The effect of temperature on the development of the predators Nephus includens (Kirsch) and Nephus bisignatus (Boheman) (Coleoptera: Coccinellidae) was studied. The duration of the development of immature stages and the pre-oviposition period of the two predators, reared on Planococcus citri (Risso) (Homoptera: Pseudococcidae) at eight constant temperatures (10, 15, 20, 25, 30, 32.5, 35, and 37.5 ± 1°C), have been recorded. The developmental zero (lower temperature threshold) was estimated to be 10.9 and 9.4°C, and the thermal constant was 490.5 and 614.3 DD for N. includens and N. bisignatus, respectively, using the linear model. Data were fitted to various nonlinear temperature-dependent models, and the thermal developmental thresholds (lower and upper), as well as the optimum temperature for development, have been estimated. Evaluation of the models took place, based on the following criteria: fit to data (residual sum of squares and coefficient of determination or coefficient of nonlinear regression), number and biological value of the fitted coefficients, number of measurable parameters, and accuracy on the estimation of the thresholds. Conclusively, linear and Lactin models are highly recommended for the description of temperature-dependent development of these two predators and possibly of other coccinellids.

Hexyl butyrate and (E)-2-hexenyl butyrate, common metathoracic scent gland compounds of plant bugs (Heteroptera: Miridae), attracted large numbers of female chloropid [Olcella trigramma (Loew), O. cinerea, Conioscinella sp.] and milichiid (Leptometopa latipes Meigen) flies. Blends of these two butyrates attracted significantly more chloropids than did the compounds individually. The optimal synergistic ratios for O. trigramma attraction ranged from 1:1–9:1 hexyl butyrate to hexenyl butyrate. These values are similar to natural ratios of the compounds in the scent gland secretion from tarnished plant bugs, Lygus lineolaris, and other mirids. Antennae of female O. trigramma gave strong electrophysiological responses to (E)-2-hexenyl and hexyl butyrates, whereas electroantennogram responses to butyl butyrate and pentyl butyrate were insignificant. (E)-2-octenyl acetate, one of the major sex pheromone components of mirids in the genus Phytocoris, was strongly attractive to the milichiid, L. latipes, and another pheromone component of Phytocoris bugs, hexyl acetate, was inactive alone, yet synergized the attraction of the milichiid and three chloropid species to (E)-2-octenyl acetate. Traps baited with (E)-2-hexenyl (E)-2-hexenoate, a volatile component of various heteropterans, were significantly attractive to both O. cinerea and L. latipes, whereas addition of γ-caprolactone and green leaf alcohols significantly reduced the numbers of both fly species caught. Our results suggest that females of these chloropid and milichiid flies use volatile defensive and pheromonal compounds from plant bugs as kairomones to find freshly injured or dead bugs on which to feed. The sex-specific attraction might indicate that females of these flies need a protein-rich meal for maximum fecundity, as do anautogenous mosquitoes.

The biology of the willow bark beetle, Trypophloeus striatulus (Mannerheim) was studied in its primary host, Salix alaxensis (Andersson) Coville, at 28 locations in Alaska, and in the laboratory. Most broods transformed to adults before fall, emerged, and excavated solitary chambers in the bark, where they passed over-winter before becoming sexually mature in spring. Emerged adults walked on the bark for protracted periods, lacking any disposition to fly. This behavior contributes to reinfesting the stem, downward for several generations, thereby conserving a susceptible host (limited resource). A fungus, Cytospora sp., most likely chrysosperma (Person) Fries, was present in stems infested by the beetles. Adults usually chose a lenticel as a site for excavating a chamber, tapping the surface with their antennae, and were possibly attracted there by odor emitted by fungus-infected, underlying tissue. Egg galleries are cavelike. Eggs are exceptionally large relative to the adult, and are laid in a cluster averaging ≈20 per female. Larvae pass through three instars, feeding en masse in the first instar, then becoming solitary. Their mines contain almost entirely excrement, lacking fragments of phloem common in galleries of most bark beetles. Pupation occurs in a cell, excavated by the larva, which usually etches the xylem. A bird preys on over-wintering larvae; otherwise the beetle has few natural enemies. An unidentified endoparasitic nematode occurs in the hemocoele of adults. Commensals in galleries include several undescribed mites, and maggots of the dipterous family Sepsidae. The ecology of feltleaf willow and population dynamics of the beetle are discussed.

Efforts to describe the complex relationships between bark beetles and the ophiostomatoid (stain) fungi they transport have largely resulted in a dichotomous classification. These symbioses have been viewed as either mutualistic (i.e., fungi help bark beetles colonize living trees by overcoming tree defenses or by providing nutrients after colonization in return for transport to a host) or antagonistic (i.e., fungi compete for a limited resource and reduce brood development with no apparent benefit to the beetle). We investigated several components of one beetle–fungus interaction. Specifically, we addressed whether beetle entry into, and development within, a host tree vary with the degree of colonization by ophiostomatoid fungi. Ips pini (Say) transports several species of ophiostomatoid fungi, the most common being Ophiostoma ips (Rumbold) Nannfeldt, in the process of colonizing its host, Pinus resinosa Aitman. We introduced this fungus 0, 3, 7, and 10 d before beetle entry to characterize its effects on I. pini colonization and development. This sequence allowed quantification of temporal effects and comparison of results with other systems. Fungal growth was greatest when inoculated before beetle colonization. Fungal colonization reduced beetle entry into logs, but increased brood production. Mate capture was not significantly affected by fungal growth. The benefits imparted by O. ips to its beetle vector during brood development are compared with results from other systems. This difference may in part be related to the exploitation of highly stressed and dead trees, rather than vigorous hosts, by I. pini.

