Behavioural Resistance in Insects: Its Potential Use as Bio Indicator of Organic Agriculture

Abstract

Abstract. Most of the investigations carried out on the resistance of insects to pesticides have been focused on the physiological and biochemical mechanisms. However, the behavioural answers that pesticide induces in the insects have received very little attention. The symptoms from getting pesticides on the cuticular surface of insects, as neurotoxical pre mortem effects, include spasmodic activity, hyperactivity and leak of the surfaces impregnated by the pesticides. These reactions provides a first barrier of defense, named behavioural resistance. Previous experiments carried out on olive groves usually subjected to pesticide application have allowed to visualize a reaction of leak of the natural enemies from treated areas, which is reflected as an increase of its rate of capture in sticky chromatic traps, in relation to the free of pesticides areas, on olive groves, usually subjected to pesticide application. The aim of this investigation is to evaluate the reaction of these insects' species under different agricultural pest management: i-A conventional olive grove, where pesticides are usually applied; and iiAn organic olive grove, where pest management depends exclusively on the role of the natural enemies. During the spring of 2016, experimental applications have been carried out in two olive groves of the province of Jaén (south of Spain) by means of a commercial pesticide application, in order to evaluate the reactions induced in the main species of olive predators. Six pairs of plots were randomly selected in both conventional and organic olive groves, three of these were pesticide sprayed, whereas a second series of three plots were free of pesticide application. Sticky yellow traps were installed in both treated and control plots just after application of pesticide. The results allow to determine the existence of two different reactions of the predators in both types of olive groves. In the plots of the conventional management, a significant increase of the capture values was observed. However, in the ecological groves, the same insects' species showed a lack of behavioural resistance. The ecological implications of this study open a new field of research, which provides new criteria to assess the qualification of the organic agriculture.

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“…They therefore showed maximum values in the Ecological management, intermediate values in the IPM, and mínimum population values in the Conventional Management. Among these species, A. decempunctata and H. laufferi seems to be the most susceptible to pesticides, since they are completely absent in the Conventional management, which agree with previous studies [45]. The implantation of herbaceous plant covers exerts multiple beneficial effects, not only by limiting erosion and soil loss [2] but also by promoting animal biodiversity, which is a biological obviousness, and has thus frequently been reported [1,4,7].…”

Induction of sublethal effects for the characterization of Olive groves under different pest management systems

“…The normality test indicates that the capture distributions of selected species do not follow a parametric distribution (Shapiro-Wilk: p <0.001), which is frequent in this type of sampling (GONZÁLEZ-RUIZ; GÓMEZ-GUZMÁN, 2019;GÓMEZ-GUZMÁN et al, 2017). Data from control plots during the years 2017 and 2018 indicate the existence of statistically significant differences between capture values in the different pest management systems (Figure 2).…”

Side Effects of Insecticides on Beneficial Insects: A Practical Tool to Identify Organic Agroecosystems

“…In addition to the lower diversity and abundance, the influence of the side effects of insecticides in the beneficial insects must be assessed for the correct interpretation of data from population monitoring. Recent studies suggest that, as in conventional agroecosystems, in IPM these species show very frequently behavioral resistance (BR+), while in organic crops, they lack it (BR-) [34,35]. A close relationship seems to exist between insecticide application and the development of behavioral resistant populations.…”

“…In the first case they are applied routinely, while in IPM their use is determined by the establishment of pest's population thresholds, which implies a considerable saving of insecticides with respect to conventional management. In view of the notable differences between them, the need to assess the impact of this reduction in the application of insecticides on the behavior of the populations of beneficial insects has been raised [34,35]. Since Insecticide applications induce behavioral modifications in natural enemies' insects affected by sublethal doses, it is likely their effects have an impact on the capture rates recorded in monitoring commonly used in olive growing, devices, such as the sticky chromatic traps, [15,36].…”