Beetle Mortality Research Articles

Effect of Time and Concentration on Mortality of the Cigarette Beetle, Lasioderma serricorne (F.), Fumigated With Phosphine

Summary The efficacy of a fumigant is determined by the gas concentration and exposure time. Typically, the gas concentration and exposure time are equally important in fumigation efficacy and their relationship is expressed as Ct = k, where C is the concentration, t is the time and k is a constant (Haber’s rule). However, deviation from Haber’s rule, i.e., the relative importance of time over concentration, has been reported for several stored-product pests, and a modified form (Cn t = k) is used to express the relationship between C and t. This study aimed to determine if this modified form could be applied to phosphine fumigation of the cigarette beetle, Lasioderma serricorne (F.). Adult beetles from six cultures with different phosphine-resistance levels were exposed to phosphine (1–2000 ppm) at 25 °C for either 24, 72, 120, or 168 h, and the phosphine concentration necessary to achieve 50% lethality (LC50) was calculated. The phosphine concentration (C) and the exposure time (t) relationship at the LC50 for all six cultures were determined by regression analyses. The equation Cn t = k was a good fit for all the cultures tested, irrespective of phosphine resistance. The results showed the exponent n was less than 1 (0.51 ≤ n ≤ 0.71, coefficient of determination 0.90–0.99), suggesting that time is more important than concentration in toxicity expression of phosphine against L. serricorne. Therefore, extending the exposure time rather than increasing the concentration should be emphasized to manage the future threat of resistance problems with phosphine.

Method Development for Monitoring Bean Leaf Beetle, Cerotoma trifurcata (Forster) (Coleoptera: Chrysomelidae), Susceptibility to Thiamethoxam Seed Treatments on Soybeans1

The increased use of thiamethoxam seed treatments for controlling pests such as the bean leaf beetle, Cerotoma trifurcata (Forster) (Coleoptera: Chrysomelidae), suggests the need for methods to measure and monitor the development of resistance to thiamethoxam. The objectives of this study were to develop a bioassay method that can be used to monitor bean leaf beetle susceptibility to thiamethoxam, and to quantify the relative concentrations of thiamethoxam and clothianidin in early growth stage soybean tissue treated with thiamethoxam as a seed treatment. Overwintered and F1 bean leaf beetles were collected from alfalfa and soybean fields and used in excised soybean leaf laboratory bioassays to measure susceptibility to thiamethoxam. Petioles of excised leaves were immersed in 0, 10, 50, 100, 500 and 1000 ng a.i./ml thiamethoxam solutions, beetles were placed on the leaves, and beetle mortality and defoliation levels were recorded. The bioassay method proved adequate to calculate an LC50 and LC90, and an EC50 based on defoliation level. The quantification of insecticide residues in soybean leaves from different vegetative stages indicates that the thiamethoxam concentration declines rapidly as the plant grows, and concentrations are at lethal levels for bean leaf beetles through V2. These results provide a method for monitoring bean leaf beetle susceptibility to thiamethoxam that is more representative of the pathway of exposure encountered by beetles in the field, particularly with respect to seed treatments, and provides an estimate of baseline susceptibility for future thiamethoxam resistance monitoring efforts.

Effect of modified atmosphere on cigarette beetle Lasioderma serricorne (F.) in stored turmeric

An experiment was conducted at the Post Harvest Technology Centre, Bapatla to study the effect of modified atmosphere on the mortality and development of cigarette beetle, Lasioderma serricorne in stored turmeric. Packing material viz., polypropylene bags (with 20, 40, 60 and 80% CO2), Super bag, Magik bag, jute bag and aluminium pouches were evaluated at different exposure periods. Among the CO2 treatments, maximum mortality (76.67%), least adult emergence (3.0) and the least weight loss (1.22%) was observed at 80% CO2 concentration in polypropylene bags at 160 days of storage. Super bag and Magik bags were also found effective as the number of adults emerged and weight loss were minimum because of the hermetic conditions developed within, due to their impermeable nature to the external gases. The results indicated that apart from the concentration of CO2, permeability of packaging material is also more important to be considered to maintain the modified atmosphere at the desired level and exposure time for effective pest management.

