Susceptibility of Grapholita molesta to insecticides in Brazil / Suscetibilidade de Grapholita molesta a inseticidas no Brasil

ABSTRACT: The use of insecticides has been the main tool for Grapholita molesta (Busck) control in Brazil, which is considered one of the most important pests in apple and peach orchards. In order to implement an Insect Resistance Management (IRM) program, studies were conducted to characterize the baseline susceptibility of G. molesta to major insecticides for its control. Then, we conducted an insecticide susceptibility monitoring in thirteen field-collected populations of the pest. Neonates (0-24h old) were exposed to insecticides applied on surface of artificial diet. A high susceptibility was verified when neonates of the Laboratory population of G. molesta were exposed to insecticides with LC50 values (µg a.i./cm2) of 0.1 (spinetoram), 1.0 (metaflumizone), 1.2 (chlorantraniliprole), 4.8 (novaluron), 5.1 (tebufenozide), 11.3 (phosmet) and 222.5 (pyriproxyfen). Based on the LC99 (µg a.i./cm2), the diagnostic concentrations of 0.6 (spinetoram), 5.5 (metaflumizone), 5.6 (chlorantraniliprole), 19.6 (tebufenozide), 37.4 (phosmet), 37.8 (novaluron) and 2011 pyriproxyfen) caused high mortality (>95%) of neonates from field populations. These diagnostic concentrations will be used in resistance monitoring programs of G. molesta in Brazil.

RESUMO: O uso de inseticidas tem sido a principal ferramenta para o controle da Grapholita molesta (Busck) no Brasil, considerada uma das mais importantes pragas em pomares de macieira e pessegueiro. Para implementar um programa de Manejo de Resistência a Insetos (MRI), estudos foram conduzidos para estabelecer uma linha básica de suscetibilidade de G. molesta a inseticidas utilizados para o seu controle. Posteriormente, foi realizado o monitoramento da suscetibilidade a inseticidas em treze populações da praga provenientes do campo. Lagartas (0-24 horas de idade) foram expostas a inseticidas aplicados na superfície da dieta artificial. Verificou-se alta suscetibilidade de lagartas neonatas de G. molesta (população de laboratório) quando foram expostas aos inseticidas, com valores de CL50 (µg i.a./cm2) de 0,1 (espinetoram), 1,0 (metoxifenozida), 1,2 (clorantraniliprole), 4,8 (novaluron), 5,1 (tebufenozida), 11,3 (fosmete) e 222,5 (piriproxifem). Com base na CL99 (µg i.a./cm2), as concentrações diagnósticas de 0,6 (espinetoram), 5,5 (metaflumizona), 5,6 (clorantraniliprole), 19,6 (tebufenozida), 37,4 (fosmete), 37,8 (novaluron) e 2.011 (piriproxifem) ocasionaram alta mortalidade (> 95%) de neonatas provenientes de populações de campo. Essas concentrações diagnósticas poderão ser utilizadas em programas de monitoramento da resistência de G. molesta no Brasil.

Potencial inseticida de óleos de origem vegetal sobre Grapholita molesta (Busck) (Lepidoptera: Tortricidae) / Insecticidal potential of vegetable oil extracts on Grapholita molesta (Busck) (Lepidoptera: Tortricidae)

Em decorrência do estudo das interações químicas entre insetos e herbívoros, e do avanço da pesquisa fitoquímica, é conhecida ampla variedade de produtos naturais com potencial inseticida. Grapholita molesta (Busck) (Lepidoptera: Tortricidae), mariposa-oriental, é uma das principais pragas do pessegueiro, danificando brotações e frutos. O objetivo do presente estudo foi verificar a mortalidade, atratividade e deterrência de óleos vegetais em G. molesta. Ovos e pupas de insetos provindos de criação artificial foram imersos nos óleos essenciais de Elionurus muticus (Spreng.) Kuntze e Cymbopogon winterianus Jowitt ex Bor nas concentrações de 0,25%, 0,5%, 1% e 0,5%, 1%, 5%. Os testes de atratividade foram realizados em olfatômetro do tipo "Y". A deterrência à oviposição foi testada em gaiolas sem escolha e de dupla escolha. O óleo de E. muticus aplicado em ovos de G. molesta nas três concentrações causou mortalidades maiores que 30%, diferindo significativamente dos controles (p<0,05). A mortalidade causada pelo óleo de citronela foi em torno de 70%, significativamente superior ao controle (p<0,01). O óleo de citronela aplicado a 1% em pupas causou mortalidade de 99,8%. No teste com o olfatômetro, não houve atratividade dos adultos para nenhum dos óleos. A média de ovos no substrato com o tratamento (0,33±0,33), foi significativamente menor que no controle (7,3±0,88) (p<0,01), indicando deterrência à oviposição.

