Physical and chemical plant characters inhibiting the searching behaviour of Trichogramma chilonis

Romeis, J and Shanower, T G and Zebitz, C P W (1998) Physical and chemical plant characters inhibiting the searching behaviour of Trichogramma chilonis. Entomologia Experimentalis et Applicata, 87 (3). pp. 275-284.

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Several plant characters are known to affect the searching behaviour and parasitization efficiency of Trichogrammaspp. (Hymenoptera: Trichogrammatidae). In this study, plant characters contributing to the low Helicoverpaarmigera (Hübner) (Lepidoptera: Noctuidae) egg parasitism levels on pigeonpea (Cajanus cajan (L.) Millspaugh)were investigated. The efficiency of T. chilonis on pigeonpeawas dependent on the plant structure on which the hosteggs were found. In a cage experiment,more than 55% of eggs placed on leaves were parasitized, while 1% of eggson calyxes and no eggs on pods were parasitized. In a filter paper bioassay, parasitoids were deterred by acetone andhexane surface extracts from pigeonpea pods but showed no response to water extract. The searching behaviour ofthe parasitoids was not affected by different solvent extracts from the surface of pigeonpea leaves. In a four-armedairflow olfactometer, T. chilonis was repelled by volatiles from pigeonpea pods but showed no response to volatilesderived from hexane extract of pod surfaces. Volatile infochemicals and hexane surface extracts from pods of twowild Cajanus species, C. scarabaeoides (L.) Thours and C. platycarpus (Bentham) van derMaesen, were similarlydeterrent to T. chilonis. The movement of the parasitoids on pigeonpea pods and calyxes was inhibited by longtrichomes and wasps were trapped by sticky trichome exudates. Parasitoids walked significantly faster on leavesthan on pods. The walking speed on both pods and leaves increased significantly after washing with hexane. Theresults presented in this paper show that the plant growth stage and the plant structures preferred by H. armigerafor oviposition are the least suitable for T. chilonis, contributing to the low parasitoid efficiency on pigeonpea.

Item Type: Article
Subjects: Others > Agriculture-Farming, Production, Technology, Economics
Depositing User: Library ICRISAT
Date Deposited: 17 Sep 2011 08:32
Last Modified: 17 Sep 2011 08:32
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Acknowledgement: UNSPECIFIED
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