Transovarial biotransference of etoxazole through a terrestrial trophic web

Transovarial transport is defined as the passage of chemicals from the maternal body to eggs within the ovaries. Little is known about the effects of transovarial transport on non-target species. This study evaluates etoxazole (a transovarial acaricidal compound) on a terrestrial trophic web consisting of a ubiquitous phytophagous mite, Tetranychus urticae Koch, and three species of predatory mites.

Predatory mite females that consumed eggs laid by etoxazole-treated T. urticae also produced infertile eggs. There was a negative relationship between the proportion of etoxazole-treated T. urticae females and the instantaneous rate of predatory mite increase at the population level (r(2) = 0.86). Reduced fertility of etoxazole-treated T. urticae females continued for 18 days following application. Eggs laid by etoxazole-treated T. urticae females remained toxic to predatory mite females for 42 days after treatment.

Transovarial transport could lead to magnification in the ecosystem by enhancing both bioavailability and movement of an active ingredient. The potential for enhancement of residual activity by terrestrial organisms and its significance once reaching the food web should be taken into account for new classes of acaricides and insecticides.