Analysis of mortality and contributing factors from Diaphorina citri (Hemiptera: Psyllidae) cohorts on orange

Estimation of natural mortality and understanding contributing factors are important for designing sustainable pest management strategies. Diaphorina citri Kuwayama also known as Asian citrus psyllid, vectors the bacterium Candidatus Liberibacter asiaticus, causal organisms of the devastating citrus disease “huanglongbing” or citrus greening. Seventeen cohorts of D. citri were followed from eggs and nymphs through adult emergence on orange trees during 2006-2007. Net reproductive rate ranged from 0-64 in unprotected cohorts to 35-135 in cohorts partially protected with a sticky barrier compared to 14-285 in cohorts completely protected from natural enemies with sleeve cages. Spiders and insect predators in the families Coccinellidae, Blattellidae, Chrysopidae, Formicidae, Syrphidae, Miridae, and Anthocoridae were observed on the cohorts or caught in sticky barriers. Spiders, the ladybeetles Curinus coeruleus, Olla v-nigrum, Harmonia axyridis, and Cycloneda sanguinea, and the lacewings, Ceraeochrysa sp. and Chrysoperla sp., were most often encountered. Parasitism by Tamarixia radiata based on adult emergence from fourth and fifth instar psyllid nymphs collected from experimental blocks ranged from 0-14% in spring and summer and 0-45% in Fall. These findings suggest that natural mortality factors play a vital role in regulating the dynamics of D. citri populations and reducing the spread of pest and disease.