EFFECT OF EMAMECTIN BENZOATE ON FEEDING RESPONSE, MORTALITY AND REPRODUCTION OF ADULT BOLLWORM

摘要

Emamectin benzoate was evaluated for its potential as an ingested toxicant and reproduction inhibitor in mixtures with 2.5 M sugar solution as a feeding stimulant on a ppm AI weight:volume basis for bollworm (BW), Helicoverpa zea (Boddie), adult control. When emamectin benzoate was mixed with 2.5 M sucrose and ingested by sex pheromone trap-captured males, LC_(90)s (95 percent Confidence Limits) after 48 and 72 h were 1.3566 (0.8590-6.7833) and 1.3411 (0.7639-8.8511) ppm, respectively; these valueswere not significantly different based on the presence of overlap in the 95 percent CLs. Mean lethal times (LTs) in h were 39.3 for 1.3 ppm (1X LC_(90)), 24 for 6.5 ppm (5X), 12.6 for 13 ppm (10X), 10.2 for 32.5 ppm (25X) and 9 for 65 ppm (50X); LTs at13 ppm and greater were not significantly different from one another and these values were significantly faster than those at 1.3 and 6.5 ppm. Compared to many insecticides evaluated earlier, emamectin benzoate has extremely high oral toxicity and is slow- acting. Compared to 2.5 M sucrose alone, emamectin benzoate at 1.3, 6.5, 13, 32.5 and 65 ppm did not significantly reduce gustatory response of sex pheromone trap-captured males. Similarly, proboscis extension response of sex pheromone trap-capturedmales to emamectin benzoate at lethal concentrations up to 200 ppm (153.8X LC90) was not significantly different when compared to 2.5 M sucrose alone. These results indicate that emamectin benzoate does not inhibit feeding. When laboratory-reared femaleswere fed emamectin benzoate at concentrations of 0.0125, 0.025, 0.05, 0.075 and 0.1 ppm in 2.5 M sucrose and mated with untreated males, fecundity was not significantly affected, but percent larval hatch of eggs was significantly reduced at concentrations of 0.05 ppm and above during 3 consecutive days when compared to females fed only 2.5 M sucrose alone. When laboratory-reared females were fed emamectin benzoate at concentrations of 0, 0.05, 0.1, 0.2, 0.6 and 1.0 ppm and mated with untreated males, fecundity was significantly reduced at concentrations above 0.6 ppm and percent larval hatch of eggs was also significantly reduced at concentrations of 0.1 ppm and above for all 3 days of evaluations when compared to females fed 2.5 M sucrose alone. Reduction in larval hatch at 0.05 ppm was not significantly different from 2.5 M sucrose alone during all 3 days of evaluations. Mating frequency of laboratory-reared females was not significantly influenced by ingestion of emamectin benzoate. The frequencyof larvae hatching from eggs oviposited by treated females found either alive or dead during development to the pupal stage was not independent of emamectin benzoate concentrations and suggests that the larval survival to the pupal stages was significantly influenced by ingestion of emamectin benzoate by laboratory-reared females. Data suggest that emamectin benzoate could be a useful toxicant and reproduction inhibitor in an attracticide formulation at the concentrations tested in this study.