Comparative bioefficacy of biorational ethylene glycol diesters and sucrose octanoate against Lipaphis erysimi (Homoptera: Aphididae)

Abstract

We report the toxicological effects of new series of biorational glycol esters and compare the efficacy with the known commercial sugar ester, sucrose octanoate. Ethylene glycol diesters were easy to prepare without any isomeric constraints and very safe compounds that were applied as sprays or as residues. The compounds were equally toxic to mustard aphid, Lipaphis erysimi nymphs and adults and the activity was significantly comparable with sucrose octanoate activity. In spray assays LC50 of various compounds ranged from 1.32 to 11.5 mg/ml and in residual assay the range was 20.3–51.4 μg/cm2. In residual assay, ethylene glycol di‐2‐ethylhexanoate (5) and dioctanoate (6) were as effective as sucrose octanoate. Structure activity relationship suggested that higher number of carbon chains in these two compounds may be playing a role in the stability of compounds under residual operation of the insecticide. Based on these results, glycol esters would be useful and easy to prepare biorational compounds in integrated pest management.

A Novel Insecticidal Peptide SLP1 Produced by Streptomyces laindensis H008 against Lipaphis erysimi

“…The insecticidal peptide SLP1 exhibited similar insecticidal activity against L. erysimi (100% mortality at 700 mg/L; molecular weight: 1691.38) with the insecticidal compounds of low molecular weight such as the ethylene glycol diesters (LC 50 : 1320 to 11,500 mg/L) [19], the two derivatives of Harmine (LC 90 : 240.10 mg/L and 418.63 mg/L) [20] and three insecticidal alkaloids from Cynanchum mongolicum (LC 50 : 292.48 mg/L, 367.21 mg/L and 487.791 mg/L) [21]. Although the peptide SLP1 showed lower activity against L. erysimi than the protein of higher molecular weight from plants such as defensins (BjD and RiD) (LC 50 : 9.01 and 45.31 mg/L) [22] and Allium sativum leaf agglutinin (LC50: 20 mg/L) [23], the peptide SLP1 showed the good stability of pH and heat, and it is easier to be produced by a cost-effective and time-saving microbial fermentation method than cultivating plants [1,4].…”