Insect association with fungi has a long history. Theories dealing with the evolution of insect herbivory indicate that insects used microbes including fungi as their principal food materials before flowering plants evolved. Subtlety and the level of intricacy in the interactions between insects and fungi indicate symbiosis as the predominant ecological pattern. The nature of the symbiotic interaction that occurs between two organisms (the insect and the fungus), may be either mutualistic or parasitic, or between these two extremes. However, the triangular relationship involving three organisms, viz., an insect, a fungus, and a vascular plant is a relationship that is more complicated than what can be described as either mutualism or parasitism, and may represent facets of both. Recent research has revealed such a complex relationship in the vertically transmitted type-I endophytes living within agriculturally important grasses and the pestiferous insects that attack them. The intricacy of the association depends on the endophytic fungus—grass association and the insect present. Secondary compounds produced in the endophytic fungus—grass association can provide grasses with resistance to herbivores resulting in mutualistic relationship between the fungus and the plant that has negative consequences for herbivorous insects. The horizontally transmitted nongrass type-II endophytes are far less well studied and as such their ecological roles are not fully understood. This forum article explores the intricacy of dependence in such complex triangular relationships drawing from well-established examples from the fungi that live as endophytes in vascular plants and how they impact on the biology and evolution of free-living as well as concealed (e.g., gall-inducing, gall-inhabiting) insects. Recent developments with the inoculation of strains of type-I fungal endophytes into grasses and their commercialization are discussed, along with the possible roles the endophytic fungi play in the galls induced by the Cecidomyiidae (Diptera).

As part of a biological control program against Spartina alterniflora Loisel. (smooth cordgrass), we simultaneously released populations of the planthopper Prokelisia marginata (van Duzee) from four geographic areas in each of five replicate field sites in the Willapa Bay estuary in Washington State. The four sources (California, Georgia, Virginia, and Rhode Island) have varying climate and seasonal regimes. We expected local adaptations would affect performance in the new environment. Using vacuum sampling, we measured population densities in spring and fall for 2 yr after release. In addition, we measured the timing of spring emergence through bi-weekly surveys of the number of nymphs residing in overwintering sites (curled leaves of senesced Spartina culms) versus on live green shoots. The observed sequence of emergence GA>CA>VA>RI was consistent with the hypothesis that this insect responds to a photoperiod cue for emergence timing. The four populations also differed in their reproductive capacity as measured by the increase in population densities over the summer months. Overall, the California and Rhode Island populations had higher population growth than those from Virginia and Georgia. Our results suggest that the climate and seasonal adaptations of biocontrol agents should be carefully considered as they can affect the performance and phenology in the new range. At the same time, it is noteworthy that all four populations were capable of establishing and growing, indicating a degree of resiliency for populations experiencing a rapid change in climate.

The blueberry gall midge, Dasineura oxycoccana Johnson, is a serious pest of rabbiteye blueberries in Florida, Georgia, and Mississippi, and a potential pest of southern and northern highbush blueberries. Its damage has been observed with increasing frequency in highbush blueberry plantings in the Great Lakes region, including in Wisconsin and in Michigan. Unlike in rabbiteye blueberry plantings, where blueberry gall midge primarily damages flowering buds, it is found to damage only the vegetative shoots of northern highbush blueberry. In this study, farms throughout Michigan were surveyed for the presence of blueberry gall midge and it was found in 43 of 46 sampled farms in 11 counties. From 2009–2011, several monitoring techniques, including yellow sticky traps, emergence traps, observational sampling, and vegetative shoot dissections were used to determine the ecology of this species in blueberry fields in southwest Michigan. Emergence traps were most useful in early detection of blueberry gall midge in April, and observational sampling for damage symptoms and vegetative shoot dissections revealed multiple population peaks throughout July and August. Infestation was detected in vegetative shoot tips in all parts of the bushes, with initial infestation greatest at the base of bushes. Degree day accumulations until first midge detection and peak infestation suggest some potential for predicting key events in the pest's phenology. This information about the distribution and timing of infestation will be useful in developing management strategies for blueberry gall midge infestation.

The complex interplay between species along environmental gradients ultimately shapes their distributions and additional community interactions. Ant-mediated seed dispersal fails in the wettest habitat of deciduous forest in eastern North America, and we examine whether this pattern corresponds with colony distributions for seed-dispersing ants and associated heterogeneity in abiotic and biotic variables. Specifically, we used spatial variation in soil moisture, temperature and diffuse light along natural habitat gradients and experimentally manipulated soil moisture gradients to examine ant habitat selection. We also examined niche segregation between effective (Aphaenogaster spp.) and ineffective (Lasius alienus Foerster) seed-dispersing ants across these environmental gradients. Whereas most research links ant foraging and nesting with temperature gradients, we find niche segregation between Aphaenogaster spp. and L. alienus by soil moisture along naturally occurring gradients and in experimentally irrigated upland habitat. The failure of Aphaenogaster spp. to occupy the wettest habitats, where L. alienus is present, is consistent with observed seed dispersal failure in these habitats. These results indicate that environmental heterogeneity drives niche segregation between effective (Aphaenogaster spp.) and ineffective (L. alienus) seed dispersers so each occupies distinct habitat. Most forest understory plants rely on ants for seed dispersal. Our research implies that climate-mediated interactions between effective and ineffective seed dispersing ant species may structure the microhabitat distributions for woodland herbs.

