Effect of gamma irradiation on the larvae of the greater wax moth, Galleria mellonella: insights into wax consumption, ultrastructure of mouth parts sensilla, and contents of trace elements

Abstract Background Galleria mellonella , the greater wax moth is a serious pest of beeswax worldwide. It causes significant damage in apiaries, leading to economic losses for beekeepers. Additionally, it damages wax combs due to larval feeding and destroys frames and wooden parts of the hive. This study aims to investigate the effects of gamma radiation on food consumption, the morphology of mouthparts, and the concentrations of elements in larvae. Results Egg hatch at 5 Gy did not differ significantly from the control, while hatch was significantly reduced at ≥ 10 Gy. The percentage of egg hatch decreased after irradiation with 5, 10, 20, 30 and 40 Gy to 82.7, 62.7, 35.3, 15.3 and 0.0% respectively, compared to 90.7% in the control. The beeswax consumption decreased with increasing the gamma radiation dose, where the minimum percentage of wax consumption reached 0.9% for 30 Gy compared to 20.8% in control. This decrease in wax consumption may be attributed to the effect of radiation on larval mouth parts and their associated sensilla, so an ultrastructure study of 3rd instar larvae head capsule was done using a scanning electron microscope (SEM.). The SEM study showed that different malformations were observed in mouth parts, including shrinkage and distorted structural shapes. Also, the associated sensilla were malformed in accordance with gamma dose applied. An analysis was also made of the elements present in the body of the larvae resulting from the irradiated eggs using an energy dispersive X-ray analyzer, and it became clear that there are eight elements, namely Carbon (C), Magnesium (Mg), Phosphorus (P), Potassium (K), Calcium (Ca), Copper (Cu), Zinc (Zn) and Molybdenum (Mo). Carbon was the most abundant element in unirradiated larvae, followed by calcium, while zinc was the least abundant element. The results indicated that the percentage of these elements in the treated larvae varies depending on the gamma irradiation dose. Conclusions The dose of 40 Gy of gamma radiation can cause a 100% reduction in egg hatchability. Also, lower doses may produce larvae with many deformities in the sensors of the mouth parts, which lead to difficulty in consuming wax and thus reducing the rate of food consumption. These findings support the use of gamma radiation as a safe and environmentally friendly alternative for controlling Galleria mellonella in stored beeswax, with minimal risk to humans and non-target organisms.