Quick Sex-Determination of the Asiatic Garden Beetle, Maladera castanea (Coleoptera: Scarabaeidae)

The orientation of the posterior abdominal sternite and pygidium allows for quick sex-determination of Maladera castanea (Arrow) (Coleoptera: Scarabaeidae: Melolonthinae) adults with a dissecting microscope or hand lens. Maladera castanea (the Asiatic garden beetle) is an emerging pest of field crops and this information will help researchers to conduct studies more easily on its biology and ecology

One gene versus two: A regional study on the efficacy of single gene versus pyramided resistance for soybean aphid management

Citation: McCarville, M. T., M. E. O’Neal, B. D. Potter, K. J. Tilmon, E. M. Cullen, B. P. McCornack, J. F. Tooker, and D. A. Prischmann-Voldseth. 2014. “One Gene Versus Two: A Regional Study on the Efficacy of Single Gene Versus Pyramided Resistance for Soybean Aphid Management.” Journal of Economic Entomology 107 (4): 1680–87. https://doi.org/10.1603/EC14047.The soybean aphid (Aphis glycines Matsumura) is a threat to soybean production in the Midwestern United States. Varieties containing the Rag1 soybean aphid resistance gene have been released with limited success in reducing aphid populations. Furthermore, virulent biotypes occur within North America and challenge the durability of single-gene resistance. Pyramiding resistance genes has the potential to improve aphid population suppression and increase resistance gene durability. Our goal was to determine if a pyramid could provide improved aphid population suppression across a wide range of environments.Weconducted a small-plot Þeld experiment across seven states and three years. We compared soybean near-isolines for the Rag1 or Rag2 gene, and a pyramid line containing both genes for their ability to decrease aphid pressure and protect yield compared with a susceptible line. These lines were evaluated both with and without a neonicitinoid seed treatment. All aphid-resistant lines signiÞcantly decreased aphid pressure at all locations but one. The pyramid line experienced lower aphid pressure than both single-gene lines at eight of 23 location-years. Soybean aphids signiÞcantly reduced soybean yield for the susceptible line by 14% and for both single-gene lines by 5%; however, no signiÞcant yield decrease was observed for the pyramid line. The neonicitinoid seed treatment reduced plant exposure to aphids across all soybean lines, but did not provide signiÞcant yield protection for any of the lines. These results demonstrate that pyramiding resistance genes can provide sufÞcient and consistent yield protection from soybean aphid in North America

Preliminary Feeding Assessments for Asiatic Garden Beetle, Maladera formosae (Coleoptera: Scarabaeidae), Grubs and Adults

The Asiatic garden beetle, Maladera formosae (Brenske) (syn. M. castanea [Arrow]), is an annual white grub species that was unintentionally introduced from east Asia to North America in 1921 in New Jersey, and has since spread to at least 25 states and two Canadian provinces. Grub populations in the Great Lakes region have recently emerged as significant early-season pests of field crops, particularly field corn, grown in sandy soils. Asiatic garden beetle has also recently become established in other regions including Alabama. Prior research on this species was conducted mainly in the 1930s in horticultural and turfgrass systems of New York and New Jersey. In this study, we document Asiatic garden beetle preference and performance on previously un-investigated food resources, in populations from Ohio and Alabama. The objectives of these experiments were to a) understand if grubs show preference to potential diet choices present in a typical Ohio corn-soybean rotation, and gained mass when provided a single diet, and b) to conduct a preliminary assessment on the development, survival, and fecundity of field-collected beetles on different diets present in suburban Alabama. In general, grubs were more likely to be found at corn and marestail and they significantly increased in body mass when subjected to those diets. However, they were also able to survive and gain mass when provided soybean, crop residues or bare soil. Adults consumed more rose flower petals than floral tissue of white clover and Queen Anne’s lace. In no-choice trials, only females that were fed a diet of rose petals laid eggs, and diet consumption rates were similar among males and females. These findings provide insight into the feeding behaviors of Asiatic garden beetle grubs and adults collected from novel environments

Extended Sentinel Monitoring of Helicoverpa zea Resistance to Cry and Vip3Aa Toxins in Bt Sweet Corn: Assessing Changes in Phenotypic and Allele Frequencies of Resistance

Transgenic corn and cotton that produce Cry and Vip3Aa toxins derived from Bacillus thuringiensis (Bt) are widely planted in the United States to control lepidopteran pests. The sustainability of these Bt crops is threatened because the corn earworm/bollworm, Helicoverpa zea (Boddie), is evolving a resistance to these toxins. Using Bt sweet corn as a sentinel plant to monitor the evolution of resistance, collaborators established 146 trials in twenty-five states and five Canadian provinces during 2020–2022. The study evaluated overall changes in the phenotypic frequency of resistance (the ratio of larval densities in Bt ears relative to densities in non-Bt ears) in H. zea populations and the range of resistance allele frequencies for Cry1Ab and Vip3Aa. The results revealed a widespread resistance to Cry1Ab, Cry2Ab2, and Cry1A.105 Cry toxins, with higher numbers of larvae surviving in Bt ears than in non-Bt ears at many trial locations. Depending on assumptions about the inheritance of resistance, allele frequencies for Cry1Ab ranged from 0.465 (dominant resistance) to 0.995 (recessive resistance). Although Vip3Aa provided high control efficacy against H. zea, the results show a notable increase in ear damage and a number of surviving older larvae, particularly at southern locations. Assuming recessive resistance, the estimated resistance allele frequencies for Vip3Aa ranged from 0.115 in the Gulf states to 0.032 at more northern locations. These findings indicate that better resistance management practices are urgently needed to sustain efficacy the of corn and cotton that produce Vip3Aa

