Effects of glyphosate on life history of the generalist predator, Chrysoperla externa.

SCHNEIDER, MARCELA INÉS; PINEDA, SAMUEL; ALIARDI, DAMIÁN; SMAGGHE, GUY

Ghent, Belgica

Simposio; 59th International 59th International Symposium on Crop Protection.; 2007

Faculty of Bioscience Engineering. Ghent University, Belgium

Life history studies have been deeply employed by ecologist to evaluate the control capacity of biological control agents. However, it is not taking into account when side effects of pesticides on beneficial organisms are evaluated. Glycine max L., soybean, is one of the most important crops in Argentina, with ~15 milliom ha. This expansion is due to the introduction of transgenic resistant soybean to glyphosate Round Up® (RR) in the last decade. Within the community of beneficial organisms associated to soybean pests, the crisopids have an important role as a potential biological control agent. In the Neotropical region, Chrysoperla externa (Hagen) is very common and acts as a predator of several pests. Nevertheless, the massive use of pesticides in transgenic soybean RR conditioned severely its role as biological control agent. Moreover, the detrimental effects of herbicides, such as glyphosate, on beneficial organisms have not been deeply documented. The objective of this work was to evaluate the effects of glyphosate, commonly used in soybean (Soybean RR) crops in Argentina, on the predator life history. Cohorts of 120 individuals were used for each treatment (control, glyphosate). Commercial compound was used (GlifoGlex 48®, glyphosate, 192 ppm) and Sitotroga cereallela eggs were treated by dipping with an herbicide dilution whereas for the control cohort they were treated with the dissolvent (water + Tween20®) and added them as food at the third larval instar of the predator. Life history data were collected. To consider both sexes and variable development rate among individual, the raw data were analyzed using the age-stage, two-sex life table. Development time during L3 in treated cohort was significantly shorter than control cohort. Besides, the control adults lived twice than the treated cohort. Pre-reproductive period in the treated cohort was higher than the control cohort. Reduction in all demographic parameter also was found. In addition, adults from treated cohort developed tumours. The present work alerts us from the possible hazards of this herbicide on beneficial organisms’ populations and its ecotoxicological consequences on the environment.