ABSTRACT
Natural enemies are more effective at controlling herbivores in diverse botanical ecosystems. Different chemical cues help to correspond in diversity of associations between prey and host plant species. Recent studies exhibited that the use of natural enemy is an ecofriendly measure to control pests. The Seven spotted ladybird beetle, Coccinella septempunctata play a prominent role in aphid management. It exploits several different cues released by plants to increase the efficiency of foraging. Aphid endoparasitoid, Diaeretiella rapae (McIntosh) (Hymenoptera: Braconidae) have an ability to locate itshosts by responding to odours from aphid hostplants or by visual searching.The treatments with different combinations of plant extracts and semiochemicals were used for natural enemypreference experiment. The experiment was conducted with seven treatments and five replications at Glass house situated in Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi field area during Feb-April, 2015. The Coccinella septempunctata were collected from wheat crop plants. They remained starved for two days before Olfactometer bioassays. For D. rapae, mummified aphidswere collected from wheat crop. Naive females were subjected to olfactometer tests. Seven different combined treatments of semiochemicals and plant extract were applied on filter paper strips at 3% concentration. The filter paper strips were placed in arms of olfactometer. The control arms were treated with n-hexane. Data pertaining to preference of C. septempunctata and D. rapae after treatment application were recorded and analysed statistically. It was found that T6 (β-pinene + E-β-Farnesene) exhibited highest mean number entries of C. septempunctata (6.13%) and highest mean time spend(6.23%) as compared to two other treatments applied. The results revealed that alarm pheromone component effective kairomone for aphid predatory beetles. It was found that T6 (β-pinene + E-β-Farnesene) exhibited highest mean number entries of D. rapae (7.50%) and highest mean time spend(6.39%) as compared to other treatments applied. The results revealed that release of insect derived semiochemicals can enhance visual searching and efficiency of parasitoid D. rapae.
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