RESUMEN
The African planthopper Leptodelphax maculigera (Hemiptera: Delphacidae) has been recently reported in many places in Brazil in association with maize. Its occurrence in maize production fields in Brazil has brought concerns to the corn production chain regarding the possibility of this planthopper to be a vector for maize bushy stunt phytoplasma (MBSP), corn stunt spiroplasma (Spiroplasma kunkelii), maize rayado fino virus (MRFV) and maize striate mosaic virus (MSMV). The phytoplasma and spiroplasma, that are bacteria belonging to the Class Mollicutes, and the two viruses are associated with the corn stunt disease complex. Given the presence of the African planthopper species and the corn stunt disease complex in Brazil, we further investigated the abundance of this planthopper species in Santa Catarina state, Brazil, and whether the planthopper can carry the four pathogens. We inspected 12 maize production fields in different municipalities in the state for 20 weeks, using two yellow sticky traps for each maize field. The sticky traps were replaced weekly. A total of 130 specimens of L. maculigera were captured, with a great discrepancy in quantity among locations and weeks. We detected the mollicute MBSP, and the viruses MRFV and MSMV in L. maculigera, whereas S. kunkelii was absent in the assessed African planthopper samples. The molecular detection of the phytoplasma and the viruses in field-collected African planthoppers is a strong evidence that this insect species has the ability of acquiring those pathogens through feeding from phloem of diseased maize plants. Nonetheless, transmission capacity needs to be experimentally proven to assert L. maculigera as a vector for the corn stunting pathogens.
RESUMEN
This work aimed to evaluate the residual action of five insecticides on larvae and adults of the predators Chrysoperla externa (Hagen) and Eriopis connexa (Germar). The insecticides gamma-cyhalothrin, imidacloprid+beta-cyfluthrin, methomyl, thiamethoxam, and thiamethoxam+lambda-cyhalothrin were sprayed in pod bean plants until the point of runoff. Weekly, at 3, 10, 17, 24, and 31 days, first instar larvae and adults of both predators were exposed to leaves containing dry residues of the insecticides. Based on the mortality observed throughout the bioassays, the insecticides were classified according to the scale of the residual effects proposed by the International Organization for Biological and Integrated Control (IOBC). Except for thiamethoxam+lambda-cyhalothrin, which was moderately persistent (class 3) to larvae of C. externa and E. connexa, all other tested insecticides were persistent (class 4) to larvae of both species. Gamma-cyhalothrin, imidacloprid + beta-cyfluthrin, and methomyl were persistent (class 4) to C. externa adults, while thiamethoxam was moderately persistent (class 3) and thiamethoxam + lambda-cyhalothrin was slightly persistent (class 2) to the adult stage. As for E. connexa adults, imidacloprid + beta-cyfluthrin and methomyl were persistent (class 4) and gamma-cyhalothrin, thiamethoxam, and thiamethoxam + lambda-cyhalothrin were moderately persistent (class 3). Thus, due to extended residual effect, these insecticides must be avoided when larvae and adults of both predators are active in the crop.
Asunto(s)
Escarabajos , Insecticidas , Piretrinas , Animales , Insecticidas/toxicidad , Larva , Piretrinas/toxicidad , TiametoxamRESUMEN
This work aimed to evaluate the persistence (duration of harmful activity) of five insecticides used for pest control in peach orchards, on larvae and adults of the predator Chrysoperla externa. The insecticides were sprayed on cv. Bordô vine plants using the maximum dosage recommended for peach orchards. Weekly, at 3, 10, 17, 24 and 31 days after spraying, larvae and adults of the predator were exposed to treated leaves in order to assess the residual effect of insecticides on mortality and possible effects on reproduction. Given the toxicity observed along the weekly bioassays, the insecticides were classified into persistence categories established by the International Organization for Biological and Integrated Control of Noxious Animals and Plants (IOBC). High persistence was obtained for the organophosphorus insecticides (% of active ingredient) phosmet (0.100) and malathion (0.200), and both were considered persistent (> 30 days of harmful activity) to larvae and adults of C. externa. Similarly, the benzoylurea insecticide lufenuron (0.005), which acts exclusively on immature stages of insects, was persistent to larvae. Differences concerning the persistence for both development stages evaluated were observed for the pyrethroid insecticide deltamethrin (0.001), that was persistent to larvae but moderately persistent (16 30 days of harmful activity) to adults; and for the organophosphate fenthion (0.050) which was considered moderately persistent to larvae and short-lived (< 5 days of harmful activity) to adults of C. externa.(AU)
