Sex pheromone saturated environment as a stressogenic factor for the populations of harmful insects | Mediul saturat cu feromon sexual ca factor stresogen asupra populatiilor de insecte daunatoare
2013
Nastas, T., Academia de Stiinte a Moldovei, Chisinau (Republic of Moldova). Inst. de Protectie a Plantelor si Agricultura Ecologica
Mating behavior, reproductive traits and ontogenetic cycle were studied in Mamestra brassicae L. kept in an environment saturated with synthetic sex pheromone, under laboratory conditions. It was found that exposure to pheromone affected sexual behavior of both males and females. Essential changes were noted in the duration of successive mating phases. The whole mating process was significantly shorter in insects exposed to pheromone _ 5 hours, while in non-exposed insects (control variant) _ 19 hours. A 2,8 times reduction in the number of eggs laid per female and an 8 times increase in the rate of sterile eggs was registered in experimental variant as compared with the control. Ontogenetic cycle was studied through two generations. From the total number of larvae, only 49,9 % survived up to pupal stage, while in the control variant 58,7%. There were many fewer females than males, sex ratio was 0,7 : 1,4B, instead of 1,0 : 1,0, characteristic for the insects of control variant. The changes were even more in the second generation. In pheromone-exposed group there were 37,5 percent fewer hatched butterflies, than there were in the control group. From experimental results it can be concluded, that the environment saturated with synthetic sex pheromone acts as a stress factor on the whole ontogenetic cycle of Mamestra brassicae L. As a consequence, deviations from the norm occur, leading to a considerable reduction in female fertility and to subsequent decrease in population density.
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