Background: The cabbage moth, Mamestra brassicae, is a polyphagous pest that attacks several crops. Here, the sublethal and lethal effects of chlorantraniliprole and indoxacarb were investigated on the developmental stages, detoxification enzymes, reproductive activity, calling behavior, peripheral physiology, and pheromone titer of M. brasssicae. Methods: To assess pesticide effects, the second instar larvae were maintained for 24 h on a semi-artificial diet containing insecticides at their LC₁₀, LC₃₀, and LC₅₀ concentrations. Results: M. brassicae was more susceptible to chlorantraniliprole (LC₅₀ = 0.35 mg/L) than indoxacarb (LC₅₀ = 1.71 mg/L). A significantly increased developmental time was observed with both insecticides at all tested concentrations but decreases in pupation rate, pupal weight, and emergence were limited to the LC₅₀ concentration. Reductions in both the total number of eggs laid per female and the egg viability were observed with both insecticides at their LC₃₀ and LC₅₀ concentrations. Both female calling activity and the sex pheromone (Z11-hexadecenyl acetate and hexadecenyl acetate) titer were significantly reduced by chlorantraniliprole in LC₅₀ concentration. Antennal responses of female antennae to benzaldehyde and 3-octanone were significantly weaker than controls after exposure to the indoxocarb LC₅₀ concentration. Significant reductions in the enzymatic activity of glutathione S-transferases, mixed-function oxidases, and carboxylesterases were observed in response to both insecticides.

The great diversity of specialist plant-feeding insects suggests that host plant shifts may initiate speciation, even without geographic barriers. Pheromones and kairomones mediate sexual communication and host choice, and the response to these behaviour-modifying chemicals is under sexual and natural selection, respectively. The concept that the interaction of mate signals and habitat cues facilitates reproductive isolation and ecological speciation is well established, while the traits and the underlying sensory mechanisms remain unknown. The larva of codling moth feeds in apple and other rosaceous fruits. We show for the first time that the response of male moths to female sex pheromone codlemone relies upon presence of pear ester, a kairomone emitted by host fruit. In the non-host tree birch, attraction to pheromone alone is very strongly reduced, but is fully rescued by blending pheromone with kairomone. This affords a mechanism how host plant shifts shape new mate-finding signals that can give rise to assortative mating and reproductive isolation.

Background: The variegated fruit fly, Phortica variegata (Drosophilidae: Steganinae), is native to Europe and has emerged as a major vector of ocular nematosis caused by Thelazia callipaeda (Rhabditida: Thelaziidae), following the its introduction into Europe from Asia. Male P. variegata transmit these nematodes by feeding on tears of mammals, including wild and domestic carnivores (foxes, beech martens, wild cats, and dogs), lagomorphs, and humans. Understanding the olfactory responses of P. variegata to volatile cues is essential for developing attractant-based surveillance and control strategies, yet its olfactory ecology remains largely unexplored. Methods: We used gas chromatography coupled electroantennography to measure antennal responses to synthetic and natural volatile blends. A comparative analysis was performed on the antennal responses of both sexes of P. variegata and its well-studied relative, Drosophila melanogaster. Components of the synthetic blends were selected based on the odorant receptor repertoire of D. melanogaster and established mosquito attractants, with the rationale that conserved olfactory receptors among dipterans may allow P. variegata to detect similar compounds. Volatile extracts collected using active carbon adsorbent traps were also tested on the antennae and analyzed using gas chromatography coupled mass spectrometry. Results: Male P. variegata showed higher antennal responses to phenol, 3-octanone, and sulcatone than females, indicating olfactory sexual dimorphism. Compared to D. melanogaster, the antennae of P. variegata did not respond to several common plant alcohols and terpenoids. Instead, they showed stronger responses to compounds such as anisole, ethyl propanoate, butyl propanoate, propyl acetate, 3-octanone, nonanal, and decanal, suggesting that peripheral olfaction in P. variegata may be more tuned to microbial volatiles. Conclusions: Phortica variegata exhibits sexual dimorphism in olfactory responsivity, with males showing greater responsiveness to volatiles associated with host-seeking in other zoophilic dipterans, potentially guiding them to mammalian hosts for tear-feeding. Compared to D. melanogaster, P. variegata is more responsive to microbial and yeast-related volatiles and less responsive to plant-derived terpenoids, suggesting a foraging ecology linked to microbial substrates. The antennally detected volatiles identified in this study can be used as candidates for further behavioral studies to develop lures for vector management. Graphical

The great diversity of specialist plant-feeding insects suggests that host plant shifts may initiate speciation, even without geographic barriers. Pheromones and kairomones mediate sexual communication and host choice, and the response to these behaviour-modifying chemicals is under sexual and natural selection, respectively. The idea that the interaction of mate signals and habitat cues facilitates reproductive isolation and ecological speciation is well-established, while the traits and the underlying sensory mechanisms remain unknown. The larva of codling moth feeds in the apple. We show for the first time that the response of male moths to female sex pheromone relies upon presence of a kairomone released from apple. In a non-host tree, attraction to pheromone alone is very strongly reduced, but is fully rescued by blending pheromone with the apple kairomone. This affords a mechanism how host plant shifts shape new mate-finding signals that can give rise to assortative mating and reproductive isolation.

The published article "Host Plant Odour and Sex Pheromone are Integral to Mate Finding in Codling Moth", pub