Sensitivity of Trogoderma graminarium Ev. to the Action of Ionizing Radiation

Abstract

The effect of different doses and dose rates of gamma radiation on the viability of khapra beetle Trogoderma granarium (larval stage) was studied in laboratory experiments in 2019–2020. The pest-infested grain of spring barley of the Nur variety was irradiated on a GUR-120 unit at dose ranges of 50–450 Gy (dose rate 100, 500, and 950 Gy/h) and 500–1000 Gy (dose rate 950 Gy/h). The irradiation of the khapra beetle at the dose range of 50–450 Gy and at a dose rate of 100 Gy/h caused a total mortality of larvae at doses of 350 and 450 Gy after 7 days, 100 and 300 Gy after 8 days, and 50, 150, 200, 250, and 400 Gy only after 14–17 days. The irradiation of larvae in the same dose range but at a rate of 500 Gy/h led to a more extended mortality rate of the pest population: 8 days at 400 Gy, 12 days at 200 and 300 Gy, 14 days at 350 Gy, and 18 days at doses of 50, 100, 250, and 450 Gy. At 150 Gy, the mortality rate reached 90% on the 14th day and remained at this level for 9 days, which can be explained by different ages of the pest larvae. When the dose rate was increased to 950 Gy/h, the dynamics of the death of khapra beetle larvae demonstrated a long plateau at doses of 350 and 450 Gy at a mortality rate of 70–90%, which caused a delay in their total death up to 20–24 days. The irradiation of the pest in the dose range of 500–1000 Gy at a radiation dose rate of 950 Gy/h proved to be more effective: the total mortality of the larvae was recorded on the fifth to sixth day. Ionizing radiation did not have a significant effect on the content of proteins, fat, fiber, dry matter, and nitrogen-free extractives in barley grain. The ash content statistically significantly changed under the effect of irradiation, but it was, however, no more than 3–6%.