|Lopez, Juan DE Dios|
Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: January 11, 2002
Publication Date: N/A
Interpretive Summary: Integrated pest management (IPM) should lead to decreased insecticide use and application of more specific and safer insecticides. Emamectin benzoate is a relatively new insecticide that has demonstrated high compatibility within IPM, but its conventional use requires that it be broadcast over areas needing treatment to control egg and larval stages of worm pests. Targeting adult pests that are highly mobile and responsive to feeding attractants/stimulants mixed with insecticides could reduce the size of specific treated areas. Emamectin benzoate mixed with a sugar solution was found to be highly toxic when ingested by the adults, but it did not kill the adults very quickly. At and above concentrations that killed the adults, emamectin benzoate was not found to interfere with adult feeding. Compared to females fed the sugar solution only, emamectin benzoate significantly reduced larval hatch of eggs laid and egg numbers were reduced only at concentrations approaching those that were lethal. Development of larvae hatching from eggs laid by treated females was also adversely affected. These results indicate that emamectin benzoate has high potential for use in adult control of corn earworm/bollworm and possibly other worm pests.
Technical Abstract: Emamectin benzoate was evaluated for its potential as an ingested toxicant and reproduction inhibitor in mixtures with 2.5 M sugar solution on a ppm AI weight:volume basis for bollworm (BW), Helicoverpa zea (Boddie), adult control. LC90s (95 percent CLs) for sex pheromone trap-captured males after 48 and 72 h were 1.3566 (0.8590-6.7833) and 1.3411 (0.7639-8.8511) ppm, respectively. Mean lethal times (LTs) in h were 39.3 for 1.3 ppm, 24 for 6.5 ppm, 12.6 for 13 ppm, 10.2 for 32.5 ppm and 9 for 65 ppm; LTs at 13 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 male gustatory or proboscis extension responses. Therefore emamectin benzoate does not inhibit feeding. When laboratory- reared females were fed emamectin benzoate at concentrations of 0.0125, 0.025, 0.05, 0.075 and 0.1 ppm and mated with untreated males, fecundity was not significantly affected, but percent larval hatch was significantly reduced at concentrations of 0.05 ppm and above. At concentrations of 0, 0.05, 0.1, 0.2, 0.6 and 1.0 ppm, fecundity was significantly reduced at concentrations above 0.6 ppm and percent larval hatch of eggs was significantly reduced as well at concentrations of 0.1 ppm and above. Reduction in larval hatch at 0.05 ppm was not significantly different from 2.5 M sucrose alone. Data suggest that emamectin benzoate could be a useful toxicant and reproduction inhibitor in an attracticide formulation at the concentrations tested in this study.