Abstract
The indiscriminate use of synthetic insecticides caused an increase in the resistance of Plutella xylostella (Linnaeus, 1758) (Lepidoptera: Plutellidae) to almost all classes of insecticides, as well as affected the environment and non-target organisms. Thus, the search for less harmful alternatives with the purpose of reducing the application of these insecticides has become a priority. A possible alternative to reduce the use of synthetic insecticides is by using botanical insecticides, given the thousands of existing compounds derived from secondary metabolism in plants. In this study, we tested the following hypotheses: (i) the aqueous and ethanolic extracts of native plants reduce the food consumption of larvae and oviposition of adults of P. xylostella; (ii) these botanical species can act as potential plant insecticides. The objective of this work was to evaluate the effect of plant extracts on the feeding preference of larvae and oviposition of adults of P. xylostella. For this, cabbage discs treated with aqueous and ethanolic extracts of Schinus terebinthifolius, Annona coriacea, Annona crassiflora and Serjania marginata were given to larvae. The concentrations used for the aqueous extracts were of 5 and 10 mg mL-1, and for the ethanolic extracts were of 1 and 5 mg mL-1. Both extracts of the four tested plant species showed oviposition suppressed. The extract of S. marginata showed the lowest rates of suppression. All treatments with ethanolic extracts showed a phagodeterrant effect being that the aqueous and ethanolic extracts of A. crassiflora and S. terebinthifolius were the most effective as antifeedants on third instar larvae by P. xylostella.
Highlights
Brassicaceae is one of the most important botanical families in the world economy (Vickers et al, 2004)
The aqueous extract showed an interaction between treatments, plant extracts, and concentration (F = 11.80; DF = 3; P ≤ 0.01)
No difference was observed in treatments of aqueous extracts at a concentration of 5%; the treatment with S. marginata extract showed a higher food preference index at a concentration of 10%, stimulating the feeding of the larvae
Summary
Brassicaceae is one of the most important botanical families in the world economy (Vickers et al, 2004). Vol 11, No 5; 2019 selection pressure due to the indiscriminate use of insecticides, and the high genetic elasticity inherent in the species, P. xylostella has developed resistance to almost all classes of insecticides, making it difficult to control (Khaliq et al, 2007; Li et al, 2016; Mohan & Gujar, 2003; Sarfraz & Keddie, 2005). According to Prakash and Rao (1997), these botanical insecticides do not contribute to the increase in resistance and pest resurgence; they do not have negative effects to natural enemies (Isman, 1994), and plants could be the best source of new chemical structures for the development of new environmentally correct and safe insect control agents (Saxena et al, 1992)
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