Pollinators of Home Garden Fruit Vegetables Along the Altitudinal Gradient in Kanglung Gewog, Trashigang, Bhutan

Abstract

Altitudinal gradient influences plant and pollinator diversity in mountain ecosystems. Small home gardens in these ecosystems are highly dependent on pollinators for fruit-vegetable production. The study evaluated the change in fruit-vegetable diversity, their pollinator species richness, abundance, crop yield and, income in the home gardens along the altitudinal gradient. Correlation between pollinator species diversity, abundance and species of fruit-vegetables and yield were studied and statistically tested for their significance. The study recorded 25 species of pollinators belonging to Vespidae, Syrphidae, Apidae, Andrenidae, Colletidae, Ichneumonidae and Scoliidae. 12 species of fruit vegetables were recorded from Cucurbitaceae, Solanaceae, Fabaceae, Brassicaceae and Lamiaceae. Correspondingly, the pollinator and vegetable species richness were found to decrease with increasing altitude, with significant negative correlation. As with increasing altitude, the vegetable yield was found to decrease significantly, affected by the decreasing pollinators. Income from the fruit-vegetables were lower at places with low diversity (i.e., higher altitudes), which is influenced by decreased yield. The fruit-vegetable and pollinator species richness and abundance, fruit set, yield and income decreased with increasing altitude, having a significant negative correlation.