The Effects of Clofentezine on Life-table Parameters in Two-spotted Spider Mite Tetranychus urticae

Author: Marcic D.

Source: Experimental and Applied Acarology, Volume 30, Number 4, 2003 , pp. 249-263(15)

Publisher: Springer

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Abstract:

Sublethal effects of the growth inhibitor, clofentezine, on life-table parameters of Tetranychus urticae Koch females treated at different developmental stages with a concentration causing

90% mortality were investigated. Females which survived treatment as ‘early’ (0–24 h old) eggs produced 12% more offspring than the untreated females during the first five days of oviposition. This resulted in a significant rise in the intrinsic rate of increase (r_j): 0.324, compared to 0.299 in the untreated females. This effect may be interpreted as hormoligosis. Clofentezine treatment at any other developmental stage of T. urticae significantly decreased both longevity and fertility of female survivors. Females which survived treatment either as ‘late’ (72–96 h old) eggs or larvae had 2.6 times lower net reproductive rate (r₀) than the untreated females, and the r_j values were significantly lower: 0.242 and 0.215, respectively (0.285 in the untreated females). Females which survived treatment either as protonymphs or deutonymphs had 3.9 times and 6 times lower r₀, respectively. Corresponding r_j values were 0.178 and 0.146, respectively (0.247 in the untreated females). The clofentezine treatment at all stages influenced the age distribution of survivors. The sublethal effects of clofentezine and their impact on T. urticae management are discussed.

Keywords: Tetranychus urticae; clofentezine; life-table parameters

Document Type: Research article

Affiliations: 1: Laboratory of Applied Entomology, Pesticide and Environmental Research Centre, Banatska 31 B, P.O. Box 163, 11080 Zemun, Yugoslavia ( ), Email: marcion@bitsyu.net

Publication date: 2003-01-01