Genetically modified corn effect over Chaetocnema pulicaria (Coleoptera: Chrysomelidae) as a non-target pest

The effect of a corn hybrid with Agrisure® Viptera^TM 3111 event with the Cry1Ab and Vip3Aa20 toxins of Bacillus thuringiensis (Bt) which provides resistance to Lepidoptera and mCry3A to Coleoptera, was tested over the abundance of the corn flea beetle Chaetocnema pulicaria, in El Camalote, Culiacan, Sinaloa and was compared with its respective non-GM conventional hybrid, provided by Syngenta Agro SA de CV. A complete randomized block design was used with three treatments and four replicates. Treatments consisted of Agrisure® Viptera^TM 3111, its conventional hybrid with two insecticide treatments using emamectin benzoate to control Spodoptera frugiperda during the crop cycle and the same hybrid without chemical control. Visual inspections were carried out every two weeks, taking 10 plants randomly and checking them carefully for the pest and recorded to determine the population abundance, frequency and fluctuation. The number of individuals (abundance) of C. pulicaria evaluated in each material was analyzed by non-parametric statistic using the Kruskal-Wallis test in order to observe changes in the insect population. The evaluation of abundance of C. pulicaria during crop development recorded 884 insects in the three hybrids; of these, Agrisure® Viptera^TM 3111 event had 397 individuals, representing 45.9%, the conventional hybrid with insecticide treatment, 188  representing 21.3% and the conventional hybrid without insect control 299 insects, a 33.8% of the population. A 100% frequency was found throughout the growing season in the three hybrids evaluated and population density does not differ among evaluated hybrids (P=0.932, df=2). Agrisure® Viptera^TM 3111 event had no fall armyworm damage but the highest number of C. pulicaria insects, probably due to a greater availability of food resources. Conventional hybrid with insecticide treatment had the lowest population density with respect to Agrisure® Viptera^TM 3111 event and the conventional hybrid without insect control, suggesting that chemical control with emamectin benzoate affected the abundance of corn flea beetle, while conventional hybrid (without insect control) presented a decrease in population density, which was influenced by leaf damage caused by fall armyworm in this hybrid, leading to a reduced availability of food for corn flea beetle. Results show that the GM corn expressing the Bt toxin does not have a negative effect on the abundance or changes in population density of C. pulicaria.