Apple flower-visiting insects’ diversity and abundance in selected central Kenya orchards

Abstract

Flower-visiting insects are essential in maintaining a healthy and productive agricultural landscape through ecosystem services such as pollination. Fruits are important sources of vitamins and micronutrients, and several fruit crops depend on animal pollination, which enhances their nutritional content. Besides honey bees, apple orchards can sustain a large number of arthropod species that also aid in pollination. In this present study, we assessed the diversity and abundance of insect flower visitors in six apple orchards in Nyeri and Laikipia East. Six plots, each with more than 20 apple trees, were purposefully selected. Data were collected through timed visual searches and sweep netting. Sampling was done from 0900 hours to 1700 hours, six days a week, for five months consecutively in 2019. Diversity indices were computed using the Shannon-Wiener diversity index, while abundance patterns were displayed using species abundance curves. Differences in species diversity and abundance between sites were compared using a one-way analysis of variance. A total of 1,221 insects belonging to 23 families, 82 species, and 4 orders (Hymenoptera, Lepidoptera, Coleoptera, and Diptera) were recorded. The order Hymenoptera (bees, wasps, and ants) was the most abundant, with 1,176 individuals, and had the most species-rich taxa, with 56 species in 9 families. The order Coleoptera (beetles) was second, with 26 individuals and 12 species in 6 families. Lepidoptera were the least abundant with 10 individuals and the least species-rich taxa with 7 species in 5 families, followed closely by Diptera with 7 individuals and 7 species in 3 families. There were significant differences in flower visitors’ composition among the six sites. The study provides important information on the status of key apple flower visitors, which can guide orchard management practises to increase apple yield through pollinator conservation. Conserving apple pollinators will enhance fruit production, promote the livelihoods of farmers, and contribute to the national economy.