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While the invasive spotted lanternfly, Lycorma delicatula(White) [Hemiptera: Fulgoridae], continues to expand its range in the United States, there remains a knowledge gap regarding the economic threat that this pest presents to forest ecosystems and production nurseries. L. delicatulauses several common hardwood trees as hosts and a previous study found that short-term feeding can reduce growth of young maple saplings. Herein, long-term feeding over 4 consecutive seasons significantly reduced diameter growth and below-ground starch storage in roots of young silver maples (Acer saccharinumL.), weeping willows (Salix babylonicaL.), river birches (Betula nigraL.), and trees of heaven (Ailanthus altissima[Mill.] Swingle) in response to L. delicatulafeeding pressure in a density-dependent manner. In Year 3 when feeding pressure was the lowest, silver maple and willow recovered with greater diameter growth than in Year 2. Nutrients essential for photosynthesis and growth (iron, sulfur, and phosphorus) were reduced in leaves of all tree species compared to controls in the second year. This 4-yr study represents a worst-case scenario in which L. delicatulafed on the same trees for 4 consecutive growing seasons. In the wild, population numbers can vary greatly from year to year on individual trees and they move frequently among hosts (until autumn when they settle on A. altissimaor other late-season hosts that have not yet senesced). Thus, we would not expect negative impacts of unconfined L. delicatulain natural settings on forest or ornamental trees to be as marked as reported here.

For the invasive planthopper Lycorma delicatula, eggs are an attractive target for surveys and management because they can persist from September through May before hatching, and remnants may be retained for years after hatching. Efforts to control this invasive species, though, are hampered by imperfect detection, which impedes early detection and rapid response, obscures management impacts, and reduces the fraction of egg masses that can be managed. To estimate egg mass detectability, we conducted 75 duplicate surveys of 20 × 5 m plots located in forest edges and disturbed areas frequently used by L. delicatula. We fit binomial mixture models and investigated the effects of weather, height (above or below 3 m), season (winter or spring), and basal area of trees within plots, finding no evidence that these factors affected detection rate, which averaged 52.2%. We additionally estimated the fraction of L. delicatulaeggs that were laid above 3 m, putting them outside of easy reach for management by scraping or targeted ovicide application. This proportion varied with basal area of trees within plots, and the estimated mean was greater than 50% across the range of basal areas in study plots. Finally, we found that counts of old egg masses correlated with counts of new egg masses laid the year prior, but the ability to infer prior years’ egg mass counts was limited. Together, these findings inform managers delimiting L. delicatulapopulations in mixed habitats and those treating egg masses to slow population growth and spread of this pest.

Neonicotinoid insecticides are used to manage spotted lanternfly (Lycorma delicatula(White); hereafter SLF), a recently introduced pest in the United States. Neonicotinoids can harm nontargets, such as pollinators potentially exposed via floral resources of treated plants. We quantified neonicotinoid residues in whole flowers of two SLF host plant species, red maple (Acer rubrumL. [Sapindales: Sapindaceae]) and tree-of-heaven (Ailanthus altissima(Mill.) [Sapindales: Simaroubaceae]), treated with post-bloom imidacloprid or dinotefuran applications that differed in timing and method of application. In red maple flowers, dinotefuran residues from fall applications were significantly higher than summer applications, while imidacloprid residues from fall applications were significantly lower than summer applications. Residues did not differ between application methods or sites. In tree-of-heaven flowers, dinotefuran residues were only detected in one of 28 samples at a very low concentration. To assess acute mortality risk to bees from oral exposure to residues in these flowers, we calculated risk quotients (RQ) using mean and 95% prediction interval residue concentrations from treatments in this study and lethal concentrations obtained from acute oral bioassays for Apis mellifera(L. (Hymenoptera: Apidae)) and Osmia cornifrons(Radoszkowski (Hymenoptera: Megachilidae)), then compared these RQs to a level of concern. For A. mellifera, only one treatment group, applied at 2X maximum label rate, had an RQ that exceeded this level. However, several RQs for O. cornifronsexceeded the level of concern, suggesting potential acute risk to solitary bees. Further studies are recommended for more comprehensive risk assessments to nontargets from neonicotinoid use for SLF management.

