Using comparative genomics to develop a molecular diagnostic for the identification of an emerging pest Drosophila suzukii.

Drosophila suzukii (Spotted Wing Drosophila) has recently become a serious invasive pest of fruit crops in the USA, Canada, and Europe, leading to substantial economic losses. D. suzukii is a direct pest, ovipositing directly into ripe or ripening fruits; in contrast, other Drosophilids utilize decaying or blemished fruits and are nuisance pests at worst. Immature stages of D. suzukii are difficult to differentiate from other Drosophilids, posing problems for research and for meeting quarantine restrictions designed to prevent the spread of this pest in fruit exports. Here we used a combined phylogenetic and bioinformatic approach to discover genetic markers suitable for a species diagnostic protocol of this agricultural pest. We describe a molecular diagnostic for rapid identification of single D. suzukii larva using multiplex polymerase chain reaction. Our molecular diagnostic was validated using nine different species of Drosophila for specificity and 19 populations of D. suzukii from different geographical regions to ensure utility within species.

The Effects of Kernel Feeding by Halyomorpha halys (Hemiptera: Pentatomidae) on Commercial Hazelnuts.

Halyomorpha halys Stål, the brown marmorated stink bug (Hemiptera: Pentatomidae), is an invasive pest with established populations in Oregon. The generalist feeding habits of H. halys suggest it has the potential to be a pest of many specialty crops grown in Oregon, including hazelnuts, Corylus avellana L. The objectives of this study were to: 1) characterize the damage to developing hazelnut kernels resulting from feeding by H. halys adults, 2) determine how the timing of feeding during kernel development influences damage to kernels, and 3) determine if hazelnut shell thickness has an effect on feeding frequency on kernels. Adult brown marmorated stink bugs were allowed to feed on developing nuts for 1-wk periods from initial kernel development (spring) until harvest (fall). Developing nuts not exposed to feeding by H. halys served as a control treatment. The degree of damage and diagnostic symptoms corresponded with the hazelnut kernels' physiological development. Our results demonstrated that when H. halys fed on hazelnuts before kernel expansion, development of the kernels could cease, resulting in empty shells. When stink bugs fed during kernel expansion, kernels appeared malformed. When stink bugs fed on mature nuts the kernels exhibited corky, necrotic areas. Although significant differences in shell thickness were observed among the cultivars, no significant differences occurred in the proportions of damaged kernels based on field tests and laboratory choice tests. The results of these studies demonstrated that commercial hazelnuts are susceptible to damage caused by the feeding of H. halys throughout the entire period of kernel development.

Comparing effects of insecticides on two green lacewings species, Chrysoperla johnsoni and Chrysoperla carnea (Neuroptera: Chrysopidae).

This study compared lethal and sublethal effects of five insecticides, chlorantraniliprole, cyantraniliprole, spinetoram, novaluron, and lambda-cyhalothrin, on adult and second instars of two green lacewing species, Chrysoperla carnea (Stephens) and Chrysoperla johnsoni Henry, Wells and Pupedis (Neuroptera: Chrysopidae) in the laboratory. Formulated pesticides were tested using concentrations equivalent to the high label rate dissolved in 378.5 liters of water. Novaluron and lambda-cyhalothrin were toxic to larvae and no treated larvae survived to the adult stage. Larva to adult survival was reduced in chlorantraniliprole, cyantraniliprole, and spinetoram treatments. Larva to adult developmental time and sex ratio were not different among the treatments within a species. Chlorantraniliprole, cyantraniliprole, spinetoram, and lambda-cyhalothrin treatments were highly toxic to adults of both species. C. johnsoni females had lower fecundity than C. carnea females in the control. Fecundity of females was similar in the control and novaluron treatment within each species. However, fertility and egg viability were negatively impacted for both species when females were treated with novaluron. C. carnea females had higher fertility and egg viability than C. johnsoni females in the control. Adults of both species had similar longevity in the control and novaluron treatment and adult longevity was not gender specific. All insecticides tested were toxic to C. johnsoni and C. carnea either at the immature or adult stage or both. Results of this study demonstrate a similarity between C. johnsoni and C. carnea for pesticide toxicity irrespective of their varied geographical distributions.

Laboratory bioassays to estimate the lethal and sublethal effects of various insecticides and fungicides on Deraeocoris brevis (Hemiptera: Miridae).

This laboratory bioassay focused on lethal and sublethal effects of five insecticides (chlorantraniliprole, cyantraniliprole, spinetoram, novaluron, and lambda-cyhalothrin) and two fungicide treatments (sulfur and a mixture of copper hydroxide and mancozeb) on the predatory mired bug, Deraeocoris brevis (Uhler) (Hemiptera: Miridae) using second instars and adult males and females. Formulated pesticides were tested using concentrations that were equivalent to the high label rate (1x) (high rate) and 1/10th of that amount (0.1x) (low rate) dissolved in 378.5 liters of water. Lambda-cyhalothrin was highly toxic to D. brevis nymphs and adults at both rates, whereas both rates of novaluron were highly toxic to nymphs. Cyantraniliprole, chlorantraniliprole, and novaluron were less toxic to adults, and chlorantraniliprole and spinetoram were less toxic to nymphs. Both rates of spinetoram caused significant mortality to adults. Fecundity of adult females was affected negatively by the high rates of either novaluron or spinetoram, whereas the fertility was affected only by the high rate of novaluron. The high rate of spinetoram reduced survival of nymphs. Adults treated with spinetoram had reduced longevity. Cyantraniliprole caused some mortality to nymphs and affected their survival. Both rates of sulfur were toxic to nymphs and affected emergence to adults. The mixture of copper hydroxide and mancozeb was less toxic to D. brevis. Neither adult longevity nor sex ratio was affected by the fungicides. The r values for D. brecis treated with lambda-cyhalothrin, novaluron, spinetoram, and sulfur were low, indicating that these products may have negative impact on population growth.

