Flower tracking in hawkmoths: behavior and energetics

Abstract

energy expenditure to track flowers is minimal compared to energy intake; therefore, patterns of net energy gain mimicked patterns of feeding rate. The direction effects of flower motion were greater than the frequency effects. While M. sexta appeared equally capable of tracking flowers moving in the horizontal and vertical motion axes, they demonstrated poor ability to track flowers moving in the looming axis. Additionally, both feeding rates and net energy gain were lower for looming axis flower motions.

Mutually opposing forces during locomotion can eliminate the tradeoff between maneuverability and stability

“…This may seem surprising because these antagonistic forces do not contribute to the cycle-averaged movement of the center of mass of the animal. Such antagonistic forces are not only present during forward locomotion but in hovering for animals such as hummingbirds, hawkmoths, and electric fish; these animals produce large antagonistic forces and exhibit extraordinary maneuverability during station keeping (6)(7)(8)(9). In this study, we demonstrate that active generation and differential control of such antagonistic forces can eliminate the tradeoff between stability and maneuverability during locomotion.…”

Wide-field motion tuning in nocturnal hawkmoths

“…Ultimately, the passage of information through the nervous system costs energy (Laughlin 2001), and if the wide-field motion pathway were the only channel of visual processing, there would be no reason to transduce spatial and temporal frequencies outside the range processed by the motiondetecting neurons. However, parallel pathways in the moth visual system perform other tasks, such as detecting looming stimuli (Farina et al 1994;Wicklein & Strausfeld 2000;Sprayberry & Daniel 2006) or small targets (Collett 1971), and these might be optimized for visual frequencies outside the bands used by the wide-field motion pathway. Information not collected by the eye, or lost during early visual processing, cannot be recovered downstream.…”

“…To siphon nectar effectively, a hovering hawkmoth must maintain a minimal distance to its flower. If it drifts in the air, it must counter that motion before it is carried out of range-roughly the length of its proboscis (Farina et al 1994;Sprayberry & Daniel 2006). Visually estimating potentially tiny deviations from a motionless hovering state requires sensitivity to low-velocity visual motion (O'Carroll et al 1996(O'Carroll et al , 1997.…”

Look and touch: multimodal sensory control of flower inspection movements in the nocturnal hawkmothManduca sexta

“…M. sexta is challenged to hover and keep its long proboscis in contact with flowers that can move by action of the wind. Nevertheless, they effectively track plain white flowers moving sinusoidally with frequencies of up to 2-3Hz in the vertical and horizontal axes (Sprayberry and Daniel, 2007). We are now set to investigate whether contrasting visual marks on the corolla could have an effect on flower movement detection and tracking performance.…”

“…This supports the hypothesis that while visual floral guides can affect initial proboscis placement, tactile guides can control subsequent inspection movements (H 2 ). It is interesting that these tactile stimuli, besides dominating inspection movements, appear to take priority over the visual stimuli used for flight stabilization while hovering (Sprayberry and Daniel, 2007;Wicklein and Strausfeld, 2000).…”