Relatively little is known about the genomic basis and evolution of wood-feeding in beetles. We undertook genome sequencing and annotation, gene expression assays, studies of plant cell wall degrading enzymes, and other functional and comparative studies of the Asian longhorned beetle, Anoplophora glabripennis, a globally significant invasive species capable of inflicting severe feeding damage on many important tree species. Complementary studies of genes encoding enzymes involved in digestion of woody plant tissues or detoxification of plant allelochemicals were undertaken with the genomes of 14 additional insects, including the newly sequenced emerald ash borer and bull-headed dung beetle. The Asian longhorned beetle genome encodes a uniquely diverse arsenal of enzymes that can degrade the main polysaccharide networks in plant cell walls, detoxify plant allelochemicals, and otherwise facilitate feeding on woody plants. It has the metabolic plasticity needed to feed on diverse plant species, contributing to its highly invasive nature. Large expansions of chemosensory genes involved in the reception of pheromones and plant kairomones are consistent with the complexity of chemical cues it uses to find host plants and mates. Amplification and functional divergence of genes associated with specialized feeding on plants, including genes originally obtained via horizontal gene transfer from fungi and bacteria, contributed to the addition, expansion, and enhancement of the metabolic repertoire of the Asian longhorned beetle, certain other phytophagous beetles, and to a lesser degree, other phytophagous insects. Our results thus begin to establish a genomic basis for the evolutionary success of beetles on plants.

Abstract This study was designed to address whether applications of methyl jasmonate (MJ) or Benzothiadiazole (BTH) to cultivated tomato, Lycopersicon esculentum, induced elevated densities of defense-related glandular trichomes on new leaves. Four-leaf tomato plants were sprayed with MJ, BTH, or control solutions, and the density of type VI glandular trichomes on new leaves was subsequently determined at 3, 7, 14, 21, and 28 d. At 7, 14, and 21 d, the density of type VI glandular trichomes on new leaves was significantly higher on MJ-treated plants than on BTH- or control-treated plants. At 7 and 14 d after treatment, the mean density of glandular trichomes on new leaves of MJ-treated plants was ninefold higher than on leaves of control-treated plants. We observed entrapment of immature western flower thrips in trichomes on MJ-treated plants at higher rates than on BTH or control plants. Studies to evaluate potential trade-offs between reductions in pest populations by increased trichome density and possible negative impacts of trichome induction on biological control agents are needed.

AbstractConventional wisdom stipulates that high power ultrasound without direct or indirect transducer contact with the medium to be treated is not possible. This seemingly correct notion is based upon two major hurdles: inefficient transmission of ultrasound from the piezoelectric material into air/gases and exorbitant attenuation of ultrasound by gases. The latter is a natural phenomenon about which nothing can be done, and the former requires an un-conventional approach to transducer design. After many years of R & D in this area, we have finally succeeded in producing transducers that generate immense acoustic pressure in air in the frequency range of ~50 kHz→10 MHz. By using these transducers without any contact with the material, we demonstrate destruction of 99.9% of dried bacterial spore samples of a close relative of anthrax, Bacillus thuringiensis.Following further refinement of the transducers and the mechanism of their excitation, we anticipate that non-contact ultrasound will have numerous applications including in-activation of agents of bioterrorism and sterilization of medical and surgical equipment, food materials, and air-duct systems of buildings, airplanes, space stations, and others.

: Conventional wisdom stipulates that high power ultrasound without direct or indirect transducer contact with the medium to be treated is not possible. This seemingly correct notion is based upon two major hurdles: inefficient transmission of ultrasound from the piezoelectric material into air/gases and exorbitant attenuation of ultrasound by gases. The latter is a natural phenomenon about which nothing can be done, and the former requires an un-conventional approach to transducer design. After many years of R& D in this area, we have finally succeeded in producing transducers that generate immense acoustic pressure in air in the frequency range of ∼50 kHz→10 MHz. By using these transducers without any contact with the material, we demonstrate destruction of 99.9% of dried bacterial spore samples of a close relative of anthrax, Bacillus thuringiensis. Following further refinement of the transducers and the mechanism of their excitation, we anticipate that non-contact ultrasound will have numerous applications including inactivation of agents of bioterrorism and sterilization of medical and surgical equipment, food materials, and air-duct systems of buildings, airplanes, space stations, and others.