Wolbachia spp. are obligate intracellular bacteria present in reproductive tissues of many arthropod species. Wolbachia infection status and roles in host reproduction were studied in the rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera, Curculionidae), an introduced species in China. We examined Wolbachia infection status in five populations in China where it reproduces parthenogenetically, and one native population in Southeast Texas, where it reproduces bisexually. All populations were infected by Wolbachia, and all specimens in each population were infected by Wolbachia of a single strain. Phylogenetic analyses based on multilocus sequence typing system indicated that Wolbachia in non-native L. oryzophilus weevils diverges evidently from those in native weevils. After treatments with tetracycline, parthenogenetic weevils reduced the fecundity significantly and eggs were not viable. Our results suggest that Wolbachia are necessary for oocyte production in L oryzophilus.

In the low nutrient environment of conifer bark, subcortical beetles often carry symbiotic fungi that concentrate nutrients in host tissues. Although bark beetles are known to benefit from these symbioses, whether this is because they survive better in nutrient-rich phloem is unknown. After manipulating phloem nutrition by fertilizing lodgepole pine trees (Pinus contorta Douglas var. latifolia), we found bolts from fertilized trees to contain more living individuals, and especially more pupae and teneral adults than bolts from unfertilized trees at our southern site. At our northern site, we found that a larger proportion of mountain pine beetle (Dendroctonus ponderosae Hopkins) larvae built pupal chambers in bolts from fertilized trees than in bolts from unfertilized trees. The symbiotic fungi of the mountain pine beetle also responded to fertilization. Two mutualistic fungi of bark beetles, Grosmannia clavigera (Rob.-Jeffr. & R. W. Davidson) Zipfel, Z. W. de Beer, & M. J. Wingf. and Leptographium longiclavatum Lee, S., J. J. Kim, & C. Breuil, doubled the nitrogen concentrations near the point of infection in the phloem of fertilized trees. These fungi were less capable of concentrating nitrogen in unfertilized trees. Thus, the fungal symbionts of mountain pine beetle enhance phloem nutrition and likely mediate the beneficial effects of fertilization on the survival and development of mountain pine beetle larvae.

Orius insidiosus (Say) and O. pumilio (Champion) were confirmed to be sympatric in north central Florida as the major predators of the Florida flower thrips, Frankliniella bispinosa (Morgan), on flowers of Queen Anne's lace, Daucus carota L. and false Queen Anne's lace, Ammi majus L. F. bispinosa was the predominant thrips observed on both flowers but colonized D. carota to a greater extent and earlier in the season than A. majus. Despite differences in the abundance of F. bispinosa on the two plants, neither Orius species showed host plant affinities. Population profiles for the thrips and Orius spp. followed a density dependent response of prey to predator with a large initial prey population followed by a rapid decline as the predator populations increased. The temporal increases in Orius spp. populations during the flowering season suggest that they were based on reproductive activity. As observed in a previous study, O. insidiosus had a larger population than O. pumilio and also had a predominantly male population on the flowers. By examining carcasses of the prey, there appeared to be no sexual preference of the thrips as prey by the Orius spp. as the prey pattern followed the demographics of the thrips sex ratio. Few immatures of either thrips or Orius spp. were observed on D. carota or A. majus, which suggests that oviposition and nymphal development occurred elsewhere. Based on these findings, D. carota and A. majus could serve as a banker plant system for Orius spp.

The parasitoid Psyttalia humilis (Silvestri) was reared on Mediterranean fruit fly, Ceratitis capitata (Wiedemann), third instars irradiated at 0–70 Gy at the USDA, APHIS, PPQ, Moscamed biological control laboratory in San Miguel Petapa, Guatemala, and shipped to the USDA, ARS, Parlier, CA. Irradiation dose did not affect the parasitoid's offspring sex ratio (53–62% females), percentage of unemerged adults (12–34%), number of progeny produced per female (1.4–1.8), and parasitism (19–24%). Host irradiation dose had no significant effect on the forewing length of female P. humilis and its parasitism on olive fruit fly, Bactrocera oleae (Rossi) and offspring sex ratio, but dissection of 1-wk-old female parasitoids reared from hosts irradiated with 70 Gy had a significantly lower number of mature eggs than females from nonirradiated hosts. Longevity of P. humilis adults decreased with increased temperature from 15 to 35°C, regardless of food provisions, gender, and host irradiation dose. Females survived 37–49 d at 15°C with water and food, and only 1–2 d at 35°C without food, whereas males lived shorter than females at all temperatures and food combinations tested. Adult P. humilis reared from fertile C. capitata and aspirated for dispensing in cups lived significantly longer after shipment than those specimens chilled and dispensed by weight. At 21 and 32°C, 50% of parasitoids departed release cages after 180 and 30 min, respectively, but none departed at 12°C. Thirteen shipments of P. humilis (2,980–21,922 parasitoids per shipment) were received between September and December 2009, and seven shipments (7,502–22,560 parasitoids per shipment) were received between October and December 2010 from San Miguel Petapa, Guatemala. Daily number of olive fruit fly adult and percentage female trap captures ranged <1–19 and 8–58% in 2009, and <1–11 and 0–42% in 2010, respectively. The number of parasitoids released ranged 848–12,257 in 2009 and 3,675–11,154 in 2010. Percentage parasitism of olive fruit fly third instars at all locations ranged 0–9% in 2009 and 0–36% in 2010.

