Minor Components Play an Important Role in Interspecific Recognition of Insects: A Basis to Pheromone Based Electronic Monitoring Tools for Rice Pests.

Qing-Hua Chen,Wancai Liu,Lieming Pan,Zhihua Tian,Rong Guo,Yongjun Du,Wan-Min Zhang,Feng Zhu

doi:10.3390/insects9040192

Qing-Hua Chen, Wancai Liu + Show 6 more

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https://doi.org/10.3390/insects9040192

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Abstract

Several lepidopteran species share the same pheromone blend consisting of (Z)-11-hexadecenal (Z11-16:Ald) and (Z)-9-hexadecenal (Z9-16:Ald) at different ratios and active doses. In rice pest Chilo suppressalis, (Z)-11-hexadecenol, (Z11-16:OH) and octadecanal (18:Ald) were identified as minor components in the pheromone gland of female moths, and these components were previously not considered as part of the sex pheromone of C. suppressalis. Z11-16:Ald, Z9-16:Ald and (Z)-13-octadecenal (Z13-18:Ald) frequently trapped other lepidopteran species, such as rice pests Scirpophaga incertulas and Mythimna separate, corn and vegetable pests Helicoverpa armigera in the field, suggesting a lack of specificity in the pheromone blend. Our data showed that the minor component Z11-16:OH did not have a synergistic effect on the attractiveness of the blend to C. suppressalis; however, pheromone mixtures containing Z11-16:OH failed in trapping male H. armigera moths. We confirmed the identity and specificity of the C. suppressalis sex pheromone and demonstrated that Z11-16:OH plays a key role in the reproductive isolation of C. suppressalis, M. separata, and H. armigera moths, and a similar role of Z9-18:Ald in that of S. incertulas and C. suppressalis. This phenomenon could be more widely applicable to interspecific interactions in the pheromone communication between insects, which is crucial to developing the electronic automatic counting device for automatically monitoring the pest population by pheromone trapping based on its species specificity.

Highlights

In the field, crowds of C. suppressalis, S. incertulas, Mythimna separate, and H. armigera moths occurred together, for instance, at the overlapping areas of rice, vegetables, and corn cropping, where the traps baited with the pheromone blends composed of C. suppressalis synthetic compoundsInsects 2018, 9, 192; doi:10.3390/insects9040192 www.mdpi.com/journal/insectsInsects 2018, 9, 192 would catch these species
It has shown that a single molecular determinant can function as a behavior modulator, as well as an all-or-nothing initiator of a complex species-specific behavioral sequence [26], which can result in no effect of the blend of major compounds on specificity; and this may account for our observation on H. armigera, M. separata, and S. incertulas
We demonstrated the important role of minor components in the species specificity of insect sex pheromones

Summary

Introduction

Crowds of C. suppressalis, S. incertulas, Mythimna separate, and H. armigera moths occurred together, for instance, at the overlapping areas of rice, vegetables, and corn cropping, where the traps baited with the pheromone blends composed of C. suppressalis synthetic compounds. Insects 2018, 9, 192 would catch these species. Such false trapping has been reported in other lepidopteran species, especially those that are closely related to each other [1,2,3,4,5,6]. Differences in diel rhythms of attraction and seasonal distribution were insufficient to maintain the reproductive isolation in these instances. The specificity of pheromone attraction is considered as the paramount premating reproductive isolating mechanism in moths among different species [3]. Several other species share the same mixture of Z11-16:Ald and Z9-16:Ald at similar ratios, such as Helicoverpa armigera (Hübner)

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