AbstractConophthorus radiataeHopkins, Ernobius punctulatusFall, and Pityophthorusspp. infest cones and twigs of Monterey pines (Pinus radiataD. Don) and thus may be important vectors of the pitch canker fungus Fusarium subglutinansf. sp. piniin the central coast of California. Fifteen percent of 1st-year Monterey pine conelets infested with C. radiataeprior to August 1990 developed pitch canker by May 1991. Conophthorus radiatae, E. punctulatus, and Pityophthorusspp. were dissected from some of these conelets and found carrying F. s. pini. Between June 1990 and May 1991, 16% of 695 randomly selected uninfested 1st-year conelets from a total of 329 separate cone whorls were infested by at least one of the above beetle species, and F. s. piniwas isolated from 42% of the attacked conelets. Average percentage contamination of beetles per conelet was highest for adults of Pityophthorusspp. (38%), followed by adults of C. radiatae(33%), larvae of E. punctulatus(24%), and larvae of Pityophthorusspp. (5%). There were significant associations between conelets that contained contaminated C. radiatae, Pityophthorusspp., and/or E. punctulatusand conelets with F. s. pini.Under experimental conditions, C. radiataeand E. punctulatustransmitted the fungus to healthy cones. Ernobius punctulatusrequired an entrance tunnel by C. radiataeto enter and infect the cone. Artificially wounded cones did not develop pitch canker. Intra- and interspecific transmission of F. s. piniwas demonstrated among these beetle species. In infested branch tips without cones, interspecific transmission of F. s. pinibetween E. punctulatusand Pityophthorusspp. was also demonstrated.The roles of C. radiataeand E. punctulatusas vectors of F. s. piniand of Pityophthorusspp. as potential vectors are discussed in relation to the epidemiology of pitch canker disease. The spread of pitch canker to California’s native pines as well as other conifers may be enhanced by interspecific transmission of F. s. pinibetween E. punctulatusand C. radiataein cones and between E. punctulatusand Pityophthorusspp. in branch tips. Ernobius punctulatusprovides a pathway for the fungus to potential insect vectors that attack several hosts and a variety of plant parts.

AbstractThe objective of this study was to determine the quantitative and seasonal association between the pitch canker fungus, Fusarium subglutinansf. sp. pini, and two potential beetle vectors, Conophthorus radiataeHopkins and Ernobius punctulatusFall. In samples of reared and dissected cones, 21.4 ± 2.5% of C. radiataeand 30.1 ± 8.0% of E. punctulatusadults carried propagules of F. s. pini. Seasonal variation in mean percentage of contaminated C. radiataeand E. punctulatusemerged from cones ranged from 0 to 67% and was highest for both species February through April. In sticky traps 12.5 ± 2.3% and 11.8 ± 3.6% of E. punctulatusand Pityophthorusspp., respectively, were contaminated with propagules of F. s. pini.Conophthorus radiataeand E. punctulatusco-occurred in 26% of the cones. The percentage of cones containing contaminated C. radiataewas greater when E. punctulatusprogeny were also contaminated than when E. punctulatuswas not. When contamination status of E. punctulatuswas not considered, there was no significant difference in C. radiataecontamination between cones with and without E. punctulatus. Because C. radiataeappears to be a vector of the pitch canker fungus, interspecific transmission of inoculum may increase the incidence of this disease.The parasitoid, Cephalonomia utahensisBrues (Hymenoptera: Bethylidae), was frequently observed parasitizing late-instar larvae of E. punctulatus, but was not found on larvae of C. radiatae. Emergence of large numbers of C. utahensisrepresents another potential source of inoculum for transmission to prey species.

Constitutive phenolase activity of plants has a profound ability to modulate disease in insects caused by baculoviruses. We investigated the influence of damage-induced plant phenolic oxidases in cotton and tomato on mortality caused by two different baculoviruses in their respective hosts, Heliothis virescens(L.) and Helicoverpa zea(Boddie). For both plant species, peroxidase (POD) and phenolic levels were predictive of larval mortality caused by baculoviruses. The higher the POD activity, the lower the mortality in both hosts. Different classes of phenolics (e.g., monohydroxyphenolics vs. catecholic phenolics) in combination with POD activity had different effects on the severity of viral disease depending upon mixture, which implies that viral efficacy is predictable only if total chemical content of the plants is specified. Inhibition of baculoviral disease by plant phenolase activity has potential implications for the compatibility of baculoviruses with induced resistance in IPM programs.

