Thermal requirements for development of <i>Bemisia tabaci</i> (Hemiptera: Aleyrodidae) biotype ‘B’ and their implication to field sample population data

Accurate prediction of insect development and emergence is essential for effective pest management, but can be quite challenging. Pesticide application must be timed precisely to maximize effectiveness and minimize the number required. Temperature-dependent development of the cotton whitefly, <i>Bemisia tabaci</i>, B biotype was examined on two host plants (cotton and eggplant) at three temperatures (20 °C, 25 °C, and 35 °C). Developmental rate was faster on eggplant than cotton, however it did not alter for egg and pupal stages on both hosts, but for nymphal stage it did. The statistically estimated lower developmental threshold (T0) for the total development (egg — adult) of <i>B. tabaci</i> was 11.94 °C and 12.33 °C on cotton and eggplant, respectively. Based on lower threshold estimation, the average heat units (dd’s) required for total development on cotton and eggplant were 299.1 and 313.3, respectively. Field data obtained from both leaf samples and yellow sticky traps for each host plant during growing seasons 2012 and 2013 were linked to lab estimation of heat units. Daily heat units (i.e., 299.1 and 313.3 dd’s) were accumulatively counted to test their accuracy in matching the field peaks of the target pest as a predictive tool. On both host plants, our estimation for thermal units (degree-days) from lab estimation is adjusted that of field populations with deviation ranged from zero to four days either before or after the apex. However, there were some false estimations which did not intersect with the peaks of abundance. This may be because the overlapping generations sometimes creates false peaks. The accumulative counts of thermal units were more correlated to yellow sticky trap catches than leaf sample data. Accordingly, degree-days could be recommended to use as a predictive tool for <i>Bemisia</i> flight activity in the field.