Nematóides entomopatogênicos como controladores biológicos de cigarrinhas do gênero Mahanarva (Hemiptera: Cercopidae)

The spittlebugs belonging to the genus Mahanarva cause damage to the Poaceae family cultures, like signal grass, elephant grass and sugar cane, by the sap feeding on roots (immature phase) and leaves (adult phase). With the increase demand to reduce use of chemical insecticides for the insect pests’ control, comes the need to develop new control methods. In this scenario, the biological control gains highlight and in the spittlebugs case, the entomopathogenic nematodes (EPNs) are potential control agents, exploring the soil surface, the same pest environment while it feeds on roots. Thus, with the aim to know the EPNs’ action and to screening strains of these pathogens against the leaf spittlebug, Mahanarva spectabilis, and the root spittlebug, Mahanarva fimbriolata, experiments were conducted with various EPNs strains over different insect development phases. In two experiments M. spectabilis and M. fimbriolata nymphs were exposed to the pathogens, in laboratory and greenhouse conditions, and then were screened the more pathogenic strains to each pest species. Following, were evaluated the efficiency of four application methods of EPNs (pippeting, spray over nymphs with and without froth and infected host cadaver) over the leaf spittlebug, at greenhouse. At last, were evaluated the efficiency of an EPN species over eggs and adults of the leaf spittlebug. All tested strains are pathogenic to the spittlebugs nymphs causing 40-92% and 38-90% mortality at laboratory and 14-71% and 48-72% at greenhouse, to M. spectabilis and M. fimbriolata, respectively. The more efficient application methods were spray over nymphs with froth and infected host cadaver, with no difference because the concentrations and strains. Observations showed that don’t occurs eggs infection by EPNs in leaf spittlebugs. The leaf spittlebug adults not were infected by the EPNs, and no egg reduction were observed. The most pathogenic EPNs strains were Steinernema riobravis, S.feltiae and Heterorhabditis amazonensis RSC1 to M. spectabilis and S. feltiae, S. riobravis, H. baujardi LPP7 and S. carpocapsae to M. fimbriolata. Thus I conclude that entomopathogenic nematodes can be utilized to control Mahanarva genus spittlebugs, and can be inserted in integrated pest management programs, should to be applied over nymphs exclusively, sprayed over the froth or through infected host cadevers.As cigarrinhas do gênero Mahanarva causam danos às culturas da família Poaceae, como braquiária, capim-elefante e cana-de-açúcar, em função da sucção de seiva das raízes (fase imatura) e folhas (fase adulta). Com a crescente demanda de redução do uso de inseticidas químicos para o controle de insetos praga, surge a necessidade do desenvolvimento de novos métodos de controle. Nesse cenário, o controle biológico recebe destaque e no caso das cigarrinhas, os nematóides entomopatogênicos (NEPs) são potenciais agentes de controle, pois exploram a superfície do solo, mesmo ambiente da praga enquanto esta se alimenta nas raízes. Portanto, com o objetivo de conhecer a ação de NEPs e selecionar isolados desses patógenos contra a cigarrinha-das-pastagens, Mahanarva spectabilis, e a cigarrinha-dasraízes, Mahanarva fimbriolata, experimentos foram desenvolvidos com diversos isolados de NEPs sobre diferentes fases de desenvolvimento do inseto. Em dois experimentos ninfas de M. spectabilis e M. fimbriolata foram expostos aos patógenos, em condições de laboratório e casa-de-vegetação e a partir daí foram selecionados os isolados mais patogênicos para cada espécie de praga. Em seguida, avaliou-se a eficiência de quatro métodos de aplicação de NEPs (pipetador, pulverização sobre ninfas com e sem espuma e inseto-cadáver) sobre a cigarrinha-das-pastagens, em casa-de-vegetação. Por último, avaliou-se a eficiência de uma espécie de NEP sobre ovos e adultos da cigarrinha-das-pastagens. Todos os isolados testados são patogênicos às ninfas das cigarrinhas causando mortalidade de 40 a 92% e 38 a 90% em condições de laboratório e 14 a 71% e 48 a 72% em casa-de-vegetação, para M. spectabilis e M. fimbriolata, respectivamente. Os métodos de aplicação mais eficientes foram o de pulverização sobre ninfas com espuma e inseto-cadáver, não havendo diferença na eficiência provocada pelas concentrações e isolados utilizados. Observou-se que não ocorre infecção de NEPs sobre ovos de cigarrinha-das-pastagens. Os adultos da cigarrinha não foram infectados pelos NEPs, e não houve redução no número de ovos em função da presença do patógeno. Dos isolados testados, os mais eficientes foram Steinernema riobravis, S.feltiae e Heterorhabditis amazonensis RSC1 para M. spectabilis e S. feltiae, S. riobravis, H. baujardi LPP7 e S. carpocapsae para M. fimbriolata. Conclui-se portanto que nematóides entomopatogênicos podem ser utilizados no controle de cigarrinhas do gênero Mahanarva, sendo incluídos em programas de manejo integrado, devendo ser empregados contra as ninfas, pulverizados sobre a espuma ou através de inseto-cadáver

