Chemical composition, antimicromicrobial activity and insecticidal activity against the lesser mealworm Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) of Origanum vulgare L. ssp. hirtum (Link) and Artemisia dracunculus L. essential oils.

BACKGROUND: Essential oils (EOs) from Artemisia dracunculus L. and Origanum vulgare L. ssp. hirtum were obtained and the qualitative and quantitative chemical composition of the extracts was investigated. The insecticidal activity of EOs against the larval stages of Alphitobius diaperinus (Panzer) was studied. Moreover, the antimicrobial activity of these oils against pathogens transmitted by this pest was also investigated. RESULTS: The obtained results indicate the possibility of using Greek oregano EO with a high content of carvacrol as a feed additive in poultry nutrition. The use of the Greek oregano oil at 1% (w/w) dose showed stronger reduction of body weight gain of stage IV larvae. Their body mass was only 10.92% of the control. Moreover, EOs from O. vulgare strongly inhibited the growth of tested bacterial strains as well as Candida albicans. CONCLUSION: Greek oregano EO may be a good alternative to antibiotic growth promoters and coccidiostats whose use in feeding farm animals has been prohibited since January 2006 under European Union directives. The introduction of O. vulgare L. ssp. hirtum EO into the premises of farm and poultry houses may help to improve sanitary conditions and control of the lesser mealworm inhabiting these buildings. © 2017 Society of Chemical Industry.

Effects of halolactones with strong feeding-deterrent activity on the growth and development of larvae of the lesser mealworm, Alphitobius diaperinus (Coleoptera: Tenebrionidae).

The effects of dietary applied of ß-damascone and its synthetic derivatives γ- and δ-halolactones, which show strong antifeedant activity, on the growth and development of larvae of the lesser mealworm, Alphitobius diaperinus Panzer (Coleoptera: Tenebrionidae), were studied. Bioassays were performed in a dose-dependent manner. In the bioassays, oat flakes treated with 1.0, 0.5, and 0.1 % (w/v) acetone solutions of the tested compound or acetone alone as control were served as food. The experiments were conducted using 2-week-old larvae with an average body weight of 4.35-4.88 mg. High correlations between antifeedant activity and larvicidal and growth-inhibitory effects were observed. Larvae reared on diets containing the compounds (at a concentration of 1 %) with high deterrent activity were characterized by a prolonged period of development, lower body weight gain, and strong tendency for cannibalism as a result of starvation. The control larvae ended their development after 24 days with a mean body weight of 22.9 mg. At the same developmental time, the mean body weights of larvae treated with the δ-halolactones γ-chloro- and γ-bromo-δ-lactone were only 60.3 % and 43.2 % of that of the control larvae. The larval periods for larvae on the diets containing γ-chloro- and γ-bromo-δ-lactone were 33 and 41 days, respectively. The larval developmental time and body weight gain were not significantly influenced by lower doses of the compounds, with the exception of γ-bromo-δ-lactone. This compound, when applied at a concentration of 0.5 %, significantly prolonged larval development as compared to the control larvae, and caused high mortality of larvae and pupae. The adult emergence percentage was 37.51 % when this treatment was applied, as compared to 90.0 % in the control. Thus, ß-damascone derivatives with a lactone ring exhibit both dose-dependent behavioral effects and post-ingestion toxicity against A. diaperinus larvae, and may have the potential to control this pest.

Structure-related antifeedant activity of halolactones with a p-menthane system against the lesser mealworm, Alphitobius diaperinus Panzer.

BACKGROUND: Feeding deterrent activity of synthetic halogen lactones against larvae and adults of the lesser mealworm, Alphitobius diaperinus Panzer, in laboratory choice and no-choice tests was studied. The compounds were synthesised from racemic and enantiomerically enriched (ee = 91-98%) cis- and trans-piperitols, which were obtained from (±)-piperitone. RESULTS: Structure-activity relationship studies identified several synthetic halolactones with a very strong feeding deterrent activity. The most active were the enantiomeric chlorolactones with chiral centre configurations (1S,4S,5R,6R) and (1R,4R,5S,6S) and their racemic mixture. The racemic bromo- and iodolactones obtained from cis-piperitol and saturated lactones with a chiral centre configuration (1R,4S,6R) were also very good antifeedants in comparison with piperitone. Most of the studied compounds were better antifeedants against adults than against larvae-among the 21 compounds, only one bromolactone with a chiral centre configuration (1S,4R,5R,6R) was a weaker deterrent for adults. CONCLUSION: Chemical transformation of the piperitone molecule by the introduction of a lactone function and a halogen atom strongly changed its antifeedant properties against the lesser mealworm. Optimum activity is dependent on the presence of a chlorine atom at C-5 of the cyclohexane ring. The activity of bromo- and iodolactones depended strongly on the chiral centre configuration and the halogen substituent.