Susceptibility of Bagrada hilaris (Hemiptera: Pentatomidae) to insecticides in laboratory and greenhouse bioassays

Authors: PALUMBO, JOHN - University Of Arizona; PRABHAKER, NILIMA - University Of California; REED, DARCY - University Of California; PERRING, THOMAS - University Of California; Castle, Steven; HUANG, TA-L - University Of Arizona

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/29/2014
Publication Date: 3/6/2015
Publication URL: http://handle.nal.usda.gov/10113/61581
Citation: Palumbo, J.C., Prabhaker, N., Reed, D.A., Perring, T.M., Castle, S.J., Huang, T. 2015. Susceptibility of Bagrada hilaris (Hemiptera: Pentatomidae) to insecticides in laboratory and greenhouse bioassays. Journal of Economic Entomology. 108:672-682.

Interpretive Summary: The bagrada bug (Bagrada hilaris) is an invasive insect pest of North America that was first discovered in southern California in 2008. By the following year, brassica crops such as broccoli and cauliflower were being attacked during the fall growing season in the lower desert agricultural valleys of Arizona and California. Feeding damage caused by the bagrada bug occurs primarily in young brassica crops, often before seedling plants produce their first true leaves. The source of attacking bagrada bugs and the distance they travel to the young crops is usually unknown as they seem to materialize in large numbers only when brassica crops are present. Preemptive management of a dispersed bagrada bug population prior to planting brassica crops is thus impractical and generally requires that vulnerable young brassica crops be protected by insecticide treatments soon after they emerge from the ground. The present study was conducted to evaluate relative toxicities of several commercial products belonging to ten different classes of insecticides. In addition, baseline responses of bagrada bugs representing various geographical populations were determined for these insecticides over a two year period. The insecticide susceptibility data generated in the controlled environments of the laboratory and greenhouse expands on efficacy data collected from the field. Both approaches are essential to the development of successful bagrada bug management that knowledgeably incorporates insecticide treatments when necessary for effective and sustainable control of crop infestations.

Technical Abstract: Field-collected populations of Bagrada hilaris (Burmeister) from Coachella Valley, CA, Imperial Valley, CA, Riverside, CA and Yuma Valley, AZ, were evaluated for susceptibility to several active ingredients representing ten classes of insecticide chemistry. Both leaf-spray and leaf-dip bioassays were used to test foliar insecticides against B. hilaris while a systemic uptake bioassay compared relative toxicities of systemic insecticides. The toxicity data determined for a population from Coachella Valley, CA using the leaf-spray bioassay showed that chlorpyrifos was the most potent insecticide against B. hilaris followed by dinotefuran and bifenthrin. There was a 37-fold variation in toxicity between chlorpyrifos, the most active compound, compared to the least effective insecticide, cyantraniliprole. Of the five products tested in the leaf-dip bioassay, the pyrethroids and chlorpyrifos had the most contact insecticidal activity and dinotefuran was the least toxic contact insecticide, but none of the compounds differed significantly across the three years or B. hilaris populations evaluated. Toxicity of dinotefuran in soil systemic bioassays was significantly greater than that of two other neonicotinoids, and the anthrillic diamide. Mortality of B. hilaris, along with feeding damage and plant growth on insecticide treated plants in greenhouse trials, were consistent with the laboratory bioassays and suggest adults are primarily susceptible to compounds with strong contact activity such as pyrethroids, organophosphates and carbamates. Among neonicotinoids, dinotefuran caused low mortality, but did protect plants from B. hilaris feeding damage and prevented significant reductions in plant growth comparable to pyrethroids. The range of responses to tested insecticides indicates that not all novel chemistries are effective against B. hilaris. The susceptibility data established by laboratory and greenhouse bioassays can be used as a baseline to monitor for development of resistance in field populations of B. hilaris.