Learning to feed in the dark: how light levels influences feeding in the hawkmoth Manduca sexta

Nocturnal insects like moths are essential for pollination, providing
resilience to the diurnal pollination networks. Moths use both vision and
mechanosensation to locate the nectary opening in the flowers with their
proboscis. However, increased light levels due to artificial light at
night (ALAN) pose a serious threat to nocturnal insects. Here we examined
how light levels influence the efficacy by which the crepuscular hawkmoth
Manduca sexta locates the nectary. We used 3D printed artificial flowers
fitted with motion sensors in the nectary and machine vision to track the
motion of hovering moths under two light levels: 0.1 lux (moonlight) and
50 lux (dawn/dusk). We found that moths in higher light conditions took
significantly longer to find the nectary, even with repeated visits to the
same flower. In addition to taking longer, moths in higher light
conditions hovered further from the flower during feeding. Increased light
levels adversely affect learning and motor control in these animals.