Studies on the incidence of parasites of scale insects infesting orange in Darjeeling, West Bengal

Ten species of hymenopteran insect parasites along with two fungal parasites were found to parasitize the scale insects infesting orange in four different orchards of Darjeeling district, West Bengal. Coccopghus ceroplastae, Metaphycus n. sp. nr. liehtensiae and Aschersonia citri were more active to parasitize the pests of orange. The percentage of parasitism was all these insects and fungi became nil during cooler months of the year (December – January), but was maximum during August – September in both the years. The insect parasite, C. ceroplastae was found to parasitize more than one species of scale insects (i.e. Saissetia coffeae and Ceroplastes floridensis), whereas both S. coffeae as well as Mytilococcus spp. were simultaneously parasitized by A. citri. The incidence patterns of these parasitoids were also significantly different from one orchard to another. More or less all the parasites were noticed in all four orchards, except Encyrtus infelix, which was only recorded at Pedong and Encyrtus lecaniorum, which was not found at Pedong. In most of the cases, maximum percentage of parasitism on scale insects was recorded at Takdah and then at Gorubathan, Dolapchand and Pedong, respectively.