César Freire Carvalho

Seletividade de Inseticidas a Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae)

The objective of this work was to evaluate the effect the insecticides endosulfan (1.05 g a.i./L), esfenvalerate (0.075 g a.i./L), fenpropathrin (0.09 g a.i./L), trichlorfon (0.09 g a.i./L) and triflumuron (0.0375 g a.i./L), used to control Alabama argillacea (Hubner), on eggs and larvae of Chrysoperla externa (Hagen), under greenhouse conditions. Egg viability, duration of the embryonic period and survival of first-instar larvae ecloded from treated eggs were evaluated. For first, second and third-instar larvae treated with the insecticides, subsequent survival of the larvae and pupae, as well as viability of the eggs produced by the emerged adults, were evaluated. The insecticides esfenvalerate and triflumuron caused a significant increase in the embryonic period of C. externa. Endosulfan, fenpropathrin, trichlorfon and triflumuron were highly toxic to larvae, with mortality rates ranging from 71% to 100%. Esfenvalerate caused only about 20% mortality of the first- and third-instar larvae and 38% of the second-instar larvae. Besides causing low larval mortality, esfenvalerate did not affect pupae survival or the reproductive capacity of the adults in the studied period, thus showing good potential for use in integrated pest management in cotton crops.

Toxicidade de produtos fitossanitários utilizados na cultura do cafeeiro a larvas de Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) e efeitos sobre as fases subseqüentes do desenvolvimento do predador

The objective was to evaluate the selectivity of pesticides used in coffee crops to larvae of Chrysoperla externa (Hagen) and their effects on the subsequent developmental stages of the predator. The treatments in g a.i./L of water were: 1 - endosulfan (Thiodan 350 CE - 1.75), 2 - chlorpyrifos (Lorsban 480 CE - 1.2), 3 - betacyfluthrin (Turbo 50 CE - 0.013), 4 - sulphur (Kumulus 800 PM - 4.0), 5 - azocyclotin (Peropal 250 PM - 0.31), 6 - copper oxichloride (Cuprogarb 500 PM - 5.0) and 7 - control (water). The products were sprayed on first, second and third-instar larvae using a Potters tower. The larvae were individualized in glass tubes and maintained at 25 ± 2oC, RH of 70 ± 10% and 12h photophase. The toxicity of the pesticides was calculated based in their total effect (E) and classified according to recommendations of IOBC. Chlorpyrifos and betacyfluthrin were harmful to first-instar larvae (E > 99%). Endosulfan, sulphur, azocyclotin and copper oxichloride were harmless to first-instar larvae and the others were selective. Chlorpyrifos was also toxic to second and third-instar larvae, and the other compounds were selective (E < 30%). None of the pesticides affected the duration and survival rate of pupae or the sex ratio of the adults originated from treated larvae. Endosulfan, sulphur, azocyclotin and copper oxichloride were harmless to the larval stage of C. externa and did not affect the subsequent stages, so that they can be recommended in IPM programs for the coffee crop.

Resposta funcional de Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) alimentada com Schizaphis graminum (Rondani) (Hemiptera: Aphididae)

The functional response of Chrysoperla externa (Hagen) fed on Schizaphis graminum (Rondani) was studied under five densities of prey. The experimental design was completely randomized with five treatments and ten replications. The tests were conducted in growth chambers at 25 ± 1oC, RH of 70 ± 10% and photophase of 12 hours. Consumption increased in function of prey density in all instars. However, consumption tended to stabilize when a pre established average density of prey was offered, except for the first instar, which showed a constant increase in aphid consumption. The duration of the first and third instars and of the larval phase, as a whole, increased in function of the increased availability of prey. The duration of the second instar, however, decreased in function of increased prey availability. The results for the 1st, 2nd and 3rd instars and the larval phase showed a Type II functional response. Handling and searching time was evaluated for the average density of offered prey. The lowest searching time was verified for second instar larvae while the first instar showed the highest searching and handling time. Handling time dimi-nished progressively with larvae development.

Seletividade de seis inseticidas utilizados em citros a pupas e adultos de Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae)

The selectivity of the insecticides abamectin, lufenuron, fenbutatin oxide, tebufenozide, thiacloprid and deltamethrin used in citrus crops was evaluated for pupae and adults of Chrysoperla externa (Hagen). The experiments were conducted in the Entomology Department of the Universidade Federal de Lavras, MG, Brazil. The spraying was accomplished by means of Potter tower with volume of application of 1.5 ± 0.5 mg/cm2. After spraying, the pupae were kept in test tubes in a climatic chamber and the adults in PVC cages in a room at 25 ± 2oC, 70 ± 10% RH and 12h photophase. A completely randomized experimental design was used, with six products and ten replicates, each one composed of three pupae or a pair of adults. The action of lufenuron on males or females of C. externa was also evaluated under a completely randomized design with three treatments and ten replicates, each one composed of one pair. The insecticides were classified following the method established by the International Organization for Biological and Integrated Control of Noxious Animals and Plants (IOBC). All compounds were selective to the pupae (E 99% of mortality), whereas fenbutatin oxide and tebufenozide were selective. Lufenuron reduced the survival rate of the egg when sprayed on the females. Thus, the results indicate that only fenbutatin oxide and tebufenozide could be used with C. externa in integrated pest management programs in citrus crops.

