Diversity and foraging behaviour of pollinators in cashew (Anacardium occidentale Linn.)

Abstract

Among the flower visitors in cashew 12 species were documented as pollinators. These belong to Apidae (four), Halictidae (four), Megachilidae (three) under Hymenoptera, and Syrphidae (one) under Dipteran. Species abundance was highest for Halictidae (49%), followed by Apidae (42.38%). In Halictidae, Halictus sp.1 was more abundant (18.54%), followed by Lasioglossum sp. (16.56%); while in Apidae, Apis cerana indica (21.85%) followed by Tetragonula sp. (17.22%). In diversity indices, Simpson diversity index (D) showed 0.16, Shannon-Weiner index (H) of 2.03 and Berger-Parker index (d) of 0.22. Foraging activity peaked between 10:00 and 13:00 h, where A. c. indica was most prevalent (12-35%). Mean foraging rate was highest for A. c. indica (15.4 flowers/trip), followed by Lasioglossum sp. (7.2 flowers/trip), Helophilus sp. (6.2 flowers/trip) and lowest for Tetragonula sp. (2.8 flowers/trip); while mean foraging speed was highest for Tetragonula sp. (6.19 s/flower), followed by Halictus sp. 1 (5.74 s/flower), Helophilus sp. (5.64 s/flower) and lowest for Hoplonomia sp. (1.49s/flower). Nesting sites of Ceratina hieroglyphica and C. binghami were also observed during the study.