Biotoxicity of Different Parts of <i>Anacardium Occidentale</i> (Linn.) against <i>Callosobruchus Maculatus</i> (F.) Infestation on Stored Cowpea Seeds

Biotoxicity of different parts of Anacardium occidentale extracted with different methods were tested against Callosobruchus maculatus infesting cowpea seed. The nut, stem bark, root bark and leaf of the plant were pulverized to fine powder. The extracts were made by soaking the powders in ethanol, hot and cold water and concentrations of 1, 2, 3 and 4% were made. The mortality of the insect was observed at 24, 48, 72 and 96h post treatment. The oviposition and adult emergence of the beetle as well as the damage and weight loss of the seeds were recorded. All the extracts recorded high beetle mortality but only nut ethanolic extract achieved 100% mortality. Probit analysis showed that only little concentration of the extracts was required to achieve high mortality of the insect. The extracts significantly reduced the oviposition of the insect while the nut extracts of the plant prevented the emergence of the beetle and damage and weight loss of the seeds. Regression analysis showed that there was great correlation between adult mortality and oviposition as well as between adult emergence and weight loss. The extracts of the plant had proven insecticidal and can therefore be introduced to management system of the insect.

Laboratory Evaluation of Residual Phytotoxicity of Some Plant Powders to the Merchant Grain. Beetle, Oryzaephilus mercator Fauvel (Coleoptera: Silvanidae), Infesting Stored Kernels of Irvingia gabonensis

Investigations were conducted on phytochemical composition and residual toxicity of seven plant powders (which had been stored for 4 months) to the merchant grain beetle, Oryzaephilus mercator Fauvel, infesting kernels of Irvingia gabonensis. Beetle mortality data taken at days 1,3,5 and 7 post-infestation showed that all test plants excluding M. myristica caused higher level of beetle mortality than occurred in control. Cashew nut shell, Anacardium occidentale, powder was the most potent (cumulative mean mortality of 52.5 %) matching the efficacy of pirimiphos-methyl, which served as insecticide check in addition to an untreated control. It was followed by powders of J. curcas (35.0 %) and P. guineense (30.2 %), while the least toxic was M myristica. Mortality value for the latter (%), though numerically lower, was not significantly different from those of C. citratus (%) and X. aethiopica (%). Mean residual toxicity increased with duration of exposure The least number of adults emerged from pirimiphos-methyl treated jars, followed by A. occidentale powder, -while M myristica was the least potent. Phytochemical analysis revealed varied proportions of typical plant constituents such as phytates, flavonoids, hydrogen cyanides, alkaloids, tannins, oxalates, phenols and saponins some of which are responsible for the residual action of the tested plants.

Radio frequency (RF) control of red flour beetle (Tribolium castaneum) in stored rapeseeds (Brassica napus L.)

Absolute and relative mortalities of red flour beetle (Tribolium castaneum) infesting the rapeseeds of a small (196.3 cm3) and a large (1766 cm3) volumes during radio frequency (RF) heating (1.5 kW, 27.12 MHz) were determined at different end temperatures (30–80 °C) and initial seed moisture contents (5%, 7%, 9%, and 11% wet basis). 100% absolute and relative mortalities of the adult insects were achieved at 80 °C for the small volume of the seeds at all moisture contents (MCs) and at 60 °C and 9% and 11% MCs, and 70 °C and 5% and 7% MCs for the large volume. Over 80% and 96% of the absolute and the relative mortalities of the adult insects were achieved at over 60 °C for both volumes of the seeds. 100% mortalities of larvae infesting the small and the large volume seeds were achieved at 55 °C at all MCs. Germination, major and minor axes, roundness, colour of the seeds and qualities of the rapeseed oil were not affected significantly by RF treatment temperature at entire MCs. Therefore, a complete mortality of the red flour beetle infesting the rapeseeds with acceptable thermal degradation to qualities of the seeds could be achieved at under 60 °C by the RF treatment with a proper design of RF disinfestation.

