Lower termites express a unique form of eusocial polyphenism in that totipotent workers can differentiate into either soldier or reproductive caste phenotypes. In this initial effort using RNA interference in termites, we found that two hexamerin genes, Hex-1 and Hex-2, participate in the regulation of caste polyphenism. Our methodology involved a dual gene-silencing approach that used a single short-interfering RNA fragment to silence the two homologous hexamerin genes. We performed validation studies that evaluated effects on nontarget housekeeping genes, silencing of a nonhousekeeping control gene, and effects at the protein level. We found that the two hexamerin proteins, which are inducible by the morphogenetic juvenile hormone and which constitute a significant proportion of total termite protein, suppress juvenile-hormone-dependent worker differentiation to the soldier caste phenotype. This mechanism allows termite colonies to retain high proportions of altruistic worker caste members, thus apparently enhancing colony-inclusive fitness. These findings demonstrate a unique status quo regulatory mechanism for termite worker caste retention and provide an example of previously undescribed preadult developmental͞caste-regulatory genes from any social insect.sociogenomics ͉ RNA interference ͉ short-interfering RNA ͉ juvenile hormone ͉ phenotypic plasticity

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Permethrin is a commonly used acaricide for tick control on domestic animals and in residential environments, while fipronil use is restricted to on-animal treatment. Following widespread reports of permethrin and fipronil application failures to control indoor infestations of Rhipicephalus sanguineus (Latreille), the brown dog tick, 31 tick populations were obtained from Florida and Texas for acaricide resistance screening. These field-collected ticks from kennels and residential facilities were challenged with technical grade permethrin and fipronil to create dose response curves that were compared with an acaricide-susceptible strain. Permethrin resistance was successfully screened in nine populations, all of which were resistant or highly resistant. Tick susceptibility to fipronil was conducted on four populations, which were found to be tolerant, with resistance ratios below 10. This is the first documentation of R. sanguineus permethrin resistance and fipronil tolerance in the United States. Potential causes of resistance development and recommendations on future brown dog tick control management plans are discussed.