Abiotic and Biotic Mortality Factors Affecting Asian Citrus Psyllid (Hemiptera: Liviidae) Demographics in Southern California

Abstract

Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is an invasive citrus pest in California that vectors a bacterium that causes the deadly citrus disease huanglongbing. From 2014–2015, 116 experimental D. citri cohorts were monitored to determine survivorship, life table parameters, and marginal rates of mortality of immature D. citri at three sites in Riverside County, CA. D. citri cohorts of ∼200 eggs were established on potted Citrus volkameriana (Rutaceae) plants. Field deployed cohorts were protected with fine or coarse mesh enclosures, sticky barriers, or left unprotected. Egg through adult emergence rates were used to assess the relative importance of biotic and abiotic factors on psyllid survivorship rates by life stage. Predation of immature D. citri by larvae of Allograpta sp. (Diptera: Syrphidae) and Chrysoperla sp. (Neuroptera: Chrysopidae) comprised 86% of all observed predation mortality. When protected from all other arthropods, parasitism by Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae) comprised 21% of the total marginal rate of immature D. citri mortality from September to November in 2014 and 2015. Overall, D. citri net reproductive rates were reduced by 55–95% when exposed to natural enemies, indicating the importance of the classical biological control agent, T. radiata , and generalist predators in reducing D. citri densities in urban areas of southern California.