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Lethal and sublethal effects of eucalyptol on T riatoma infestans and R hodnius prolixus , vectors of C hagas disease
Author(s) -
Moretti Ariad.,
Zerba Eduardo N.,
Alzogaray Raúl A.
Publication year - 2015
Publication title -
entomologia experimentalis et applicata
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.765
H-Index - 83
eISSN - 1570-7458
pISSN - 0013-8703
DOI - 10.1111/eea.12256
Subject(s) - eucalyptol , nymph , triatoma infestans , biology , toxicology , veterinary medicine , botany , essential oil , medicine , parasite hosting , trypanosoma cruzi , world wide web , computer science
Abstract Eucalyptol is the common name for a cyclic ether monoterpene found in essential oils from E ucalyptus species and other plants. Several reports showed its insecticidal activity. In this work, visible symptoms of intoxication, effect on locomotor activity, knock‐down, and repellence produced by eucalyptol were evaluated on nymphs of T riatoma infestans K lug and R hodnius prolixus S tåhl (both H emiptera: R eduviidae). Both insects are among the main vectors of C hagas disease in L atin A merica. Visible symptoms of intoxication were similar to those observed for neurotoxic insecticides. A video tracking technique was used to evaluate locomotor activity and repellence by exposing the nymphs to impregnated papers. Hyperactivity (a non‐directional increase in locomotor activity) is a symptom of intoxication that is used to detect triatomines in rural houses, because it causes the insects to leave their refuges. Eucalyptol produced hyperactivity only in T . infestans at a concentration 1 000× higher than the positive control, deltamethrin [( S )‐cyano(3‐phenoxyphenyl)methyl (1 R ,3 R )‐3‐(2,2‐dibromoethenyl)‐2,2‐dimethylcyclopropanecarboxylate]. It also produced repellence on both species at a concentration 10× higher than the positive control, DEET ( N , N ‐diethyl‐3‐methylbenzamide). Knock‐down effect was evaluated by exposing the nymphs to impregnated papers in closed containers (contact and fumigation simultaneously). Values of knock‐down time for 50% of exposed nymphs ( KT 50 ) were calculated for various concentrations of eucalyptol. The onset of knock‐down occurred more rapidly as the concentration increased. In the best cases, eucalyptol was 12–15× less toxic than the positive control dichlorvos (2,2‐dichlorovinyl dimethyl phosphate). After these results, eucalyptol seems discouraged as a hyperactivant agent for monitoring insects in rural houses. Nevertheless, its knock‐down and repellence effect on vectors of C hagas disease deserve further investigation.