ABSTRACT
Abstract: Objective: To compare the efficacy of three modern larvicides with the organophosphate temephos for control of Aedes aegypti in water tanks in Chiapas. Materials and methods: Trials were performed to compare the efficacy of pyriproxyfen, novaluron, two formulations of spinosad (granules and tablets) and temephos in oviposition traps and domestic water tanks. Results: Pyriproxyfen and temephos provided 2-3 weeks of complete control of larvae in oviposition traps, whereas spinosad granules and novaluron provided 7-12 weeks of control. Treatment of water tanks resulted in a significant reduction in oviposition by Ae. aegypt in houses (p<0.001). Higher numbers of larvae were present in temephos and pyriproxyfen-treated water tanks compared to novaluron and spinosad tablet treatments during most of the study. Conclusion: Spinosad formulations and novaluron were effective larvicides in this region. The poor performance of temephos may be indicative of reduced susceptibility in Ae. aegypti populations in Chiapas.
Resumen: Objetivo: Comparar la eficacia de tres larvicidas modernos para el control de Aedes aegypti en tanques de agua doméstica en Chiapas. Material y métodos: Se comparó la eficacia de piriproxifeno, novalurón, dos formulaciones de spinosad (gránulos y tabletas) y temefos en ovitrampas y tanques domésticos de agua. Resultados: El piriproxifeno y el temefos proporcionaron de 2 a 3 semanas de control de larvas en ovitrampas, mientras que los gránulos de spinosad y novaluron proporcionaron de 7 a12 semanas. Los tanques de agua tratados produjeron una reducción significativa en la oviposición por Ae. aegypti en las casas (p<0.001). Se encontró gran cantidad de larvas en los tanques tratados con temefos y piriproxifeno en comparación con los tratados con novaluron y tabletas de spinosad durante la mayor parte del estudio. Conclusión: Las formulaciones de spinosad en tabletas y novaluron fueron larvicidas efectivos en esta región. El bajo desempeño de temefos puede indicar una susceptibilidad reducida en poblaciones de Ae. aegypti en Chiapas.
Subject(s)
Animals , Female , Phenylurea Compounds , Pyridines , Temefos , Macrolides , Aedes , Insecticides , Oviposition , Water/parasitology , Mosquito Control/methods , Aedes/anatomy & histology , Drug Combinations , Housing , Larva , MexicoABSTRACT
Invertebrate iridescent viruses (IIVs) are icosahedral DNA viruses that infect invertebrates, mainly insects and terrestrial isopods, in damp and aquatic habitats. Exhaustive searches of databases resulted in the identification of 79 articles reporting 108 invertebrate species naturally infected by confirmed or putative iridoviruses. Of these, 103 (95%) were arthropods and the remainder were molluscs, an annelid worm and a nematode. Nine species were from marine habitats. Of the 99 non-marine species, 49 were from terrestrial habitats and 50 were aquatic, especially the aquatic stages of Diptera (44 species). The abundance of records from species of Aedes,Ochlerotatus and Psorophora contrasts markedly with a paucity of records from species of Anopheles,Culex and Culiseta. Records from terrestrial isopods are numerous (19 species), although the diversity of IIVs that infect them is mostly unstudied. IIV infections have been reported from every continent, except Antarctica, but there are few records from Africa, southern Asia and Latin America. Most reports describe patent IIV infections as rare whereas inapparent (covert) infection may be common in certain species. The relationship between particle size and iridescent colour of the host is found to be consistent with optical theory in the great majority of cases. Only 24 reported IIVs from insect hosts have partial characterization data and only two have been subjected to complete genome sequencing. I show that the rate of publication on IIVs has slowed from 1990 to the present, and I draw a number of conclusions and suggestions from the host list and make recommendations for future research efforts.
Los virus iridiscentes de invertebrados (VIIs) son virus icosaedrales de ADN que infectan a invertebrados, principalmente insectos e isópodos terrestres en hábitats húmedos y acuáticos. Búsquedas extensivas de bases de datos resultaron en la identificación de 79 artículos científicos, los cuales reportaron 108 especies de invertebrados infectados naturalmente por iridovirus. De estos, 103 (95%) fueron artrópodos y los otros fueron moluscos, un anélido y un nematodo. Nueve especies fueron de hábitats marinos. De las 99 especies no marinas, 49 fueron terrestres y 50 fueron acuáticas, especialmente los estadios acuáticos de dípteros (44 especies). La abundancia de infecciones en especies de Aedes,Ochlerotatus y Psorophora se contrasta marcadamente con la escasez de casos en especies de Anopheles,Culex y Culiseta. Reportes de infecciones de los isópodos terrestres son numerosos (19 especies), aunque la diversidad de los VII que los infectan es desconocida. Se han reportado infecciones por VIIs de todos los continentes, excepto Antártica, pero se notan pocos ejemplos de África, Asia y Latinoamérica. La mayoría de los artículos señala que las infecciones patentes son poco comunes, mientras que las infecciones enmascaradas (subletales) pueden ser comunes en algunas especies. La relación entre el tamaño de la partícula y el color iridiscente concuerda con la teoría óptica en casi todos los casos. Veinticuatro de los VIIs de insectos han sido caracterizados parcialmente y solo dos de éstos han sido secuenciados completamente. Demuestro que el ritmo de publicación sobre los VIIs ha disminuido en los últimos 15 años, señalo varias conclusiones y sugerencias de la lista de especies de huéspedes y presento algunas recomendaciones para la investigación futura con este grupo de patógenos.
Subject(s)
Animals , Iridovirus , Insecta/virologyABSTRACT
Os efeitos da estrutura etária e da densidade do hospedeiro na transmissão horizontal de um baculovírus foram investigados em laboratório, utilizando-se populações de lagarta do repolho, Mamestra brassicae L. (Lepidoptera: Noctuidae). Os insetos foram mantidos a três combinações de ínstares e três densidades populacionais em recipientes fechados contendo larvas infectadas. As larvas foram observadas diariamente e o número de mortes e o tempo letal foram registrados. Os níveis de mortalidade viral foram marginalmente superiores em recipientes contendo hospedeiros sob maior densidade populacional. As larvas apresentaram um risco de infecção aparentemente maior quando combinações de instares mais avançados foram usadas. Os níveis de mortalidade de larvas mais velhas foram maiores que as de larvas mais jovens. As médias de tempo letal das populaç ões larvais foram maiores para larvas mais jovens, observando-se um declínio mais acentuado na curva de sobrevivência das larvas em estágio mais adiantado de desenvolvimento.
The effects of stage structure and host density on baculovirus horizontal transmission were examined in the laboratory using larvae of the cabbage moth, Mamestra brassicae L. (Lepidoptera: Noctuidae). Insects were reared at three instar combinations and three host densities in closed containers with infected larvae. Insects were observed daily and the number of deaths and time to death were recorded. Levels of virus mortality were marginally higher in the containers where a higher density of hosts was introduced. Larvae appeared to have a greater risk of infection when late instar combinations were used. Final levels of mortality of older larvae were significantly higher than those of younger larvae. Mean times to death of larval populations were longer for larvae at earlier instar combinations, with a faster decrease in survivorship of older larvae over time.