Swarms of locusts (Schistocerca gregaria) invaded the western Negev sand dunes in Israel during March 2013. Four weeks later, tens of millions of locust nymphs hatched and marched across the dunes. In order to control locust numbers, the Israeli Ministry of Agriculture utilized spraying aircrafts and pesticides over a period of six weeks, covering more than 100 km2. Some of the sites were sprayed a few times a day, in what had been perhaps to most intense pesticide usage within a natural environment in the history of Israel. Arthropod-specific pesticides were used and no secondary poisoning of vertebrates was observed. Our research aim was to examine the impacts of this intensive pesticide application on the terrestrial arthropod community. Arthropods were sampled 50 days after the initial spraying (spring 2013) and in the springs of 2014 to 2016, in eight intensively sprayed plots and eight unsprayed plots. In each plot, 25 dry pitfall-traps were used, open for 48 hours. The distances between the sprayed and the control plots were on average 600 meter.
Results/Conclusions
A total of 13,000 specimens represented by 282 morphospecies were collected in four springs. No significant differences were observed in the arthropod community between sprayed and unsprayed plots in 2013. However, in 2014 and 2015 univariate and multivariate analyses revealed a significant decrease in diversity indices in the sprayed plots. On spring 2016, sprayed plots were becoming more similar again to the control plots. Interestingly, on spring 2014, a year after spraying, the population of the scavenger ant, Cataglyphis savigny, dramatically increased to 66% of all the sampled composition in the sprayed plots, while in control plots it was 30%. On 2015, Cataglyphis's population had dropped and the declining trend continued to spring 2016. Our findings suggest that there is a short leg in the sever impacts of the spraying on the ecosystem, and demonstrates the duration required for the recovery of the system. As arthropods constitute a major role in any terrestrial environment, this four years research deepened our understanding of the consequences of spraying on the ecosystem.