Insecticidal effects of canatoxin on the cotton stainer bug Dysdercus peruvianus (Hemiptera: Pyrrhocoridae)

• Published in: Toxicon (Oxford) Vol. 45; no. 6; pp. 753 - 760
• Main Authors: Stanisçuaski, F., Ferreira-DaSilva, C.T., Mulinari, F., Pires-Alves, M., Carlini, C.R.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.05.2005; Elsevier Science
• Subjects: Age Factors; Animals; Biological and medical sciences; Body Weight - drug effects; Brazil; Callosobruchus maculatus; Canatoxin; Canavalia - chemistry; Canavalia ensiformis; Cathepsins - metabolism; Control; Digestive System - enzymology; Dysdercus peruvianus; Fundamental and applied biological sciences. Psychology; Hemiptera; Heteroptera - drug effects; Insecticide; Integrated pest control; Medical sciences; Molting - drug effects; Pesticides, fertilizers and other agrochemicals toxicology; Phytopathology. Animal pests. Plant and forest protection; Plant Proteins - toxicity; Proteolytic enzymes; Protozoa. Invertebrates; Pyrrhocoridae; Rhodnius prolixus; Seeds - chemistry; Survival Analysis; Toxicology; Toxins, Biological - toxicity; South America; Brazil; America; Insecticide; Canavalia ensiformis; Canatoxin; Proteolytic enzymes; Dysdercus peruvianus; Enzyme; Insecta; Botanical insecticide; Heteroptera; Peptidases; Leguminosae; Arthropoda; Dicotyledones; Angiospermae; Hydrolases; Pyrrhocoridae; Spermatophyta; Biopesticide; Invertebrata; Dysdercus
• ISSN: 0041-0101; 1879-3150
• DOI: 10.1016/j.toxicon.2005.01.014

Canatoxin (CNTX) is a variant form of urease isolated from Canavalia ensiformis (Leguminosaea) seeds. A possible role in the plant defense was proposed for CNTX, due to its toxicity upon feeding to the beetle Callosobruchus maculatus, and the hematophagous bug, Rhodnius prolixus. The toxic effect is caused by a canatoxin-derived peptide (∼10 kDa) formed by insect cathepsin-like digestive enzymes. In order to evaluate their potential as bioinsecticides, the effects of CNTX and its peptide were evaluated on a phytophagous hemipteran insect Dysdercus peruvianus, a pest of cotton culture. For the bioassays, the insects fed on gelatin capsules containing powdered cotton seeds, mixed with the freeze-dried protein and other test materials and were observed for survival rate, weight gain and molting. Ingestion of canatoxin, or a recombinant 10 kDa peptide derived from it, severely affected young forms of the insects, delaying their development or leading to their death. In contrast, adults were insensitive to diets containing higher concentrations of canatoxin. Cathepsin-like proteinases predominated and showed distinct pattern of enzymatic activities in midguts homogenates according to the developmental stage of the insect, a fact which may explain the different susceptibility of nymphs as compared to adult D. peruvianus. The data presented confirm the potential use of canatoxin-like proteins and derived peptides as bioinsecticides.