α-Solanine and α-Tomatine Affect the Retrocerebral Complexes of Tenebrio molitor and Zophobas atratus Beetles.

Presently, the European Commission is moving forward with a plan to reduce the use of chemical pesticides and increase the percentage of organic farming by 2030; this plan demands increased availability of biopesticides for organic farming. Glycoalkaloids are a class of molecules found in certain plants, including tomatoes and potatoes, which contain sugar and an alkaloid group. These compounds are known to have insecticidal properties, as they can act as natural defenses against insect pests. This study examined how a biological substance, glycoalkaloids, affects mortality and the retrocerebral complex of two beetle species, Tenebrio molitor and Zophobas atratus. More specifically, we focused on two glycoalkaloids, α-solanine and α-tomatine. Although these two insects belong to the same taxonomic family, they were not equally susceptible to these substances. In the mortality test, we observed that the T. molitor beetle seemed more susceptible, whereas the changes in the retrocerebral complex were more significant in the case of Z. atratus. In general, the effects vary between substances and insects, and changes in the retrocerebral complex may impair the reproduction of insects.