Seasonal Development and Management Strategies for Cornstock Mealybug (Homoptera: Pseudococcidae) in New York Pear Orchards

Abstract

Laboratory and field studies were conducted during 1988-1990 to investigate Cornstock mealybug, Pseudococcus Cornstocki (Kuwana), infestations in pears ( Pyrus cummunis L.) grown for processing in New York. The incidence and size of external infestations were reduced on pears that were put through various baths and dry brushing treatments, but not sufficiently to alleviate the nuisance posed by the insects to food handlers. In pear purees, insect fragment contaminants were found at rates directly related to the proportion of infested fruits used in the process. Contact toxicity of selected insecticides was assayed in the laboratory for mealybugs infesting the calyx of mature fruits. Chlorpyrifos, methomyl, carbaryl, and microencapsulated methyl parathion caused the greatest mortality; azinphosmethyl, phosmet, esfenvalerate, and endosulfan were no more effective than distilled water. Two generations of mealybugs develop per year in New York pear orchards; peak crawler emergence occurred at the petal fall stage and again in mid-July to early August. Crawlers emerge from egg masses laid under bark scales in the trees and predominate on green tissue and in the calyx of fruits. Acceptable control can be attained with one or two sprays of methyl parathion, diazinon, or methomyl, timed to coincide with each generation of crawlers; double-sided tape traps on the scaffold branches are the recommended monitoring tactic for the timing of sprays. Heavily infested orchards with no history of mealybug control measures may initially require a total of three or four applications, but this number can be reduced in subsequent years.