In vivo real-time monitoring of aphrodisiac pheromone release of small white cabbage butterflies (Pieris rapae)

Abstract

The study of insect behavior is of practical importance for developing possible control methods in Integrated Pest Management. Currently, one model of butterfly mating behavior suggests that the initial location of potential mates occurs visually followed by the release of one or more short-range male aphrodisiac pheromones. This model is supported by data obtained from field observations and inferences based on the behavioral effects of chemicals extracted or isolated using indirect and offline techniques. In this study, we performed in vivo real-time monitoring of the male aphrodisiac pheromones released by the small white cabbage male butterfly (Pieris rapae Linnaeus) using confined direct analysis in real time (cDART) mass spectrometry. cDART is a new method easily adapted to the study in real time of chemicals released into the environment by virtually any insect. The major compound released by the male Pieris rapae was identified as ferrulactone. The experimental results reported here indicate that the release of ferrulactone occurs less than 1s after the male visualizes its partner, and reaches a maximum after about one half minute. This study is the first reported in vivo detection and monitoring of butterfly male aphrodisiac pheromones in real time.

Rapid Divergence of Wing Volatile Profiles Between Subspecies of the Butterfly Pieris rapae (Lepidoptera: Pieridae)

“…In P. r. rapae , it is known that supplementing the wings of males with a titre of ferrulactone, hexahydrofarnecyl acetone, and phytol (compounds 2 , 3 , and 5 ) does generate a behavioral response ( Yildizhan et al 2009 ). In fact, in both previous studies that investigated pheromones in P. r. rapae , addition of pheromone titres resulted in increased mating success, suggesting a ‘more is better’ mechanism of female preference in this species ( Yildizhan et al 2009 , Li and Mathews 2016 ). Given that there is no change in the observed rank order of chemical production between subspecies with the exception of cholesterol (which has previously been shown not to be detectable by P. rapae ), we might anticipate that P. r. rapae males, which have higher quantities of these volatile compounds, would be successful when courting females of either subspecies.…”

“…Both males and females have diverged in their wing volatile chemical composition, but both our principle component analyses and linear discriminant analyses revealed that divergence in volatile profiles was more dramatic for males. Importantly, three of the compounds that differ in amount between subspecies males have been definitively shown to be detectable by these butterflies, and to affect the success of male courtship in P. r. rapae ( Yildizhan et al 2009 , Li and Mathews 2016 ). For females, it appears that the observed chemical profile differences are predominantly due to an increase in female P. r. crucivora wing size.…”

“…First, the multivariate analysis was performed using the IS normalized values for all identified compounds (hereafter ‘Analysis 1’). A second analysis (hereafter ‘Analysis 2’) was then performed using only compounds shown to be detectable to P. r. rapae from previous studies ( Yildizhan et al 2009 , Li and Mathews 2016 ). The detectability of compounds is noted in Table 1 .…”

Tools in the Investigation of Volatile Semiochemicals on Insects: From Sampling to Statistical Analysis

“…There are two main classifications of HS sampling [35]: static (SHS), in which the analytes on the vapor phase are accumulated passively on capture material by sorption; and dynamic (DHS), which employs a gas flow to assist with the extraction and concentration of volatile compounds on the adsorbent phase [36]. There are a huge number of published cases using DHS sampling, so the collection of VOCs has been achieved, for instance, from whole intact plants [37] or those with controlled herbivory [38,39], flowers [40,41], fresh fruits [42], insect dregs [37], roots [43], and living insects [44].…”

“…Among these, the utilization of ion trap mass spectrometers (itMS) is referenced in studies addressing VOCs related to insect attraction in flowers [69] and whole plants [73], phytopathogenic vectors [115], and parasites [42]. In parallel, the magnetic sector analyzer has been reported for real-time monitoring of insect pheromone release [44] and time-of-flight (TOF) analyzers in the assessment of biosynthesis of VOCs important for pollinator attraction [21], in the characterization of volatile secretions from Graphosoma lineatum [116], or in the profiling of compounds present in Tilia spp. nectar, which allowed to discard the assumption of the toxic character of nectar for bumblebees [117], among other studies.…”