Influence of Conspecific Male Odour and Host Kairomones on the Behaviour of Sternochetus mangiferae, a Pest of Mangoes in Brazil and Ghana

Sternochetus mangiferae is a pest of mangoes, occurring worldwide in regions where mangoes are cultivated. In Brazil, this insect was first detected in 2014 in Seropédica, Rio de Janeiro, and since then, various measures and studies have been conducted to contain, monitor and potentially eradicate it. Semiochemicals may provide feasible targets to develop sensitive detection and monitoring tools. Therefore, this study aimed to evaluate whether S. mangiferae use pheromones from conspecifics and kairomones from mango tree host in their chemical communication. The findings identify a blend of mango volatiles that influence the behaviour of S. mangiferae females. A synthetic blend containing the EAD-active compounds γ-butyrolactone, benzaldehyde, 6-methyl-5-hepten-2-one, myrcene, (Z)-ocimene, 2-methoxyphenol, (S)-linalool, methyl salicylate and methyl benzoate was attractive to females of S. mangiferae from Ghanaian and Brazilian populations in two-choice olfactometry experiments. The results also indicate that the absolute configuration of linalool in the mango synthetic blend is crucial for female attraction, as females respond only to blends containing (S)-linalool. Furthermore, females from both populations were attracted to the odour of live males from their respective localities. Chemical analysis of aeration samples from the Brazilian population revealed that males and females emitted qualitatively similar volatile profiles. Although no male-specific compounds could be identified to fully explain female attraction, this study provides the first evidence of intraspecific chemical communication in S. mangiferae. These findings advance our understanding of the chemical ecology of this pest and support the development of semiochemical-based monitoring and management strategies for mango orchards.