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 the present study, we assessed the diversity and abundance of insect flower visitors in six apple orchards in Nyeri and Laikipia Counties. Six plots, each with a population of more than 20 apple trees were purposively 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 was 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 collected belonging to four orders (Hymenoptera, Lepidoptera, Coleoptera, and Diptera) were recorded including 23 families and 82 species. The order Hymenoptera (bees, wasps & ants) were the most abundant, with 1,176 individuals, and the most species-rich taxa, with 56 species in 9 families. The order Coleoptera (beetles) was second having 26 individuals and 12 species in 6 families. Lepidoptera was 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 clearly provides important information regarding the status of key insect flower visitors of apples which can inform suitable management practices to increase crop yield through conservation. Conserving apple pollinators will enhance fruit production and promote the livelihoods of farmers while contributing to the national economy.