Population dynamics and crop damage assessment of Scarabaeid pests in the North-Western Himalayas

Scarabs are pests of horticultural crops in the north-western Himalayan regions. However, our current understanding falls short in comprehending the factors driving the population flare-ups of these pests. We investigated the pest population dynamic of Melolontha sp. Fabricius (Coleoptera: Scarabaeidae) and Polyphylla sikkimensis Brenske (Coleoptera: Scarabaeidae) by monitoring seven sites using UV traps and damage caused by them in 2017 and 2018. Melolontha furcicauda (Ancey) (Coleoptera: Scarabaeidae) was the most dominant species, followed by Melolontha Cuprescens Blanchard (Coleoptera: Scarabaeidae) and Melolontha indica Hope (Coleoptera: Scarabaeidae) and P. sikkimensis. The activity of species peaked in July. The highest Shannon (1.35-1.36), Simpson (0.73-0.74) and Pielou's evenness indices (0.97-0.98) were recorded at Badagaon in both years. Scarab species from Badagaon and Janjehli were similar in species richness and abundance while Palampur and Sangla were most dissimilar. Melolontha indica and M. furcicauda preferred rose the most and M. cuprescens preferred apple. Maximum damage rate of potato (42.5-47.5%), cabbage (26.2-28.8%) and kidney beans (18.7-20.0%) by P. sikkimensis was recorded at Badagaon.