Sex-related response to organophosphorus and carbamate insecticides in adult Oriental fruit moth, Grapholita molesta.

During the development of a resistance-monitoring bioassay that uses males as the life-stage tested, the relationship of adult female and male susceptibility of Grapholita molesta to different classes of insecticides was investigated. Preliminary results indicated that more males survived diagnostic doses of azinphos-methyl than females. Additional research revealed that, although the body mass of adult male G molesta was only 69% of that of female moths (5.67 and 8.20 mg, respectively), their LC50 values were 2.6, 4.1 and 10.3 times higher than those of females for azinphosmethyl, malathion and parathion-methyl, respectively. However, female G molesta moths were more tolerant to methomyl than were male moths. There was no indication that this sex-related response occurred in G molesta larvae. The results presented here raise concerns regarding the use of pheromone traps for determining whether insecticide treatments are required and as part of resistance monitoring programs.

Sex-related differences in the tolerance of Oriental fruit moth (Grapholita molesta) to organophosphate insecticides.

In vivo toxicity assays have shown that organophosphate insecticides are less toxic to male than to female Oriental fruit moths Grapholita molesta. While male moths have higher levels of acetylcholinesterase and general esterase activities, female moth acetylcholinesterase enzymes are less sensitive to aromatic and aliphatic organophosphates than male enzymes. Elevated esterase and acetylcholinesterase activities in male moths explain their greater tolerance to aromatic and aliphatic organophosphates. Male and female acetylcholinesterase enzymes are equally tolerant to heteroaromatic organophosphates, the most widely used of this class of insecticides in G molesta control. This observation, in contrast to the greater sensitivity of male acetylcholinesterases to aromatic and aliphatic organophosphates, shows the potential for the evolution of insensitive target sites in male moths, which would increase male G molesta tolerance to these insecticides. Significant sex-linked differences in insecticide tolerance have not been reported previously in lepidopterans. The practical implications of the observed differences in tolerance in male and female G molesta question the practice of using pheromone traps to monitor populations of these moths in orchards.

Susceptibility of male oriental fruit moth (Lepidoptera: Tortricidae) populations from New Jersey apple orchards to azinphosmethyl.

Toxicological responses to azinphosmethyl of male Oriental fruit moth, Grapholita molesta (Busck), from five commercial orchards in which control failures had occurred were examined for azinphosmethyl resistance and for potential resistance mechanisms by using topical pheromone trap bioassay and compared with a reference population that had no history of control failure and had received little selection pressure. The 1998 field survey indicated moderate level of resistance to azinphosmethyl (2.7-4.1-fold); slopes of regressions lines (2.47-2.76) indicate genetically heterogeneous populations. An approximate twofold decline was observed between the fourth flight of 1998 and the first flight of 1999, suggesting the presence of unstable resistance in moths collected from these study sites. The 1999 field surveys indicated lower levels of tolerance to azinphosmethyl. The resistance ratios ranged from 1.17 to 1.86 during the first flight of 1999 and 1.24-2.64 during the fourth flight of 1999. Steep slopes of the concentration-response lines during 1999 season indicated the presence of genetically homogeneous populations with some exceptions. A 1.5-2.0-fold increase was observed between the first and fourth flights of 1999, indicating that resistance can build up during the growing season. S,S,S,-tri-n-butyl phosphorotrithioate (DEF), but not piperonyl butoxide, significantly enhanced the toxicity of azinphosmethyl, suggesting that enhanced metabolism by esterases is involved in the tolerance of azinphosmethyl in moths collected from these study sties.

Entomopathogenic nematodes to control black vine weevil (Coleoptera: Curculionidae) on strawberry.

We investigated the potential of heterorhabditid nematodes to control larvae of the black vine weevil, Otiorhynchus sulcatus (F.), in 2 field experiments in commercial strawberry plantings. In both experiments, nematodes were applied directly onto the straw mulch, or onto the soil after temporary removal of the mulch. Heterorhabditis marelatus Lui & Berry (Rhabditida: Heterorhabditidae) reduced numbers of weevil larvae and the percentage of plants infested in both experiments, irrespective of straw removal. In the 1st field experiment, a sponge-packed H. marelatus formulation produced lower numbers of O. sulcatus larvae per strawberry plant (mean O. sulcatus larvae per plant = 0.7) and proportion of infested plants (42%) compared with a vermiculite formulation (mean O. sulcatus larvae per plant = 1.8, proportion infested plants 67%) and an untreated control (mean O. sulcatus larvae per plant = 1.9, proportion infested plants 75%). In the first 2 wk after application, more H. marelatus were found in soil samples collected from plots treated with sponge-packed nematodes, than from plots treated with vermiculite-formulated nematodes. In the 2nd field experiment, sponge-packed formulations of H. bacteriophora Poinar (Rhabditida: Heterorhabditidae) and H. marelatus were tested. H. marelatus caused a reduction in both numbers of weevil larvae (mean O. sulcatus larvae per plant = 0.1) and proportion of infested plants (9%) but H. bacteriophora did not (mean O. sulcatus larvae per plant = 0.45, proportion infested plants 34%). More H. bacteriophora were recovered from soil samples than H. marelatus during the first 7 d of this experiment. However, laboratory studies revealed no difference in the persistence of these 2 nematodes in sand.