Assessing and Augmenting Biological Control of Tarnished Plant Bug in New York Strawberries

NYS IPM Type: Project ReportThe goal of this project is to evaluate the potential for encouraging long term, stable biological control interactions between the tarnished plant bug, Lygus lineolaris, and an introduced parasitoid wasp, Peristenus digoneutis. We are investigating biological control of the tarnished plant bug in strawberry

Assessing and Augmenting Biological Control of Tarnished Plant Bug in New York Strawberries

NYS IPM Type: Project ReportThe objective for this project is to investigate biological control of the tarnished plant bug in New York strawberries by the introduced parasitoid wasp Peristenus digoneutis. The first project goal for 1998 was to evaluate the impact of companion plantings of alfalfa on parasitism rates in nearby strawberries. The field experiment aimed at this goal was unsuccessful because plots did not survive overwintering in 1997-1998. The second goal was to continue a sampling program for parasitoids of tarnished plant bug in New York strawberries, including day-neutral varieties

Assessing and Augmenting Biological Control of Tarnished Plant Bug in New York Strawberries

NYS IPM Type: Project ReportThe general objective of this project is to investigate biological control of the tarnished plant bug in New York strawberries by the introduced parasitoid wasp Peristenus digoneutis. The first project goal for 1999 was to evaluate the impact of companion plantings of alfalfa on parasitism rates in nearby strawberries. Sample have been collected from this experiment, but they have not been analyzed yet, and no results are available. The second project goal was to evaluate P. digoneutis activity in New York strawberries (and other plant habitats) near the edge of the known P. digoneutis range and beyond

Infestation ratings database for soybean aphid on early-maturity wild soybean lines

Soybean aphid (Aphis glycines Matsumura; SA) is a major invasive pest of soybean [Glycine max (L.) Merr.] in northern production regions of North America. Although insecticides are currently the main method for controlling this pest, SA-resistant cultivars are being developed to sustainably manage SA in the future. The viability of SA-resistant cultivars may depend on identifying a diverse set of resistance genes from screening various germplasm sources, including wild soybean (Glycine soja Siebold and Zucc.), the progenitor of cultivated soybean. Data consisted of infestation ratings generated for a total of 337 distinct plant introduction lines of wild soybean that were exposed to avirulent SA biotype 1 for 14 d in 25 separate tests. Individual plants of the test lines were given a common rating by two researchers, based on a rating scale that progressed from 1=0 to 50, 2=51 to 100, 3=101 to 150, 4=151 to 200, 5=201 to 250, and 6 with >250 SA per test plant. Public dissemination of this dataset will allow for further analyses and evaluation of resistance among the test lines. Keywords: Crop ancestors, Resistance screening, Host-plant resistanc

Felsenstein's“one-allele model”of speciation: The role of philopatry in the initial stages of host plant mediated reproductive isolation in Enchenopa binotata

The study of speciation genetics is primarily concerned with identifying the genetic traits that allow divergent selection to overcome the homogenizing effects of gene flow. Felsenstein reviewed this race between gene flow and selection, concluding that speciation with gene flow was unlikely under a “two-allele model” (where two traits were necessary for reproductive isolation) but that divergence could occur quite easily under a “one-allele model.” Despite this finding, much of the sympatric speciation research involving phytophagous insects has relied on a two-trait model, where insects evolve both preferences for and increased performance on novel host plants. Philopatry (a tendency to remain where one was born) is known to occur in phytophagous insects and is a single trait isolation mechanism. However, it is traditionally invoked as simply augmenting reproductive isolation. Species in the Enchenopa binotata complex are believed to have speciated in sympatry. They exhibit host plant prefe­rences, host specific performance advantages and strong philopatry. We experimentally shifted E. binotata to evolutionarily novel host plants. Previous research has demonstrated that the experimental population of insects possesses genetic variation in prefe­rence and performance to the novel host. The degree of philopatry at mating and egg-laying was assayed for the first four years under full choice conditions. Host plant preference and performance was assayed after eight years. Philopatry was an immediate and strong isolating mechanism, while preference for and performance on the novel host lagged. We therefore suggest that philopatry may be a more important mechanism in the early stages of a host shift than previously believed [Current Zoology 59 (5): 658-666, 2013]