Nest management increases pollinator density in passion fruit orchards

The yields of yellow passion fruit are vulnerable to pollinator decline because the crop is strictly self-incompatible. Nectar foraging carpenter bees are the main pollinators of this crop, whereas honeybees and stingless bees take pollen and nectar without pollination, and can be classified as “thieves”. In many cropping areas, the density of effective pollinators is very low and precludes optimal yield. We investigated, over a period of 6 months, whether the provision of unoccupied and occupied carpenter bee nests could lead to (a) an increase in crop visitation by carpenter bees and (b) a decrease in visitation by thieves. We found that introduction of occupied nests can influence visitation by both carpenter bees and thieves in the expected ways, while the sole provision of unoccupied nests did not achieve this. Our study can be regarded as an important step for increasing pollinators’ population in yellow passion fruit orchards using trap-nests as nesting substrate.