Protocol for Heat Treating Black Walnut Wood Infested with Walnut Twig Beetle

Abstract Black walnut (Juglans nigra) is one of the most important tree species in the United States for producing lumber and other forest products. However, a recent outbreak of thousand cankers disease vectored by the walnut twig beetle (Pityophthorus juglandis) threatens the population of black walnut in the United States. Infected walnut trees are typically removed to prevent spread of the vector, resulting in large quantities of potential sawlogs that must be sanitized. The objective of this study was to identify the temperature and time combination necessary to heat treat infested materials to 100% beetle mortality. Testing was done on infested sample blocks that contained sapwood and bark. The specimens were heated to various temperatures and examined, both through emergence chambers and destructive sampling, for the presence of P. juglandis at any life stage. Results of the study indicate that heat treating black walnut products to 50.1°C at a depth of 3.8 cm (1.5 in.) for 30 minutes will result in 100 percent beetle mortality. As a side product, this study also produced 3,000 board feet of rough-cut lumber. These boards were heat treated and sold, following the protocol developed in this study. This study demonstrates that wood from black walnut trees infected with thousand cankers disease can be effectively heat sterilized and utilized, reducing the need to chip, landfill, or otherwise dispose of the material without economic return.

Efficacy of Five Insecticides Targeting Spring and Fall Populations of Sugarcane Beetle Adults

Summary Sugarcane beetle (Euetheola rugiceps LeConte; Coleoptera: Scarabaeidae) is a pest of turfgrass in the southeastern United States. This study was conducted to evaluate the toxicity of 5 products for sugarcane beetle pest management in managed bermudagrass (Cynodon dactylon L.; Poaceae). Spring and fall populations of sugarcane beetle adults were exposed to 4 active ingredients and combinations (bifenthrin, bifenthrin plus clothianidin, carbaryl, clothianidin, and dinotefuran) under greenhouse conditions. At 7 d after treatment, there were no significant differences among insecticide treatments applied to spring beetles at either a low or a high field rate, although all insecticides caused a significant increase in beetle mortality relative to untreated (control) beetles. In contrast, bifenthrin caused significantly greater control of fall populations at the low field rate compared with other treatments. Target population (spring or fall) appears to have more impact on pesticide efficacy than either...

Unintended effects of the herbicides 2,4-D and dicamba on lady beetles.

Weed resistance to glyphosate and development of new GM crops tolerant to 2,4-dichlorophenoxyacetic acid (2,4-D) and dicamba is expected to lead to increased use of these herbicides in cropland. The lady beetle, Coleomegilla maculata is an important beneficial insect in cropland that is commonly used as an indicator species in safety evaluations of pesticides. Here, we examined the lethal and non-lethal effects of 2,4-D and dicamba active ingredients and commercial formulations to this lady beetle species, and tested for synergistic effects of the herbicides. Second instars of lady beetles were exposed to an experimental treatment, and their mortality, development, weight, sex ratio, fecundity, and mobility was evaluated. Using similar methods, a dose-response study was conducted on 2,4-D with and without dicamba. The commercial formulation of 2,4-D was highly lethal to lady beetle larvae; the LC90 of this herbicide was 13% of the label rate. In this case, the "inactive" ingredients were a key driver of the toxicity. Dicamba active ingredient significantly increased lady beetle mortality and reduced their body weight. The commercial formulations of both herbicides reduced the proportion of males in the lady beetle population. The herbicides when used together did not act synergistically in their toxicity toward lady beetles versus when the chemistries were used independently. Our work shows that herbicide formulations can cause both lethal and sublethal effects on non-target, beneficial insects, and these effects are sometimes driven by the "inactive" ingredients. The field-level implications of shifts in weed management practices on insect management programs should receive further attention.