We find that spatial structure, and in particular, differences in gross plant morphology, can alter the consumption rates of generalist insect predators. We compared Asian lady beetle, Harmonia axyridis Pallas, and green lacewing larvae, Chrysoperla carnea Stephens, consumption rates of pea aphids, Acyrthosiphon pisum Harris, in homogeneous environments (petri dishes) and heterogeneous environments (whole plants). Spatial complexity is often described as reducing predator success, and we did find that predators consumed significantly more aphids on leaf tissue in petri dishes than on whole plants with the same surface area. However, subtle differences in plant morphology may have more unexpected effects. A comparison of consumption rates on four different isogenic pea morphs (Pisum sativum L.) controlled for surface area indicated that both lady beetles and lacewings were more successful on morphologies that were highly branched. We speculate that predators move more easily over highly branched plants because there are more edges to grasp.

Plant morphology influences insect predators' abilities to capture prey and control pest populations. Several mechanisms for this effect of plants on predator foraging have been proposed. In particular, it is often claimed that increased complexity of plant structures may increase search time and reduce foraging success. Using time-lapse photography we recorded search paths, and compared the total path lengths, percentages of plants searched, and path tortuosity of adult multicolored Asian lady beetles (Harmonia axyridis Pallas) and green lacewing larvae (Chrysoperla carnea Stephens) foraging for pea aphids (Acyrthosiphon pisum Harris) on pea near-isolines (Pisum sativum L.) that differed in shape. We found that H. axyridis searched leafy morphologies less thoroughly than those with more branches, while C. carnea larvae search paths did not differ on any of the pea morphologies. In addition, the ability of H. axyridis to attach to plants and maneuver was increased on morphologies with many branches and edges, while C. carnea was able to attach to all morphologies. Both species, however, had significantly reduced predation success on inverted leaf surfaces. We conclude that undersides of leaves, far from the leaf margin, may serve as partial prey refugia. In addition, we find increased plant branching or an increase in other morphological features which provide predator attachment points may promote foraging success.

Herbivores can alter plant physiology through the induction of abnormal wood formation. Feeding by some insects induces the formation of false rings, a band of thick-walled latewood cells within the earlywood portion of the tree ring that reduces water transport. Hemlock woolly adelgid (Adelges tsugae Annand) and elongate hemlock scale (Fiorinia externa Ferris) are invasive insects that both feed on eastern hemlock [Tsuga canadensis (L.) Carrière]. Adelges tsugae has a greater effect on tree health than F. externa, but the mechanism underlying their differential effect is unknown. We explored the effects of these herbivores by assessing growth ring formation in branches of trees that had been experimentally infested for 4 yr with A. tsugae, F. externa, or neither insect. We measured false ring density, ring growth, and earlywood: latewood ratios in the two most recently deposited growth rings. Branches from A. tsugae-infested trees had 30% more false rings than branches from F. externa-infested trees and 50% more than branches from uninfested trees. In contrast, branches from F. externa-infested trees and control trees did not differ in false ring formation. Radial growth and earlywood: latewood ratios did not differ among treatments. Our results show that two invasive herbivores with piercing-sucking mouth parts have differing effects on false ring formation in eastern hemlock. These false rings may be the product of a systemic plant hypersensitive response to feeding by A. tsugae on hemlock stems. If false rings are responsible for or symptomatic of hemlock water stress, this may provide a potential explanation for the relatively large effect of A. tsugae infestations on tree health.

Cucumber (Cucumis sativus L.) is among the plants highly dependent on insectmediated pollination, but little is known about its unmanaged pollinators. Both domestic and wild bee populations in central Wisconsin pickling cucumber fields were assessed using a combination of pan trapping and floral observations before and during bloom. Together with land cover analyses extending 2,000 m from field centers, the relationship of land cover components and bee abundance and diversity were examined. Over a 2-yr sample interval distributed among 18 experimental sites, 3,185 wild bees were collected representing >60 species. A positive association was found between both noncrop and herbaceous areas with bee abundance and diversity only during bloom. Response of bee abundance and diversity to land cover was strongest at larger buffers presumably because of the heterogeneous nature of the landscape and connectivity between crop and noncrop areas. These results are consistent with previous research that has found a weak response of wild bees to surrounding vegetation in moderately fragmented areas. A diverse community of wild bees is present within the fields of a commercial cucumber system, and there is evidence of floral visitation by unmanaged bees. This evidence emphasizes the importance of wild pollinators in fragmented landscapes and the need for additional research to investigate the effectiveness of individual species in pollen deposition.

We compared the richness and abundance of free-feeding herbivore insects (sap-sucking and leaf-chewing), leaf herbivory damage, leaf toughness and total phenolic content between two ontogenetic stages (juvenile and reproductive) of Handroanthus spongiosus (Rizzini) S. O. Grose (Bignoniaceae) throughout the rainy season in a Brazilian seasonally dry tropical forest. Twenty marked individuals of H. spongiosus were sampled per ontogenetic stage in each period of the rainy season (beginning, middle, and end). Herbivore richness and abundance did not differ between ontogenetic stages, but higher percentage of leaf damage, higher concentration of phenolic compounds, and lower leaf toughness were observed for juvenile individuals. The greatest morphospecies abundance was found at the beginning of the rainy season, but folivory increment was higher at the end, despite the fact that leaf toughness and total phenolic content increased in the same period. No significant relationships between leaf damage and both total phenolic content and leaf toughness were observed. These results suggest that insect richness and abundance do not track changes in foliage quality throughout plant ontogeny, but their decrease along rainy season confirms what was predicted for tropical dry forests. The general trends described in the current study corroborate those described in the literature about herbivores and plant ontogeny. However, the lack of relationship between herbivore damage and the two plant attributes considered here indicates that the analyses of multiple defensive traits (the defense syndrome) must be more enlightening to determine the mechanisms driving temporal and spatial patterns of herbivore attack.

