Two sub-Saharan Africa 1 populations of Bemisia tabaci exhibit distinct biological differences in fecundity and survivorship on cassava

Abstract

A study was conducted to determine the fecundity (number of eggs laid) and survivorship of two sub-Saharan Africa 1 (SSA1) populations of Bemisia tabaci: subgroup 1 (SSA1-SG1) obtained from the Lake Victoria Basin, and subgroup 3 (SSA1-SG3) from Coast Region, on healthy and cassava mosaic begomovirus (CMB)-infected cassava plants in Tanzania in April (first trial) and June (repeat trial) 2012. Colonies of the two SSA1 B. tabaci populations, SSA1-SG1 and SSA1-SG3 were established on healthy cassava plants in separate insect-proof cages within a screen house at Mikocheni Agricultural Research Institute, Dar es Salaam, Tanzania. Field-collected cassava plants infected with African cassava mosaic virus-[Tanzania:2001] (ACMV-[TZ:01]) and East African cassava mosaic virus-Kenya (EACMV-KE) were raised in containment as sources of viruses. Single female, 1–4-day old adults of SSA1-SG1 and SSA1-SG3 B. tabaci populations were allowed to feed and oviposit on healthy and CMB-infected cassava for 3 days. Results show that there were significant differences (P < 0.05) in the mean number of eggs laid and emerged adults between SSA1-SG1 and SSA1-SG3 in both the first and repeat trials. Overall, SSA1-SG1 produced a higher number of eggs and emerged adults (30.5 ± 3.3 & 17.7 ± 2.5) than SSA1-SG3 (23.4 ± 3.1 & 13.6 ± 2.3). Interestingly, CMB-infection had no significant effect on the number of eggs laid and emerged adults in both the first and repeat trials. Overall, there were no significant differences (P > 0.05) between the survivorship of the 1st, 2nd & 3rd, 4th instars and emerged adults of both SSA1-SG1 and SSA1-SG3 populations on healthy and CMB-infected cassava plants. Irrespective of the virus treatment, survivorship of SSA1-SG1 and SSA1-SG3 populations was similar across all developmental stages. In conclusion, our study did not reveal any synergistic interaction between CMB infection and whitefly fecundity and survivorship. However, the results point to genetic differences as the likely explanation of the differences in the biology of the two SSA1 (SSA1-SG1 and SSA1-SG3) B. tabaci populations.