Insecticidal Properties of Ocimum basilicum and Cymbopogon winterianus against Acanthoscelides obtectus, Insect Pest of the Common Bean (Phaseolus vulgaris, L.)

Abstract

The bean weevil, Acanthoscelides obtectus Say (Coleoptera: Chrysomelidae: Bruchinae), causes severe post-harvest losses in the common bean, Phaseolus vulgaris L. The control of this insect is still poor and involves the use of conventional insecticides. There is an increasing demand in the search for new active substances and products for pest control towards reduction of adverse effects on human health and the environment. The protection of grains with alternative products, such as essential oils, is a possible alternative to meet the needs described above. Therefore, this investigation evaluated the applications of basil, Ocimum basilicum, and citronella, Cymbopogon winterianus, essential oils for A. obtectus control. These essential oils significantly reduced the bean weight losses and the number of beans damaged by A. obtectus at higher doses than 60 or 120 μL/sample. The number of holes per bean did not differ between the doses of basil essential oil, not even at the dose of 60 μL, while it was higher at 120 μL, probably due to a lower capacity of movement of the insects treated with this dose and/or the oil’s direct or indirect effects on the insects. Basil and citronella oils exhibited similar patterns of insecticidal activity over the insect, both directly in adult insects or indirectly over bean seeds. These essential oils affected the development of A. obtectus since the greatest doses applied on beans decreased the emergence of the bean weevil. The results prove the insecticidal capacity of the tested essential oils and hence their potential as active substances against A. obtectus in environmentally low risk pest control strategies. Supplementary trials should be conducted under real storage conditions.

Toxic, Oviposition Deterrent and Oxidative Stress Effects of Thymus vulgaris Essential Oil against Acanthoscelides obtectus

“…Many studies on storage and other pest insects recorded significant influence of thyme EO on pest survival and behavior [ 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 ]. Lamiaceae EOs applied as fumigants have been extensively tested for the activity against A. obtectus [ 61 , 62 , 91 , 92 , 93 ] and several recent studies dealt with the effects of their application on bean seeds [ 63 , 67 , 71 ]. Here we evaluated efficacy of thymol chemotype of the thyme oil as residual contact insecticide and oviposition deterrent against A. obtectus .…”

“…Previous studies of EO effects in A. obtectus have involved EOs isolated from plants belonging to families of Amaranthaceae [58], Asteraceae [59], Cupressaceae [60], Lamiaceae [61][62][63], Lauraceae [64], Meliaceae [65], Myrtaceae [60,62,64,66], Piperaceae [65], Poaceae [67], Rutaceae [68]. In the present study we examined how thyme EO (Thymus vulgaris L., Lamiaceae, thymol chemotype) applied by contact affected A. obtectus mortality, F1 progeny production and choice of seeds for oviposition.…”

Evaluation of Five Medicinal Plant Extracts on Aphis craccivora (Hemiptera: Aphididae) and Its Predator, Chrysoperla carnea (Neuroptera: Chrysopidae) under Laboratory Conditions

“…Plants produce secondary metabolites and chemical substances to protect themselves from the attack of pests and pathogens [1]. There is a growing need for new active substances and products for pest control that decrease the unfavorable impacts of chemical insecticides on the environment and especially on human health [2]. Thus, thousands of plant extracts have been evaluated as alternatives to chemical insecticides.…”

Extracts of Common Pesticidal Plants Increase Plant Growth and Yield in Common Bean Plants

“…Sustainable technologies for pest management in legume crops often relies on the breeding of resistant varieties [15]. However, the use of pesticidal plant extracts in smallholder farming systems is also an established agro-ecologically sustainable pest control method [16][17][18][19][20]. Although the economics and cost-benefits of smallholder use of crude plant extracts for pest management are certainly favourable in many situations [19], uptake and promotion of pesticidal plants could be further facilitated by increased evidence on potential multiple benefits of their use [21], making their use even more attractive to smallholder farmers.…”