As a result of the study on the chemical interactions between insects and herbivores and the advancement of phytochemical research studies, a variety of natural products with great insecticidal potential are described in the literature. The Grapholita molesta (Busck) (Lepidoptera: Tortricidae), commonly known as Oriental Fruit Moth, is a major peach pest damaging shoots and fruits. The purpose of this study was to assess the mortality, attractiveness and deterrence of vegetable oils in G. molesta. Insect eggs and pupae artificially created were immersed in the essential oils of Elionurus muticus (Spreng.) Kuntze and/or Cymbopogon winterianus Jowitt ex Bor at the concentrations of 0.25%, 0.5%, 1% and 0.5%, 1%, 5%, respectively. The attractiveness tests were performed in a Y-Tube olfactometer. Oviposition deterrence was tested in no-choice and dual-choice cages. Oil of E. muticus applied in eggs of G. molesta at three concentrations caused mortality above 30%, which differs significantly from controls (p<0.05). Mortality caused by citronella oil was approximately 70%, significantly higher than control (p<0.01). The application of citronella oil at 1% in pupae caused mortality of 99.8%. There was no attractiveness of adults in the olfactometer test for any of the oils. Citronella oil presented oviposition deterrence, as the mean number of eggs in the substrate with the treatment (0.33 ± 0.33) is significantly lower than in the control (7.3 ± 0.88) (p<0.01).

Age and multiple mating effects on reproductive success of Grapholita molesta (Busck) (Lepidoptera, Tortricidae) / Efeito da idade e de múltiplos acasalamentos no sucesso reprodutivo de Grapholita molesta (Busck) (Lepidoptera, Tortricidae)

The reproductive success of the oriental peach moth was evaluated in four experiments: 1) assessment of the mating duration, fecundity, fertility and longevity of females paired with virgin and immediately mated males; 2) mating duration, spermatophore size, fecundity, fertility and longevity in females paired with virgin and up to four times mated males; 3) receptivity of females to additional copulations after mating with virgin or mated males, and the effects of this behavior in female fecundity, fertility and longevity; 4) influence of insects age in the reproductive output. Males (33%) could copulate immediately after a previous copula. They were fertile until the fourth mating, but only in the first copula they transferred the longest (1.43 ± 0.10 mm) and widest (0.83 ± 0.11 mm) spermatophore, presenting the fastest mating duration (34.8 ± 2.62 min). A high proportion of females copulated by non-virgin males (84%) was receptive to other copulas, in comparison to those copulated by virgin males (32.4%). However, the fecundity, fertility, and longevity were similar among females that copulate once or more. The age was the most important factor affecting reproductive variables, where one and three day old insects had a significant higher fecundity, fertility and presented a shorter mating duration in comparison with older individuals. Results pointed out that the reproductive capacity of Grapholita molesta changes a little with respect to the analyzed factors, highlighting the elevated biotic potential of the species.

O sucesso reprodutivo da mariposa-oriental foi avaliado em quatro bioensaios: 1) avaliação do tempo de cópula, fecundidade, fertilidade e longevidade de fêmeas pareadas com machos virgens e imediatamente acasalados; 2) tempo de cópula, tamanho do espermatóforo, fecundidade, fertilidade e longevidade em fêmeas pareadas com machos virgens e acasalados até quatro vezes; 3) receptividade de fêmeas a cópulas adicionais após o acasalamento com machos virgens ou acasalados, e o efeito deste comportamento na fecundidade, fertilidade e longevidade das fêmeas; 4) influência da idade dos insetos no sucesso reprodutivo. Machos (33%) foram capazes de copular logo após o primeiro acasalamento. Os machos foram igualmente férteis até o quarto acasalamento, mas somente na primeira cópula transferiram espermatóforo com maior comprimento (1,43 ± 0,10 mm) e na largura (0,83 ± 0,11 mm), e apresentaram cópula de menor duração (34,8 ± 2,62 min). Uma maior proporção de fêmeas copuladas por machos não virgens (84%) foram receptivas a novos acasalamentos em comparação as pareadas com virgens (32,4%). No entanto, a fecundidade, fertilidade e longevidade foram semelhantes entre as fêmeas que copularam uma ou várias vezes. A idade foi o fator que mais afetou as variáveis reprodutivas, onde insetos de um e três dias de idade foram significativamente mais fecundos, férteis e apresentaram menor tempo de cópula que os mais velhos. Os resultados apontam que a capacidade de reprodução de G. molesta altera-se pouco com relação aos fatores analisados, ressaltando assim, elevado potencial biótico da espécie.