Biologia de Aphis gossypii Glover, 1877 (Hemiptera: Aphididae ) em abobrinha cultivar caserta (Cucurbita pepo L.) em diferentes temperaturas

As cucurbitaceas apresentam grande demanda no mercado mundial e uma das principais pragas que atacam essas culturas e o pulgao Aphis gossypii. Assim, objetivou-se estudar aspectos da biologia desse afideo em funcao da temperatura na cultivar de abobrinha Caserta (Cucurbita pepo L.). Utilizaram-se discos foliares (2,5cm de ∅) acondicionados, com a face abaxial para cima, em placas de Petri (5cm de ∅) contendo uma lâmina de agar-agua. Em cada placa foi deixada uma ninfa recem-nascida, acompanhandose o seu desenvolvimento ao longo de todo o ciclo de vida, em diferentes temperaturas (18, 21, 24, 27 e 30±1oC), 70±10% UR e fotofase de 12 horas. O delineamento foi inteiramente casualizado, com 60 repeticoes. Verificou-se que as temperaturas afetaram o desenvolvimento de A. gossypii. Menor duracao do periodo ninfal e maior producao diaria de ninfas foram observadas a 24 e 27oC. A temperatura de 30oC provocou efeito deleterio, causando 68% de mortalidade na fase ninfal.

Efeitos de inseticidas usados na cultura do algodoeiro sobre Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae)

The physiological action of the insecticides trichlorfon, triflumuron, endosulfan, fenpropathrin, chlorpiryfos, tebufenozide and esfenvalerate to 2nd-instar larvae of Chrysoperla externa (Hagen) and subsequent effects on 3rd-instar larvae, pupae and adults were evaluated. The bioassays were carried out under greenhouse conditions. The effect on larvae fed on eggs of Anagasta kuehniella (Zeller) treated with the insecticides was evaluated, as well as the contact effect on 2nd-instar larvae kept on sprayed cotton plants. The survival percentage of individuals in the second- and 3rd-instar and in the pupae stage was determined. For adults, the daily and total production of eggs during 30 days, the viability and the fertility of eggs were evaluated. Endosulfan, tebufenozide and esfenvalerate were selective to 2nd-instar larvae by contact on sprayed plants as well as by suction of treated eggs. For 3rd-instar larvae, neither endosulfan, tebufenozide, esfenvalerate nor triflumuron were harmful. The survival of pupae from treated 2nd-instar larvae with fenpropathrin and tebufenozide was not affected. Trichlorfon, fenpropathrin and tebufenozide caused no reduction in the total number of eggs produced by females derived from 2nd-instar larvae fed with treated eggs of A. kuehniella. Females originated from larvae that kept contact with sprayed cotton plants with esfenvalerate, had no significant reduction in the total egg production. Although tebufenozide affected the reproductive traits of C. externa, it can be recommended for controlling the pests on cotton crop in association with inundative releases of this predator.

Influência de Diferentes Dietas em Fases Imaturas de Ceraeochrysa cubana (Hagen) (Neuroptera: Chrysopidae)

Larval and pupal development of the predator Ceraeochrysa cubana (Hagen) on different diets was evaluated. Larvae (20/treatment), were reared in laboratory at 20 ± 2 oC, 70 ± 10 % RH and 12 hours photophase on the following diets; eggs of Anagasta kuehniella; Toxoptera sp.; Pinnaspis sp.; eggs of A. kuehniella + Toxoptera sp.; eggs of A. kuehniella + Pinnaspis sp.; Toxoptera sp. + Pinnaspis sp.; and eggs of A. kuehniella + Toxoptera sp. + Pinnaspis sp. In all treatments, larvae fed on A. kuehniella eggs, showed shorter larval and pupal duration, higher number of adults, with viability of 75, 70, 95 and 80 % for treatments eggs of A. kuehniella, eggs of A. kuehniella + Toxoptera sp.; eggs of A. kuehniella + Pinnaspis sp., respectively. The diets with Toxoptera sp., Pinnaspis sp. and eggs of Toxoptera sp. + Pinnaspis sp. were the least suitable for the development of the predator with viability as low as 0; 5; and 15 %, respectively.

Toxicidade de produtos fitossanitários utilizados em citros para Apis mellifera

The aim of this research was to evaluate the toxicity of several acaricides/insecticides used in Brazilian citrus crop to africanized workers of Apis mellifera Linnaeus. The exposition of honey bees to the chemicals was performed by direct spraying, contamination of food, and contact in treated surface (citrus leaves and Petri dishes), using recommended rates of application. The assays were carried out at 25±2°C, RH 70±10%, 12h of photophase and the data was statistically analyzed, with mean values of mortality being compared through cluster analysis. In all assays acephate was highly toxic, with mortality at 24 hours around 90.0%. When spirodiclofen and pyriproxyfen, was sprayed directly into the honeybees, they caused mortality levels of 11.0 and 15.0%, respectively; buprofezin, sulphur and tetradifon were less toxic, with mean mortality of 5.0% among these compounds. For the assays from contamination surface (citrus leaves and Petri dishes) and food, two groups of chemicals with the same toxic effects were observed, one with acephate and other with buprofezin, sulphur, spirodiclofen, pyriproxyfen, tetradifon and water. The average mortality after 96 hours of exposition was 31.0; 8.3 and 15.7%, respectively, for each method of contamination.