Sirex noctilio (Hymenoptera: Siricidae) e seus inimigos naturais em Pinus taeda e caracterização morfológica de Deladenus siricidicola

Espécies de pínus são plantadas em vários países e a área plantada no Brasil ocupa atualmente 1.562.782 hectares. O Estado de São Paulo possui 144.802 ha de pínus plantado e junto com os estados da região Sul do país possuem 94% da área brasileira. A principal praga dessa cultura é a vespa-damadeira Sirex noctilio (Hymenoptera: Siricidae) e está presente em mais de 1.000.000 ha no país. A utilização de métodos silviculturais e controle biológico auxiliam no controle dessa praga. No Brasil ela é considerada sob controle, com relatos esporádicos de surtos. Sendo assim, é importante prever a dispersão e ocorrência de novos surtos da praga para manter sua população controlada. Os objetivos do presente trabalho foram desenvolver uma ferramenta para definir a susceptibilidade de talhões à ocorrência da praga; verificar o controle proporcionado pelos principais inimigos naturais da vespa-da-madeira; e caracterizar morfologicamente a população de Deladenus (=Beddingia) siricidicola presente no Brasil através de microscopia eletrônica de varredura e microscopia ótica. Verificou-se que a metodologia de atribuição de níveis de risco de ocorrência da vespa-da-madeira poderá ser adotada como ferramenta para auxiliar o gerenciamento dos povoamentos de pínus em relação à ocorrência da praga, já que os níveis de risco atribuídos e o ataque efetivamente observados apresentaram relação direta (r=0,5127). A partir dessa metodologia foi desenvolvido uma planilha eletrônica no qual o usuário pode preencher os dados dos talhões de pínus plantado e o nível de risco é calculado automaticamente. Constatouse que o parasitoide I. leucospoides está bem estabelecido na região estudada e proporciona nível de controle em torno de 40% em talhões onde o nematoide não foi aplicado. O nematoide não apresentou alto índice de parasitismo, possivelmente em função da baixa ocorrência da vespa-da-madeira, provocada ...Pine species are planted in various countries and the current area occupied by this crop in Brazil is 1.562.782 hectares. São Paulo State has 144.802 ha of pine stands and in addition to the southern States, they have 94% of the Brazilian area occupied with pine. This crop’s main pest is the sirex woodwasp Sirex noctilio (Hymenoptera: Siricidae) which is present in more than 1,000,000 ha in the country. The employment of silvicultural and biological control methods help in monitoring and controlling such pest and allow to keep it under control, with some outbreaks reported occasionally. This way, the need is to predict the pest’s spread and occurrence. Therefore, the objectives in this thesis were develop a tool to define the susceptible of pine stands to the occurrence of the pest; verify the control promoted by the sirex woodwasp’s main natural enemies; and morphologically characterize the population of Deladenus (=Beddingia) siricidicola present in Brazil using scanning electron microscopy and optical microscopy. We verified the risk-level prediction methodology can be used as a tool to assist the management of the pine stands in relation to the pest’s occurence, as the risk-levels attributed and the effectively observed attack presented direct relation (r=0,5127). From this methodology an electronic sheet was developed, in which the user can fill with pine stands data and the risk-level is automatically calculated. We observed that the parasitoid I. leucospoides is well established in the region studied as it promotes a control level around 40% in stands where the nematode was not applied. The nematode didnnot presented a high parasitism, possibly due to the low occurrence of the sirex woodwasp, promoted by the control measures in previous years. Beside this, it was presented morphometric data of the population of D. siricidicola present in Brazil, highlighting some morphological traits not described before, such as the ..

