The effect of pine trees surrounding wheat fields on the infestation of wheat sunn pest, Eurygaster integriceps in Shahr-e-Rey/Tehran region

The sunn pest, Eurygaster integriceps Put. (Hem.: Scutelleridae) is one of the most important pests of wheat in Iran and the Middle East. At present, the control of this pest in the country is based on chemical control, which due to the limitation of using chemical pesticides, the use of other eco-friendly control methods, including the cultivation of companion plants is considered. Therefore, in this study, the effect of windbreakers, especially pine trees, around wheat fields, on the infestation of the sunn pest was investigated during 2019 and 2020. In this experiment, three treatments were considered in three replications, including three areas surrounded by pine trees, three areas surrounded by non-pine trees, and three areas without windbreakers. In each area, sampling of the mother's bug was performed several times by quadrate and insect net during an outbreak of pest in two consecutive years. Furthermore, the correlation of meteorological parameters with the pest density at sampling dates in different treatments was investigated. As well as, in the laboratory studies, the repellency of pine essential oils on the adult insect was tested in three concentrations, including LC10, LC25, LC50 by olfactometer and wind tunnel. The results of field sampling showed that the density of the pest in fields with windbreakers, especially pine windbreakers, was much lower than the farms without windbreakers in both years. Bioassay results showed that pine trees essential oils have a high lethal effect on adult bug, and the values of LC50, LC25 and LC10 were 362, 82 and 21 µl/l of air, respectively. The results also showed that increasing the concentration of essential oils increased the rate of repellency. The results of the correlation of meteorological parameters with adult bug density showed that in all treatments, there was a positive and significant correlation between sunn pest density and wind direction in both studied years. Therefore, based on this study's results, planting of pine trees around wheat fields can reduce infestation of sunn pest, and the repellency properties of the volatile compounds of this plant on the pest are probably adequate.