Chemical composition of an insecticidal extract from Robinia pseudacacia L. seeds and it's efficacy against aphids in oilseed rape

Abstract

Interest in the use of plant extracts to replace chemicals as insecticides is growing. In the present study, the chemical composition and insecticidal activity of Robinia pseudoacacia L. seed extract were investigated. The insecticidal extract of R. pseudoacacia seeds was analyzed by GC×GC-TOFMS. A total of 51 compounds were identified and the major constituents found in the seed extract were 9,12-octadecadienoic acid (20.9%), 9,12,15-octadecatrienoic acid methyl ester (14.3%) and 9,12-octadecadienoic acid methyl ester (10.9%). The results showed that the petroleum ether fraction of R. pseudoacacia seeds exhibited strong insecticidal activity against cotton aphid and cabbage aphid with LD50 values of 7.04 ng/insect and 6.87 ng/insect, respectively (at 24 h post-treatment) using a topical application method. The seed extract formulation showed notable efficacy on aphids in a field test, and the mortality was above 95% by 7 days after treatment in the oilseed rape field. The results of a laboratory bioassay and a field experiment have shown that R. pseudoacacia seeds could be considered as a potential source for development of a botanical insecticide for controlling aphids.