Baculoviruses are arthropod-specific, dsDNA viruses primarily used to control lepidopteran pests. A limitation of the use of baculoviruses for pest control is that their efficacy is modifiable by host-plant chemicals. The levels of phenolic substrates and two foliar oxidative enzymes, peroxidase (POD) and polyphenol oxidase (PTO), were significant predictors of disease caused by a baculovirus in Heliothis virescensfed on either cotton or lettuce; POD was the more influential of the two enzymes. The higher the plant phenolase activity, the lower the percent mortality and the slower the insects died from viral infection. Whether a particular class of phenolic substrates was correlated with enhanced or attenuated baculoviral disease depended upon context, i.e., admixture. Diminution of viral efficacy by plant oxidative activity may compromise the compatibility of baculoviruses with other components of an integrated pest management system such as host plant resistance.

The susceptibility of noctuid larvae to baculoviral infection is markedly affected by phytochemicals ingested during the acquisition of viral inoculum on foliage. We hypothesized that a major process causing phytochemical inhibition of viral disease is phenolic oxidation by phenolases, particularly peroxidase (POD), which subsequently generates free radicals. To test this hypothesis, we manipulated the chemical interactions in foliage of cotton, tomato, and lettuce by application of antioxidants, prooxidants, enriched extracts of phenolases, and/or phenolic substrates. Larvae of Heliothis virescensor Helicoverpa zeathat received viral inoculum on treated foliage were less likely to die from viral infection the higher the POD activity of this foliage. Furthermore, the higher the POD activity, the more free radicals were generated in crushed foliage, and the more free radicals generated, the lower the incidence of viral disease. We present a series of reactions hypothesized to lead to inhibition of viral disease by free radicals, the generation of which is mediated, at least in part, by POD. Phenolic redox cycling catalyzed by POD involving clastogenesis (generation of H2O2) appeared to be a critical driver of phytochemical reactions leading to free radical generation and inhibition of baculoviral disease in their noctuid hosts. We also report application of an assay for the detection of free radicals by using methemoglobin as a new modification of this method for detecting radicals in plant foliage in the immediate aftermath of an oxidative burst.

Both wild-type and recombinant baculoviruses are becoming more attractive for the control of insect pests. Thus, there is an increased incentive to address and resolve logistical problems associated with large-scale production of these viruses. In this study, we have compared the potential of two insect cell lines, Tn5B1-4 and Sf21, for the production of polyhedra and compared the efficacy of both cell culture-derived and host-derived viruses by bioassay. The efficacy of both wild-type AcMNPV and AcAaIT, a recombinant baculovirus expressing an insect-specific scorpion toxin, were compared. Yields of polyhedra from Tn5B1-4 were sixfold higher than those from the cell line Sf21. Morphological analysis of polyhedra derived from cell culture showed greater variability in size relative to host-derived polyhedra. The maximum size of cell culture-derived polyhedra was over 1.5 times larger than that of insect-derived polyhedra. The efficacy of AcMNPV and AcAaIT derived from cell culture, or from amplification in larvae of Trichoplusia ni or Heliothis virescens, was compared by bioassay in H. virescens. There was a significant difference between the slopes for lethal time data for host-derived and cell culture-derived wild-type virus. Mortality occurred at a faster rate following infection with host-derived virus. No significant difference was seen for the recombinant virus AcAaIT. Lethal doses of cell- and host-derived polyhedra were not significantly different. The reasons for and implications of this for pest control are discussed. The data suggest that polyhedra production in larvae may be preferable to production in cell culture for the wild-type virus, but that this does not hold for recombinant viruses with enhanced speed of kill. Copyright 1995, 1999 Academic Press

