Sensory Organ Investment Varies with Body Size and Sex in the Butterfly Pieris napi

Abstract

In solitary insect pollinators such as butterflies, sensory systems must be adapted for multiple tasks, including nectar foraging, mate-finding, and locating host-plants. As a result, the energetic investments between sensory organs can vary at the intraspecific level and even among sexes. To date, little is known about how these investments are distributed between sensory systems and how it varies among individuals of different sex. We performed a comprehensive allometric study on males and females of the butterfly Pieris napi where we measured the sizes and other parameters of sensory traits including eyes, antennae, proboscis, and wings. Our findings show that among all the sensory traits measured, only antenna and wing size have an allometric relationship with body size and that the energetic investment in different sensory systems varies between males and females. Moreover, males had absolutely larger antennae and eyes, indicating that they invest more energy in these organs than females of the same body size. Overall, the findings of this study reveal that the size of sensory traits in P. napi are not necessarily related to body size and raises questions about other factors that drive sensory trait investment in this species and in other insect pollinators in general.

Morphological Characterization of the Antenna and Scent Patch of Three Danaus Species (Papilionoidea: Nymphalidae, Danainae)

“…However, no quantitative comparison was made between the morphological characteristics of the antennae and scent patches of the different Danaus species. It is also important to consider how the morphological characteristics of the antennae and scent patches fit together, as larger sensory organs can enhance sensitivity by increasing the number or size of sensing structures, but this often comes at a higher developmental cost [17]. However, there has been no investigation into the correlation between the morphological characterization of these two organs.…”