Este trabalho teve como objetivo avaliar a persistência (duração da atividade nociva) de cinco inseticidas utilizados no controle de pragas em pessegueiro, em larvas e adultos do predador Chrysoperla externa. Os inseticidas foram pulverizados em plantas de videira cv. Bordô utilizando-se a máxima dosagem recomendada para o pessegueiro. Semanalmente, aos 3, 10, 17, 24 e 31 dias após a pulverização, larvas e adultos do predador foram expostos a folhas pulverizadas para determinação do efeito residual dos inseticidas na mortalidade e possíveis efeitos na reprodução. Em função da toxicidade observada ao longo dos bioensaios semanais, os inseticidas foram classificados conforme a escala de persistência da International Organization for Biological and Integrated Control of Noxious Animals and Plants (IOBC). Alta persistência foi obtida para os inseticidas (% de ingrediente ativo) fosmete (0,100) e malationa (0,200), sendo ambos considerados persistentes (> 30 dias de ação nociva) para larvas e adultos de C. externa. De forma semelhante, o inseticida do grupo das benzoilureias, lufenurom (0,005), que age exclusivamente sobre estágios imaturos de insetos, foi persistente para larvas. Diferenças quanto a persistência para ambos os estágios avaliados foi observada para o inseticida piretroide deltametrina (0,001), que se mostrou persistente para larvas, porém moderadamente persistente (16 30 dias de ação nociva) para adultos; e para o organofosforado fentiona (0,050), que foi considerado moderadamente persistente para larvas e de vida curta (< 5 dias de ação nociva) para adultos de C. externa.(AU)
Asunto(s)
Control de Plagas , Prunus persica , Bioensayo , Control Biológico de Vectores , InsecticidasRESUMEN
Objetivou-se com este trabalho avaliar a seletividade de dezenove agrotóxicos utilizados na cultura do pessegueiro sobre ovos e pupas do predador Chrysoperla externa em condições laboratoriais (temperatura 25±1ºC, umidade relativa 70±10% e fotofase 14 horas). Os agrotóxicos foram pulverizados diretamente sobre ovos e pupas por meio de uma torre de Potter, utilizando a máxima dosagem recomendada para a cultura do pessegueiro. Foi avaliada a viabilidade de ovos e pupas, além da fecundidade e fertilidade de adultos emergidos de pupas tratadas. Os agrotóxicos foram classificados para ovos em função da redução na eclosão e, para pupas, em função do efeito total, conforme a escala de toxicidade proposta pela IOBC. A maioria dos agrotóxicos avaliados (8 inseticidas, 8 fungicidas e 2 herbicidas) se mostrou inócua (classe 1) a ovos e pupas, com redução na eclosão de larvas e efeito total em pupas inferiores a 30%. A exceção se deu para o inseticida óleo mineral, que reduziu a eclosão de larvas em 69,55% quando pulverizado em ovos e proporcionou efeito total em pupas de 36,22%, sendo classificado como levemente nocivo (classe 2) a ovos e pupas de C. externa .
This research aimed to evaluate the effect of nineteen pesticides used in peach orchards on eggs and pupae of the predator Chrysoperla externa in bioassays carried under laboratory conditions (temperature of 25±1ºC, relative humidity 70±10% and 14 hours photophase). The pesticides were directly sprayed on eggs and pupae trough a Potter tower using the maximum recommended dosage for peach orchards. It was evaluated eggs and pupae viability, in addition to fecundity and fertility of adults emerged from treated pupae. The pesticides were classified to eggs according to reduction in eggs hatch, and to pupae according to the total effect into IOBC toxicity categories. Most of pesticides evaluated (8 insecticides, 8 fungicides and 2 herbicides) were harmless (category 1) to eggs and pupae, with a reduction in eggs hatch and total effect to pupae lower than 30%, except for the insecticide mineral oil, which reduced eggs hatch in 69.55% and caused a total effect of 36.22% in pupae, being therefore classified as slightly harmful (category 2) to eggs and pupae of C. externa .
RESUMEN
Neste trabalho foi avaliada em condições de laboratório a seletividade dos produtos fitossanitários (g ou mL produto comercial 100L-1) abamectina (80), carbaril (360), deltametrina (40), dimetoato (120), enxofre (600), etofenproxi (150), fentiona (100), fenitrotiona (150), fosmete (200), glufosinato de amônio (2L ha-1), óleo mineral (2000) e triclorfom (300), utilizados na cultura do pessegueiro, em relação a diferentes estágios imaturos de desenvolvimento do parasitóide de ovos Trichogramma atopovirilia Oatman & Platner, 1983. Os bioensaios consistiram na pulverização direta dos produtos fitossanitários sobre ovos de Anagasta kuehniella (Zeller, 1879), contendo, em seu interior, o parasitóide em distintos estágios de desenvolvimento. A porcentagem de emergência de adultos do parasitóide foi avaliada. Reduções na emergência (RE) de adultos em relação à testemunha foram calculadas e os produtos fitossanitários classificados de acordo com índices propostos pela IOBC/WPRS. Produtos fitossanitários à base de abamectina, deltametrina, dimetoato, enxofre, etofenproxi, fosmete, glufosinato de amônio e óleo mineral não apresentaram reduções na emergência e foram classificados como inócuos (<30 por cento RE). Inseticidas à base de carbaril, fenitrotiona e triclorfom reduziram a porcentagem de emergência de adultos em todos os estágios imaturos de desenvolvimento do parasitóide, sendo levemente nocivos (30-79 por cento RE) ou moderadamente nocivos (80-99 por cento RE), conforme o estágio de desenvolvimento, enquanto que fentiona reduziu apenas nos estágios de pré-pupa e pupa, sendo classificado como levemente nocivo (30-79 por cento RE) para estes estágios. A associação dos métodos químico e biológico, na cultura do pessegueiro, é viável para os produtos fitossanitários inócuos quando T. atopovirilia encontra-se nos estágios imaturos de desenvolvimento.
