COMPARATIVE BIOLOGY, MORPHOMETRICS, AND DEVELOPMENT OF 2 POPULATIONS OF BEMISIA-TABACI (HOMOPTERA, ALEYRODIDAE) ON COTTON AND POINSETTIA

Development rates and body sizes of two populations (a "cotton strain" and a "poinsettia strain") of Bemisia tabaci (Gennadius) were observed on both cotton and poinsettia at 25.4 +/- 0.2-degrees-C. There were no significant differences in female longevity between populations reared on the same host plant or within populations reared on different hosts. Females originating from poinsettia (poinsettia population) laid significantly more eggs if reared on either poinsettia (85.0 eggs per female) or cotton (51.2 eggs per female) than did females from the cotton population (22.3 eggs per female if reared on poinsettia and 31.8 eggs per female if reared on cotton). Four instars were confirmed using the Brooks-Dyar rule of geometric growth. First through fourth instars from either population had significantly longer body lengths when reared on cotton than those reared on poinsettia. Development times of first through fourth stadia varied among the whitefly populations and test hosts; however, total development times were similar, ranging from 23.2 d for the poinsettia population whiteflies reared on poinsettia to 25.6 d for the cotton population whiteflies reared on poinsettia. Pupae of the cotton population were longer and wider than pupae of the poinsettia population, and within populations, female pupae were significantly larger than male pupae. Although tibiae of adult females were longer than those of males, there were no differences between populations within the same sex.