Insecticidal Properties of a Highly Potent Wax Isolated from Dolichandra cynanchoides Cham

Abstract

Bioassay-guided fractionation of an ethanolic extract of the aerial parts of Dolichandra cynanchoides Cham. (Bignoniaceae) led to the isolation of a natural wax with anti-insect activity against Spodoptera frugiperda (Noctuidae) and Epilachna paenulata (Coleptera). The compound was identified spectroscopically as an ester of a C27 fatty acid and a C25 alcohol, pentacosyl heptacosanoate (1). The effective doses of 1 for 50% feeding inhibition (ED 50 ) of S. frugiperda and E. paenulata were 0.82 and 8.53 µg/cm 2 , respectively, in a choice test, while azadirachtin showed ED 50 of 0.10 and 0.59 µg/cm 2 , respectively. In a no-choice test, both insects refused to feed on leaves treated with 1 at doses of 0.1 µg/cm 2 or greater inhibiting larval growth and dramatically reducing survival. The lethal doses 50 (LD 50 ) of 1 were 0.39 and 0.68 µg/cm 2 for S. frugiperda and E. paenulata, respectively. These results indicate that 1 has potential for development as botanical insecticides. Similar esters might be obtainable in large quantities as many edible crops produce wax esters that are discarded during food processing. Research on these materials could lead to the detection of similar waxes with insecticidal activity.

Chemical Composition of an Aphid Antifeedant Extract from an Endophytic Fungus, Trichoderma sp. EFI671

“…Hexadecanoate methyl (methyl palmitate) and ethyl (ethyl palmitate) esters were antifeedant against the aphids M. persicae and Diuraphis noxia [47]. Pentacosyl heptacosanoate has been isolated from the natural wax of the plant Dolichandra cynanchoides as an insecticidal agent against S. frugiperda and Epilachna paenulata [48]. Therefore, fatty acids, which are non-toxic substances, are a promising class of molecules for the control of phytophagous insects.…”