Egg laying and host stage preference at constant temperatures inEncarsia tricolor [Hym.: Aphelinidae] |
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Authors: | M Artigues J Avilla M J Sarasua R Albajes |
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Institution: | (1) Area de Protecció de Conreus, Centre UPC-IRTA, Rovira Roure, 177.25006 Lleida, Spain |
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Abstract: | Encarsia tricolor Foërster is a facultative autoparasitoid that develops on the important pestTrialeurodes vaporariorum (Westwood) in outdoor crop conditions, which makes this aphelinid species promising for biological control programs in regions where field and protected crops coexist. In this paper we report the results obtained in the study of daily and totalE. tricolor egg laying and of adult female preference for different host stages in which to lay eggs at constant temperatures in the range 10 to 32 °C. Only whitefly nymphs were present in the searching arena (tomato leaflets). The mean number of eggs laid per female in one day ranged from 4.0 (10 °C and 32 °C) to 15.2 (24 °C). The mean total number of eggs increased with temperature from 10 to 28 °C, reaching a maximum of 123 eggs per female at 28 °C, and decreased sharply from 28 to 32 °C. The relation between the intrinsic rate of increase (rm) and temperature in the range 10 to 28 °C followed a straight line whose equation was rm=?0.076+0.011*T (R2=0.99). The rm ofE. tricolor was greater than the rm ofT. vaporariorum when temperature was higher than 9.2 °C. The preference for any particular host instar in which to lay eggs was not always significant. However, N4 was the host instar preferred whenever preference was statistically significant. |
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Keywords: | Encarsia tricolor autoparasitoid egg laying rm host preference temperature |
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