TOXIC EFFECTS ON INSECTS OF VENOMS FROM Tityus metuendus AND Brotheas amazonicus AMAZONIAN SCORPIONS

HIGA A. M. (1,3), ARAÚJO J. DE S.(2), ARAÚJO T. F. (1,3), NORONHA M. D. N. (1,3), MARTINS MARX J.P. , MEDEIROS B. M. (4), MUNIZ, E.G. (3), AGUIAR, N. O. (5), LOPEZ-LOZANO, J.L. (1,3).

(1) Pós-Graduação em Biotecnologia – UEA; (2) Pós-Graduação em Entomologia – INPA. (3) Fundação de Medicina Tropical do Amazonas; (4) Pós-Graduação em Biotecnologia – UFAM; (5) Curso de Ciências Biológicas UFAM.

Neurotoxic peptides from scorpions venoms show depressant and excitatory effects in insects. Tityus metuendus is responsible of scorpionism in urban area of Manaus region and Brotheas amazonicus occur in Manaus region forest areas but has not medical importance. Specimens were captured in Manaus region. Venoms were collected by low voltage electric stimulation. Insect toxicity test was done in adult crickets (Gryllus assimilis), cockroaches (Blaberus discoidale) and tenebrioid beetle larvae (Zophobas morio). LD50 and PD50 were calculated by Probitos method. Venoms were inoculated in insect thoracic region and neurotoxic effects as paralysis, locomotion difficulty, body and leg trembling  and death were studied. T. metuendus venom showed lethal activity in crickets (LD50 6.3 mg) and  cockroaches (LD50  74.3 mg) but with doses tested was not observed death in larvae. T. metuendus venom also showed fast paralyzing effects, locomotion difficulty and trembling legs in crickets (PD50 2.5 mg) but abdominal contractions with normal locomotion in cockroaches were seen, but this venom provoked fast paralysis (30 sec. approx.) in larvae. B. amazonicus venom showed fast paralyzing effects in crickets (PD50 2.5 mg) but in cockroach paralyzing effects were not seen. In larvae low venom doses showed fast paralyzing effect (30 sec. approx.) but with high venom doses (³ 20 µg) larvae was paralyzed by 24 hours. Our results suggest insect neurotoxins in scorpion venoms studied and different susceptibility to scorpion venoms of insect species. Molecular characterization of specifics insect neurotoxins are in course.

KEY WORDS: Amazonia, Tityus metuendus, Brotheas amazonicus, neurotoxins.

FINANCIAL SUPPORT: CAPES, FAPEAM, FMTAM, FINEP.

CORREPONDENSE TO: ANDRE MIASATO HIGA, Centro de Ofidismo Prof. Paulo Friedrich Bürnheim / FMTAM, Manaus, Brasil. Phone: + 55 92 3238 42 94. E-mail: andmhiga@yahoo.com.br.