In response to herbivory, plants have evolved defense strategies to reduce herbivore preference and performance. A strategy whereby defenses are induced only upon herbivory can mitigate costs of defense when herbivores are scarce. Although costs and benefits of induced responses are generally assumed, empirical evidence for many species is lacking. Soybean (Glycine max L. Merr.) has emerged as a model species with which to address questions about induced responses. To our knowledge, this is the first study to examine the fitness costs and benefits of jasmonic acid-induced responses by soybean in the absence and presence of soybean loopers (Chrysodeix includens Walker) (Lepidoptera: Noctuidae). In a greenhouse experiment we demonstrated that soybean induction was costly. Induced plants produced 10.1% fewer seeds that were 9.0% lighter, and had 19.2% lower germination rates than noninduced plants. However, induction provided only modest benefits to soybeans. In a choice experiment, soybean loopers significantly preferred leaves from noninduced plants, consuming 62% more tissue than from induced plants. Soybean loopers that fed on plants that were previously subjected to treatment with jasmonic acid matured at the same rate and to the same size as those that fed on control plants. However, at high conspecific density, soybean looper survivorship was reduced by 44% on previously induced relative to control plants. Reduced soybean looper preference and survivorship did not translate into fitness benefits for soybeans. Our findings support theoretical predictions of costly induced defenses and highlight the importance of considering the environmental context in studies of plant defense.

Diabrotica speciosa (Germar) is an economically important pest of Neotropical cultures and represents a quarantine risk for Neartic and Paleartic Regions. Despite its agricultural importance, few studies have been done on mating behavior and chemical communication, which has delayed the development of behavioral techniques for population management, such as the use of pheromone traps. In this study, we determined 1) the age at first mating; 2) diel rhythm of matings; 3) number of matings over 7 d; 4) the sequence of D. speciosa activities during premating, mating, and postmating; 5) the duration of each activity; and 6) response to male and female conspecific volatiles in Y-tube olfactometer. The first mating occurred between the third and seventh day after adult emergence and the majority of pairs mated on the fourth day after emergence. Pairs of D. speciosa showed a daily rhythm of mating with greater sexual activity between the end of the photophase and the first half of the scotophase. During the 7 d of observation, most pairs mated only once, although 30% mated two, three, or four times. In a Y-tube olfactometer, males were attracted by virgin females as well as by the volatile compounds emitted by females. Neither males nor their volatiles were attractive to either sex. Our observation provide information about mating behavior of D. speciosa, which will be useful in future research in chemical communication, such as identification of the pheromone and development of management techniques for this species using pheromone traps.

The sugarcane borer, Diatraea saccharalis (F.), is a pest of a variety of graminaceous crops in the southern United States, including sugarcane, maize, and rice in Louisiana. This study examined several aspects of D. saccharalis oviposition behavior on rice (Oryza sativa). The vertical distribution of egg masses on four phenological stages of rice in the field showed that D. saccharalis prefers to oviposit on the uppermost portions of rice plants, regardless of plant stage. In greenhouse choice experiments, females strongly preferred plants at the boot and panicle differentiation stages over plants at the tillering stage for oviposition. Greenhouse studies were also conducted to quantify the oviposition preference of D. saccharalis for different cultivars of. When plants were at the tillering stage, cultivars Cocodrie, Priscilla, Bengal, Cheniere, and CL161 were more preferred than cultivars Jupiter, XL723, and XP744. When plants reached the panicle initiation stage, cultivars Cocodrie, CL161, and Priscilla were more preferred than Bengal, Cheniere, Jupiter, XL723, and XP744. Females also oviposited significantly more egg masses on the adaxial surfaces of rice leaves than on the abaxial surfaces. These results will facilitate scouting and management of sugarcane borer and can be used as a foundation for the development of sugarcane borer resistant cultivars.

Warren root collar weevil, Hylobius warreni Wood, is a native, flightless insect distributed throughout the boreal forest of North America. It is an emerging problem in young plantings of lodgepole pine, Pinus contorta variety latifolia, in western Canada, where larval feeding can kill young trees by girdling the root collar. Susceptible plantings are becoming more abundant following salvage harvesting and replanting activities in the wake of an ongoing epidemic of mountain pine beetle, Dendroctonus ponderosae (Hopkins). Previous studies using mark-trap-recapture methods found that movement rates of adult H. warreni were elevated in areas with high numbers of dead trees, consistent with a hypothesis that the insects immigrate from stands with high mountain pine beetle-caused tree mortality to young plantings in search of live hosts. Sampling methods were necessarily biased to insects captured in traps; however, potentially missing individuals that had died, left the study area, or simply remained stationary. Here, we used harmonic radar to examine weevil movement in three different habitats: open field, forest edge, and within a forest. We were able to reliably monitor all but two of 36 insects initially released, over 96 h (4 d). Weevils released in the open field had the highest rates of movement, followed by weevils released at the forest edge, then weevils released within the forest. Movement declined with decreasing ambient air temperature. Our results suggest that weevils tend to be relatively stationary in areas of live hosts, and hence may concentrate in a suitable area once such habitat is found.

