Lufenuron is a chitin synthesis inhibitor used for controlling several pest insects. The German cockroach, Blattella germanica, is a cosmopolitan insect of medical and economic importance. Resistance to insecticides has been worldwide reported in this species. The objective of this work was to evaluate the effect of lufenuron in two colonies of B. germanica, one susceptible to insecticides (CIPEIN) and another pyrethroid-resistant (JUBA). Experimental populations from each colony were exposed to flter papers treated with 50 mg of lufenuron/m2. Controls were exposed to flter papers treated with solvent alone. After seven weeks, the average size of both lufenuron-treated populations was 1.33 ± 0.7 individuals, while the average size of control populations were 206.5 ± 39.5 (CIPEIN) and 136.5 ± 43.5 (JUBA) individuals. This drastic effect suggests that lufenuron could be used as an alternative for the control of pyrethroid-resistant German cockroaches. Future studies should explore the toxicity of lufenuron on other populations of B. germanica resistant to pyrethroids or other insecticides.

Lufenurón es un inhibidor de la síntesis de quitina usado para controlar diversas plagas de insectos. La cucaracha alemana, Blattella germanica, es un insecto cosmopolita de importancia médica y económica. Existen numerosos reportes de resistencia a insecticidas en poblaciones de B. germanica alrededor del mundo. El objetivo de este trabajo fue evaluar el efecto de lufenurón en dos colonias de B. germanica, una susceptible a insecticidas (CIPEIN) y otra resistente a deltametrina (JUBA). Se expusieron poblaciones experimentales de ambas colonias a papeles de fltro tratados con 50 mg de lufenurón/m2. Los controles fueron expuestos a papeles de fltro tratados con solvente solo. Al cabo de siete semanas, las dos poblaciones expuestas a lufenurón presentaron el mismo tamaño promedio (1,3 ± 0,7 individuos); mientras que los tamaños promedio de las poblaciones controles fueron 206,5 ± 39,5 (CIPEIN) y 136,5 ± 43,5 individuos (JUBA). Este drástico efecto sobre el tamaño poblacional sugiere que lufenurón podría ser usado como una alternativa para controlar cucarachas alemanas resistentes a deltametrina. A la vista de estos resultados, se debería explorar la toxicidad de lufenurón en otras poblaciones de B. germanica resistentes a piretroides u otros insecticidas.

A susceptible strain of Aedes albopictus derived from the Gainesville strain (Florida, USA) was established in our laboratory. The larvicidal efficacies of the neurotoxic insecticides temephos, permethrin and the pure cis and trans-permethrin isomers and the microbial insecticide Bacillus thuringiensis israelensis (Bti) against Ae. albopictus were estimated and compared to a susceptible strain of Aedes aegypti. The larvicidal effect of insect growth regulator pyriproxyfen was also evaluated in both mosquito strains. The median lethal concentration/median emergency inhibition values for Ae. aegypti and Ae. albopictus, respectively, were: temephos, 3.058 and 6.632 ppb, permethrin, 3.143 and 4.933 ppb, cis-permethrin, 4.457 and 10.068 ppb, trans-permethrin, 1.510 and 3.883 ppb, Bti, 0.655 and 0.880 ppb and pyriproxyfen, 0.00774 and 0.01642 ppb. Ae. albopictus was more tolerant than Ae. aegypti to all six larvicides evaluated. The order of susceptibility for Ae. aegypti was pyriproxyfen > Bti > trans-permethrin > temephos > permethrin > cis-permethrin and for Ae. albopictus was pyriproxyfen > Bti > trans-permethrin > permethrin > temephos > cis-permethrin. Because both species can be found together in common urban, suburban and rural breeding sites, the results of this work provide baseline data on the susceptibility of Ae. albopictus to insecticides commonly used for controlling Ae. aegypti in the field.