The poinsettia strain of the cotton whitefly,<i>Bemisia tabaci</i>(Homoptera: Aleyrodidae), biological and demographic parameters on poinsettia (<i>Euphorbia pulcherrima</i>) in relation to temperature

AbstractBiological characteristics of the poinsettia strain ofBemisia tabaciGennadius were investigated on poinsettia by laboratory experiments at five temperatures (range: 16°C–28°C). In addition, the effect of rearingB. tabacion the two plant species,Nicotiana tabacum(tobacco) (Solanaceae) andEuphorbia pulcherrima(Euphorbiaceae) (poinsettia) was investigated. The temperature-dependencies were established for the developmental time for eggs and egg-to-adult phase, juvenile mortality, adult female life-span, pre-oviposition period, age-specific fecundity, and sex-ratio. The lower temperature thresholds for egg-development, development from egg to adult and for ovipositional adults were estimated as well as the lower temperature threshold for oviposition. The thresholds were 12°C, 14°C, 8°C and 14°C, respectively. Egg-development required 126 day-degrees and the entire development into adults 327 day-degrees. Mortality was highest at 16°C, being 19.3% in the egg-stage and 95% from egg to adult. The pre-oviposition period and the adult life-span were 40 and 360 day-degrees. The age-specific fecundity ofB. tabaciwas described by a temperature-dependent model. The maximum daily fecundity rate was attained after 60 and 125 day-degrees forB. tabacireared on tobacco and poinsettia, respectively. The fecundity was highest forB. tabacireared on poinsettia. The sex-ratio was in favour of females at and above 19°C and increased with temperature. Estimates of the net reproductive rate, the intrinsic rate of increase, the finite rate of increase, the mean generation time and the doubling time were obtained. A positive linear relationship was found between rmand temperature, the values ranging from 0.0012 at 16°C to 0.1263 at 28°C.</jats:p