Biological control of the Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae) in California

The parasitoid Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae) is being used world-wide for the biological control the Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae). The parasitoid is strongly synovigenic, as it is born with very few mature eggs. Synovigenic insects need to feed on host haemolymph to mature additional eggs, and are able to resorb mature eggs to allocate resources toward maintenance. We investigated the effect of host feeding on parasitism behavior, longevity and egg load dynamics, and estimated egg maturation and resorption rates. We showed that, whilst host feeding does not increase survival or longevity, it results in increased parasitization rates when parasitoids are seven days old (the age at which they are usually released in California), that a single host meal leads to an average gain of three eggs and accelerates the egg maturation rate. We argue that the host feeding gains could be exploited at the mass rearing level to improve the nutritional status of mass reared T. radiata females upon release. We modeled parameters gathered by laboratory experiments to predict the effect of pre-release host feeding on the foraging and parasitization behavior of T. radiata in the field, and performed field cage experiments to test the model. We will discuss the effect of host feeding on the efficacy of augmentative biological control of ACP from a theoretical and practical perspective.