Search

Abroca-da-cana, Diatraea saccharalis, é considerada a principal praga da cana-de-açúcar, causando prejuízos de maneira direta e indireta. Entre os danos diretos, devido à abertura de galerias no interior do colmo da planta pela lagarta, podemos citar a redução da translocação de seiva e a quebra e perda de peso de colmos.

Helicoverpa armigera (Hubner, 1805) (Lepidoptera: Noctuidae) is an insect pest that attacks several cultures and has been a cause of concern in Brazil. The objective of this study was to evaluate parasitism in pupae and caterpillars of H. armigera by Tetrastichus howardi (Olliff, 1893) (Hymenoptera: Eulophidae), in laboratory, as well as checking if T. howardi parasitoid has the ability to locate and infect H. armigera. In the laboratory, pupae of H. armigera and Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae) were exposed to 15 T. howardi females for 24 hours. Third, fourth and fifth instars of H. armigera were exposed to three T. howardi females for 24 hours. In the field experiment, cages were installed. Ten caterpillars of the fifth instar of H. armigera were released in each cage and waited for the necessary period for them to soak in the soil. After this period, 150 T. howardi females were released in each of four cages and in one cage there was no release of parasitoids. In the laboratory, the percentage of parasitized and emergent pupae was 100% in both hosts. The life cycle of T. howardi in H. armigera pupae was 15 days, and for D. saccharalis it was 16 days. The progeny was significantly larger for the host H. armigera (689.00) compared to D. saccharalis (358.27). The sex ratio was 0.91 and 0.87 for H. armigera and D. saccharalis, respectively. The longevity of males (25.60 days) and females (26.95 days) in the treatment with H. armigera differed from the treatment with D. saccharalis, which was 21.70 days for males and 22.95 days for females. For the experiment with H. armigera caterpillars, it was found that only two caterpillars from the fifth instar were parasitized with emergence of parasitoids in the pupal phase, with a progeny of 81 individuals; egg-adult cycle was 19.5 days; sex ratio of 0.88; male longevity was 19.6 days and for females 20.3 days. Despite the high rate of parasitism of T. howardi in H. armigera pupae in the laboratory, the same did not occur for caterpillars. In the field evaluation, of the total of 50 caterpillars released in the cages, 34 pupae were collected. Of these, 31 pupae had emergence of the H. armigera moth. No parasitism by T. howardi was found in H. armigera pupae. Further studies should be conducted to evaluate T. howardi parasitism in H. armigera pupae under field conditions.

Made available in DSpace on 2019-11-20T00:43:18Z (GMT). No. of bitstreams: 1 36923.pdf: 340862 bytes, checksum: d6899b07800ae1ba982c852474293a4b (MD5) Previous issue date: 2019

Managing Helicoverpa armigera is still a major challenge for Brazilian farmers, due to limited information available about chemicals and biological control of this pest in Brazil. This study focused on evaluating the biological aspects of Podisus nigrispinus fed with H. armigera, under laboratory conditions, as well as verifying the capacity of the P. nigrispinus in preying on caterpillars of H. armigera in the field, in soybean crops. The experiments were conducted in laboratory under controlled temperature conditions of 25±2 ºC, relative humidity (RH) 60±10% and 14-hour photophase, as well as in the field, at the experimental station of Fundação MS in Maracaju, MS. In the laboratory, second instar nymphs of P. nigrispinus were placed in plastic jars and fed with H. armigera larvae or Tenebrio molitor larvae throughout the nymphal phase. When they reach adulthood, 15 couples were formed, remaining with the same prey of the previous phase. For the field trial, soybean plants were caged, and inside these cages were released eight quarter-instar H. armigera caterpillars. Subsequently, in each cage were released an adult female or a fifth instar nymph, and after 24 hours, the number of prey caterpillars were assessed. Predator nymphal duration was shorter in treatment with H. armigera than with T. molitor. Nymphal viability was similar between treatments. Adult females and males fed with H. armigera presented greater body mass than those fed with T. molitor. The number of postures per female and the number of eggs per female were similar between treatments. The incubation period of eggs was longer for treatment with H. armigera, differing statistically from treatment with T. molitor. Eggs from treatment with H. armigera showed similar viability to treatment with T. molitor, not differing statistically. Females and males under treatment with H. armigera showed longer longevity compared to treatment with T. molitor. Adult females preyed on average 2.26 caterpillars within 24 hours and fifth instar nymphs preyed on 1.73 caterpillars/day. P. nigrispinus showed better development when fed with H. armigera, demonstrating that it can be used as an alternative host for breeding this predator. The predator showed satisfactory performance for predation rate/day. Release of fifth instar nymphs and adult females of P. nigrispinus may reduce the pest population in relation to the absence of the predator under field conditions, an important alternative to be used in H. armigera integrated management programs.

Made available in DSpace on 2018-07-08T00:39:20Z (GMT). No. of bitstreams: 1 RevistaPlantiodireto1.pdf: 2211360 bytes, checksum: 9ec553e801551e38846c9e2164b9e0eb (MD5) Previous issue date: 2018-06-22

Herbicides and plant growth regulators are often used in sugarcane management. However, the use of non-selective pesticides can cause adverse effects on the efficiency of beneficial insects in integrated pest management. Within this context, this study aimed to evaluate the effect of such products on the immature stages of the parasitoid Trichogramma galloi. Eggs of Diatraea saccharalis containing the parasitoid at the egg-larva stage and at the prepupal and pupal stages were immersed in test solutions of the following pesticides (maximum recommended doses for sugarcane): herbicides clomazone and diuron + hexazinone, and plant growth regulators trinexapac-ethyl and sulfometuron-methyl. The biological properties evaluated were emergence (F1 and F2) and number of eggs parasitized by T. galloi (F1). The products were classified according to percentage of reduction in emergence and parasitism: harmless (99%). The pesticides evaluated were considered to be harmless or slightly harmful to immature T. galloi and, thus, their use should be preferred for preserving this parasitoid species in sugarcane management programs.

