Natural mortality of Asian citrus psyllid (Homoptera: Psyllidae) in central Florida

Abstract

The survival rate of nymphs of the Asian citrus psyllid, Diaphorina citri Kuwayama, was estimated in central Florida citrus groves by reiterative, non-destructive sampling of newly expanding terminal shoots on grapefruit trees. Feeding by D. citri nymphs often resulted in the abscission of leaves and even whole shoots. Shoot elongation was abated when death of the apical meristem occurred. Key predators of nymphal psyllids were the coccinellid beetles Harmonia axyridis Pallas, Olla v-nigrum Mulsant, Cycloneda sanguinea L., and Exochomus childreni Mulsant. Two lacewings, Ceraeochrysa sp. and Chrysoperla rufilabris Burmeister, a spider, Hibana velox (Becker), and the introduced parasitoid Tamarixia radiata (Waterston) contributed additional mortality. Exclusion of primary predators from infested terminals with field cages doubled the duration of psyllid infestation, improved parasitoid survival by 40-fold, and improved psyllid maturation success (first instar to adult) by 120-fold. The results indicate that coccinellid beetles are the most important biological control agents of high-density D. citri populations in central Florida and that intraguild predation causes >95% mortality of immature stages of T. radiata.