The selectivity of the pesticides (g or mL commercial product 100L-1) abamectin (80), carbaryl (360), deltamethrin (40), dimethoate (120), ethofenprox (150), fenthion (100), fenitrothion (150), glufosinate ammonium (2L ha-1), mineral oil (2000), phosmet (200), sulphur (600) and trichlorphon (300) used in peach orchards was evaluated under laboratory conditions, expounded in different immature stages of the egg parasitoid Trichogramma atopovirilia Oatman & Platner, 1983. Bioassays were carried out by direct applied of treatments on eggs of Anagasta kuehniella (Zeller, 1879) with the immature stages egg-larva, pre-pupa and pupa of T. atopovirilia. The percentage of emergence adult parasitoids was assessed. Reduction in the emergence adult compared with the control was measure and the pesticides were classified according to IOBC/WPRS. Abamectin, deltamethrin, dimethoate, ethofenprox, glufosinate ammonium, mineral oil, phosmet and sulphur were not affected and were harmless (<30 percent). The insecticides carbaryl, fenitrothion and trichlorphon affected the emergence adult in all developmental stages and were slightly harmful (30-79 percent) or moderately harmful (80-99 percent) according developmental stage. Fenthion affected to pre-pupa and pupa stages and was slightly harmful (30-79 percent). The association between biological and chemical control, in peach orchards, is possible for the pesticides harmless and immature stages of T. atopovirilia.
RESUMEN
A toxicidade de dezesseis formulações comerciais de agrotóxicos utilizados na cultura do pessegueiro foi avaliada em laboratório (temperatura 25±1oC, umidade relativa 70±10 por cento e fotofase de 14 horas), expondo-se adultos do parasitóide Trichogramma atopovirilia Oatman & Platner, 1983 (Hymenoptera: Trichogrammatidae) em contato com uma película seca dos produtos fitossanitários pulverizados sobre placas de vidro, mensurando-se posteriormente o número de ovos parasitados por fêmea. Reduções na capacidade de parasitismo em relação à testemunha (somente água) foram utilizadas para classificar os produtos em inócuo (<30 por cento), levemente nocivo (30-79 por cento), moderadamente nocivo (80-99 por cento) e nocivo (>99 por cento). Os agrotóxicos ( por cento da formulação comercial na calda) Captan 500 PM (0,240), Cobre Sandoz BR (0,240), Delan (0,125), Dodex 450 SC (0,175), Rovral SC (0,150) e Intrepid 240 SC (0,060) foram inócuos; Manzate 800 (0,200) foi levemente nocivo; Assist (2,000), Finale (1,000) e Roundup (original) (3,000) foram moderadamente nocivos; Kumulus DF (0,600), Hokko Cihexatim 500 (0,050), Vertimec 18 CE (0,080), Imidan 500 WP (0,200), Tiomet 400 CE (0,120) e Trebon 100 SC (0,150) foram nocivos a T. atopovirilia.
The toxicity of sixteen commercial formulations of pesticides used in peach production was assessed in the laboratory (25±1oC temperature, 70±10 percent relative humidity and 14h photophase) on adults of egg parasitoids Trichogramma atopovirilia Oatman & Platner, 1983 (Hymenoptera: Trichogrammatidae) by exposing the adult parasitoids to fresh dry pesticide film applied on glass plates and further evaluation of the capacity of parasitism per adult female. The reduction in capacity of parasitism compared with the control (treated with water) was used to measure the effect of the chemical. Pesticides were then classified into four categories, according to the reduction in parasitization: 1, harmless (<30 percent); 2, slightly harmful (30-79 percent); 3, moderately harmful (80-99 percent); 4, harmful (>99 percent). The pesticides ( percent commercial formulation in spray water) Captan 500 PM (0.240), Cobre Sandoz BR (0.240), Delan (0.125), Dodex 450 SC (0.175), Rovral SC (0.150) and Intrepid 240 SC (0.060) were harmless; Manzate 800 (0.200) was slightly harmful; Assist (2.000), Finale (1.000) and Roundup (original) (3.000) were moderately harmful; Kumulus DF (0.600), Hokko Cihexatim 500 (0.050), Vertimec 18 CE (0.080), Imidan 500 WP (0.200), Tiomet 400 CE (0.120) and Trebon 100 SC (0.150) were harmful to T. atopovirilia.