We used two types of laboratory apparatus to test whether rotation-resistant and wild-type Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) responded differently to corn phenology. Beetles from Nebraska where injury to rotated corn has not been reported were defined as wild type, and beetles from Illinois where injury to rotated corn is common represented “rotation-resistant” populations. A two-chamber emigration arena assayed propensity of both populations to leave corn during and after anthesis. A side-arm olfactometer tested whether the relative attraction of beetles to soybean versus corn was influenced by corn phenology. Beetle origin did not influence departure from corn of varying phenology; both emigrated significantly less from young (shedding pollen) than old (no pollen) corn. Significantly more beetles entered olfactometer chambers with soybean than empty control chambers, but there was no difference in response between the two populations. Numbers of beetles entering chambers with soybean varied with the addition of young versus old corn. Replacing young with old corn approximately doubled the percentage of beetles not selecting corn. As corn aged, adult visitation of soybean increased significantly. We suggest this mechanism is sufficient to explain injury to rotated corn, when linked to a corn crop planted early and synchronously within a landscape limited to corn and soybean. This explanation based on preexisting behavioral plasticity should be given due consideration along with conceptual models of D. v. virgifera rotation resistance that imply genetic change.

Dung beetle (Coleoptera: Geotrupidae, Scarabaeidae) assemblages were monitored by dung-baited pitfall trapping at three sites distributed along a bioclimatic gradient from semiarid to mesic temperate. For each type of dung, both small and large sized baits were used. Under semiarid conditions (Morocco), three dung beetle assemblages were distinguished: small bait assemblages in any dung; large cattle bait assemblages; large sheep bait assemblages. Under more temperate conditions (southern France and the Alps), only large and small bait assemblages were observed, whatever the origin of the dung. Large baits attracted significantly more species and more beetles than did small baits, and very few species were attracted significantly more by either sheep or goat baits than by cattle baits. A significant, positive correlation between dung beetle size and dung pat size was observed in Morocco where the large species are predominant, whereas a negative relationship was observed in southern France where the small species are predominant. Cattle pats were more attractive for beetles under xeric and Mediterranean conditions (Morocco and southern France) that under cold temperate conditions (Alps).

A new Helicosporidium spp. isolate recently purified from an aquatic weevil, Cyrtobagus salviniae Calder & Sands, was capable of infecting and reproducing in three heterologous noctuid hosts. Regardless of host species, oral treatment of Heliocoverpa zea (Boddie), Spodoptera exigua (Hübner), or Trichoplusia ni (Hübner) early instars with cyst preparations of Helicosporidium spp. resulted in ≈50% infection of the challenged larvae. The sex ratio did not differ between infected and control groups, suggesting the existence of a natural, nonsex-related resistance to the disease. Injection of Helicosporidium spp. into the hemocoels of late instars resulted in virtually 100% infection, indicating that resistance is related to the ingestion of the pathogen and therefore affiliated with midgut-mediated barriers. The pathogen’s development was not interrupted by metamorphosis; likewise, the infection did not necessarily interrupt the insects’ development. When treated as early instars, 50–90% of the infected larvae formed pupae, of which 20–30% emerged as adults. However, a high proportion of the infected adults (62–86%) had malformed wings, and their longevity was reduced compared with that of healthy adults. Infected S. exigua adults that seemed to be morphologically healthy were able to mate and produce viable offspring. The disease was detected in five of 12 groups of progeny produced by infected adults. However, the relative infection rate in the filial generation was low (2–5%). To our knowledge, this is the first evidence for a vertical transmission of helicosporidial infection.

Three field experiments using cages were conducted in Anhui, China, to test the efficacy of entomopathogenic fungi against adult Asian longhorned beetles, Anoplophora glabripennis (Motschulsky). The use of two commercially available Beauveria spp. strains, Beauveria bassiana (Balsamo) Vuillemin and Beauveria brongniartii (Saccardo) Petch, applied as cultures in fiber bands fastened around tree trunks, was compared with trunk sprays in the first cage experiment. Longevity of A. glabripennis was decreased by both strains compared with controls, with females killed earlier by B. brongniartii than by B. bassiana. This decrease in longevity was independent of the application method used. In addition, oviposition scars per cage and daily oviposition rate per female were also reduced by both strains, showing a sublethal effect of the entomopathogens. After 10 d, conidial viability was still high on the bands but was drastically reduced when the strains were sprayed onto tree trunks. In the second cage experiment, four strains, proven to be highly pathogenic in the laboratory, were applied as bands alone. During the second cage experiment, daily temperatures were much higher and relative humidities were much lower than during the first cage experiment, and these conditions probably reduced fungal pathogenicity and decreased the sublethal oviposition reduction effect. It was demonstrated that one other B. bassiana strain and one Metarhizium anisopliae (Metchnikoff) Sorokin strain reduced male A. glabripennis longevity. None of the four strains tested had any significant effect on A. glabripennis when applied as 15-d-old bands in a third field experiment.

