Assessment of the occurrence of natural enemies associated with invasive coconut whitefly in Inhambane province, Mozambique

The whitefly (Aleurotrachelus atratus Hempel) is a Neotropical whitefly, originally described from coconut (Cocos nucifera) in Brazil. In the Comoro Islands, A. atratus was responsible for an economic loss of 55% to local coconut producers in 2002 whereas its arrival in Seychelles in 2007 represented a threat to environmental tourism. In Mozambique, the coconut whitefly, A. atratus was first reported in 2010. A. atratus is currently considered a serious pest of coconut in the country and reduction of 77.1 Kg ha-1 by 1% infestation severity has been reported in the southern province of Inhambane. The present study was conducted to assess the occurrence of natural enemies associated with the invasive coconut whitefly A. atratus in Inhambane province. A survey was conducted in four sites including Ravene, Bambela, Lindela and Cumbana in Jangamo District, Inhambane province. At each site, six coconut fields were randomly selected. Leaflet samples were taken from 5 coconut plants. The samples were taken to the laboratory for rearing for emergence of natural enemies. The occurrence of predators was assessed on-farm. The A. atratus, was the only species identified from the coconut samples. The results show no significant differences between sites regarding the percentage of infestation which varied from 97.32 to 99.85% in all locations. While the severity of infestation ranged from 3 to 4 (moderate to high) in all locations, the population density varied from 97,75 to 167.33 pupae/leaflet. Predators belonging to the genus Delphastus were the only natural enemies reported at 1.5 to 4.5 individuals/plant. There were no parasitoids associated to the A. atratus that emerged from the coconut whitefly samples. In light of these results, classical biological control should be considered by the introduction of specific parasitoids of A. atratus.