Eficiência de Chrysoperla externa (Hagen, 1861)(Neuroptera: Chrysopidae) no controle de Myzus persicae (Sulzer, 1776) (Hemiptera: Aphididae) em pimentão (Capsicum annum L.)

Avaliou-se a eficiencia de larvas de primeiro instar de Chrysoperla externa no controle Myzus persicae em pimentao, em experimentos realizados em câmara e sala climatizadas a 25 ± 1oC, UR de 70 ± 10% e fotofase de 12 horas. Larvas de C. externa recem-eclodidas foram liberadas em discos foliares, contendo 5; 10 ou 20 ninfas do afideo, acondicionados em placas de Petri. Em um segundo experimento, larvas do predador foram liberadas nas proporcoes 1:5, 1:10 e 1:20, em plantas inoculadas com 60; 100 e 140 ninfas do pulgao. O potencial predatorio de C. externa nos discos foliares foi influenciado pela densidade inicial do pulgao. A eficiencia do predador nas densidades de 5; 10 e 20 pulgoes foi de 100%; 96,7% e 79,3%, respectivamente. A eficiencia das larvas em eliminar as populacoes do pulgao nas plantas de pimentao variou em funcao do tempo. Na proporcao 1:5, a eliminacao das ninfas ocorreu entre um e dois dias apos a liberacao do predador, enquanto nas proporcoes 1:10 e 1:20 o periodo de quatro dias nao foi suficiente para que os pulgoes fossem eliminados. As larvas de C. externa quando liberadas nas tres proporcoes promoveram reducoes na populacao de M. persicae, se comparada a testemunha. No entanto, nas proporcoes 1:5 e 1:10 o predador se mostrou mais eficiente.

Aspectos biológicos de Chrysoperla externa (Hagen, 1861)(Neuroptera: Chrysopidae) em casa-de-vegetação

Objetivou-se estudar em casa-de-vegetacao alguns aspectos biologicos das fases imaturas e adulta de Chrysoperla externa (Hagen), alimentando suas larvas com ovos do piralideo Anagasta kuehniella (Zeller) e os adultos com dietas artificiais. O periodo embrionario foi determinado utilizando-se tubos de vidro de 2,5 x 8,5 cm, gaiola plastica transparente de 2,5 x 1,0 cm e tubo de pvc de 10,0 x 10,0 cm (com e sem umidificador). Os aspectos biologicos das fases de larva e pupa foram determinados confinando-as em tubos de vidro e gaiolas plasticas e os adultos em gaiolas de pvc de 10,0 x 10,0 cm, alimentando-os com levedo de cerveja + mel, extrato de soja + mel e polen + mel, nas consistencias semiliquida e pastosa. O periodo embrionario nao foi influenciado pelo tipo de recipiente, variando de 6,3 ± 0,2 a 7,6 ± 0,7 dias. Quando os ovos foram mantidos nas gaiolas plasticas, a viabilidade foi de 71,0%; contudo, naquelas de pvc e sem umidificador, obtiveram-se 88,0 ± 5,0%. A duracao do primeiro e segundo instares nao foi influenciada pelo tipo de recipiente; larvas de terceiro instar confinadas em tubos de vidro apresentaram uma duracao de 2,3 ± 0,1 dias e aquelas criadas em gaiolas plasticas de 1,6 ± 0,1 dias. A maior capacidade predatoria (2.630,0 ± 224,8 ovos) foi obtida para larvas de terceiro instar mantidas em tubos de vidro, constatando-se um consumo de 1.919,9 ± 151,6 ovos quando mantidas em gaiolas plasticas fixadas em folhas do algodoeiro. A duracao e a viabilidade dessa fase tambem nao foram influenciadas pelo tipo de recipiente de criacao, com uma variacao de 5,5 ± 0,4 a 6,1 ± 0,4 dias e 67,9 ± 3,9 a 74,4 ± 3,9%, respectivamente. A duracao e a viabilidade da fase de pupa nao foram afetadas pelo tipo de gaiola, constatando-se uma media de 13,5 ± 0,3 dias e 60% de pupas viaveis. Com relacao a fase adulta, verificou-se que a dieta constituida por levedo de cerveja + mel, na forma semiliquida ou pastosa, proporcionou os melhores resultados, obtendo-se uma fecundidade total de 387,8 ± 86,2 e 221,0 ± 41,4 ovos/femea, respectivamente. As femeas alimentadas com esse mesmo tipo de dieta na forma semiliquida foram as mais longevas, vivendo cerca de 45 dias.