Virulence of entomopathogenic nematodes (Rhabditida: Steinernematidae, Heterorhabditidae) to spittlebug Mahanarva spectabilis (Hemiptera: Cercopidae)

The spittlebug can seriously limit the production of forage, and the use of chemical products to control insect pests is costly and can harm the environment. Thus, there is a need to reduce the reliance on chemical agents by developing new strategies. The virulence of nine strains of entomopathogenic nematodes (EPNs) to spittlebugs was investigated under laboratory and greenhouse conditions. Fourth/fifth-instar nymphs of Mahanarva spectabilis were exposed to EPNs in the laboratory and the most virulent strains were applied on the nymphs in the greenhouse at concentrations of 2,000 and 4,000 EPNs/mL. The efficacy of the pathogenic agent was confirmed by the dissection of dead hosts. All the tested strains were pathogenic to the M. spectabilis nymphs in laboratory, particularly Steinernema carpocapsae, S. feltiae, S. riobraveand Heterorhabditis amazonensisRSC1, each of which caused nymph mortality higher than 80%. The concentration did not influence the efficiency of the strains, and those selected in the laboratory had similar efficiency in the greenhouse, except for S. carpocapsae, which was not as effective as the others. Entomopathogenic nematodes can be included in integrated pest management programs to M. spectabilis

Virulence of entomopathogenic nematodes (Rhabditida: Steinernematidae, Heterorhabditidae) to spittlebug Mahanarva spectabilis (Hemiptera: Cercopidae)

A cigarrinha-das-pastagens pode causar sérias limitações na produção de forragens, e o uso de produtos químicos para o controle é caro, além de poder prejudicar o ambiente. Então, existe a necessidade de reduzir o uso de agentes químicos através do desenvolvimento de novas estratégias de controle dessa praga. A virulência de nove isolados de nematoides entomopatogênicos (NEPs) sobre a cigarrinha-das-pastagens foi avaliada em condições de laboratório e casa-de-vegetação. Ninfas de quarto/quinto ínstar de Mahanarva spectabilis foram expostas aos isolados de NEPs em laboratório, e os mais virulentos foram aplicados sobre as ninfas em casa-de-vegetação sob as concentrações de 2000 e 4000 JIs/mL. A eficácia do agente patogênico foi confirmada pela dissecação dos hospedeiros mortos. Todos os isolados testados foram patogênicos às ninfas da cigarrinha-das-pastagens em laboratório, particularmente Steinernema carpocapsae, S. feltiae, S. riobrave e Heterorhabditis amazonensis RSC1, cada um deles causando mortalidade maior que 80%. A concentração não influenciou a eficiência, exceto para S. carpocapsae, o qual não foi tão efetivo como os demais em casa-de-vegetação. Nematoides entomopatogênicos podem ser incluídos em programas de manejo integrado de M. spectabilis.The spittlebug can seriously limit the production of forage, and the use of chemical products to control insect pests is costly and can harm the environment. Thus, there is a need to reduce the reliance on chemical agents by developing new strategies. The virulence of nine strains of entomopathogenic nematodes (EPNs) to spittlebugs was investigated under laboratory and greenhouse conditions. Fourth/fifth-instar nymphs of Mahanarva spectabilis were exposed to EPNs in the laboratory and the most virulent strains were applied on the nymphs in the greenhouse at concentrations of 2,000 and 4,000 EPNs/mL. The efficacy of the pathogenic agent was confirmed by the dissection of dead hosts. All the tested strains were pathogenic to the M. spectabilis nymphs in laboratory, particularly Steinernema carpocapsae, S. feltiae, S. riobrave and Heterorhabditis amazonensis RSC1, each of which caused nymph mortality higher than 80%. The concentration did not influence the efficiency of the strains, and those selected in the laboratory had similar efficiency in the greenhouse, except for S. carpocapsae, which was not as effective as the others. Entomopathogenic nematodes can be included in integrated pest management programs to M. spectabilis

