Pesticidal potential of some wild plant essential oils against grain pests Tribolium castaneum (Herbst, 1797) and Aspergillus flavus (Link, 1809)

Abstract

• Essential oils of wild plant, Conyza sumatrensis exhibited excellent insecticidal activity against red flour beetle, Tribolium castaneum. • Erigeron canadensis and Chenopodium ambrosioides inhibited the growth of Aspergillus flavus. • The major component of C. sumatrensis essential oil was cis -lachnophyllum ester. • Major components of Erigeron canadensis and Chenopodium ambrosioides were limonene and α-terpinene respectively. The red flour beetle, Tribolium castaneum , and the mold Aspergillus flavus are well known threats of stored grain commodities, causing nutritional loss and poisoning of stored products, respectively. T. castaneum has developed resistance against most insecticides, leading to the use of extensive amounts of synthetic insecticides to protect stored grains. Synthetic pesticides not only toxify the environment but also cause serious health issues in humans using pesticide treated grains. This study aimed to identify plant-based natural pesticides to control T. castaneum and A. flavus . Essential oils were extracted from fresh aerial parts of Chenopodium ambrosioides, Conyza sumatrensis, Erigeron canadensis, and Tagetes minuta through steam distillation and investigated for insecticidal and anti-fungal activities against adult T. castaneum and A. flavus , respectively . GC–MS analysis of C. sumatrensis revealed the presence of 37.7% cis -lachnophyllum ester, 13.4% germacrene D, and 21.6% limonene, whereas in E. canadensis the major compounds were limonene, germacrene D, and cis -lachnophyllum ester (43.4%, 12.9% and 5.9%, respectively). In bioassays with treated grain, C. sumatrensis and E. canadensis essential oils exhibited excellent toxicity against adult T. castaneum with LD 50 of 3.7 and 5.6 mg per 10 g grains whereas in a fumigation bioassay they showed LD 50 of 6.6 and 10.6 mg/L, respectively. The essential oils extracted from C. ambrosioides and E. canadensis exhibited good anti-fungal activity against A. flavus . Our findings suggest that essential oils of C. sumatrensis and E. canadensis can play an important role in protecting stored grains from T. castaneum and A. flavus contamination.