Zoophytophagous predator sex pheromone and visual cues of opposing reflectance spectra lure predator and invasive prey

Bashiru Adams; Fathiya Mbarak Khamis; Abdullahi Ahmed Yusuf; Baldwyn Torto

doi:10.1016/j.jare.2024.05.005

Zoophytophagous predator sex pheromone and visual cues of opposing reflectance spectra lure predator and invasive prey

J Adv Res. 2024 May 4:S2090-1232(24)00182-6. doi: 10.1016/j.jare.2024.05.005. Online ahead of print.

Authors

Bashiru Adams¹, Fathiya Mbarak Khamis², Abdullahi Ahmed Yusuf³, Baldwyn Torto⁴

Affiliations

¹ International Centre of Insect Physiology and Ecology (icipe), P.O. Box 30772 00100, Nairobi, Kenya; Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa.
² International Centre of Insect Physiology and Ecology (icipe), P.O. Box 30772 00100, Nairobi, Kenya. Electronic address: fkhamis@icipe.org.
³ Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa.
⁴ International Centre of Insect Physiology and Ecology (icipe), P.O. Box 30772 00100, Nairobi, Kenya; Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa. Electronic address: btorto@icipe.org.

PMID: 38710469
DOI: 10.1016/j.jare.2024.05.005

Abstract

Introduction: In sub-Saharan Africa, the invasive South American leafminer Phthorimaea absoluta is the most damaging tomato pest. Females of the pest can reproduce both sexually and through parthenogenesis and lay their eggs on all tomato plant parts. The mirid predator Nesidiocoris tenuis, a biological control agent for the pest, is also a tomato pest when prey population is low. To date, however, no study has developed an eco-friendly solution that targets both the predator and its host in a tomato farming system.

Objective: To develop a bio-based management system for both pest and predator based on the combined use of sexual communication in the predator and visual cues.

Methods: We collected volatiles from both sexes of the Kenyan population of the predator N. tenuis and identified candidate sex pheromone components by coupled gas chromatography-mass spectrometry (GC-MS). We used electrophysiological assays to identify antennally-active odorants in the volatiles, followed by field trials with different pheromone-baited colored traps to validate the responses of both predator and prey. Thereafter, we compared the reflectance spectra of the colored traps with those of different tomato plant tissues.

Results: Our results reveal an interplay between different sensory cues which in the predator-prey interaction may favor the predator. Antennae of both sexes of predator and prey detect the predator sex pheromone identified as 1-octanol and hexyl hexanoate. Unexpectedly, our field experiments led to the discovery of a lure for P. absoluta females, which were lured distinctly into a pheromone-baited trap whose reflectance spectrum mimicked that of ripe tomato fruit (long wavelength), an egg-laying site for females. Contrastingly, N. tenuis males were lured into baited white trap (short wavelength) when the predator is actively searching for prey.

Conclusion: Our results demonstrate the novel use of a predator sex pheromone and different visual cues to assess complex trophic interactions on tomatoes.

Keywords: Mirid; Nesidiocoris tenuis; Olfaction; Phthorimaea absoluta; Predator–prey interaction; Sex pheromone.