Dual resistance to lambda-cyhalothrin and dicrotophos in Hippodamia convergens (Coleoptera: Coccinellidae)

Insecticide resistance is usually associated with pests, but may also evolve in natural enemies. In this study, adult beetles of three distinct North American populations of Hippodamia convergens Guérin-Méneville, and the progeny of reciprocal crosses between the resistant and most susceptible population, were treated topically with varying concentrations of lambda-cyhalothrin and dicrotophos. In addition, the LD50s of both insecticides were applied in combination to resistant individuals. The developmental and reproductive performance of each population was assessed in the absence of insecticide exposure to compare baseline fitness. California and Kansas populations were susceptible to both materials, whereas Georgia (GA) beetles exhibited a resistance ratio (RR50) of 158 to lambda-cyhalothrin and 530 to dicrotophos. Inheritance of lambda-cyhalothrin resistance was X-linked, whereas inheritance of dicrotophos resistance was autosomal. Mortality of resistant beetles treated with a mixture of LD50s of both materials was twice that of those treated with lambda-cyhalothrin alone, but not significantly different from those receiving dicrotophos alone. Life history parameters were largely similar among populations, except that Georgia beetles had higher egg fertility relative to susceptible populations. We conclude that the high levels of resistance to lambda-cyhalothrin and dicrotophos in Georgia beetles reflect heavy loads of these insecticides in local environments, most likely the large acreage under intensive cotton cultivation.

Forest disturbance interactions and successional pathways in the Southern Rocky Mountains

The pine forests in the southern portion of the Rocky Mountains are a heterogeneous mosaic of disturbance and recovery. The most extensive and intensive stress and mortality are received from human activity, fire, and mountain pine beetles (MPB; Dendroctonus ponderosae). Understanding disturbance interactions and disturbance-succession pathways are crucial for adapting management strategies to mitigate their impacts and anticipate future ecosystem change. Driven by this goal, we assessed the forest disturbance and recovery history in the Southern Rocky Mountains Ecoregion using a 13-year time series of Landsat image stacks. An automated classification workflow that integrates temporal segmentation techniques and a random forest classifier was used to examine disturbance patterns. To enhance efficiency in selecting representative samples at the ecoregion scale, a new sampling strategy that takes advantage of the scene-overlap among adjacent Landsat images was designed. The segment-based assessment revealed that the overall accuracy for all 14 scenes varied from 73.6% to 92.5%, with a mean of 83.1%. A design-based inference indicated the average producer’s and user’s accuracies for MPB mortality were 85.4% and 82.5% respectively. We found that burn severity was largely unrelated to the severity of pre-fire beetle outbreaks in this region, where the severity of post-fire beetle outbreaks generally decreased in relation to burn severity. Approximately half the clear-cut and burned areas were in various stages of recovery, but the regeneration rate was much slower for MPB-disturbed sites. Pre-fire beetle outbreaks and subsequent fire produced positive compound effects on seedling reestablishment in this ecoregion. Taken together, these results emphasize that although multiple disturbances do play a role in the resilience mechanism of the serotinous lodgepole pine, the overall recovery could be slow due to the vast area of beetle mortality.

Dosage Response Mortality of Japanese Beetle, Masked Chafer, and June Beetle (Coleoptera: Scarabaeidae) Adults When Exposed to Experimental and Commercially Available Granules Containing Metarhizium brunneum.

