D. E. Meyerdirk

Discrimination of three whitefly species (Homoptera, Aleyrodidae) by electrophoresis of non-specific esterases

Polyacrylamide gel electrophoresis was used to detect non‐specific esterase isoenzymes in adults of 3 species of whiteflies, Bemisia tabaci (Gennadius), Trialeurodes abutilonea (Haldeman) and Trialeurodes vaporariorum (Westwood). Based on the mobilities of the isoenzyme, the esterase loci can be used to differentiate between two of the species, B. tabaci and T. abutilonea. Trialeurodes vaporariorum produced no esterase bands under the conditions of this study. A relative increase in the intensity of some of the isoenzymes was observed as development proceeded. Malate dehydrogenase and phosphoglucomutase patterns that were observed in the adults cannot be used to discriminate the 3 species. None of the adults of the 3 species from the populations tested exhibited intraspecific genetic variability.

Attraction of Males by Virgin Females of the Mealybug Maconellicoccus hirsutus (Hemiptera: Pseudococcidae)

Abstract The mealybug Maconellicoccus hirsutus (Green) has extended its range throughout the Caribbean region since it was first detected in Grenada in 1994, and has recently been detected in Southern California, Mexico, and Central America. Laboratory and field experiments using virgin females were conducted on St. Croix, U.S. Virgin Islands, to determine if females attract males with pheromones. Virgin females isolated in gelatin capsules attracted on average one male to each capsule over a period of 18 h in the laboratory compared with gelatin capsules without females. Adhesive traps baited with virgin females and placed on hibiscus, Hibiscus rosa-sinensis L., in the field, captured more males at all three study localities on St. Croix than did unbaited traps. Virgin females attracted more males than controls at 0–10 m from infested hibiscus, but were capable of attracting males at 50 m distance from an infestation. The attractiveness of virgin females to flying males strongly suggests the involvement of a female-produced sex pheromone. Isolation and synthesis of such a sex pheromone would provide a valuable tool for population monitoring and control of this invasive pest.

Population dynamics and control strategy for Bemisia tabaci in the imperial valley, California☆

Abstract Bemisia tabaci (Gennadius) populations were monitored in 1983 in the Imperial Valley of California on cotton and alfalfa utilizing yellow sticky traps and leaf samples. The influence of B. tabaci populations on cotton and early defoliation of cotton on autumn-planted crops was discussed. Infrared aerial photography was used as a survey tool to locate high whitefly densities in cotton. Insecticide resistance, adverse effects of pesticides on beneficial arthropods and different developmental rates on cultivated crops were factors that enhanced B. tabaci population increases.