Leafhopper (Idioscopus spp.) excreted honeydew distracts honey bees (Apis spp.) from visiting mango (Mangifera indica L.) flowers: an indirect loss inflicted by the sucking pests hitherto unaccounted

Abstract

Honeydew is a sugar-rich sweet substance excreted by the phloem-feeding herbivorous insects like aphids, leafhoppers, mealybugs and scales of the Order Hemiptera. The honeydew is generally deposited on the surface of leaves and other plant parts and serves as a food source to other nectar feeders including honey bees. There is a possibility that the presence of honeydew might distract honey bees from visiting flowers, leading to depriving them of adequate pollination services. In order to establish this hypothesis, field studies were conducted for two consecutive flowering seasons (2017 and 2018) in a mango orchard at Bengaluru, India to assess the effect of honeydew excreted by leafhoppers (Idioscopus spp.), a serious sap-sucking pest of mango (Mangifera indica L.), on honey bee visitation to mango flowers. The number of bees foraging on the inflorescence of mango trees which were allowed to have hopper infestation and subsequent honeydew on foliage was compared with those on trees which were maintained free from leafhoppers incidence and honeydew. The mean number of bees of all three species of Apis foraging on mango flowers on trees maintained free from hopper infestation was significantly higher (4.58/10 panicles/5 min) compared to that on trees with leafhopper infestation and subsequent honeydew deposits on leaves (1.98), which translates to a very considerable 55.53% reduction. Since mango is a cross-pollinated crop, the fruit set is directly proportional to the extent of pollinator activity. This study highlights a different ecological implication of honeydew excreted by a sucking pest of a fruit crop.