Addition of the antibiotic streptomycin to two artificial diets routinely used in bioassays of neonate lar vae ofHeliothis virescens(tobacco budworm) infected withAutographa californicaM nucleopolyhedrovirus (AcMNPV) increased lethal times of the virus. After storage of diets for 3 weeks at 4°C, lethal times of infected larvae were significantly slower compared to those for larvae bioassayed using diets stored for 2 weeks or less. The effect of diet-age on rate of mortality was not the result of a change in total protein content or pH of the diet, but was apparently the result of some other alteration in the quality of the diet (e.g. microbial spoilage, palatibility, and/or nutritional value unrelated to total protein). Although we did not determine why lethal times were slower in response to streptomycin concentration or diet-age, we did find that slower lethal times were correlated with slower relative growth rates (RGR) of infected larvae. In addition, RGR of infected larvae decreased as a function of increasing streptomycin concentration, diet-age, and the interaction of the two factors. These results demonstrate that it is difficult to obtain consistent and comparable bioassay results if antibiotic composition and diet-age are not controlled. We suggest a standardized diet or highly standardized procedures for a given diet be developed that permits comparison of bioassays among and within laboratories.

Recombinant baculoviruses that express insect-specific toxins under the control of viral late gene promoters can kill susceptible lepidopteran hosts faster than the wild-type virus. In an effort to improve the efficacy of genetically engineered baculovirus pesticides, we have produced a recombinant that contains an insect specific toxin gene (AaIT) under the control of the promoter from an immediate early gene (ie1) ofAutographa californicanuclear polyhedrosis virus (AcNPV). AaIT protein was detected as early as 4 h postinfection in cultured insect cells infected with this recombinant. The protein continued to accumulate as the infection progressed and, even as late as 24 h postinfection, the amount of AaIT was about equal to that provided by a recombinant that expressed AaIT under the control of the very latep10promoter. Similar results were obtained with a recombinant that expressed a modified insect juvenile hormone esterase (JHE–KK) underie1control, confirming the ability of this promoter to provide early and abundant expression of gene products with potential pesticidal activity. Bioassays showed that theie1–AaIT recombinant killedHeliothis virescenslarvae faster than wild-type virus, but not faster than thep10–AaIT recombinant. However, larvae infected with theie1–AaIT recombinant were smaller than those infected with thep10–AaIT recombinant, suggesting that expression of AaIT earlier in infection enhanced the ability of the virus to reduce the feeding activity ofH. virescenslarvae.

Scymnus (Neopullus) camptodromus Yu and Liu (Coleoptera: Coccinellidae) was brought to the United States from China as a potential biological control agent for hemlock woolly adelgid (Adelges tsugae Annand) (Hemiptera: Adelgidae). Scymnus camptodromus phenology is closely synchronized with that of A. tsugae and has several characteristics of a promising biological control agent. As a prerequisite to field release, S. camptodromus was evaluated for potential nontarget impacts. In host range studies, the predator was given the choice of sympatric adelgid and nonadelgid prey items. Nontarget testing showed that S. camptodromus will feed to some degree on other adelgid species, but highly prefers A. tsugae. We also evaluated larval development of S. camptodromus on pine bark adelgid (Pineus strobi (Hartig)) (Hemiptera: Adelgidae) and larch adelgid (Adelges laricis Vallot) (Hemiptera: Adelgidae); a small proportion of predator larvae was able to develop to adulthood on P. strobi or A. laricis alone. Scymnus camptodromus showed no interest in feeding on woolly alder aphid (Paraprociphilus tessellatus Fitch) (Hemiptera: Aphididae) or woolly apple aphid (Eriosoma lanigerum (Hausmann)) (Hemiptera: Aphididae), and minimal interest in cotton aphid (Aphis gossypii Glover) (Hemiptera: Aphididae) in choice and no-choice experiments. Scymnus camptodromus females did not oviposit on any host material other than A. tsugae-infested hemlock. Under the circumstances of the study, S. camptodromus appears to be a specific predator of A. tsugae, with minimal risk to nontarget species. Although the predator can develop on P. strobi, the likelihood that S. camptodromus would oviposit on pine hosts of this adelgid is small.

