Field management practices and altitudes drive the abundance of ladybird beetles (Coleoptera: Coccinellidae) in cultivated cucurbit crops in Morogoro, Tanzania

Abstract

Ladybird beetles are helpful insects in agricultural ecosystems affected by locally accepted agroecological techniques. Conventional farming practices are known to harm these insects, which led to the exploration of agroecology as an alternative. From May to November 2021, yellow pan traps, hand picking, and hand netting were utilised in cultivated cucurbits such as Cucumis sativus, Citrullus lanatus, and Cucurbita moschata. The study found 222 ladybird beetles from nine genera and twelve species. The plateau had 64.9% ladybirds, 46.4% in conventional fields, and 18.47% in agroecological fields. Mountain fields supplied 35.1%, conventional fields 24.77%, and agroecological fields 10.36%. Conventional plateau fields favoured Cheilomenes sulphurea, while agroecological fields selected Hippodamia variegata. Cheilomenes lunata dominated traditional fields in mountainous areas and agroecological fields. Ladybird beetles were more abundant in conventional fields across all seasons and agroecological zones, which were influenced by seasons, management strategies, and elevations. The present study found negative associations between ladybird abundance and maximum temperature, minimum temperature, mean temperature, number of flowers, and relative humidity. Mountainous precipitation increased ladybird abundance. This study shows how management practises, agroecological zones, and seasons affect ladybird populations, which can inform pest management strategies in agricultural systems and help conserve beneficial ladybird beetles.