The biology and behavior of insects are strongly influenced by environmental conditions such as temperature and precipitation. Because some of these factors present a within day variation, they may be causing variations on insect diurnal flight activity, but scant information exists on the issue. The aim of this work was to describe the patterns on diurnal variation of the abundance of Ichneumonoidea and their relation with relative humidity, temperature, light intensity, and wind speed. The study site was a tropical dry forest at Ría Lagartos Biosphere Reserve, Mexico; where correlations between environmental factors (relative humidity, temperature, light, and wind speed) and abundance of Ichneumonidae and Braconidae (Hymenoptera: Ichneumonoidea) were estimated. The best regression model for explaining abundance variation was selected using the second order Akaike Information Criterion. The optimum values of temperature, humidity, and light for flight activity of both families were also estimated. Ichneumonid and braconid abundances were significantly correlated to relative humidity, temperature, and light intensity; ichneumonid also showed significant correlations to wind speed. The second order Akaike Information Criterion suggests that in tropical dry conditions, relative humidity is more important that temperature for Ichneumonoidea diurnal activity. Ichneumonid wasps selected toward intermediate values of relative humidity, temperature and the lowest wind speeds; while Braconidae selected for low values of relative humidity. For light intensity, braconids presented a positive selection for moderately high values.

Herbivorous insects are often exposed to broad temporal and spatial variations in microclimate conditions within their host plants and have adapted a variety of behaviors, such as avoidance or basking, to either offset or benefit from such variation. Field experiments were carried out to investigate the influence of daily and intratree variations in microclimate on the behaviors (feeding, resting, dispersal, and hiding) and associated performance of late-instar larvae of the yellowheaded spruce sawfly, Pikonema alaskensis (Rohwer) (Hymenoptera: Tenthredinidae) within crowns of 1.25–1.5 m tall black spruce (Picea mariana [Miller] Britton Sterns Poggenburg); late instars feed on developing shoots of young spruce and are often exposed to microclimatic extremes with unknown effects on performance. Larvae fed diurnally from just after dawn (0800 h) until dusk (2000 h) and rested throughout the night, with brief periods of dispersal occurring in the morning and evening. Neither larval behavior nor abiotic conditions differed significantly between the upper and lower crowns of trees. Temperature, humidity, and solar insolation all explained >90% of variation in feeding; however, sunrise and sunset were the most likely cues influencing diurnal behavior. Most larvae (94%) fed on the bottom, shaded side of shoots, and field experiments indicated that this behavior is adaptive with respect to microclimate, probably reducing hygrothermal stress. Thus, behavioral adaptations by P. alaskensis to daily and within-shoot microclimatic variation may reduce the risk of hygrothermal stress during dispersal or feeding, while still allowing larvae to feed on the preferred and highly nutritious upper crown foliage of young spruce.

Codling moth, Cydia pomonella (L.), larvae cause severe internal feeding damage to apples, pears, and walnuts worldwide. Research has demonstrated that codling moth neonate first instar larvae are attracted to a pear-derived kairomone, ethyl (2E,4Z) -2,4-decadienoate, the pear ester (PE). Reported here are the behavioral activities of neonate codling moth larvae to microencapsulated pear ester (MEC-PE) applied in aqueous solutions to both filter paper and apple leaf surfaces that were evaluated over a period of up to 20 d of aging. In dual-choice tests the MEC-PE treatment elicited attraction to and longer time spent on treated zones of filter papers relative to water-treated control zones for up to 14 d of aging. A higher concentration of MEC-PE caused no preferential response to the treated zone for the first 5 d of aging followed by significant responses through day 20 of aging, suggesting sensory adaptation as an initial concentration factor. Estimated emission levels of PE from treated filter papers were experimentally calculated for the observed behavioral thresholds evident over the aging period. When applied to apple leaves, MEC-PE changed neonate walking behavior by eliciting more frequent and longer time periods of arrestment and affected their ability to find the leaf base and stem or petiole. Effects of MEC-PE on extended walking time and arrestment by codling moth larvae would increase temporal and spatial exposure of neonates while on leaves; thereby potentially disrupting fruit or nut finding and enhancing mortality by increasing the exposure to insecticides, predation, and abiotic factors.

Bell pepper plots intercropped with flowering plants were measured for improving biological control provided by natural enemies of the European corn borer [Ostrinia nubilalis (Hübner)]. The intercropped plants Dill, Anethum graveolens L.; coriander, Coriandrum sativum L.; and buckwheat, Fagopyrum escuelentum Moench; were established on the edge of two pepper plots and compared with nonintercropped control plots. Predation by the three species Orius insidiosus Say; Coleomegilla maculata DeGeer; and Chrysoperla, sp. Stephens, was monitored by installing O. nubilalis egg masses on sentinel plants in 2008, 2009, and 2010. To assess negative impacts of alternative prey on O. nubilalis egg predation, green peach aphid, Myzus persicae (Sulzer) populations were monitored via whole-plant counts in 2009 and 2010. Myzus persicae densities on pepper plants peaked in June or July and then declined rapidly. Predation on O. nubilalis eggs increased rapidly after aphid populations declined. Aphid populations were reduced in two out of three field-seasons in intercropped plots. Seasonal predation by O. insidiosus was significantly higher in the intercropped system four out of five field-seasons and one field season by C. maculata. Results indicate that biocontrol of O. nubilalis can be improved by intercropping with flowering plants, although this capacity may depend on the abundance of alternative prey.

