EFFECT OF TEMPERATURE AND CASSAVA GENOTYPE ON THE DEVELOPMENT, FECUNDITY AND REPRODUCTION OF Bemisia tabaci SSA1

Abstract

The Bemisia tabaci complex is currently recognised as key agricultural pests that cause economic damage globally. Temperature is the most important driver of changes in behaviour, abundance and distribution of insect pests, including the whitefly (Bemisia tabaci). The objective of this study was to evaluate the development, fecundity and reproduction of B. tabaci SSA1 on cassava genotypes under a range of temperatures. A laboratory study was conducted using three cassava genotypes (Alado alado, NAROCASS 1 and NASE 14) at five constant temperatures (16, 20, 24, 28 and 32 \ub0C). The parameters assessed included development duration, survival, fecundity and population parameters for B. tabaci SSA1. Temperature had significant effects (P<0.001) on development time, survival and fecundity of B. tabaci; while cassava genotype had no effect (P>0.05). An inverse relationship was observed between development time and temperature for all stages across all cassava genotypes. The total life cycle was 63.8 days at 16 \ub0C and 17.9 days at 32 \ub0C on NAROCASS 1. Survival for each stage throughout the entire life cycle increased with temperature and was highest at 32 \ub0C, although this was not significantly different from that at 28 \ub0C. Fecundity increased with temperature and was highest at 32 \ub0C on all cassava genotypes. For all cassava genotypes, the intrinsic rate of increase (rm), finite rate of increase (\u3bb) and net reproductive rate (Ro) increased with temperature, while mean generation time (T) reduced following a similar pattern. At 32 \ub0C, rm, Ro, \u3bb and T were 0.2, 48.7, 1.2 and 22.6 days, respectively; compared to 0.01, 1.9, 1.0 and 71.2 days at 16 \ub0C on Alado alado. Therefore, the ideal development temperature for B. tabaci SSA1 is 32 \ub0C. Thus, there is a risk of accelerated future expansion of B. tabaci SSA1 populations globally, with global warming and climate variability.Le complexe Bemisia tabaci est actuellement reconnu comme un ravageur agricole cl\ue9 causant des dommages \ue9conomiques \ue0 l\u2019\ue9chelle mondiale. La temp\ue9rature est le facteur le plus important des changements de comportement, d\u2019abondance et de r\ue9partition des insectes ravageurs, y compris l\u2019aleurode (Bemisia tabaci). L\u2019objectif de cette \ue9tude \ue9tait d\u2019\ue9valuer le d\ue9veloppement, la f\ue9condit\ue9 et la reproduction de B. tabaci SSA1 sur des g\ue9notypes de manioc sous une gamme de temp\ue9ratures. Une \ue9tude en laboratoire a \ue9t\ue9 men\ue9e en utilisant trois g\ue9notypes de manioc (Alado alado, NAROCASS 1 et NASE 14) \ue0 cinq temp\ue9ratures constantes (16, 20, 24, 28 et 32 \ub0C). Les param\ue8tres \ue9valu\ue9s comprenaient la dur\ue9e du d\ue9veloppement, la survie, la f\ue9condit\ue9 et les param\ue8tres de population pour B. tabaci SSA1. La temp\ue9rature a eu des effets significatifs (P<0,001) sur le temps de d\ue9veloppement, la survie et la f\ue9condit\ue9 de B. tabaci, tandis que le g\ue9notype du manioc n\u2019a eu aucun effet (p>0,05). Une relation inverse a \ue9t\ue9 observ\ue9e entre le temps de d\ue9veloppement et la temp\ue9rature pour tous les stades dans tous les g\ue9notypes de manioc. Le cycle de vie total \ue9tait de 63,8 jours \ue0 16 \ub0C et de 17,9 jours \ue0 32 \ub0C sur NAROCASS 1. La survie pour chaque \ue9tape tout au long du cycle de vie entier augmentait avec la temp\ue9rature et \ue9tait maximale \ue0 32 \ub0C. Cependant, la survie \ue0 28 \ub0C n\u2019\ue9tait pas significativement diff\ue9rente de celle observ\ue9e \ue0 32 \ub0C. La f\ue9condit\ue9 augmentait avec la temp\ue9rature et \ue9tait maximale \ue0 32 \ub0C sur tous les g\ue9notypes de manioc. Pour tous les g\ue9notypes de manioc, le taux d\u2019accroissement intrins\ue8que (rm), le taux d\u2019accroissement fini (\u3bb) et le taux net de reproduction (Ro) ont augment\ue9 avec la temp\ue9rature, tandis que le temps de g\ue9n\ue9ration moyen (T) a diminu\ue9 selon un sch\ue9ma similaire. A 32 \ub0C, rm, Ro, \u3bb et T \ue9taient respectivement de 0,2, 48,7, 1,2 et 22,6 jours ; contre 0,01, 1,9, 1,0 et 71,2 jours \ue0 16 \ub0C sur Alado alado. Par cons\ue9quent, d\u2019apr\ue8s cette \ue9tude, la temp\ue9rature de d\ue9veloppement id\ue9ale pour B. tabaci SSA1 est de 32 \ub0C. Ainsi, il existe un risque d\u2019expansion future acc\ue9l\ue9r\ue9e des populations de B. tabaci SSA1 \ue0 l\u2019\ue9chelle mondiale, avec le r\ue9chauffement climatique et la variabilit\ue9 climatique