Étude comportementale et écologie chimique de la recherche d'un partenaire sexuel chez le puceron de la pomme de terre, Macrosiphum euphorbiae (Thomas) (Homoptera : Aphididae)
|Authors:||Goldansaz, Seyed Hossein.|
|Advisor:||McNeil, Jeremy Nichol|
|Abstract:||In order to use insect sex pheromones in integrated management programme of pest species, it is essential to have the correct identification of the chemical composition of pheromones and a solid understanding of the reproductive biology for the species in question. In this thesis, I examined the two aspects in the potato aphid, Macrosiphum euphorbiae (Homoptera: Aphididae), an agricultural pest of importance worldwide. Virgin female oviparae of the potato aphid release sex pheromone to attract conspecific males. At cooler temperatures females express this behavior at a younger age that at warmer ones. Under all constant temperature regimes in the laboratory there was a significant change in calling behavior as a function of age, with older females calling sooner after the “lights on” signal and spending more time calling. However, under field conditions the age related changes were much less evident due to the effects of low temperatures, high winds and rain on female calling activity. The sex pheromone emitted by calling females of M. euphorbiae was identified as a mixture of two monoterpenoids nepetalactol (I) and nepetalactone (II). The two components were present in a 4:1 ratio in the young females, but this changed with age and older females released a 2:1 ratio. A similar proportion of M. euphorbiae males responded to 3:1, 4:1, and 5:1 synthetic blends and to calling virgin, although the time taken to reach the source was less when conspecific females were used. Males’ behaviour to the calling females was examined in the laboratory and field bioassays. In the laboratory, males detected and oriented themselves to the source but did not fly upwind when exposed to calling females or appropriate lures, and only reached the source if there was a bridge available between the release cage and pheromone source allowing them to walk upwind. Under field conditions female calling, and male walking behavior were observed under variable wind speeds < 5m/s, but male flight behavior was inhibited at variable winds > 2m/s. In contrast to laboratory results where males only reached the source by walking, nearly 40% of males reaching the source did so by flying. A detailed examination of the wind patterns showed that in the presence of wind males walked towards the source but would take flight and make forward progress when there was a temporary lull in the wind.|
|Document Type:||Thèse de doctorat|
|Open Access Date:||11 April 2018|
|Collection:||Thèses et mémoires|
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