Pollinator supplementation mitigates pollination deficits in smallholder avocado (Persea americana Mill.) production systems in Kenya.

• Avocado fruit set in Kenya is highly dependent on insect pollination. • Smallholder avocado farms face a pollination deficit of 20.7%. • The placement of honey bee colonies mitigates this pollination deficit. • Small farm size benefits avocado fruit retention rates, possibly due to reduced nutrient competition and easy pest management. Avocado (Persea americana Mill.) is a major horticultural crop that relies on insect mediated pollination. In avocado production, a knowledge gap exists as to the importance of insect pollination, especially in East African smallholder farms. In this study, conducted in a leading smallholder avocado production region in Kenya, we assessed the dependence of avocado fruit set on insect pollination and whether current smallholder production systems suffer from a deficit in pollination services. Furthermore, we assessed if supplementation with colonies of the Western honey bee (Apis mellifera L.) to farms mitigated potential pollination deficits. Our results revealed a very high reliance of avocado on insect pollinators, with a significantly lower fruit set observed for self- and wind-pollinated (17.4%) or self-pollinated flowers (6.4%) in comparison with insect-pollinated flowers (89.5%). We found a significant pollination deficit across farms, with hand-pollinated flowers on average producing 20.7% more fruits than non-treated open flowers prior to fruit abortion. This pollination deficit could be compensated by the supplementation of farms with A. mellifera colonies. Our findings suggest that pollination is limiting fruit set in avocado and that A. Mellifera supplementation on farms is a potential option to increase fruit yield. [ABSTRACT FROM AUTHOR]