Field-collected adults of three genera of turf-infesting scarabs, Japanese beetle ( Popillia japonica Newman), June beetles ( Phyllophaga spp.), and masked chafers ( Cyclocephala spp.), were exposed to experimental and commercial granule formulations of the entomopathogenic fungus Metarhizium brunneum (Petch) strain F52 to determine their relative susceptibility. Experimental granules contained microsclerotia produced by liquid fermentation with the ability to produce fresh conidia when rehydrated and commercial granules were Met 52 granular bioinsecticide. All three groups of scarab adults showed a positive dosage response to the fungus when exposed in cups of potting mix treated with the granules. LC 50 values for microsclerotia granules were 1.9 × 10 7 , 7.1 × 10 6 , and 3.2 × 10 6 conidia cup -1 for P. japonica , Phyllophaga spp., and Cyclocephala spp., respectively. LC 50 values for Met 52 granules were 5.9 × 10 7 , 5.1 × 10 7 , and 7.6 × 10 6 conidia cup -1 , respectively. The experimental granules containing microsclerotia show promise as a viable commercial control agent. They can be produced using lower cost fermentation methods and applied at lower dosages (97 g for 100 m 2 as opposed to 489 g per 100 m 2 for Met 52). If M. brunneum is applied to control the aforementioned white grubs, our data indicate the potential for the adult beetles to also be infected as they enter the soil to lay eggs.

Influence of mating and age on susceptibility of the beetle Anoplophora glabripennis to the fungal pathogen Metarhizium brunneum

The age and life history of an insect can influence its susceptibility to pathogens. Reproduction can be costly and may trade off with immunity while it is generally assumed that immunity will decrease with increasing age through a process called immunosenescence. Fungal pathogens are used as biological control agents for a variety of insect pests, and Metarhizium brunneum is being developed to control the Asian longhorned beetle (Anoplophora glabripennis), an invasive wood-borer. Because adult female A. glabripennis take 1–2weeks to mature after eclosion and both sexes can be long-lived, we investigated how age and mating status would influence susceptibility of A. glabripennis to M. brunneum. Young (6.5day-old) unmated, mature (27–33day-old) mated and unmated, and old (57–71day-old) unmated and mated adults were inoculated with a lethal dose of M. brunneum. The presence of M. brunneum in the hemolymph was quantified and beetle mortality was monitored daily. There was a cost to reproduction for mated mature male and female beetles which died a median of 1.6–1.9days earlier than unmated beetles, while there was no effect of mating on susceptibility for old beetles. We found no evidence for immunosenescence in old beetles, as they did not die faster than young or mature beetles. Young unmated males however were more susceptible than mature or old unmated males, while there was no effect of age on susceptibility of unmated females.

The influence of potato endophytes on Leptinotarsa decemlineata endosymbionts promotes mortality of the pest

Plants are exposed to pervasive attack by diverse attackers, such as pathogens and pests. But plants have their own endophytic microflora as well as the attacking insects. These microbiomes contact face to face in the nature. It has been found that the endophytic strain Bacillus subtilis 26D increases mortality of Colorado potato beetles, disturbing the development of insect microsymbionts Enterobacter ssp. and Acinetobacter ssp.

Laboratory Evaluation of Residual Phytotoxicity of Some Plant Powders to the Merchant Grain Beetle, Oritzaephilus mercator Fauvel (Coleoptera: Silvanidae), Infesting Stored Kernels of lrvingia qabonensis.

Investigations were conducted on phytochemical composition and residual toxicity of seven plant powders (which had been stored for 4 months) to the merchant grain beetle, Oryzaephilus mercator Fauvel, infesting kernels of lrvingia gabonensis. Beetle mortality data taken at days 1,3,5 and 7 post-infestation showed that all test plants excluding M myristica caused higher level of beetle mortality than occurred in control. Cashew nut shell, Anacardium occidentale, powder was the most potent (cumulative mean mortality of 52.5 %) matching the efficacy of pirimiphos-methyl, which served as insecticide check in addition to an untreated control. It was followed by powders of J. curcas (35.0 %) and P. guineense (30.2 %), while the least toxic was M. myristica. Mortality value for the latter ( %), though numerically lower, was not significantly different from those of C. citratus ( %) and X. aethiopica ( %). Mean residual toxicity increased with duration of exposure The least number of adults emerged from pirimiphos-methyl treated jars, followed by A. occidentale powder, -while M. myristica was the least potent. Phytochemical analysis revealed varied proportions of typical plant constituents such as phytates, flavonoids, hydrogen cyanides, alkaloids, tannins, oxalates, phenols and saponins some of which are responsible for the residual action of the tested plants.