Insects are unable to synthesize essential amino acids (EAAs) de novo, thus rely on dietary or symbiotic sources for them. Wood is a poor resource of nitrogen in general, and EAAs in particular. In this study, we investigated whether gut microbiota of the Asian longhorned beetle, Anoplophora glabripennis (Motschulsky), a cerambycid that feeds in the heartwood of healthy host trees, serve as sources of EAAs to their host under different dietary conditions. δ13C-stable isotope analyses revealed significant δ13C-enrichment (3.4 ± 0.1‰; mean ± SEM) across five EAAs in wood-fed larvae relative to their woody diet. δ13C values for the consumers greater than 1‰ indicate significant contributions from non-dietary EAA sources (symbionts in this case). In contrast, δ13C-enrichment of artificial diet-fed larvae (controls) relative to their food source was markedly less (1.7 ± 0.1‰) than was observed in wood-fed larvae, yet still exceeded the threshold of 1‰. A predictive model based on δ13CEAA signatures of five EAAs from representative bacterial, fungal, and plant samples identified symbiotic bacteria and fungi as the likely supplementary sources of EAA in wood-fed larvae. Using the same model, but with an artificial diet as the dietary source, we identified minor supplementary bacterial sources of EAA in artificial diet-fed larvae. This study highlights how microbes associated with A. glabripennis can serve as a source of EAAs when fed on nutrient-limited diets, potentially circumventing the dietary limitations of feeding on woody substrates.

Development time and prey consumption of Scymnus (Neopullus) camptodromus Yu and Liu (Coleoptera: Coccinellidae) larvae by instar, strain, and temperature were evaluated. S. camptodromus, a specialist predator of hemlock woolly adelgid Adelges tsugae (Annand) (Hemiptera: Adelgidae), was brought to the United States from China as a potential biological control agent for A. tsugae. This beetle has been approved for removal from quarantine but has not yet been field released. We observed that temperature had significant effects on the predator’s life history. The larvae tended to develop faster and consume more eggs of A. tsugae per day as rearing temperature increased. Mean egg consumption per day of A. tsugae was less at 15°C than at 20°C. However, as larvae took longer to develop at the lower temperature, the total number of eggs consumed per instar during larval development did not differ significantly between the two temperatures. The lower temperature threshold for predator larval development was estimated to be 5°C, which closely matches the developmental threshold of A. tsugae progrediens. Accumulated degree-days for 50% of the predator neonates to reach adulthood was estimated to be 424. Although temperature had a significant effect on larval development and predation, it did not impact survival, size, or sex ratio of the predator at 15 and 20°C. Furthermore, no remarkable distinctions were observed among different geographical populations of the predator.

Xylophagous insects often thrive on nutritionally suboptimal diets through symbiotic associations with microbes that supplement their nutritional requirements, particularly nitrogen. The wood-feeding cerambycid Anoplophora glabripennis (Motschulsky) feeds on living, healthy host trees and harbors a diverse gut microbial community. We investigated gut microbial contributions to larval nitrogen requirements through nitrogen fixing and recycling (urea hydrolysis) processes, using a combination of molecular, biochemical, and stable isotope approaches. Genes and transcripts of conserved regions of the urease operon (ureC) and nitrogen fixing (nif) regulon (nifH) were detected in A. glabripennis eggs and larvae from naturally infested logs and from larvae reared on artificial diet. Significant nitrogen fixation and recycling were documented in larvae using 15N2 gas and 15N-urea, respectively. Subsequent 15N-routing of incorporated recycled nitrogen into larval essential and nonessential amino acids was shown for 15N-urea diet-fed larvae. Results from this study show significant gut microbial contributions to this insect's metabolic nitrogen utilization through nitrogenous waste product recycling and nitrogen fixation.

Herbivore microbial associates can affect diverse interactions between plants and insect herbivores. Some insect symbionts enable herbivores to expand host plant range or to facilitate host plant use by modifying plant physiology. However, little attention has been paid to the role of herbivore-associated microbes in manipulating plant defenses. We have recently shown that Colorado potato beetle secrete the symbiotic bacteria to suppress plant defenses. The bacteria in oral secretions from the beetle hijack defense signaling pathways of host plants and the suppression of induced plant defenses benefits the beetle’s performance. While the defense suppression by the beetle-associated bacteria has been investigated in local damaged leaves, little is known about the effects of the symbiotic bacteria on the manipulation of plant defenses in systemic undamaged leaves. Here, we demonstrate that the symbiotic bacteria suppress plant defenses in both local and systemic tissues when plants are attacked by antibiotic-untreated larvae.

