Effects of plant derived salicylic acid on growth and development of moringa budworm larva, Noorda moringae (Lepidoptera: Crambidae)

Abstract

The experimental trials were carried out to evaluate the impact of plant-derived salicylic acid (SA) treatment on the development of moringa budworm. The SA obtained from plant sources were form into three different concentrations (5mg/l, 10mg/l, and 20mg/l) by serial dilution. Moringa plants were treated by spraying with varying doses of SA hormones at week intervals. The treated plants were blocked in screened cages in a completely randomized blocked pattern. Five pairs of freshly emerged Noorda moringae were maintained in the various blocks for mating and oviposition, after which all adult insects were removed thereafter. The treated moringa plants exhibited different responses to budworm development. There was a significant (P<0.001) effect among hormone concentrations and spray regimes, with 20mg/l salicylic acid (SA) showing greater influence on various developmental stages of larval N. moringae compared to lower concentrations (10 & 5mg/l SA) and the control (Distilled H₂O). The higher levels of SA at median spray regime (2 weeks after spray) hindered larval development more, as evidenced by low growth rate (RGR) and Larval Fitness Indices (LFI) respectively. Phytochemical analysis of the extracts revealed notable concentrations of 9-octadecanoic acid methyl ester, Methyl tetradecanoate, Methyl 4-hydroxy butanoate, and Hexadecanoic acid methyl ester, which displayed toxic effects on the developing larvae.