The sawtoothed grain beetle, Oryzaephilus surinamensis (L.), is an important pest of packaged consumer foods, yet little is known of its behavioral response to food odors. Adults and larvae are not believed to chew holes through packaging materials, but they may invade packaged food by entering through openings caused by improper sealing or handling, through holes intentionally placed in packages by the manufacturer, or through openings made by insects or other organisms. To better understand the mechanism of infestation of packaged foods by the sawtoothed grain beetle, we determined how food odor coming through the surface and through holes in consumer food packaging materials influences female sawtoothed grain beetle movement. Mated female beetles responded with an area-concentrated search to the odor of dog food emitted from 0.5-mm-diameter holes punctured in two commonly used food packaging materials (Cello and 120 AB-X). Holes emitting no food odor did not influence beetle behavior. Velocity and distance moved differed between film types, perhaps because of surface characteristics of the film influencing traction, but no influence of food odors coming through the films was detected. This study indicates the necessity for improved package designs and better sealing and handling methods to prevent flaws in packaging through which insects may enter.

Chromatic and achromatic plant cues are expected to be particularly important for parasitoids of endophytic pupal hosts, because these stages do not feed and therefore avoid volatile emission caused by plant tissue damage. Endophytic feeding can cause discoloration or desiccation, leading to changes in color and/or brightness of infested plant parts that may be visually detected by parasitoids. The role of color cues in the host-finding behavior of parasitoids is poorly understood, and the visual system of most parasitoid species has not yet been investigated. We studied color discrimination ability and innate color preferences in the pupal parasitoid Pimpla turionellae (L.) (Hymenoptera: Ichneumonidae) during location of concealed hosts. Responses to combinations of yellow and blue bands of different reflectance intensities were investigated on cylindrical models of plant stems. The parasitoid’s reaction to these chromatic cues was evaluated by scoring the number of ovipositor insertions into the colored bands. Female parasitoids discriminated blue from yellow irrespective of total reflectance and inserted their ovipositors significantly more often into the blue area. True color vision is demonstrated for the examined species, and responses to chromatic cues are discussed in relation to their importance for host location in parasitoids. Results of this study and of our previous work suggest that P. turionellae uses contrasts (chromatic or achromatic) rather than specific color characteristics in visual host location.

California’s viticulture and ornamental industries have suffered significant losses since the introduction of Homalodisca coagulata (Say), an important vector of the Pierce’s disease bacterium. A better understanding of the factors that influence the dispersal of H. coagulata, as well as other native sharpshooters could enhance our ability to institute areawide management programs. Studies were conducted to establish the validity of an immunoglobulin G (IgG) protein marker for sharpshooter dispersal studies, to compare the dispersal of H. coagulata with that of a native sharpshooter Homalodisca liturata Ball, and to develop a better understanding of the factors that influence their dispersal. Field trials showed that the marker remained detectable for at least 19 d and did not affect sharpshooter survival. Four concentrations (0.04, 0.2, 1, and 5 mg/ml) and two different IgG markers (chicken and rabbit) were effective for marking sharpshooters. In mass-mark-recapture studies, ≈95% of the marked insects flew during the releases and the timing of flight initiation was similar for H. coagulata and H. liturata. Mean wind speeds >3 m s⁻¹ were associated with a decline in flight initiation for both species. Most sharpshooters were trapped at heights below 4.2 m, and based on sex ratio comparisons, traps were equally attractive to males and females. Regression analyses of recapture data and a diffusion model were used to assess and compare sharpshooter dispersal. The majority (95%) of H. coagulata and H. liturata were recaptured within 90 and 155 m of the release site, respectively.

The carpenter bee, Xylocopa virginica (L.), acts as a primary nectar thief in southeastern plantations of native rabbiteye blueberry, Vaccinium ashei Reade, perforating corollae laterally to imbibe nectar. Honey bees, Apis mellifera L., learn to collect nectar from these perforations and thus become secondary thieves. We conducted a 2-yr study to assess how nectar robbing in honey bees affects fruit production in rabbiteye blueberry. Various harvest parameters were measured from fruit collected from plants tented with honey bees and carpenter bees (AX), carpenter bees (X), honey bees (A), no bees (0), or in open plots (open). In open plots, rates of illegitimate honey bee flower visitation increase from initial lows to fixation at ≥95%. Fruit set is higher in open, A, and AX plots than in X and 0 plots. Even though fruit set is similar in A and AX plots, seed numbers are significantly reduced in AX plots in which X. virginica-induced illegitimate honey bee flower visitation approaches 40%. Open-pollinated berries were larger than berries from all other treatments in 2001, whereas in 2002 berry weight followed the pattern A > open > AX > (X ≈ 0). Sucrose content of juice and speed of ripening were unaffected by treatments.