Following the increasing international phasing out of methyl bromide for quarantine purposes, the development of alternative treatments for timber pests becomes imperative. The international accreditation of new quarantine treatments requires verification standards that give confidence in the effectiveness of a treatment. Probit-9 mortality is a standard for treatment effectiveness that has its origin in fruit fly research, and has been adopted by the United States Department of Agriculture for fruit flies and several other pests. Following this, the probit-9 standard has been adopted as a benchmark for many quarantine treatments worldwide. This article discusses aspects of the application of this concept for a range of timber pests. Problematic issues include the often small pest populations available for testing, the limits of modeling pest responses to a treatment in the absence of sufficient numbers for treatment verification, the species diversity of pests and host materials and the physical and chemical conditions of host material or treatment conditions. Where treatment verification by killing large numbers of individuals is impossible, data collected from small populations or under specific conditions must be interpreted with caution. We discuss possible alternative approaches to probit-9 as a treatment efficacy standard.

Anoplophora glabripennis, the Asian longhorned beetle, is a wood-boring insect that can develop in a wide range of healthy deciduous hosts and requires gut microbes to aid in wood degradation and digestion. Here we show that larval A. glabripennis harbor a diverse gut bacterial community, and this community can be extremely variable when reared in different host trees. A. glabripennis reared in a preferred host (Acer saccharum) had the highest gut bacterial diversity compared with larvae reared either in a secondary host (Quercus palustris), a resistant host (Pyrus calleryana), or on artificial diet. The gut microbial community of larval A. glabripennis collected from field populations on Brooklyn, NY, showed the highest degree of complexity among all samples in this study. Overall, when larvae fed on a preferred host, they harbored a broad diversity of gut bacteria spanning the -, ß-, ?-Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes. Cellulase activities (ß-1,4-endoglucanase, ß-1,4-exoglucanase, and ß-1,4-glucosidase) in the guts of larvae fed in a preferred host (A. saccharum) or a secondary host (Q. palustris) were significantly higher than that of artificial diet fed larvae. Larvae that fed on wood from a resistant host (P. calleryana) showed suppressed total gut cellulase activity. Results show that the host tree can impact both gut microbial community complexity and cellulase activity in A. glabripennis.

Analysis of bioassays data from experiments with mixtures require use of special statistical techniques, especially when responses are recorded over time. Often, response curves from bioassays with mixtures do not fit a probit or logit curve. In addition, observations recorded over time are not independent. As a result, standard statistical packages for probit or logit analysis are not applicable. In these bioassays, the shape of the response curve depends on the type of interactions between mixture components. Here we present models that describe response (e.g., mortality) curves over time when mixtures are applied to insects. The shapes of the response curves depend on the modes of both action and interaction between the mixture compounds. We describe a procedure to assess whether the assumed modes of interaction (e.g., independent action or similar action additive models) are appropriate. We demonstrate use of the statistical methods with data obtained when a baculovirus and a synthetic organic insecticide were mixed.

Insecticidal pathogens such as baculoviruses are currently under intensive development as biorational agents for the control of lepidopteran pests. However, because the efficacy of these orally infective viruses is influenced by host diet, our ability to use baculoviruses effectively in an integrated pest management program requires understanding the influence of dietary components on the disease process. Nutritional stress caused by differences in the quality (casein or soy) or quantity (0–8%) of dietary protein altered the postinfectional course of disease caused by Autographa californica M nucelopolyhedrovirus in 2 species of noctuids, Heliothis virescens (F.) and Trichoplusia ni (Hübner). Lethal times of larvae infected with either the wild-type virus or a recombinant expressing a scorpion toxin (AaIT) derived from this parent virus were similarly affected by dietary protein. In general, the higher the level of dietary protein the shorter the lethal times. However, the influence of protein quality on lethal times depended on the insect species tested. The effect of chlorogenic acid on disease depended on dietary protein levels. At high protein concentrations, chlorogenic acid decreased speed of kill; whereas, at low protein levels, the phenolic had the opposite effect. The common factor among all treatments was that the faster larvae grew, the faster they died from viral infection. We suggest that insects that grow faster may support faster rates of viral replication in infected hosts. From an ecological perspective, it is possible that plants of higher protein content may increase the potential for the development of baculoviral epizootics in insect populations.