Effects of Initial Infestation Levels of Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) on Cowpea and Use of Nicotiana tabacum L. Aqueous Extract as Grain Protectant

This study determined the effects of initial infestation of cowpea seeds (Ife brown variety) with different insect densities (0, 2, 4 and 6 pairs per 50 g seeds) of Callosobruchus maculatus (F.) and evaluated the effects of aqueous leaf extract of Nicotiana tabacum L. on C. maculatus in the laboratory. It was observed that adult beetle population increased significantly (p<0.05) with increase in insect density. The increase in population of beetles and corresponding weight loss of the seeds in different levels of infestation showed that the cowpea variety was susceptible to beetle infestation, emergence and survival of progeny. Significantly more adults emerged on higher infestation compared to lower and no infestation. In Nigeria, Nicotiana tabacum L. is a locally available plant, with known insecticidal properties. The plant leaf extract was easily extracted with water and confirmed its effectiveness as a protective agent for stored cowpea seeds. Experiment was conducted to assess the effects of aqueous extracts of N. tabacum at 0, 0.1, 0.2 and 0.3 mL · 50 g−1 cowpea seeds on C. maculatus. Data was recorded and showed varying levels of effectiveness against C. maculatus. Result showed that seed appearance was dependent on levels of insect population, while N. tabacum aqueous extract exerted effects on survival of C. maculatus. Aqueous leaf extract of N. tabacum probably contained some insecticidal properties which might have significantly conferred beetle mortality and reduced beetle emergence leading to a decrease in seed weight loss.

Insecticide Dip Treatments to Prevent Walnut Twig Beetle Colonization of Black Walnut Logs

Abstract The health, sustainability, and commercial viability of eastern black walnut (Juglans nigra) are currently under threat from thousand cankers disease. The disease is caused by an invasive bark beetle species, the walnut twig beetle (Pityophthorus juglandis), and its associated fungal pathogen (Geosmithia morbida). Range expansion of the beetle and pathogen has likely been facilitated by transport of infested walnut forest products. Preventing colonization of these products is crucial to limiting further spread of thousand cankers disease. This study evaluated three insecticides for their ability to induce walnut twig beetle mortality and prevent colonization of black walnut bolts, 3 to 5 cm in diameter, after dip treatment applications. Treatments included 0.003 percent azadirachtin, 15 percent disodium octaborate tetrahydrate (DOT), 0.5 percent permethrin, and water in Trial 1, and 0.013 percent azadirachtin, 30 percent DOT, 0.5 percent permethrin, and water in Trial 2. A total of 40 beetles, 4 beetles per sample, were exposed to treated samples and observed for 120 hours in each trial. Permethrin was the only treatment to achieve 100 percent mortality and prevent all colonization activity. The 30 percent DOT treatment increased mortality compared with the control; however, it did not reduce the mean number of attacks or mean gallery length. Azadirachtin was not effective at either concentration. Results suggest that insecticide dip treatments can prevent walnut twig beetles from colonizing cut black walnut logs. Treatments could be used in conjunction with phytosanitation to help prevent further spread of thousand cankers disease while allowing for the continued transport of bark-on walnut forest products.

