Fourth International Bemisia Workshop International Whitefly Genomics Workshop
Impact of temperatures and plant species on the biological features of the castor bean whitefly Trialeurodes ricini
Economic Entomology Department, Faculty of Agriculture, Mansoura University, Mansoura, Egypt. Correspondence: nafabdel@mans.edu.eg
Laboratory studies were carried out to determine the influence of temperature (abiotic) and host plant species (biotic) on the biological characters of the castor bean whitefly, Trialeurodes ricini Misra. Four temperatures (15, 20, 25 and 30°C), as well as the three plant species, castor bean (Ricinus communis L), papaya (Carica papaya L.), and sweet potato (Ipomoea batatas L.) were tested. Temperature affected insect development, oviposition, and generation time of T. ricini when reared on castor bean plants. At 30 °C, egg incubation period, development of nymphal instars, adult longevity and generation time were shortest, followed by 25 °C, while these characters were longer when the insects were reared at 15 °C. The hatching percentage and female fecundity were greater at both 30 and 25 °C and lower at 15 °C. The temperature threshold (t0) and thermal accumulative effect (degree-days) were also calculated. The laboratory studies were confirmed by field applications examining the relationship between seasonal temperature and insect populations. The study demonstrates that T. ricini can, in otherwise unlimited conditions, persist and increase in number within the range 20–30 °C. Therefore, the pest is well adapted to high temperatures and may extend its distribution if the mean world temperatures increase because of global warming. Regarding the plant host species, the castor bean was the preferred host followed by papaya, while the sweet potato was not preferred. Host plant species had a significant effect on egg hatching, nymphal survival, female fecundity and the duration of the life cycle of T. ricini.