fire ant, Solenopsis invicta Buren, is an important pest in the southern United States, in part because few natural enemies exist. Beauveria bassiana is an entomopathogenic fungus that holds great promise as a biological control agent against S. invicta. In previous studies, B. bassiana was effective in laboratory trials, but field applications were less effective. In the current study, we compared the efficacy of different application methods of B. bassiana mycelia encapsulated in alginate pellets against S. invicta in heavily infested areas. Direct insertion of pellets into S. invicta mounds caused some reduction in activity rating. However, observations of ants removing pellets from mounds shortly after insertion led to the development of a bait system to encourage pellet retention in the mounds. Broadcast applications and individual mound treatments of B. bassiana alginate pellets coated with peanut oil reduced activity ratings of S. invicta populations.