A Review of Organic Lawn Care Practices and Policies in North America and the Implications of Lawn Plant Diversity and Insect Pest Management

There are ≈40 million acres of turfgrass lawns throughout the United States, most of which are managed under chemical-intensive pest and fertilizer programs. “Organic lawn care” is being adopted more widely; however, unlike the formally defined policies and regulations that govern organic agriculture, the label organic lawn management has not been formally defined and is used to describe a variety of practices. Neighborhoods, cities, states, and provinces across North America are adopting policies regulating the use of pesticides and fertilizers in the landscape. In addition, a small but growing number of public institutions and individual consumers are successfully adopting alternative lawn care methods, including organic lawn care. Although perceived as environmentally friendly, the effects of organic management on insect diversity and pest management remain understudied. Organic lawn management may lead to increased lawn plant diversity, which in agroecosystems has enhanced ecological services provided by beneficial insect species. Effects of vegetative diversity on lawn pest management are less clear. Vegetative complexity and increased plant diversity in urban landscapes may enhance insect predator efficacy. The diversity of predatory insects varies between turfgrass varieties in response to prey populations. Mortality of insectivorous and granivorous ground beetles (Carabidae) while not directly impacted by pest management programs in turfgrass may be indirectly impacted by a reduction in the prevalence of plant species that provide alternative food resources. Previous studies have focused on herbivorous insects as well as predatory and parasitic insects that feed on them. Future studies should assess how lawn plant diversity resulting from organic management practices might impact insect communities in turfgrass.

Phenotypic and molecular characterization of the causal agent of chafer beetle mortality in the wheat fields of the Kurdistan province, Iran

AbstractWe report the first case of chafer beetle [Anisoplia austriaca(Herbst 1783)] mortality caused byActinomucor elegansvar.elegansin wheat fields of the Kurdistan province, Iran. For three years, dead larvae ofAnisoplia austriacawere collected from wheat fields of the Kurdistan province. Similar isolates of a fast-growing fungus were recovered from all samples. The fungal isolates were identified asA. elegansvar.elegansbased on morphological and cultural characteristics. The identity of the species was further confirmed using sequence data of the ITS (Internal Transcribed Spacer) region of ribosomal DNA. Koch’s postulates were fulfilled by the inoculation of the larvae ofA. austriacaandGalleria mellonella(Linnaeus, 1758) (as the model insect) using the spore suspension ofA. elegansvar.elegans. The viability of sporangiospores was evaluated using a spore dilution technique on germination medium. The results on the pathogenicity (100% mortality inA. austriacalarvae) and viability tests (germination: 95.45%) demonstrated thatA. elegansvar.eleganscan be considered as a potential biocontrol agent against the chafer beetle. Field experiments are still required to evaluate the capacity ofA. elegansas a biological control agent.

Assessment of the impact of symbiont Ophiostomatales (Fungi) on mountain pine beetle (Coleoptera: Curculionidae) performance on a jack pine (Pinaceae) diet using a novelin vitrorearing method

AbstractA novel “rearing-tube” method was developed and used to investigate the performance of mountain pine beetle (MPB),Dendroctonus ponderosaeHopkins (Coleoptera: Curculionidae: Scolytinae), with its three main ophiostomatalean fungal symbionts,Grosmannia clavigera(Robinson-Jeffrey and Davidson) Zipfel, de Beer, and Wingfield (Ophiostomataceae),Ophiostoma montium(Rumbold) von Arx (Ophiostomataceae), andLeptographium longiclavatumLee, Kim, and Breuil (Ophiostomataceae). Transparent glass tubes filled with sterile ground jack pine (Pinus banksianaLambert; Pinaceae) phloem and sapwood (9:1 ratio) were used to rear MPB from egg to adult with each fungus under controlled environmental conditions. Mountain pine beetle mortality was higher and development longer in fungus-free controls compared to fungal treatments. Among fungal treatments, insects developed faster, constructed shorter larval galleries, and had fewer supernumerary instars withL. longiclavatum.Insect survival was not affected by fungal treatments. Hyphal extension through the rearing medium was fastest forL. longiclavatum. Phloem nitrogen was reduced significantly by the presence ofL. longiclavatum.Results support the hypothesis that ophiostomatalean symbionts provide benefits to MPB. The rearing-tube method is useful to tease apart confounding interspecific interactions between bark beetles and symbiotic fungus species.