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The mating behaviour and evidence for sex-specific pheromones of the main pest of green mate, Ilex paraguariensis, of the southern region of Brazil, Hedypathes betulinus (Klug, 1825) (Coleoptera: Cerambycidae: Lamiinae), were studied in the laboratory. The mating sequence of H. betulinus includes: female approaching the male, antennal contact, male mounting the female and start of copulation. This mating sequence provided support for our hypothesis that recognition of males by females may be mediated by a male-produced pheromone and males recognize females by contact pheromones. The behavioural responses in an olfactometer of male and female H. betulinus to volatiles released by male and female conspecifics confirmed the presence of a male-produced sex pheromone. This finding suggests that visual cues are not primary in eliciting a sexual response from females. Three male-specific compounds were detected in the chromatographic analysis, providing chemical support to the behavioural data. Males did not respond to dead-washed females but 70% of males attempted to mate with dead-washed extract-treated females, suggesting that extracts contained contact pheromones. Based on these results, a male-produced sex pheromone and a female-produced contact pheromone should be essential in the communication system of H. betulinus. [ABSTRACT FROM AUTHOR]

The Brazilian soybean stalk weevil, Sternechus subsignatus Boehman (Coleoptera: Curculionidae), is a pest of economic importance in many regions of Brazil. Volatiles from both sexes of S. subsignatus were collected by aeration and the behavioural response of males and females was evaluated using a Y-olfactometer. The results obtained demonstrate that the communication in S. subsignatus is mediated by aggregation pheromone as both sexes were attracted to host plant (HP) volatiles, and this attraction was increased by the addition of male volatiles. At least five male-specific compounds (1–5) were detected in the chromatographic analysis, providing chemical support to the behavioural data. Release of these volatiles is dependent on the presence of the HP as the amount of compounds differs significantly when volatiles are collected from weevils with or without access to food. The release takes place mainly during photophase, showing a peak between 4 and 6 h after its beginning, which is also a peak of the insect activity in the field. Studies are underway to elucidate the structures of these putative aggregation pheromone components, in order to evaluate their biological activity under laboratory and field conditions. [ABSTRACT FROM AUTHOR]