|Lopez, Juan DE Dios|
Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: January 8, 2001
Publication Date: N/A
Technical Abstract: Abamectin (Agri-Mek or Zephyr 0.15EC) was evaluated in the laboratory for its potential use as a toxicant or biologically-active material when combined with a feeding stimulant for adult control of bollworm, Helicoverpa zea (Boddie) using a feeding-based approach. Abamectin when mixed with 2.5 M sucrose (ppm ai wt:vol) was evaluated for effects on feeding response and mortality [lethal concentration (LC) and lethal time (LT)] of sex pheromone trap-captured males. Feeding responses and LTs were determined at 1, 2, 5, 10, 25, and 50 times the 48-h LC90 and 1,000 ppm concentrations. Sublethal abamectin concentrations in 2.5 M sucrose of 0.05, 0.1, 0.25, 0.5 and 1.0 ppm were then fed to laboratory-reared females which were paired individually with untreated males and the effect on mating frequency, fecundity, larval hatch, and development of larvae to pupation was determined. LC90s (95% Confidence Limits) after 24, 48, and 72 h were calculated to be 280.0 (97.7-5220), 14.8 (12.2-20.7), and 7.0 (5.5-9.8) ppm, respectively. Lack of overlap in the 95% CLs indicate that these values are significantly different, thus abamectin can be considered a relatively slow-acting, but highly effective adult toxicant when ingested. Toxicity of abamectin to males especially at 72 h was comparable to the most toxic insecticides that have been evaluated previously including methomyl, thiodicarb, cyfluthrin and lambda cyhalothrin. Compared to 2.5 M sucrose alone as a control, the percentage of males that extended their proboscis when the front tarsi contacted the insecticide solutions was significantly reduced at concentrations of 750 and 1000 ppm. Males ingested similar amounts of abamectin at 15 ppm compared to control, but significant inhibition of gustation occurred at higher concentrations.