The twospotted spider mite, Tetranychus urticae Koch, is a worldwide pest of numerous agronomic and horticultural plants. Sulfur fungicides are known to induce outbreaks of this pest on several crops, although mechanisms associated with sulfur-induced mite outbreaks are largely unknown. Studies were conducted during 2007–2009 in Oregon and Washington hop yards to evaluate the effect of timing of sulfur applications on T. urticae and key predators. In both regions, applications of sulfur made relatively late in the growing season (mid-June to mid-July) were associated with the greatest exacerbation of spider mite outbreaks, particularly in the upper canopy of the crop. The severity of mite outbreaks was closely associated with sulfur applications made during a relatively narrow time period coincident with the early exponential phase of spider mite increase and rapid host growth. A nonlinear model relating mean cumulative mite days during the time of sulfur sprays to the percent increase in total cumulative mite days (standardized to a nontreated plot) explained 58% of the variability observed in increased spider mite severity related to sulfur spray timing. Spatial patterns of spider mites in the Oregon plots indicated similar dispersal of motile stages of spider mites among leaves treated with sulfur versus nontreated leaves; however, in two of three years, eggs were less aggregated on leaves of sulfur-treated plants, pointing to enhanced dispersal. Apart from one experiment in Washington, relatively few predatory mites were observed during the course of these studies, and sulfur-induced mite outbreaks generally occurred irrespective of predatory mite abundance. Collectively, these studies indicate sulfur induces mite outbreaks through direct or indirect effects on T. urticae, mostly independent of predatory mite abundance or toxicity to these predators. Avoidance of exacerbation of spider mite outbreaks by sulfur sprays was achieved by carefully timing applications to periods of low spider mite abundance and slower host development, which is generally early to mid-spring for hop.

Xylosandrus germanus (Blandford) and other species of ambrosia beetles are key pests of ornamental nursery trees. A variety of laboratory- and field-based experiments were conducted in pursuit of improved monitoring strategies and to develop a trap tree strategy for ambrosia beetles. Traps baited with bolts prepared from Magnolia virginiana L. injected with ethanol caught five times more X. germanus than ethanol-baited traps. Basal stem injections of ethanol into M. virginiana induced more ambrosia beetle attacks than irrigating or baiting with ethanol, and no attacks occurred on water-injected trees. A positive correlation was also detected between concentration of injected ethanol and cumulative attacks. Solid phase microextraction-gas chromatography-mass spectrometry characterized bark emissions from ethanol- and water-injected M. virginiana at 1, 2, 10, and 16 d after treatment. Ethanol emission from injected trees steadily declined from 1 to 16 d after treatment, but was not emitted from water-injected trees. A variety of monoterpenes were also emitted in trace amounts from the ethanol- and water-injected trees. Antennal responses of X. germanus via gas chromatography-electroantennographic detection to volatiles from ethanol-injected M. virginiana occurred for ethanol, but not the various monoterpenes. X. germanus and other ambrosia beetles were also equally attracted to traps baited with ethanol alone compared with a synthetic mixture of ethanol plus various monoterpenes formulated to mimic ethanol-injected M. virginiana. Injecting concentrated solutions of ethanol into trees may be useful for establishing odor-based trap trees, which could aid with monitoring programs and/ or potentially deflect ambrosia beetles away from valuable nursery stock.

Attraction of emerald ash borer, Agrilus planipennis Fairmaire, to a volatile pheromone was demonstrated in three field experiments using baited green sticky traps. A dose-response curve was generated for male A. planipennis to increasing release rates of (3Z)-dodecen-12-olide ((3Z)lactone) in combination with the green leaf volatile, (3Z)-hexenol. Only the lowest release rate (<2.50 µg/d) of (3Z)-lactone significantly increased captures of male A. planipennis, as compared with traps baited with (3Z)-hexenol alone. Effect of trap height, (3Z)-lactone, and (3Z)-hexenol and their interactions on the trap capture of A. planipennis was determined in a factorial experiment. Number of males per trap was significantly and positively affected by (3Z)-lactone, (3Z)-hexenol, and trap height whereas number of females per trap was affected by trap height only; none of the interactions were significant. As predicted, the greatest mean catch of males was in traps baited with (3Z)-lactone and (3Z)-hexenol placed high in the canopy. Electroantennogram tests on the bark volatile, 7-epi-sesquithujene, demonstrated the ability of male and female A. planipennis antennae to detect and respond to this compound, particularly the ( )-7-epi-sesquithujene isomer. Results from an olfactometer bioassay and field testing did not demonstrate attraction of either males or females to ( )-7-epi-sesquithujene. These data increase our understanding of the pheromone ecology of the invasive emerald ash borer, provide further confirmation of the behavioral activity of the female-produced lactone pheromone, and should increase the ability to detect A. planipennis infestations where they are present.

Microplitis manilae Ashmead (Hymenoptera: Braconidae), a larval parasitoid, is a potential biological control agent of both Spodoptera exigua (Hübner) and Spodoptera litura (F.) (Lepidoptera: Noctuidae). Aspects of the climatic requirements for development, including survival, longevity, and fecundity of M. manilae were studied at six constant temperature regimes (17, 20, 23, 26, 29, and 32°C) in the laboratory. The results showed that developmental duration for egg, larva, pupa, and the entire immature stages shortened in response to temperature increasing from 17 to 32°C. Survival rates of different developmental stages were higher at 20–29°C than at other temperatures. Longevity of M. manilae adults shortened with increasing temperature. The maximum fecundity of M. manilae female equaled 261.0 eggs/female at 26°C. Minimum threshold temperature and effective accumulated temperature for completing a generation of M. manilae were 11.04°C and 205.98 degrees-days, respectively. Both intrinsic rate of increase (r) and finite rate of increase (λ) of M. manilae did not differ between 26 and 29°C, but those were significantly higher at 26 and 29°C than at any other temperatures. The highest net reproduction rate (R₀) was observed at 26°C, with the value of 97.77, but the lowest was 11.79 at 32°C. These results suggest that the parasitoid is well adapted to temperate and subtropical climates, which implies a significant potential for using M. manilae to control S. exigua because most of areas occupied by these two pests belong to temperate and subtropical regions in southeastern Asia.

