Evaluation of the synthetic aggregation pheromones and host plant volatiles for trapping of two sympatric species: Oryctes elegans Prell. and O. agamemnon Burmeister

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عنوان دوره: سومین کنگره بین المللی حشره شناسی ایران

¹Iranian Research Institute of Plant Protection, AREEO, Tehran, Iran,

²Plant Protection Research Department, Bushehr Agricultural and Natural ResourcesResearch and Education Center, AREEO, Bushehr, Iran,

Oryctes elegans and O. agamemnon matthiseseni (Col.: Scarabaeidae), are two sympatric species causing damages on date palms in South of Iran. The 4-methyloctanoic acid and a blend of ethyl 4-methyloctanoate and 4-methyloctanoic acid, with the same ratio of each component, have been identified as the aggregation pheromones of O. elegans and O. agamemnon, respectively. The efficiency of the pheromones (acid and the blend of ester and acid) and the trap position (on ground and below the palm crown) were studied on the capture of these two rhinoceros beetles in two field trapping trials using factorial arrangements based on randomized complete block designs with 4 blocks in Bushehr province during 2016 and 2017. in 2016. Moreover, the effects of the pheromones and two synergists, including date palm core tissue and a host plant-based synthetic blend were also compared in 2017 experiments. Results showed that O. elegans were captured 3 times more by traps baited with the blend of ester and acid compared with those baited with acid alone in 2016. But there was no significant difference between the capture of two pheromones for females, males and both sexes pooled together. In 2017, significantly more females of O. elegans were trapped by the blend of ester and acid compared with acid alone. Even if two times more beetles were caught by the blend in comparison with acid alone, the captures of males and both sexes pooled together were not significantly different by two pheromones. It seems that ethyl 4-methyloctanoate is a behaviorally active component of O. elegans pheromone, especially it is attractive for females. Only 8 females of O. agamemnon were trapped during both trials (7 females by acid alone), resulting serious hesitation on the behavioral activity of acid alone or mixed with the ester, for the Iranian population of this species. Results revealed the probable divergence in pheromone composition of O. agamemnon in sympatry with O. elegans in Iran. The captures of traps on the ground level and those attached below the palm crown were not significantly different for both species. No significant difference was observed between the capture of traps baited with date palm core tissue and those baited with host plant-based synthetic blend. Thus the synthetic blend can be used efficiently as the pheromone synergist of O. elegans. Regarding the possible divergence in pheromone of the Iranian population of O. agamemnon, it is suggested to identify the pheromone composition of both sympatric species as well as the optical isomer of components.

Rhinoceros beetles؛ Pheromone divergence؛ 4-methyloctanoic acid؛ ethyl 4-methyloctanoate؛ Date palm