Effects of temperatures and plant host species on certain biological characters of the castor bean whitefly, Trialeurodes ricini Misra (Himeptera: Alyrodidae) [electronic resource].

Includes references.

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 namely 15, 20, 25 and 30oe, as well as the three plant species, castor bean (Ricinus communis L), Papaya (Carica papaya L.). and sweet potato (Ipomoea batatas L.) were tested. Various temperatures affected greatly the insect development, oviposition, life cycle and generation time when reared on castor bean plants. At 30 º c., egg incubation period, development of nymphal instars, adult longevity and life cycle were shortest, followed by 25 º c., while these characters were longer when the insect reared at 15 º c. The hatchability percentage and female fecundity were greater at both 30 and 25 º c. Meanwhile they were lower at 15 ºc the temperature threshold (to) and thermal accumulative effects (degree-days) were also calculated. The laboratory studies were confirmed by field applications regarding the relationship between temperatures among the geographical seasons and the insect populations. The study demonstrates that T. ricini can, in otherwise unlimited conditions, persist and increase in number within the range 20-30 º 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.

Summary in Arabic.

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