Egg laying and host stage preference at constant temperatures inEncarsia tricolor [Hym.: Aphelinidae]

Abstract

Encarsia tricolor Fo~rster is a facultative autoparasitoid that develops on the important pest Trialeurodes 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 total E. 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). 9 The mean number of eggs laid per female in one day ranged from 4.0 (10 ~ and 32 *C) to 15.2 (24 *C). The mean total number of eggs increased with temperature from I0 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 r m = -0.076 + 0.01 I*T (R 2 = 0.99). The rm of E. tricolor was greater than the rm of T. vaporariorum when temperature was higher than 9.2 *C.

Egg allocation of the autoparasitoid Encarsia tricolor at different relative densities of the primary host (Trialeurodes vaporariorum) and two secondary hosts (Encarsia formosa and E. tricolor)

“…Parasitism. Female age in the range 3-10 days old did not influence the number of parasitized hosts nor the number of eggs laid per 48 h, this confirms previous observations on females daily exposed to T. vaporariorum nymphs (Artigues et al, 1991).…”

Life table and biological characteristics of Macrolophus pygmaeus when feeding on Myzus persicae and Trialeurodes vaporariorum

“…The linear relationship between r m values and temperature found in this study can be used to interpolate r m values at temperatures between the lowest and highest temperature tested. The relationships between r m values and temperature (both linear and non-linear) have been recorded also in other studies (Force & Messenger, 1964;van Lenteren & Hulspas-Jordaan, 1983;Artigues et al, 1992;Kocourek et al, 1994).…”