The foxglove aphid, Aulacorthum solani (Kaltenbach), recently was documented using the invasive species pale and black swallow-wort (Vincetoxicum rossicum (Kleopow) Barbar, and V. nigrum (L.) Moench, respectively) as host plants. Because these are new host plant records for this polyphagous species, we investigated foxglove aphid development and reproduction on pale and black swallow-wort relative to a known crop host, potato (Solanum tuberosum L.), at a 25:20°C thermophase and a photoperiod of 16:8 (L:D) h. Almost no such data have been previously reported for a noneconomic host plant. Larval development and survival, as well as adult reproductive development and fecundity, were similar between the two swallow-wort species and potato. Adult aphids lived significantly longer on pale swallow-wort than the other two host plants, but this extended longevity encompassed the postreproductive stage. Foxglove aphid population parameters were therefore similar among the three plant species as well as most previous reports on crop plants. Pale and black swallow-wort appear to be suitable secondary hosts for foxglove aphid; other factors possibly limit aphid abundance on these two plant species in the field.

Delphastus catalinae (Horn) is a coccinellid predator that is commercially sold for the management of whiteflies. A study was conducted to assay the effect of selected diets on the survival of adult D. catalinae. Treatments of water (as a control), 10% honey, honeydew, and whiteflies [Bemisia tabaci (Gennadius)] were provided to the beetles in laboratory assays. Newly emerged, unfed adult insects were used at the start of a survival experiment with trials lasting 50 d. Another survival experiment used mixed-aged adults from a greenhouse colony, and the trials lasted 21 d. Survival was poor on a diet of solely water; ≈1% survived beyond a week at 26°C Survival using the newly emerged insects was similar between those fed honeydew and honey diets, but those on the whitefly diet had the greatest survival (≈60% on day 50). However, in the experiment with mixed-aged beetles, adults on honey, and whitefly diets performed the same over a 21-d experiment. Excluding those on the water diet, survival of beetles on the various diets ranged from ≈50–80% after 21 d. In an open choice assay across 7 h, D. catalinae adults were found on the whitefly diet in a much greater incidence than on the other diets, and the number of beetles found on the whitefly diet increased over time. The data supports that when D. catalinae are employed in greenhouses or fields for whitefly management, during low prey populations, honeydew from the whitefly can help sustain the population of this predator. Moreover, a supplemental food such as a honey solution can help sustain the population of D. catalinae when the prey is decreased to low numbers. These results may help in the development of strategies to enhance the utility of predators for the management of whiteflies.

Two climate chamber experiments were performed to simulate the effects of global warming on life table parameters of coccinellids. We investigated the effects of two daily temperature profiles during preimaginal development (larval and pupal) and the young adult period (first 10 d) on body weight and fat body content of adult Coccinella septempunctata L. and Harmonia axyridis (Pallas) fed English grain aphids [Sitobion avenae (F.)] ad libitum: 1) normal, i.e., current daily temperatures in central Europe (T0: mean, 17.8°C; maximum, 21.8°C; minimum, 13.4°C) and 2) increased by 3K (T3: mean, 20.8°C; maximum, 25.5°C; minimum, 15.7°C). The first experiment was performed at the same temperatures (T0 or T3) during both periods to establish the responses of the two species to temperature. The second was conducted to identify the period (preimaginal or adult) in which the responses occurred and to confirm the results of the first experiment. Compared with normal temperatures (T0), elevated temperatures (T3) resulted in significant decreases in preimaginal development time and increases in aphid consumption rates in both species. C. septempunctata (10-d-old adults) had the highest weights when reared at T3, H. axyridis at T0. C. septempunctata was significantly heavier than H. axyridis in most cases, particularly in females. The body fat content of C. septempunctata was higher than that of H. axyridis at T0 and T3 temperatures. At T3 temperatures, fat accumulation in C. septempunctata increased, whereas that in H. axyridis remained relatively low. Body weight and fat body content of 10-d-old adults of both species seemed to be determined by temperature conditions during preimaginal development.

The impacts of different doses of the plant growth regulator gibberellic acid (GA₃) in diet on the number of total and differential hemocytes, frequency of apoptotic, and necrotic hemocytes, mitotic indices, encapsulation, and melanization responses were investigated using the greater wax moth Galleria mellonella L. (Lepidoptera: Pyralidae) larvae. Total hemocyte counts increased in G. mellonella larvae at all treatment doses whereas GA₃ application had no effect on the number of different hemocyte types. The occurrence of apoptosis, necrosis and mitotic indices in GA₃ treated and untreated last instars were detected by acridine orange or ethidium bromide double staining by fluorescence microscopy. While the ratio of necrotic hemocytes increased at all GA₃ treatments, that of late apoptotic cells was only higher at doses >200 ppm when compared with untreated larvae. The percentage of mitotic index also increased at 5,000 ppm. Positively charged DEAE Sephadex A-25 beads were used for analysis of the levels of encapsulation and melanization in GA₃ treated G. mellonella larvae. At four and 24 h posttreatments with Sephadex A-25 bead injection, insects were dissected under a stereomicroscope. Encapsulation rates of larval hemocytes were dependent on the extent of encapsulation and time but not treatment groups. While the extent of melanization of hemocytes showed differences related to time, in general, a decrease was observed at all doses of GA₃ treated larvae at 24 h. We suggest that GA₃ treatment negatively affects hemocyte physiology and cell immune responses inducing cells to die by necrosis and apoptosis in G. mellonella larvae.

