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Field margins and botanical insecticides enhance Lablab purpureus yield by reducing aphid and supporting natural enemies

Field margins and botanical insecticides enhance Lablab purpureus yield by reducing aphid and supporting natural enemies

Ochieng, Lawrence O., Ogendo, Joshua O., Bett, Philip K., Nyaanga, Jane G., Cheruiyot, Eric K., Mulwa, Richard M. S., Arnold, Sarah E. J. ORCID: 0000-0001-7345-0529, Belmain, Steven R. ORCID: 0000-0002-5590-7545 and Stevenson, Philip C. ORCID: 0000-0002-0736-3619 (2022) Field margins and botanical insecticides enhance Lablab purpureus yield by reducing aphid and supporting natural enemies. Journal of Applied Entomology, 146 (7). pp. 838-849. ISSN 0931-2048 (Print), 1439-0418 (Online) (doi:https://doi.org/10.1111/jen.13023)

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Abstract

Botanical insecticides offer an environmentally benign insect pest management option for field crops with reduced impacts on natural enemies of pests and pollinators while botanically rich field margins can augment their abundance. Here we evaluated the non-target effects on natural enemies and pest control efficacy on bean aphids in Lablab of three neem and pyrethrum based botanical insecticides (Pyerin75EC®, Nimbecidine® and Pyeneem 20EC®) and determine the influence of florally rich field margin vegetation on the recovery of beneficial insects after treatment. The botanical insecticides were applied at early and late vegetative growth stages. Data was collected on aphids (abundance, damage severity and percent incidence) and natural enemy (abundance) both at pre-spraying and post-spraying alongside Lablab bean yield. The efficacy of botanical insecticides was similar to a synthetic pesticide control and reduced aphid abundance by 88% compared to the untreated control. However, the number of natural enemies was 34% higher in botanical insecticide treated plots than in plots treated with the synthetic insecticide indicating that plant-based treatments were less harmful to beneficial insects. The presence of field margin vegetation increased further the number of parasitic wasps and tachinid flies by 16% and 20%, respectively. This indicated that non-crop habitat can enhance recovery in beneficial insect populations and that botanical insecticides integrate effectively with conservation biological control strategies. Higher grain yields of 2.55-3.04 and 2.95-3.23 t/ha were recorded for both botanical insecticide and synthetic insecticide in the presence of florally enhanced field margins in consecutive cropping seasons. Overall, these data demonstrated that commercial botanical insecticides together with florally rich field margins offer an integrated, environmentally benign and sustainable alternative to synthetic insecticides for insect pest management and increased productivity of the orphan crop legume, Lablab.

Item Type: Article
Uncontrolled Keywords: botanicals; integrated pest management; conservation biological control; field margin; legume cropping systems
Subjects: S Agriculture > S Agriculture (General)
Faculty / School / Research Centre / Research Group: Faculty of Engineering & Science
Faculty of Engineering & Science > Natural Resources Institute
Faculty of Engineering & Science > Natural Resources Institute > Agriculture, Health & Environment Department
Faculty of Engineering & Science > Natural Resources Institute > Chemical Ecology Research Group
Last Modified: 25 Jul 2022 09:55
URI: http://gala.gre.ac.uk/id/eprint/35952

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