The Influence of Selected Insecticides on the Oxidative Response of Atta sexdens (Myrmicinae, Attini) Workers

Abstract

Reactive oxygen species (ROS) are generated as products of normal cellular metabolic activities; however, the use of pesticides to control leafcutter ants leads to unbalanced ROS production. We evaluated the effects of two insecticides (fipronil, sulfluramid) and metallic insecticide complex (magnesium complex [Mg(hesp)2(phen)] (1)) on the superoxide dismutase (SOD), glutathione (GSH) and the overall antioxidant capacity using two different methodologies: total radical-trapping potential (TRAP) and oxygen radical absorbance capacity (ORAC). Media workers of Atta sexdens (C. Linnaeus) were exposed to the insecticides for 24 h, 48 h, 72 h and 96 h before their fat bodies were dissected for analysis. The results showed that although the sulfluramid may cause the production of ROS, its slow action in the organism does not lead to oxidative stress. There is a rise in oxidative stress in workers of leafcutter ants treated with fipronil because SOD significantly increased when compared to the control group. On the other hand, Mg1-complex suppressed both GSH and SOD, indicating that the immune system may be affected by Mg1-complex, which has a delayed activity ideal for its use in chemical pest control. Both TRAP and ORAC evaluated total antioxidant capacities; however, ORAC proved to be a more sensitive method. In conclusion, the Mg1-complex is a new compound that should be further investigated as a potential replacement for fipronil and sulfluramid in pest control.

Keywords: Antioxidant; Fipronil; Flavonoid; Magnesium complex; Sulfluramid.

Fig. 1

A Timetable showing the design of insecticide treatment and sample collection in the control and experimental groups. The mode of action for each tested insecticide was considered in the design of sampling intervals. The colour indicates the time points when samples were collected for analysis. B Scheme of bioassay design showing the experimental groups and number of workers used in the study. C Petri dish containing workers fed on the artificial food. D Fat body dissected after exposition to an insecticide; scale bar corresponds to 50 μm

Fig. 2

Glutathione (GSH) concentration analyzed at 24 h, 48 h, 72 h and 96 h in the control and insecticide-treated groups. The results are shown as mean ± standard deviation; the results of multiple comparisons (Tukey’s post hoc test) are marked with letters above columns. The data bars labelled with a different letter are significantly different at the 5% level (P < 0.05)

Fig. 3

The activity of superoxide dismutase (SOD) at 24 h, 48 h, 72 h and 96 h in the control and insecticide-treated groups. The results are shown as mean ± standard deviation; the results of multiple comparisons (Tukey’s post hoc test) are marked with letters. The data bars labelled with a different letter are significantly different at the 5% level (P < 0.05)

Fig. 4

Total radical-trapping antioxidant parameter (TRAP). Means and standard deviation of the quantity of total antioxidant capacity with time among the analyzed groups at 24 h, 48 h, 72 h and 96 h. The results of multiple comparisons (Tukey’s post hoc test) are marked with letters. The data bars labelled with a different letter are significantly different at the 5% level (P < 0.05). No significant effect of insecticides on total antioxidant capacity was observed (ANOVA, P ˃ 0.05)

Fig. 5

The antioxidant capacity measured as ORAC and its changes with time among the analyzed groups at 24 h, 48 h, 72 h and 96 h. The results are shown as mean ± standard deviation; the results of multiple comparisons (Tukey’s post hoc test) are marked with letters. The data bars labelled with a different letter are significantly different at the 5% level (P < 0.05). The capacity of antioxidants is expressed in mol Trolox equivalent (TE)