Control effect of almond oil and black cumin seed oil mixtures towards four stored product pests
The efficiency of essential oils from the mixture of almond (Prunus dulcis) and black cummin seed oil (Nigella spp.) combined with other phytochemicals (garlic, onion, chilli pepper) was tested to assess their enhanced toxicity against the 1-7 days old adults of four stored product pest, Plodia interpunctella, Tribolium confusum, Stegobium paniceum and Sitophilus granarius. The plant essential oils mixtures were prepared in two combinations (Mix 1 and Mix 2) and applied in 1 ml/kg, 2 ml/kg and 5 ml/kg on the filter papers inside the jar glasses. 30 adults were placed with approximately 20 ml grain substrate in the 250 ml jar glasses with plastic screw cap. The saturated filter papers were fixed on the screw cap. Mix 1 and Mix 2 with 30 insect adults placed in climatic chambers for an exposure time of 24 h, 48 h, 72 h, 96 h and 120 h under two different climatic conditions, 20 °C and 25 °C. Each concentration was replicated 3 times. It was shown that the toxicity effect of essential oils mixtures was increased against stored product pests. According to the results obtained from present study insects mortality increased with increasing concentration levels and exposure times. S. granarius and S. paniceum were more sufficient than P. interpunctella and T. confusum after 120 h exposure time. The highest mortality was achieved with 5 ml of Mix 1 and Mix 2 after 120 h at all species (> 80%). The present study suggests that essential oils mixtures in combinations with other phytochemicals have the potential to apply as alternative to synthetic toxic chemicals in stored product protection.