Evaluation of the occurence of parasitoids associated with the invasive coconut whitefly (Aleurotrachelus atratus) in Inhambane Province, Mozambique

The coconut whitefly, Aleurotrachelus atratus Hempel (Homoptera; Aleyrodidea) is a highly invasive pest of coconut and ornamental palms (Arecaceae). In Mozambique, it was first detected in 2011 and 100% of infested plants have been reported. Currently, biological control is the most preferred, safest and nontoxic method in controlling invasive pest species, such as A. atratus. Since its first detection in Mozambique, no parasitoids were known being associated with this pest. A study was conducted to evaluate the occurrence of parasitoids associated with A. atratus as a basis for the introduction of classical biological control in Inhambane province. Data from samples collected from five districts of the province in September and December 2015 showed that whitefly infestation was 99.9+0.14% with no significant differences among districts and between sampling periods. Whitefly severity varied between severe to very severe with no significant differences among districts but differed significantly between sampling periods, being higher in September compared to December. Mean whitefly density for the province was 26.5±1.2 larvae per leaflet. There were no significant differences among districts but sampling periods differed significantly in terms of whitefly density, being higher in September compared to December. Four parasitoid species being associated with A. atratus were recovered during the study period including; Encarsia basicincta, Eretmocerus cocois, Encarsia sp. and Signiphora sp. with parasitism rates of; 4.08%, 0.22%, 5.99% and 0.45% respectively. Overall parasitism was 10.74+2.03% varying significantly among districts. The recovery of Encarsia basicincta and Eretmocerus cocois from the coconut whitefly is an indication that A. atratus was introduced with parasitoids considered efficient for the suppression of its population in its native range and it may constitute potential biological control agents against the invasive whitefly in Mozambique. Therefore, the national phytosanitary authorities should consider development of integrated pest management (IPM) including classical biological control and augmentative approaches to reduce the pest population, crop damage and yield loss.