Floral visitation of European honey bees and hoverflies in selected cultivated cucurbitaceous crops in Morogoro, Eastern-Central Tanzania

Abstract

Cucurbit production in many parts of the world is constrained by the absence of effective pollinators. Due to the decline of European honey bees (Apis mellifera), main pollinators of cucurbits, there is a need to explore other cucurbits flowers visiting insects to supplement pollination services and for their conservation. Studies were carried out in the two agroecological zones of Morogoro Region, Eastern - Central Tanzania. We assessed visitation abundance, visitation frequency and visitation rate of four cucurbits flowers visiting insects under the family Syrphidae [Eristalinus megacephalus, Mesembrius caffer, Paragus borbonicus and Toxomerus floralis] and A. mellifera on cucumber (Cucumis sativus), watermelon (Citrullus lanatus) and squash (Cucurbita moschata). Field trials were conducted in a 5 × 3 × 2 × 2 factorial arrangement in a randomized complete block design for two seasons. Results showed significant effects of the interaction between agroecological zones × cucurbit species × season × flowers visiting insects on visitation abundance, visitation frequency and visitation rate (p < 0.0001) of flower visiting species. Apis mellifera was the dominant species in cucurbit flowers at both agroecological zones during the two growing seasons. Given its relatively higher visitation, T. floralis is a promising hoverfly species to be explored for its role in the pollination of C. sativus and C. lanatus. Agroecological zone, season and cucurbit species determined the visitation of European honey bees and hoverflies on cucurbits flowers. Cucurbit growers are suggested to employ management practices on farms that favour the abundance and foraging activities of these flower visiting insects for improved and sustainable cucurbit production.