Allium sativum, rosmarinus officinalis, and salvia officinalis essential oils: A spiced shield against blowflies

Blowflies are known vectors of many foodborne pathogens and unintentional human ingestion of maggots by meat consumption may lead to intestinal myiasis. In fact, the control of insect pests is an important aspect of industrial and home-made food processing and blowflies (Diptera: Calliphoridae), which are among the most important pests involved in the damage of meat products. Most spices, largely used in food preparations and industry, contain essential oils that are toxic and repellent against insects and exert antimicrobial activity. In this study, we assessed the electro-antennographic responses, the oviposition deterrence, the toxicity, and the repellence of the essential oils (EOs) of Allium sativum L., Salvia officinalis L., and Rosmarinus officinalis L. against the blowfly Calliphora vomitoria L. We tested the EOs antibacterial and antifungal properties and the efficacy of an A. sativum EO-charged mist sprayed in the tunnel entryway of a meat processing room to form an olfactive barrier against the entrance of flies. The results showed that the EOs are perceived by female blowfly’ antennae and exert an evident repellent activity against them completely deterring the oviposition for up to 24 h starting from the concentration of 2.5 μL cm-2 EO. The EOs also exhibited toxic activity by both topical application (LD50 from 0.44 to 1.97 μL insect- 1 ) and fumigation (LC50 from 1.76 to 31.52 μL L-1) against adults of C. vomitoria and were able to exert a clear antimicrobial activity toward pathogens. Lastly, the EO-charged mist was able to reduce by about 40% the presence of Calliphoridae in the meat processing room of a dry-ham factory.