Heterorhabditis bacteriophora (Rhabditida: Heterorhabditidae) HP88 for biological control of Rhipicephalus microplus (Acari: Ixodidae): The effect of different exposure times of engorged females to the nematodes

AbstractThe aim of this study was to assess the influence of different exposure times of engorged female the Rhipicephalus microplus to infective juveniles of Heterorhabditis bacteriophora isolate HP88. The engorged females were divided into seven groups (six treatments and one control) of 20 ticks each with statistically similar average weights (p>0.05) and exposed to concentrations of 300 nematodes/tick for periods of 3, 6, 12, 24, 48 and 72h. The following biological parameters were monitored: pre-oviposition period; egg mass weight; hatching percentage; and efficacy of treatment. There was no influence of the exposure time on the pre-oviposition period (p>0.05), while there were significant differences (p<0.05) between the groups exposed for 24, 48 and 72h and the control group with respect to the egg mass weight, and 24h for hatching percentage. Treatment efficacy reached 100% after exposure for 48 and 72h. These results demonstrate that infective juveniles of H. bacteriophora HP88, under laboratory conditions, interfere in the majority of the biological parameters of the non-parasitic phase of engorged R. microplus females when the exposure time is greater than or equal to 24h

Spray Nozzles, Pressures, Additives and Stirring Time on Viability and Pathogenicity of Entomopathogenic Nematodes (Nematoda: Rhabditida) for Greenhouses

The objective of this study was to evaluate different strategies for the application of entomopathogenic nematodes (EPN). Three different models of spray nozzles with air induction (AI 11003, TTI 11003 and AD-IA 11004), three spray pressures (207, 413 and 720 kPa), four different additives for tank mixtures (cane molasses, mineral oil, vegetable oil and glycerin) and the influence of tank mixture stirring time were all evaluated for their effect on EPN (Steinernema feltiae) viability and pathogenicity. The different nozzles, at pressures of up to 620 kPa, were found to be compatible with S. feltiae. Vegetable oil, mineral oil and molasses were found to be compatible adjuvants for S. feltiae, and stirring in a motorized backpack sprayer for 30 minutes did not impact the viability or pathogenicity of this nematode. Appropriate techniques for the application of nematodes with backpack sprayers are discussed. © 2013 Moreira et al

Compatibility of spray with different adjuvants on viability and pathogenicity of <i>Steinernema feltiae</i>.

<p>Compatibility of spray with different adjuvants on viability and pathogenicity of <i>Steinernema feltiae</i>.</p

Viability (%) and pathogenicity (%) of infective juveniles of <i>Steinernema feltiae</i> subjected to different nozzles at different pressures in 2010.

1<p>Spray not subjected to pressurization; averages followed by the same uppercase letters in columns and lowercase letters in lines are not different according to Tukey test results (P≤0.01).</p>*<p>Original pathogenicity data were transformed into √ <i>x</i>+0.5.</p

Viability (%) and pathogenicity (%) of infective juveniles of <i>Steinernema feltiae</i> subjected to different nozzles at different pressures in 2011.

1<p>Spray not subjected to pressurization; averages followed by the same uppercase letters in columns and lowercase letters in lines are not different according to Tukey test results (P≤0.01).</p>*<p>Original pathogenicity data were transformed into √ <i>x</i>+0.5.</p