A case study of insect visitors and pollen vectors in sponge gourd (Luffa cylindrica (Linn.)) during summer and rainy seasons in India

Abstract

Insect crop visitations do not necessarily always translate to transfer or carriage of pollen. To determine the potential of the various insects visiting summer and rainy seasons sponge gourd (Luffa cylindrica (Linn.)) flowers to facilitate the pollen transfer, the present study examines the diversity of visiting insects to sponge gourd seed crops in relation to the time of day and season, diversity and abundance to its flowers, fruits and seed yield. These visiting insects taxonomically belonged to 8 different insect orders viz. Coleoptera, Diptera, Hymenoptera, Hemiptera, Neuroptera, Lepidoptera, Odonata and Orthoptera/Dictyoptera. Rainy season sponge gourd crops had higher numbers of insect visitors and higher diversity (0.80 of Simpson’s Diversity Index and 1.71 of Shannon–Weaver Index of diversity as compared to summer season crop (0.72 and 1.51, respectively). The summer crop had the highest number of visiting insects belonged to the order Coleoptera followed by Hemiptera and Hymenoptera and their reciprocal form of Berger Parker’s dominance indices were 2.21, 5.05 and 6.17, respectively. In summer crop, honeybees were the main pollinators comprising 57.69% of total pollinators in sponge gourds. All the four honeybee species viz., Apis cerana indica, A. dorsata, A. florea and A. mellifera were found to visit in sponge gourd. However, the dominant species was A. florea with 39% of total honeybee share. In rainy season crop, in contrary, honeybees comprised only 16.32% share on total visiting pollinators in sponge gourd. Rice skipper, Pelopidas mathias (46.84% share) was found almost thorough out the day with higher visitation during evening hours. Other pollinators were stingless bees (11.58% share), butterflies and moths. Consequently, we suggest optimizing pollinators’ management including honeybees and thereby improving the attraction of sponge gourd lines to these pollinators to improve pollination rates for sponge gourd seed crops.