Toxicity of the Jaburetox Peptide to the Multi-Host Insect-Pest Helicoverpa armigera (Lepidoptera: Noctuidae) Larvae

Abstract

Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) causes extensive damage to crops. The entomotoxic peptides fragments from Jack bean urease, Jaburetox and its truncated version Jaburetox Δ-β, present potential for controlling some insect species, and could provide an alternative for pest insect control in agricultural crops. This paper evaluated the effectiveness of these 2 peptides on consumption by and survival of the H. armigera larvae in 2 different instars of the larval stage. Neonates were fed leaves for 8 d with 2 peptide topical leaf treatments: (T1) 16 µg of Jaburetox, (T2) 16 µg of Jaburetox Δ-β; and 2 control treatments: (T3) sodium phosphate buffer, and (T4) distilled water. Leaves coated with either of the peptides induced higher mortality than the controls. The Jaburetox Δ-β induced the greatest mortality during the first d of feeding, but after 6 d both peptides were effective equally and caused about 75% mortality. Both peptide versions caused a delay in larval development, but the larger peptide caused a greater reduction in feeding. In a second experiment, third instar larvae were fed 1 of 2 treatments for 9 d: (T1) 80 µg of Jaburetox, and (T2) buffer control. Jaburetox treatment induced a delay in the larval development and a significantly higher mortality than the control. By 9 d, Jaburetox treatment caused 100% mortality. These results support further evaluation of the use of Jaburetox peptide in control strategies for H. armigera, including transgenic expression of this peptide in crops plants.