Effects of Extracts from Four Pesticidal Plants on the Management of the Sugarcane Stem Borer Eldana saccharina Walker in Côte d'Ivoire

Abstract

The stem borer Eldana saccharina Walker causes substantial production losses in the sugarcane estates of Côte d'Ivoire, where its control still relies largely on synthetic chemical insecticides that are harmful to human health and the environment. The present study aimed to evaluate the effects of extracts from pesticidal plants on infestation rates and the agro-technological parameters of sugarcane. A field trial was conducted under natural infestation conditions, using a randomised complete block design (Fisher blocks) with thirteen treatments and four replications. The essential oils of Cymbopogon citratus (DC.) Stapf, Ocimum gratissimum L. and Zingiber officinale Roscoe, as well as an oil concentrate of Azadirachta indica A. Juss. (A. indica OC), were applied at doses of 1, 2 and 3 ml · l−1. Three applications were made at fifteen-day intervals from the fifth month of vegetation, and the phytosanitary and agro-technological parameters were assessed at harvest. The microplots treated with the essential oils of C. citratus and Z. officinale, as well as with the A. indica OC, were significantly less infested than the untreated control microplots. Those treated with C. citratus essential oil recorded, on average, the lowest percentages of bored internodes (3.15%) and bored stalks (35.97%); they also produced the longest stalks and the highest cane and extractable sugar yields. These extracts improve the agro-technological parameters of sugarcane and can be used as bio-insecticides in the control of E. saccharina Walker.