Search

The sugarcane borer, Diatraea saccharalis, makes tunnels in the cane stalk, causing weight loss, as well as bud death, impairing germination. The weakened stalks are also more prone to breakage by wind, and in young plants the inner whorl of the leaves can die, resulting in a condition known as “dead heart”. Chemical control is used, but with low efficiency. This work was designed to test biological control of D. saccharalis using entomopathogenic nematodes (NEPs). Two trials in the greenhouse were performed using Heterohabditis baujard LPP7 and Steinernema carpocapse NCAll by foliar application associated with adjuvants. In the first assay, the number of holes per stalk was 3.4 for the control without nematodes and with Joint* Oil; 3.14 for the control without nematodes and with Gotafix®; 2.44 for S. carpocapsae NCAll + Joint* Oil; 2.06 for H. baujardi LPP7 + Gotafix® and also for S. carpocapsae NCAll + Gotafix®; and 1.84 for H. baujardi LPP7 + Joint* Oil. In the second assay, the treatments showed an average of 4.78 holes per stalk for the control without nematodes and with Gotafix®; 4.76 for the control without nematodes and with Joint* Oil; 2.18 for S. carpocapsae NCAll + Joint* Oil and for S. carpocapsae NCAll + Gotafix®; 1.96 for H. baujardi LPP7 + Gotafix®; and 1.90 for H. baujardi LPP7 + Joint* Oil. In the two experiments, the treatments with and without the EPNs differed significantly, but there was no difference between the adjuvants or between the two EPN species. A broca-da-cana, Diatraea saccharalis, causa danos à cana-de-açúcar devido ao seu hábito de formar galerias nos colmos, o que acarreta em perda do peso do produto, redução da sacarose e a seca dos ponteiros. O controle químico é utilizado, porém, com baixa eficiência, pois a larva permanece maior parte do tempo de seu desenvolvimento dentro dos colmos. Este trabalho teve como objetivo testar o controle biológico da D. saccharalis, utilizando-se nematóides entomopatogênicos (NEPs). Para tanto, foram realizados dois ensaios em casa de vegetação utilizando-se Heterohabditis baujardi LPP7 e Steinernema carpocapse NcAll por pulverização foliar, associados a produtos adjuvantes. No primeiro ensaio, o número médio de furos causados pela broca-da-cana, nas testemunhas Joint* Oil e Gotafix® foram de 3,4 e 3,14 respectivamente. Já quanto aos tratamentos, o número de furos por colmo analisado foi de 2,44 para S. carpocapsae NCAll + Joint* Oil; 2,06 para H. baujardi LPP7 + Gotafix®; 2,06 para S. carpocapsae NCAll + Gotafix®; e 1,84 para H. baujardi LPP7 + Joint* Oil. Quando o experimento foi repetido, o número médio de furos nas testemunhas Gotafix® e Joint* Oil, foram respectivamente 4,78 e 4,76. Quanto aos tratamentos S. carpocapsae NCAll + Joint* Oil, S. carpocapsae NCAll + Gotafix®, H. baujardi LPP7 + Gotafix® e H. baujardi LPP7 + Joint* Oil, apresentaram o número médio de 2,18; 2,18; 1,96 e 1,96 furos por colmos avaliados. Assim, ambos nematóides controlaram a broca da cana, contudo não houve diferença significativa entre NEPs e produtos adjuvantes.

Despite massive losses of primary forest, the Amazonian rainforest remains an extremely rich source of biodiversity. In recent years, entomopathogenic nematodes (EPNs) have been isolated from soil in various parts of the world and used successfully as biological control agents against numerous insect pests. Therefore, a sampling in the rainforest of Monte Negro, Rondônia, Brazil was conducted with the aim of discovering new strains and/or species of EPNs for future development as biological control agents. From 156 soil samples taken at nine collecting sites, 19 isolates were obtained, all of them belonging to the genus Heterorhabditis. Four strains were subjected to detailed morphological and molecular evaluation. Based on morphometrics and internal transcribed spacer (ITS) sequence data, the strains LPP1, LPP2 and LPP4 were identified as Heterorhabditis indica, whereas LPP7 was considered Heterorhabditis baujardi. Comparative analysis of the ITS1 sequence of H. indica and H. baujardi isolates showed a polymorphic site for the restriction enzyme Tth 111 that could be used to distinguish the two species. Consequently, strains LPP1, LPP2, LPP3, LPP4, and LPP9 were identified as H. indica, whereas LPP5, LPP7, LPP8 and LPP10 were identified as H. baujardi.

