Repurposing chicken eggshells, Gallus gallus domesticus, as nanoparticles to manage red flour beetles, Tribolium castaneum

Abstract

The red flour beetle (RFB), Tribolium castaneum, is one of the most serious pests on stored grains and in high-value grain products such as milled flour and baked products. They may cause significant problems in stored grain by direct feeding, damaging the grain, which may cause mold to increase and cause flour to change color. Currently, the management of RFB relies on insecticides with various modes of action which has resulted in pesticide resistance in beetles. Therefore, safer and more effective ways to treat stored product pests are needed. This research examined the use of chicken eggshell nano-powder alone and eggshell nano-powder combined with the biopesticide Spinosad in treated glass vials to control RFB adults and larvae. Laboratory trials with eggshell nano-powder alone at 0.04 mg/mm² and 0.13 mg/mm² were applied to glass vials adult RFBs were killed at or close to 100%. When RFB larva was exposed to eggshell nano-powder at 0.04 mg/mm², it had a mortality rate of only 48 ± 13 % after 7 days. Spinosad alone, when exposed to RFB larva had a mortality rate of only 56 ± 4 % after 7 days. When the eggshell nano-powder was combined with 1 ppm of commercial Spinosad, RFB larval mortality increased to 98 ± 2 % after 7 days. Thus, the eggshell nano-powder alone was sufficient to kill RFB adults, but in order to kill the RFB larvae, Spinosad had to be added to the eggshell nano-powder. The addition of Spinosad to nano-powder eggshells had an additive effect on the mortality rate of RFB larvae.