Oviposition behavior of Grapholita molesta Busck (Lepidoptera: Tortricidae) at different temperatures

Cultivation of temperate-climate fruits is economically important for Brazil. Grapholita molesta Busck is a pest that causes damage to apples, peaches, plums, and pears growing in different micro-regions of southern Brazil, and understanding its reproductive behavior is essential to develop control strategies. The objective of this study was to ascertain the influence of different temperatures (13, 16, 19, 22, and 25ºC) on the oviposition behavior of G. molesta. Females of G. molesta were placed in individual plastic containers, and the pre-oviposition period and the number of eggs laid were assessed until adult death. Temperature influenced the pre-oviposition period, and females kept at 22º were the first to lay their eggs. Oviposition occurred over a longer period of time at 13ºC than at the higher temperatures. The highest total number of eggs was obtained at 19ºC, with the mean daily oviposition being directly proportional to the temperature. There was a negative interaction between the pre-oviposition period and the total number of eggs laid by females. The most suitable temperature for oviposition of G. molesta was 19ºC.

Efeito de fatores endógenos na percepção química de Grapholita molesta(Busck) (Lepidoptera: Tortricidae) ao feromônio sexual / Effect of endogenous factors on the chemical perception of Grapholita molesta (Busck) (Lepidoptera: Tortricidae) to sex pheromone

The oriental fruit moth, Grapholita molesta (Busck), stands out as one of the most important pest in Rosaceae orchards in Brazil. During feeding, caterpillars bore into shoots, branches and fruits, impairing the commercial production. This work aimed to study the effect of endogenous factors in the chemical perception and in the species chemotactic behavior, seeking to optimize monitoring and the behavioral control of this pest. We evaluated male electroantennographical (EAG) and chemotactical (olfactometry) responses to the synthetic sex pheromone in different ages, virgins or mated and fed or unfed. The EAG responses of males did not differ for all evaluated factors. Nevertheless, the chemotactical behavior of males seems to decrease with age, not varying as a function of mating or feeding conditions. The knowledge about the interference of these factors in G. molesta may help with the interpretation of field results, allowing the development of suitable and reliable control measures based on infochemicals for behavioral control.

Controle de pragas do pessegueiro através do ensacamento dos frutos / Control peach crop pests by fruits bagging

Objetivou-se, no trabalho, buscar opções ao ensacamento de pêssegos, visando o controle eficiente das principais pragas do pessegueiro. Para isso, instalou-se um experimento em um pomar comercial de pêssego do cultivar Aurora 2, conduzido em sistema de vaso e espaçamento de 6 x 4 m. Os tratamentos foram os seguintes: T1 - Sacolas de TNT branco (45 g/m²) fechado, T2 - Sacolas de TNT branco (45 g/m²) aberto, T3 - Sacolas de TNT branco (20 g/m²) fechado; T4 - Sacolas de TNT branco (20 g/m²) aberto; T5 - Sacolas de polipropileno microperfurado transparente (furos de 1mm) fechado; T6 - Sacolas de polipropileno microperfurado transparente (furos de 1mm) aberto; T7 - Sacolas de polipropileno microperfurado transparente (furos de 2mm) fechado; T8 - Sacolas de polipropileno microperfurado transparente (furos de 2mm) aberto; T9 - Sacolas de polietileno microperfurado leitoso (furos de 1mm) fechado; T10 - Sacolas de polietileno microperfurado leitoso (furos de 1mm) aberto; T11 - Sacolas de polietileno microperfurado leitoso (furos de 2mm) fechado; T12 - Sacolas de polietileno microperfurado leitoso (furos de 2mm) aberto; T13 - Sacolas de papel impermeável fechado; T14 - Sacolas de papel impermeável aberto; T15 - Testemunha (sem ensacamento). De acordo com os resultados concluiu-se que todas as embalagens foram eficientes no controle de moscas-das-frutas e pássaros, porém não para mariposa oriental. As sacolas com abertura no fundo podem ser utilizadas como opção ao ensacamento de pêssegos.

Aiming to look for new options of peach bagging in the control of peach insect pests, an experiment was carried out in a treeyear-old peach crop. The cultivar Aurora 2 was accomplished in vase system with 6 m among rows and 4 m among plants. The treatments were: T1 - white and closed TNT (tissue non-tissue) bag (45g/m²), T2 - white and opened TNT bag (45g/m²), T3 - white and closed TNT bag (20g/m²), T4 - white and opened TNT bag (20g/m²), T5 - transparent polypropelene microperfurated and closed bag (1mm of diameter), T6 - transparent polypropelene microperfurated and opened bag (1mm of diameter), T7 - transparent polypropelene microperfurated and closed bags (2mm of diameter), T8 - transparent polypropelene microperfurated and opened bag (2mm of diameter), T9 - milky microperfurated polyetilene and closed bag (1mm of diameter), T10 - milky microperfurated polyetilene and opened bag (1mm of diameter), T11 - milky microperfurated polyetilene and closed bag (2mm of diameter), T12 - milky microperfurated polyetilene and opened bags (2mm of diameter), T13 - closed and waterproof paper bag, T14 - opened and waterproof paper bag, T15 - check treatment (unbagging fruits). According to the results, it may be concluded that all bags are efficient to control fruit flies and birds, but not the oriental fruit moth. The opened bags may be used in peach bagging.