RESUMO
The purpose of this study was to evaluate the effect of the EPN Heterorhabditis bacteriophora HP88 on Stmoxys. calcitrans larvae in sugarcane bagasse ash. Groups of 10 stable fly larvae were placed in Petri dishes containing filter paper and bagasse ash. Concentrations of 50, 150 and 250 EPNs/larva of S. calcitrans in four milliliters of distilled water were added to each plate. In the control group contained only distilled water, without EPNs. The bioassay had three replications and was maintained at 27 ± 1°C and 70-80% relative humidity. It was observed that mortality rate in all treated groups was significantly higher than in the control group (26,6%). The mortality rate in the presence of 50 EPNs/larva (46,6%) was lower than in 150 EPNs/larva (76,3%), which in turn was lower than 250 EPNs/larva group (93,3%). It was verified by analysis of variance and regression that there was a linear pattern of mortality, that is, the higher the EPNs/larva concentration, the higher the larval mortality. It was concluded that EPN H. bacteriophora HP88 was capable of infecting and causing mortality of stable fly larvae in sugarcane bagasse ash.
O objetivo deste estudo foi avaliar o efeito do NEP Heterorhabditis bacteriophora HP88 sobre larvas de Stomoxys calcitrans em cinzas de bagaço de cana-de-açúcar. Grupos de 10 larvas da mosca dos estábulos foram depositadas em placas de Petri contendo papel filtro e cinzas. Foram adicionadas concentrações de 50, 150 e 250 NEPs/larva de S. calcitrans em cada placa. No grupo controle não havia NEPs, somente água destilada. O bioensaio teve três repetições e foi mantido em 27 ± 1°C e 70-80% de umidade relativa. Observou-se que a mortalidade em todos os grupos tratados foi significativamente superior à do grupo controle (26,6%). A taxa de mortalidade na presença de 50 NEPs/larva (46,6%) foi menor do que em 150 NEPs/larva (76,3%), que por sua vez foi menor do que no grupo 250 NEPs/larva (93,3%). Verificou-se pela análise de variância e de regressão que houve um padrão linear de mortalidade, ou seja, quanto maior a concentração de NEPs/larva, maior a mortalidade larval. Conclui-se que o NEP H. bacteriophora HP88 foi capaz de infectar e causar mortalidade das larvas da mosca dos estábulos em cinza de bagaço de cana e que aparentemente este subproduto não interfere negativamente na ação deste NEP.
RESUMO
Stomoxys calcitrans is a hematophagous dipteran. Several agents are used in biological control, including entomopathogenic nematodes (EPNs). Bioassay I involved an evaluation of the effect of Heterorhabditis bacteriophora HP88 and Heterorhabditis baujardi LPP7 on S. calcitrans larvae in different periods of exposure. Groups of 10 larvae were placed in Petri dishes and 200 EPNs/larva were added, which were divided into groups according to the exposure times of 2, 4, 6, 12, 24 and 48 hours. The purpose of Bioassay II was to evaluate the efficacy of the EPNs in infecting S. calcitrans larvae when they were isolated from stable fly larvae in Bioassay I. Groups of 10 larvae were placed in Petri dishes and 200 EPNs/larva were added. In bioassay I, H. bacteriophora caused mortality rates of 51.7, 83.3 and 91.7% in 12, 24 and 48 hours, respectively, while H. baujardi caused mortality rates of 9.3 (12h), 35 (24h) and 35% (48h). In Bioassay II, H. bacteriophora and H. baujardi resulted in mortality rates of 35% and 25%, respectively. It was concluded that the longest exposure times presented the highest larval mortality and that EPNs isolated from S. calcitrans are not efficient in controlling the larvae fly.
Assuntos
Muscidae , Nematoides , Animais , Larva , Controle Biológico de Vetores , Reinfecção/veterináriaRESUMO
Abstract Stomoxys calcitrans is a hematophagous dipteran. Several agents are used in biological control, including entomopathogenic nematodes (EPNs). Bioassay I involved an evaluation of the effect of Heterorhabditis bacteriophora HP88 and Heterorhabditis baujardi LPP7 on S. calcitrans larvae in different periods of exposure. Groups of 10 larvae were placed in Petri dishes and 200 EPNs/larva were added, which were divided into groups according to the exposure times of 2, 4, 6, 12, 24 and 48 hours. The purpose of Bioassay II was to evaluate the efficacy of the EPNs in infecting S. calcitrans larvae when they were isolated from stable fly larvae in Bioassay I. Groups of 10 larvae were placed in Petri dishes and 200 EPNs/larva were added. In bioassay I, H. bacteriophora caused mortality rates of 51.7, 83.3 and 91.7% in 12, 24 and 48 hours, respectively, while H. baujardi caused mortality rates of 9.3 (12h), 35 (24h) and 35% (48h). In Bioassay II, H. bacteriophora and H. baujardi resulted in mortality rates of 35% and 25%, respectively. It was concluded that the longest exposure times presented the highest larval mortality and that EPNs isolated from S. calcitrans are not efficient in controlling the larvae fly.
Resumo Stomoxys calcitrans é um díptero hematófago. Vários agentes são usados no controle biológico, incluindo nematoides entomopatogênicos (NEPs). O bioensaio I objetivou avaliar o efeito de Heterorhabditis bacteriophora HP88 e Heterorhabditis baujardi LPP7 sobre larvas de S. calcitrans em diferentes períodos de exposição. Grupos de 10 larvas foram colocados em placas de Petri, adicionou-se 200 NEPs/larva, e foram divididos de acordo com tempos de exposição de 2, 4, 6, 12, 24 e 48 horas. O objetivo do Bioensaio II foi avaliar a eficácia dos NEPs na infecção de larvas de S. calcitrans, quando esses foram isolados de larvas da mosca oriundos do Bioensaio I. Os grupos de 10 larvas foram colocados em placas de Petri e 200 NEPs/larva foram adicionados. No bioensaio I, H. bacteriophora causou taxas de mortalidade de 51,7%, 83,3% e 91,7% em 12, 24 e 48 horas, respectivamente, enquanto H. baujardi causou taxas de mortalidade de 9,3% (12h), 35% (24h) e 35% (48h). No Bioensaio II, H. bacteriophora e H. baujardi resultaram em taxas de mortalidade de 35% e 25%, respectivamente. Concluiu-se que os maiores tempos de exposição apresentaram as maiores mortalidades larvais e que NEPs isolados de S. calcitrans não são eficientes no controle das larvas mosca.
