RELATIVE SUSCEPTIBILITY OF SOME COTTON CULTIVARS TO NFESTATION BY WHITEFLY BEMISIA TABACI GENN. AND ITS RELATION TO THE PRESCENCE OF NATURAL ENEMIES

S. Jasim, S.; S. A. Ali, A.; H. Sameer, S.

	RELATIVE SUSCEPTIBILITY OF SOME COTTON CULTIVARS TO NFESTATION BY WHITEFLY BEMISIA TABACI GENN. AND ITS RELATION TO THE PRESCENCE OF NATURAL ENEMIES
IRAQ JOURNAL OF AGRICULTURE
Article 1, Volume 11, Issue 1, 2006, Pages 0-0
Authors
S. S. Jasim; A. S. A. Ali; S. H. Sameer
Abstract
Laboratory and field studies were conducted to evaluate the susceptibility of some cotton cultivars, grown in Iraq (Altamim 5949, Cocker 310, Lashata, Ashoor) to infestation by whitefly Bemisia tabaci. The relation of these cultivars to the presence of some natural enemies was also evaluated under field conditions. Results indicated that caltivar, Altamim 5949 was the most preferred host for feeding and egg laying of the insect . The least preferred host was the cultivar Ashoor. The same trend was observed under field conditions. Average number of egg, nymphs and adults recorded on cotton cultivars Altamim; Koker310, Lashata and Ashoor were 185, 157, 147, 132 egg / leaf respectively and 96, 87, 82, 80 nymph / leaf and 75, 59, 51, 44 adult/ leaf. Field data also have indicated the presence of some predators and parasitoids feeding on whitefly stages on cotton cultivars.These include: Scolothrips sexmaculatus (Perg.), Stethorus gilvifrons (Muls.),Clitostethus arcuatus (Rossi.), Scymnus syriacus (Mars.), Scymnus apetzi (Muls.),Coccinella septempunctata, L. Coccinella undecempunctata L, Orius albidipennis (Reut.), Chrysoperla carnea (Stephens), Metasyrphus corollae F., Trithemia annulata (Beauvois), Mantis sp. And the Parasitoid Eritmocerus mundus Mercet .The predators Stethorus gilvifrons and Scolothrips sexmaculatus were the most dominant species during the course of the study. The predator S. gilvifrons was first observed during the last week of April. The highest population was recorded at the end of September. Average numbers of larvae, pupae and adults were 38,25,18/15 leaves respectively.The first presence of S.sexmaculatus was recorded during the fourth week of May . The highest population density was 43, 27, 21/15 leaves for larvae, pupae, and adults respectivey. At the end of September and early October. The possibilities of integrating these natural enemies with host plant resistant for whitefly control on cotton was discussed .

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