Biological Effect of 1-Dodecanol in Teneral and Post-teneral Rhodnius prolixus and Triatoma infestans (Hemiptera: Reduvidae)

MOUGABURE CUETO G., E.N. ZERBA AND M.I. PICOLLO

MEMóRIAS DO INSTITUTO OSWALDO CRUZ.

Instituto Oswaldo Cruz

Lugar: Río de Janeiro, Brasil; Año: 2005 vol. 100 p. 59 - 61

0074-0276

The biological effect of 1-dodecanol against Rhodnius prolixus and Triatoma infestans was assesed in relation to the cuticle development. The 1-dodecanol evaluated by topical application was significantly more toxic against recently hatched first nymphs (1-3 h old) than the older first nymphs (24 h old). The lethal dose ratios between recently hatched and 24 h old nymphs (LDR) were 711,500 for R. prolixus and 3613 for T. infestans. However, no significative difference between LD50 was found when 1-dodecanol was injected in recently hatched adult R. prolixus (1-4 h old) nor in older adults (24 h old). The LD50 were 160.8 mg/i and 436.8 mg/i respectively. The comparison between these values and those calculated for deltamethrin (0.003 mg/i), a highly effective triatomicide, clearly showed that 1-dodecanol had no insecticidal properties when applied by injection. Topical application of high dose of 1-dodecanol (1 mg/i) on 1-3 h old first nymphs of R. prolixus, produced an interruption in the darkening process of the cuticle, and probably in the development of its physiological properties. The insecticidal activity demonstrated for 1-dodecanol applied on the cuticle of recently nymphs, the ineffectiveness of injection treatment and the effect on the cuticular tanning process, suggest that the insecticidal mode of action of 1-dodecanol could be associated with the developing cuticle.