ABSTRACT
Sitotroga cerealella is a serious pest of a wide range of stored cereal grains. An essential element of an integrated pest control approach is the application of plant oils as a substitute for chemical insecticides. This study aimed to investigate the fumigant toxicity of Allium sativum and Mentha piperita essential oils against S. cerealella adult moths and the egg parasitoid Trichogramma evanescens. Gas chromatography-mass spectrometry analyses detected that Diallyl trisulfide (37.97%) and DL-Menthol (47.67%) as main compounds in A. sativum and M. piperita, respectively. The results showed that, A. sativum at 10.0, 5.0, and 2.5 µL/L air resulted in 100% insect mortality after 24 h exposure. The concentrations of 10.0 and 5.0 µL/L air of M. piperita oil resulted in 100 and 96% insect mortality, respectively. The parasitoid adult emergence in the F1 reduced when exposed to LC99 of A. sativum and M. piperita oils by 10.89 and 9.67%, respectively. Also, the parasitism of emerged parasitoid decreased by 9.25 and 5.84% (class I-harmless), respectively. Therefore A. sativum and M. piperita have the potential to be used as bio-fumigant for the management of S. cerealella and can be used alongside the T. evanescens in integrated pest management.
Subject(s)
Hymenoptera , Insecticides , Moths , Oils, Volatile , Pesticides , Animals , Oils, Volatile/toxicity , Insecticides/toxicityABSTRACT
Due to excessive use of synthetic pesticides the pest resistance developed along with pesticide residues accumulation in crops. Therefore, many nations are switching from chemical-based agriculture to "green" agriculture for pest control. The destructive pest black cutworm, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae), is a polyphagous species that economically lead to extensive loss of a broad range of crops including corn, cotton, wheat, and many vegetables through the damage of foliar and roots. In this study, lemon peel essential oil (LPEO) was subjected to nano-formulation using polyethylene glycol as nanocarrier. The lethal activity of LPEO and its nano-form (LPEO-NPs) were tested against A. ipsilon second larval instar using feeding bioassay at different concentrations. Growth and developmental parameters, including larval and pupal duration, larval and pupal mortality, malformations % and adult emergence were evaluated. Results showed that LPEO exhibited insecticidal activity and causes different levels of effects on the development of A. ipsilon according to its concentration and formulation. In addition, at 75 mg/ml LPEO and LPEO-NPs significantly increased the larval mortality to 80.00% and 90.00%, respectively. The overall data revealed that insecticidal toxicity of LPEO was increased by nano-formulation.