The present study was carried out to evaluate the action of Steinernema glaseri Santa Rosa strain and Heterorhabditis bacteriophora CCA strain as biological control agents of Boophilus microplus. Engorged females ticks were distributed on Petri dishes containing different concentrations of infective juvenile (IJ) nematodes (0, 375, 500, 750, 1,500, 2,500, 5,000 and 25,000). The data showed a reduction of approximately 90% in the eggs laid at a concentration of 5,000 S. glaseri IJs and approximately 80% at a concentration of 1,500 H. bacteriophora IJs. The female mortality increased linearly with the increase in S. glaseri concentrations. However, in the tests with H. bacteriophora this linearity was not observed. The effectiveness of the treatment with both species of entomopathogenic nematodes was compatible with other control methods. The results show the potential of S. glaseri and H. bacteriophora as biological control agents for the control of B. microplus under laboratory conditions. [ABSTRACT FROM AUTHOR]

Entomopathogenic nematodes (EPNs) are currently being used as successful biological control agents of soil-dwelling insect pests. Previous field and greenhouse studies demonstrated that application techniques and non-biotic factors (temperature and pressure) have a significant effect on EPNs efficacy. The objective of this study was to evaluate the influence of an irrigation spray application system on the viability, infectivity and host search capability of Heterorhabditis baujardi LPP7 (Nematoda: Heterorhabditidae) infective juveniles (IJ). Two assays were proposed. Their viability was evaluated under the microscope after the IJ passed through the irrigation system. Infectivity on Galleria mellonella larvae, and host search capability, as evidenced by larval mortality, were evaluated in containers (Experiment 1). In the field (Experiment 2), mortality of G. mellonella larvae was evaluated under different nematode concentrations (0, 100,000, 300,000 and 500,000 IJ per tree). No differences were recorded on the viability, infectivity and host search capability of the IJ in Experiment 1. In Experiment 2, differences were recorded among the different concentrations used (p < 0.05), and a higher mortality was observed at the highest nematode concentration (28.3% and 37% in each one of the two experiment repetitions). This irrigation system did not affected adversely the viability, infectivity and host search capability of H. baujardi LPP7.Nematóides entomopatogênicos (NEPs) vêm sendo usados com sucesso como agentes do controle biológico de pragas de solo. Estudos anteriores mostraram que técnicas de aplicação e fatores abióticos (temperatura e pressão) afetam a eficiência dos NEPs em testes de campo e casa-de-vegetação. O objetivo deste trabalho foi avaliar a influência de condições geradas por um sistema de irrigação por microaspersão, na viabilidade, infectividade e na capacidade de busca de hospedeiros nos juvenis infectantes (JI) de Heterorhabditis baujardi LPP7 (Nematoda: Heterorhabditidae). Dois experimentos foram propostos. A viabilidade dos juvenis infectantes (JI) foi avaliada no microscópio imediatamente após sua passagem pelo sistema de irrigação. A infectividade e a capacidade de busca pelo hospedeiro em larvas de Galleria mellonella foram avaliadas em vasos (Experimento 1). A campo (Experimento 2), foi avaliada a mortalidade de larvas de G. mellonella sob diferentes concentrações do nematóide (0, 100.000, 300.000 e 500.000 JI por árvore). A viabilidade, infectividade e a capacidade de busca dos nematóides após a passagem pelo sistema não foi diferente da testemunha. No Experimento 2, houve diferença entre os tratamentos (p < 0.05) e se observou maior mortalidade na maior concentração de nematóides, com mortalidade de 28,3% e 37% em cada uma das duas repetições do experimento. Este sistema de micro-aspersão não afeta a viabilidade, infectividade e capacidade de busca dos JIs de H. baujardi LPP7 até o inseto-alvo.

Engorged and partially engorged females of Boophilus microplus were exposed to 600; 3,000; 6,000 and 30,000 infective juveniles of Steinernema carpocapsae Weiser, 1955 Santa Rosa and All strains per dish, under lab conditions. Eggs weight, pre-laying period, laying period, survival period, reproductive efficiency rate, percentage of larval eclosion and lethal concentrations of 50% and 90% (CL50 and CL90) were calculated for engorged females. In the case of partially engorged females, only egg weight, survival period and CL50 and CL90 were calculated. All biological parameters of engorged or partially engorged females were altered by exposition of S. carpocapsae infective juveniles (IJs), Santa Rosa and All strains (pFêmeas ingurgitadas e parcialmente ingurgitadas de B. microplus foram expostas a 600, 3000, 6000 e 30000 juvenis infectivos de Steinernema carpocapsae Weiser, 1955 linhagens Santa Rosa e ALL por placa, sob condições de laboratório. Foram investigados para fêmeas ingurgitadas: peso da massa de ovos, período pré-postura, período de postura, tempo de sobrevivência, índice de eficiência reprodutiva, percentual de aclosão de larvas e concentrações letais 50% e 90% (CL50 e CL90). Para fêmeas parcialmente ingurgitadas somente foram observados peso da massa de ovos, tempo de sobrevivência, CL50 e CL90. Todos os parâmetros biológicos de fêmeas ingurgitadas foram e parcialmente ingurgitadas foram alterados pela exposição a juvenis infectivos de S. carpocapsae linhagens Santa Rosa e ALL (P