Effect of abamectin on feeding response, mortality, and reproduction of adult bollworm (Lepidoptera: Noctuidae)

Authors: Lopez, Juan De Dios; Latheef, Mohamed - Ab; Hoffmann, Wesley

Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/28/2011
Publication Date: 6/1/2011
Citation: Lopez, J., Latheef, M.A., Hoffmann, W.C. 2011. Effect of abamectin on feeding response, mortality, and reproduction of adult bollworm (Lepidoptera: Noctuidae). Southwestern Entomologist. 36:155-166.

Interpretive Summary: Bollworms are a serious pest of cotton throughout the United States and must be controlled due to the economic damage they cause. Abamectin is derived from a fermentation process with soil microorganisms and is both a contact and ingested poison for many caterpillar species, such as bollworms. Studies were conducted to characterize the effect of abamectin on toxicity, proboscis extension, ingestion, reproduction, and survival of the offspring of bollworms when the abamectin was integrated into a feeding stimulant solution. Data suggest that this insecticide is a useful toxicant in an attracticide formulation for use against the suppression of bollworm on field crops. The method of application of abamectin, via ingestion, provides an additional tool for farmers and researchers to control and mitigate damage to cotton caused by bollworms.

Technical Abstract: Newly eclosed adult bollworm, Helicoverpa zea (Boddie) feeds on carbohydrate sources from plants and other exudates prior to dispersal and reproduction. The objective of this study was to determine whether or not this nocturnal behavior could be exploited for pest management by presenting the insect with a feeding stimulant mixed with a toxicant. Commercially-formulated abamectin (Agri-mek 0.15EC) was evaluated as a toxicant mixed with a 2.5 M sucrose solution against bollworm adults, relative to toxicity, mortality, gustatory and proboscis extension response and reproduction. Sublethal doses of abamectin at 0.05, 0.10, 0.25 and 0.50 mg/litre fed to laboratory-reared females within 24 h of emergence significantly reduced percentage hatch of eggs compared with females fed sucrose only. Mating frequency was significantly inhibited at 0.25 mg/litre and above. Regression of log numbers of eggs oviposited on log concentrations of abamectin showed that egg production declined significantly, and was reduced to zero at 1.00 mg/litre, and explained up to 91% of the variance in the model. Although the reduction in percentage hatch of eggs was less impressive than expected, the dramatic decline in fecundity and inhibition of mating frequency does show promise for the use of abamectin as a toxicant for suppression of bollworm adults. Although this research was primarily based upon investigations in the laboratory, we posit that field studies should be conducted to see if actual suppression can be obtained.