Resumo. Durante o manejo da cultura da cana-de-acucar sao utilizados diversos produtos fitossanitarios que podem afetar o desempenho de parasitoides, inimigos naturais da broca-da-cana, Diatraea saccharalis (Fabricius) e consequentemente, o controle biologico da mesma. Assim, objetivou-se avaliar em laboratorio o efeito de herbicidas e reguladores de crescimento de plantas utilizados na cultura da cana-de-acucar, sobre a sobrevivencia, e parasitismo de adultos do parasitoide de ovos Trichogramma galloi Zucchi , assim como sobre a emergencia do parasitoide (F1). Os produtos testados foram: Clomazone, Diuron + Hexazinone (herbicidas); Sulfometuron-methyl e Trinexapac-ethyl (reguladores de crescimento de plantas) nas maiores doses recomendadas a cultura. Ovos de D. saccharalis foram imersos durante 5 segundos em uma das caldas quimicas e, apos secos por 1 hora, oferecidos as femeas de T. galloi, totalizando 20 repeticoes . Avaliou-se a mortalidade e o numero de ovos parasitados pela geracao F0, assim como, a emergencia da geracao F1 de T. galloi , sendo os produtos classificados quanto a toxicidade, conforme percentual de reducao da sobrevivencia, parasitismo e emergencia do parasitoide. Em relacao a sobrevivencia de T. galloi , numero de ovos parasitados pela F0 e a emergencia da F1, Clomazone e Trinexapac-ethyl foram classificados como levemente prejudicais. Diuron + Hexazinone e Sulfometuron-methyl foram inocuos em todos os parâmetros avaliados, com excecao do parasitismo, onde Diuron + Hexazinone foi classificado como levemente prejudicial. Conclui-se que, Clomazone, Diuron + Hexazinone, Trinexapac-ethyl e Sulfometuron-methyl sao inocuos ou levemente prejudiciais a sobrevivencia e parasitismo (F0) de adultos de T. galloi , e a emergencia (F1) desse parasitoide, em laboratorio. Herbicides and Plant Growth Regulators Used in SUGARCANE and their Action on Adult Trichogramma galloi Zucchi (Hymenoptera: Trichogrammatidae) Abstract. During crop sugarcane management, several used pesticides can affect the performance of parasitoids, natural enemies of sugarcane borer, Diatraea saccharallis (Fabricius) and consequently the biological control ofit . Thus, the objective was to evaluate in laboratory the effect of herbicides and plant growth regulators used in the sugarcane crops on survival and parasitism in adults of the eggs parasitoids, Trichogramma galloi Zucchi. The products tested were the herbicides Clomazone and Diuron + Hexazinone, and the plant regulators Sulfometuron-methyl and Trinexapac-ethyl, all in the higher recommended dosages for sugarcane. The eggs of D. saccharalis were immersed during 5 seconds in chemical solutions and, after dry for 1 hour, offered to T . galloi females with 20 repetitions. We evaluated the mortality and number of eggs parasitized by the F0 generation of T. galloi , as well as the emergence of the F1. The products were classified by their toxicity, according to the percentage of reduction in the survival, parasitism and emergence of the parasitoid. In relation to the survival of adult T. galloi , the number of eggs parasitized by F0 as well as the percentage of F1 emergence, clomazone and trinexapac-ethyl were classified as slightly harmful. Diuron+hexazinone and sulfometuron-methyl were harmless in all parameters, except for parasitism, where diuron+hexazinone was classified as slightly harmful. We conclude that clomazone, diuron+hexazinone, trinexapac-ethyl and sulfometuron-methyl, are harmless or slightly harmful the survival and parasitism (F0) of T. galloi adults and emergence (F1) of this parasitoid in the laboratory.

Helicoverpa armigera e uma praga recentemente identificada no Brasil ocasionando perdas significativas em varias culturas em varias regioes do pais. O controle biologico tem sido relatado como uma das alternativas promissoras para o manejo desta praga. O objetivo deste trabalho foi avaliar o parasitismo de pupas de H. armigera pelos parasitoides Tetrastichus howardi e Trichospilus diatraeae , em laboratorio. Pupas de H. armigera foram individualizadas e expostas ao parasitismo por 15 femeas de Trichospilus diatraeae ou por 15 femeas de Tetrastichus howardi , durante 24 h. Apos este periodo, as pupas permaneceram em observacao ate a emergencia dos parasitoides. As porcentagens de parasitismo de Tetrastichus howardi e Trichospilus diatraeae foram de 100%. Em relacao a emergencia, a porcentagem foi de 100% para Tetrastichus howardi e de 90% para Trichospilus diatraeae. O ciclo de vida de Tetrastichus howardi em pupas de H. armigera foi de 15,0 ± 0,0 dias, enquanto que Trichospilus diatraeae completou o desenvolvimento em 15,90 ± 0,10 dias. O numero de individuos de Tetrastichus howardi e Trichospilus diatraeae emergidos por pupa foi de 669,30 ± 33,47 e 816,11 ± 89,22, e razao sexual de 0,91 ± 0,01 e 0,94 ± 0,01, respectivamente. Os parasitoides Tetrastichus howardi e Trichospilus diatraeae parasitam com sucesso pupas de H. armigera em condicoes de laboratorio, demonstrando que esse pode ser um bom hospedeiro para criacao de ambos os parasitoides. Contudo, estudos mais detalhados da relacao parasitoide-hospedeiro sao necessarios para avaliar a viabilidade de inclusao desses parasitoides em programas de manejo integrados de H. armigera.