With the exception of 4Asp, all quinine-based QASs showed very good (T > 150) antifeedant properties toward confused flour beetle larvae regardless of the type of substituent in the cation or anion structure . This is most likely due to the very strong effect of quinine structure on inhibiting the feeding of this speciesthe T value determined for quinine free base in confused flour beetle tests was equal to 189. Thus, it can be concluded that the activity of quinine against T. confusum larvae is comparable to that of azadirachtin (T = 194) , a substance known for its very potent biopesticidal properties. Although quinine is characterized by potent antifeedant activity toward some mosquito species , its activity toward stored product pests is reported to be significantly lower compared to azadirachtin or neem oil formulations . The very good antifeedant activity of quinine (in the form of the free base and hydrochloride) toward T. confusum larvae, that also determines high efficacy of quinine-based QASs, is therefore a surprising result and indicates the legitimacy of further research into the use of this alkaloid and its derivatives in the protection of plants and seeds against pests. Moreover, given the high antimicrobial activity of salts 3Br, 3Asp, and 3Ala toward F. graminearum (a fungal pathogen of seeds and plants) and other microorganisms (see Fig. ), a comprehensive biopesticidal protection of stored grain against both pest insects and harmful plant pathogens can also be achieved.