Optimizing production of Tamarixia radiata (Hymenoptera: Eulophidae), a parasitoid of the citrus greening disease vector Diaphorina citri (Hemiptera: Psylloidea)

Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae) established and spread throughout Florida following first release in 1999 for control of the Asian citrus psyllid (ACP) Diaphorina citri (Kuwayama) (Hemiptera: Psylloidea). Nevertheless, persistence of the pest and continued losses from citrus greening disease have created the need for more effective biological control, including mass rearing and augmentative release of T. radiata. However, information is lacking on efficiency of current rearing methods including ways to increase the proportion of hosts parasitized as a function of host density. This “functional response” has been studied under lab conditions, but not yet related to mass rearing efficiency. Three release rates of D. citri per flush shoot, four host: T. radiata ratios and five photophases were evaluated. Results indicated that 20 psyllid adults per flush provided optimal host density without excessive stickiness from honeydew. Sixty T. radiata females per cage of approximately 4800 nymphs provided most economical use of wasps and hosts. Progeny sex ratio was not influenced by parental sex ratio. A photophase of 12 h maintained high fecundity. A type II functional response was observed with estimates of handling time and searching efficiency falling within previously estimated ranges. Modifications in rearing parameters suggested by this study improved parasitoid production three-fold compared to previous procedures.