Resumen El objetivo de este trabajo fue evaluar el potencial de los nematodos entomopatógenos (NEPs) de los géneros Steinernema y Heterorhabditis en el control de Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae). Para esto, se realizaron ensayos de selección de aislamientos, se evaluó la susceptibilidad en diferentes instares del insecto, se analizaron las diferentes concentraciones de NEPs y la producción in vivo de estos aislados, y se realizaron pruebas en invernadero en el Laboratorio de Entomología y control biológico de la Universidade Estadual do Norte do Paraná, Brasil. En los ensayos de selección con nueve aislamientos, los que causan mayor porcentaje de mortalidad en los insectos, se utilizaron diferentes concentraciones (0, 50, 100, 150, 200 Juveniles Infectivos/cm2) sobre diferentes instares del insecto (2do, 3er, 4to, 5to, 6to instar y pupa), en la producción in vivo en larvas de A. ipsilon y en pruebas de patogenicidad en invernadero. En el ensayo de selección, el aislamiento CH3 (Steinernema sp.) causó el 100 % de la mortalidad en A. ipsilon mientras que los aislados GL (Heterorhabditis amazonensis), IBCB-n02 (S. carpocapsae) e IBCB-n05 (H. indica) causaron 90 % de mortalidad. En la prueba de concentraciones, el aislado IBCB-n02 presentó una CL99 de 140 IJs/cm2 y el aislado IBCB-n05, una CL99 de 190 IJs/cm2. Las larvas de 3er y 4to instares fueron más susceptibles. En la prueba in vivo para la producción de larvas de A. ipsilon, no se observó diferencia entre los dos aislamientos. En el ensayo en invernadero, el aislado IBCB-n02 fue el único que difirió del tratamiento de control.

Abstract This work aims to evaluate the potential of Brazilian isolates of entomopathogenic nematodes through the selection of isolates for Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae). In order to analyze the susceptibility at different instars of the insect and different concentrations, to investigate the in vivo production of these isolates, and to perform greenhouse tests in the Laboratory of Entomologia e Controle Microbiano of Universidade Estadual do Norte do Paraná, Brazil. Selection tests were carried out with nine isolates, and those that caused greater percentages of insect mortality were used in concentration tests (0, 50, 100, 150, 200 Infective Juveniles (IJs)/cm2), with different instars of the insect (2nd, 3rd, 4th, 5th, 6th instars and pupa), in the in vivo production of A. ipsilon larvae, and in pathogenicity tests in a greenhouse. In the selection test, the isolate CH3 (Steinernema sp.) caused 100 % of mortality in A. ipsilon, and the isolates GL (Heterorhabditis amazonensis), IBCBn-02 (S. carpocapsae) and IBCB-n05 (H. indica) caused 90 % mortality. In the tests of different concentrations, the isolate IBCB-n02 had CL99 estimated at a concentration of 140 IJs/cm2, and the isolate IBCB-n05 had CL99 estimated at a concentration of 190 IJs/cm2. The most susceptible larval stages were the 3rd and 4th instars. In the in vivo test for production of A. ipsilon larvae, no difference was observed between the two isolates. In the greenhouse test, the isolate IBCB-n02 was the only one that differed from the control treatment.

Vários fatores devem ser considerados na avaliação da eficiência de um entomopatógeno no controle de um inseto-praga. Com relação aos nematóides entomopatogênicos, além da patogenicidade e virulência, é importante conhecer a capacidade de busca, pois quanto maior sua eficiência, maior a chance de encontro com o hospedeiro. Assim, neste trabalho, objetivou-se avaliar o deslocamento vertical de nematóides entomopatogênicos (Heterorhabditis), visando ao controle da cochonilha-da-raiz-do-cafeeiro Dysmicoccus texensis (Tinsley). Para avaliação em laboratório, foi feito teste em coluna de areia de 5 cm (em delineamento inteiramente casualizado) onde os isolados CCA e JPM3 foram aplicados em suspensão aquosa no topo da coluna em três concentrações (50, 100 e 500 JIs/inseto), com avaliação da mortalidade após 5 dias. No experimento de coluna de solo, foi usada uma coluna de 25 cm, composta por cinco extratos de 5 cm. Foram utilizados dois isolados (CCA e JPM3) e dois métodos de aplicação: cadáver infectado e suspensão aquosa, ambos avaliados nas diferentes profundidades. O experimento foi conduzido num delineamento fatorial 3x2x5, em condições de casa-de-vegetação. No experimento de coluna de areia, não houve diferença entre os isolados avaliados e ambos alcançaram valor de 92% de mortalidade. No experimento de deslocamento em coluna de solo, observou-se que JPM3 foi mais eficiente que CCA, nos dois métodos de aplicação avaliados. Quanto aos métodos de aplicação, o de suspensão aquosa apresentou melhores resultados para os dois isolados, e JPM3 aplicado em suspensão aquosa, foi o melhor tratamento em quase todas as profundidades avaliadas.

Many factors must be considered in evaluating the efficiency of an entomopathogen in the control of an insect pest. With regards to entomopathogenic nematodes, in addition to their pathogenicity and virulence, it is important to know the ability to search the host, which is directly linked with its efficiency. The objective of this study was to evaluate the vertical displacement of entomopathogenic nematodes (Heterorhabditis) to control the coffee root scale Dysmicoccus texensis (Tinsley). A test was conducted in a sand column of 5 cm depth under laboratory conditions, using a randomized design, with the strains CCA and JPM3 being applied in aqueous suspension at the top of the column in three concentrations (50, 100 and 500 IJs/insect), with evaluation of mortality after 5 days. It was also conducted an experiment in a 2x2x6 factorial design, at greenhouse conditions with a soil column of 30 cm depth, composed of six extracts of 5 cm. Two nematode strains (CCA and JPM3) and two methods of application (infected cadaver and aqueous suspension) were evaluated at different depths. There was no difference between the strains evaluated in the laboratory experiment, and both reached values of 92% mortality. In the experiment conducted at the greenhouse, it was observed that JPM3 was more efficient than CCA, at the two methods of application assessed. Regarding With application methods, aqueous suspension showed better results for both strains and JPM3 was the best treatment in almost all depths evaluated.