Mealybugs Attacking Citrus in California–A Survey of Their Natural Enemies and the Release of New Parasites and Predators1

Abstract

From 1953 through 1955 a survey was made of the natural enemies of the mealybugs attacking citrus in California. Pseudococcus citri (Risso), the most destructive mealybug on citrus in California, was most abundant in the intermediate citrus areas or zones of moderate humidity. Pseudococcus maritimus (Ehrh.), closely rivaling P. citri in severity on citrus, requires high humidity for optimum development. Its distribution overlaps that of P. citri in the intermediate zone and that of Pseudococcus adonidum (L.), which was damaging to citrus in the more humid coastal areas. Pseudococcus gahani Green is rare. It overlaps the three other species in its distribution Cryptolaemus montrouzieri Muls. was in general the most efficient predator of heavy infestations of mealybugs on citrus. However, Sympherobius spp. and Chrysopa spp. are sometimes major factors in reducing heavy populations in certain areas. Leucopis bella Loew, Coccinella californica Mann., Hyperaspis lateralis Muls., and Scymnus sordidus Horn are less efficient Mealybug predators in the order named. The relative abundance of the different parasites permanently established on each of the four citrus-infesting mealybugs is shown in a table along with the stages of host attacked. Some of these parasites attack a number of mealybug species, but always select the same host stages. A synoptic list of 19 species of mealybug-feeding natural enemies imported into California within the past 10 years is presented along with their host preferences and stages of host attack. Of the newly imported natural enemies, Allotropa citri Mues. and Anagyrus pseudococci Gir. have been recovered from field release sites.