Characterization of Male-Produced Aggregation Pheromone of the Bean Flower Thrips Megalurothrips sjostedti (Thysanoptera: Thripidae)

Saliou Niassy,Cassie Sims,Roland Mumm,Amanuel Tamiru,James G C Hamilton,Sunday Ekesi,Nguya K Maniania,Krishnakumari Bandi,Fraser Mitchell,William D J Kirk,Willem Jan De Kogel,Sevgan Subramanian

doi:10.1007/s10886-019-01054-8

Abstract

Aggregation of the bean flower thrips, Megalurothrips sjostedti (Trybom) (Thysanoptera: Thripidae), has been observed on cowpea, Vigna unguiculata (L.) Walp. To understand the mechanism underpinning this behavior, we studied the responses of M. sjostedti to headspace volatiles from conspecifics in a four-arm olfactometer. Both male and female M. sjostedti were attracted to male, but not to female odor. Gas chromatography/mass spectrometry (GC/MS) analyses revealed the presence of two distinct compounds in male M. sjostedti headspace, namely (R)-lavandulyl 3-methylbutanoate (major compound) and (R)-lavandulol (minor compound); by contrast, both compounds were only present in trace amounts in female headspace collections. A behavioral assay using synthetic compounds showed that male M. sjostedti was attracted to both (R)-lavandulyl 3-methylbutanoate and (R)-lavandulol, while females responded only to (R)-lavandulyl 3-methylbutanoate. This is the first report of a male-produced aggregation pheromone in the genus Megalurothrips. The bean flower thrips is the primary pest of cowpea, which is widely grown in sub-Saharan Africa. The attraction of male and female M. sjostedti to these compounds offers an opportunity to develop ecologically sustainable management methods for M. sjostedti in Africa.

Highlights

Cowpea, Vigna unguiculata (L.) Walp., is widely grown in sub-Saharan Africa for human consumption, as a source of income and livestock feed
Our study of the behavioral responses of M. sjostedti from Mbita, Kenya to conspecific odors revealed that both male and female M. sjostedti were attracted to headspace volatiles from males, demonstrating the presence of a maleproduced aggregation pheromone. These results are similar to the behavioral responses reported in four other thrips species, F. occidentalis, F. intonsa, T. palmi and P. kellyanus, in which males and females responded to male odor (Akella et al 2014; Kirk and Hamilton 2004; Webster et al 2006; Zhang et al 2011)
Two compounds were detected in F. occidentalis and F. intonsa (Hamilton et al 2005; Zhang et al 2011), whereas only one compound was detected in T. palmi (Akella et al 2014)

Summary

Introduction

Vigna unguiculata (L.) Walp., is widely grown in sub-Saharan Africa for human consumption, as a source of income and livestock feed. The bean flower thrips, Megalurothrips sjostedti (Trybom) (Thysanoptera: Thripidae), is one of the major limitations of cowpea production in Africa, causing 21–83% yield loss due to flower abortion and reduction in quality (Alao et al 2011; Mfuti et al 2017; Tamò et al 2002). Male aggregation in species such as Frankliniella occidentalis (Pergande), F. schultzei (Trybom), Thrips fuscipennis (Haliday) and T. major (Uzel), takes place in the corolla of flowers (Kirk 1985; Milne et al 2002; Terry and Gardner 1990). The chemical constituents of the aggregation pheromones of F. occidentalis (Hamilton et al 2005), F. intonsa (Trybom) (Zhang et al 2011) and Thrips palmi Karny, 1925 (Akella et al 2014) have been identified

Methods

Results

Conclusion