Eco-Friendly Management Options for Sesame Webworm (Antigastra catalaunalis Dup.)

Sesame (Sesamum indicum L; Pedaliaceae) is an important oilseed crop that contributes significantly to the Ethiopian economy through foreign exchange but it is heavily attacked by the sesame webworm which causes 83% yield loss.

The aim was to evaluate efficacy of aqueous extracts of seven locally available bio-pesticides (Azadirachta indica, Lantana camara, Rumex patientia, Nicotiana glauca, Ricinus communis, Phytolacca dodecandra and Tagetes minuta) along with dimethoate 40% EC (standard test) and untreated control (only tap water) against sesame webworm (Antigastra catalaunalis) insect pest, and its effects on sesame yield and yield losses under outdoor conditions.

Field experiment was conducted at Humera agricultural research center during the 2020 harvest season. Treatments were arranged in a randomized complete block design with 3 replications and applied 3 times at 2-week intervals.

ANOVA results showed that all aqueous extracts were significantly (P<0.05) higher than the control. Uninterrupted growth of the test insect resulted in an incidence of 82.59%. However, it was decreased to 28.89% and 29.63% by spraying A. indica and R. Communis aqueous extracts. A. indica was statistically equivalent to R. communis and dimethoate 40% EC in reducing damage to leaves (8.56%), flowers (10.20%), capsules (3.34%) and seeds (29.67%) yet significantly different from controls which scored 21.8%, 20.88%, 11.51%, and 79.34%, leaf, flower, capsule, and seed damage respectively. R. communis also effectively condensed injuries on leaves (8.68%), flowers (12.64%), capsules (2.66%) and seeds (23.42%). Likewise, aqueous solutions of A. indica showed impressive yields (0.71 t ha^-1) followed by R. communis (0.53 t ha^-1) compared with the control (0.22 t ha^-1). Yield increase over control was also higher for A. indica (222.73%) and R. communis (140.91%) compared to other treatments. The maximum (69.01%) estimated yield loss was recorded in control plots due to webworm invasion in sesame.

From this result, it can be concluded that A. indica and R. communis can be excellent substitutes for synthetic insecticides to increase sesame yield under outdoor conditions.