Survival of Diaphorina citri (Homoptera: Psyllidae), and its two parasitoids, Tamarixia radiata (Hymenoptera: Eulophidae) and Diaphorencyrtus aligarhensis (Hymenoptera: Encyrtidae), under different relative humidities and temperature regimes

The ability of an exotic citrus pest, Diaphorina citri Kuwayama, and its two parasitoids, Tamarixia radiata (Waterston) and Diaphorencyrtus aligarhensis (Shafee, Alam & Agarwal), to survive under different relative humidities (7%, 33%, 53%, 75% and 97%) at 25 and 30 degreesC was compared. The data obtained may help to predict potential climatic limitations to their establishment in Florida and indicate whether the pest has different climatic tolerances compared to these parasitoid populations. Adult survival was evaluated under relative humidities maintained by saturated salt solutions. D. citri survived longer than the parasitoid populations at all experimental conditions, suggesting it has a lower net water loss rate. The T. radiata (Taiwan) population showed the greatest moisture requirement at all temperatures and relative humidities tested. The T. radiata (Vietnam) population survived longer than the Taiwan, suggesting that the two populations may perform differently in different geographical regions. D. aligarhensis and T. radiata (Vietnam) survived similar lengths of time, except at the higher relative humidities, so the moisture requirements for these two populations are comparable.