Development of the parasitoid Habrobracon hebetor (Say) (Hymenoptera: Braconidae) at low temperatures was determined to identify rearing conditions that might result in adults that were in reproductive diapause. Diapausing adults would be expected to survive cold storage longer than nondiapausing adults for use in biological control programs. Only a few eggs were found in the ovaries when H. hebetor females were reared during the immature stages at 17.5 and 20°C with a 16-h photoperiod, and the ovaries were poorly developed and contained no eggs when females were reared with a 10-h photoperiod in these low temperatures. Rearing H. hebetor at 17.5 and 20°C did not result in diapause of immature stages, but did appear to result in possible adult reproductive diapause when the immature stages were reared with a 10-h photoperiod. Females reared during the immature stages at 17.5°C with a10-h photoperiod lived longer and took longer to lay their first eggs and to lay 50% of their eggs than those females reared at 17.5°C with a16-h photoperiod. Females reared during the immature stages at 20°C with a10-h photoperiod took longer to lay their first eggs and to lay 50% of their eggs, and they had a lower respiration rate, than those females reared at 20°C with a16-h photoperiod. Females that were reared in conditions that appeared to induce reproductive diapause resumed oviposition and their respiration rate increased soon after being transferred to a higher temperature (27.5°C). Thus, females reared at a 10-h photoperiod at 17.5 and 20°C appear to enter reproductive diapause.

Echinothrips americanus Morgan, an invasive pest on various ornamentals and greenhouse crops, was introduced into mainland China recently, posing a potential threat to ornamentals and greenhouse crops. It exhibits two different reproductive modes: arrhenotokous parthenogenesis and sexual reproduction. Laboratory studies were conducted to compare the developmental and reproductive biology of E. americanus in these two reproductive modes. Results showed that the oviposition period, and longevity of female adults using sexual reproduction were longer than those using parthenogenesis. Furthermore, sexual female adults had higher fecundity and survival rates. However, no significant differences were found among immature stages in the durations of first and second instars, prepupae, and pupae between the two reproductive modes, with the exception of the duration of the egg stadium. The survival rates for eggs and first and second instars were higher in sexual E. americanus whereas there were no survival differences for prepupae and pupae. These results provide valuable insights into the mechanisms of parthenogenesis and sex determination in Thysanoptera.

Temperature can notably affect development rate and intrinsic rate of increase of the diamondback moth, Plutella xylostella L. The intrinsic rate of increase is usually regarded as a good measure of fitness in insects, and the constant temperature at which the intrinsic rate of increase reaches its maximum is defined as the “optimal” temperature for an insect species to survive. The estimates of optimal temperature for some insects and mites are ≈30°C. However, the Sharpe— Schoolfield—Ikemoto model provides an estimate about the intrinsic optimum temperature at which the probability of an enzyme being in the active state is maximal. The intrinsic optimum temperature is considered to be the most suitable temperature for an insect species to survive. The estimates of intrinsic optimum temperature for some insects and mites are ≈20°C. The optimal temperature and the intrinsic optimum temperature of the diamondback moth were estimated in the current study. The former estimate is 28.4 (95% CI: 26.2–28.8°C), whereas the latter estimate is 19.4°C (95% CI: 17.9– 20.5°C). Considering the daily average air temperatures during the peaks of the diamondback moth in China, the intrinsic optimum temperature of 19.4°C might represent the most suitable temperature for this insect to survive. We also discussed whether it is sounded to use the intrinsic rate of increase as the fitness. Because the intrinsic rate of increase cannot reflect the density-dependence of population and the trade-off between individual body mass and population size, it is inappropriate to equate these two concepts.

While most bark beetles attack only dead or weakened trees, many species in the genus Dendroctonus have the ability to kill healthy conifers through mass attack of the host tree, and can exhibit devastating outbreaks. Other species in this group are able to successfully colonize trees in small numbers without killing the host. We reconstruct the evolution of these ecological and life history traits, first classifying the extant Dendroctonus species by attack type (mass or few), outbreaks (yes or no), host genus (Pinus and others), location of attacks on the tree (bole, base, etc.), whether the host is killed (yes or no), and if the larvae are gregarious or have individual galleries (yes or no). We then estimated a molecular phylogeny for a data set of cytochrome oxidase I sequences sampled from nearly all Dendroctonus species, and used this phylogeny to reconstruct the ancestral state at various nodes on the tree, employing maximum parsimony, maximum likelihood, and Bayesian methods. Our reconstructions suggest that extant Dendroctonus species likely evolved from an ancestor that killed host pines through mass attack of the bole, had individual larvae, and exhibited outbreaks. The ability to colonize a host tree in small numbers (as well as gregarious larvae and attacks at the tree base) apparently evolved later, possibly as two separate events in different clades. It is likely that tree mortality and outbreaks have been continuing features of the interaction between conifers and Dendroctonus bark beetles.