Evaluating and improving methods for rearing the biological control agent, Aphytis melinus (DeBach)

Aphytis melinus was introduced into California in the 1950’s for the control of California red scale (CRS), Aonidiella aurantii (Maskell), and has since become an important contributor to CRS biological control in southern California. Insectaries have been rearing A. melinus using the same methods that were developed over forty years ago, despite several scientific advances that could improve the fitness of these parasitoids. We evaluated A. melinus from five California insectaries using simple life-history trait measurements (longevity, sex ratio and size) to estimate fitness. We are also studying the fitness effects of Wolbachia, an endosymbiotic bacteria that causes mating incompatibility, in A. melinus and many other insects. Lastly, microsatellites have been developed to compare the genetic diversity of insectary-reared A. melinus with that of endemic populations. Our goal is to improve the effective utilization of A. melinus by commercial citrus growers in California.