Anti-aphrodisiac pheromone, a renewable signal in adult butterflies

Raimondas Mozuraitis,Christer Wiklund,Yuxin Pei,Leopold Ilag,Rushana Murtazina,Javier Zurita,Anna Karin Borg Karlson

doi:10.1038/s41598-019-50838-1

Abstract

The male butterfly Pieris napi produces the anti-aphrodisiac pheromone methyl salicylate (MeS) and transfers it to the female during mating. After mating she releases MeS, when courted by conspecific males, which decreases her attractiveness and the duration of male harassment, thus increasing her time available for egg-laying. In previous studies we have shown that males produced MeS from the amino acid L-phenylalanine (L-Phe) acquired during larval stage. In this study we show that adult males of P. napi can utilize L-Phe and aromatic flower volatiles as building blocks for production of anti-aphrodisiac pheromone and transfer it to females during mating. We demonstrate this by feeding butterflies with stable isotope labelled molecules mixed in sugar solutions, and, to mimic the natural conditions, we fed male butterflies with floral nectar of Bunias orientalis plants treated with labelled L-Phe. The volatiles from butterflies and plants were collected and identified by solid phase micro extraction, gas chromatography and mass spectrometry techniques. Since P. napi is polygamous, males would gain from restoring the titre of MeS after mating and the use of aromatic precursors for production of MeS could be considered as an advantageous trait which could enable butterflies to relocate L-Phe for other needs.

Highlights

After mating, female butterflies become unreceptive for either the rest of their lives in monandrous species or for a certain period in polyandrous species[1,2]
The comparison of emissions from spermatophores between those from crushed male and mated female abdomens revealed that methyl salicylate (MeS), 2-methoxyphenol and benzyl cyanide released from spermatophores were present in the emissions from crushed abdomens of males and mated females (Fig. 2a–c, Table 1)
In previous work we have shown that methyl salicylate (MeS) acts as an anti-aphrodisiac pheromone in two Pieris species[3,4] and with 13C-labelling we demonstrated that only males of P. napi are able to produce MeS from labelled L-phenylalanine (L-Phe) acquired in the larval stage, which at the first mating is transferred to the female[3]

Summary

Introduction

Female butterflies become unreceptive for either the rest of their lives in monandrous species or for a certain period in polyandrous species[1,2]. In a number of butterfly species, mated females signal unreceptiveness by releasing an anti-aphrodisiac, a pheromone transferred from males to females during mating that reduce attractiveness of females to subsequent courting males[3,4,5,6]. Previous experiments have shown that the amount of anti-aphrodisiac released by P. napi females, having received a male’s first ejaculate, was on average 2.5 times higher than that released by females that had received a male’s second ejaculate, when the male re-mated on the day following his first mating[9]. Previous studies have shown that males produce anti-aphrodisiac from precursors acquired during larval feeding[3,4,5], there are no studies reporting male butterflies’ ability to produce anti-aphrodisiac from resources acquired during adult feeding

Objectives

Methods

Results

Conclusion