ABSTRACT
Larvae of Leucothyreus spp. have been reported causing damage to several crops in Brazil. From May 2012 to April 2013, adults and immatures of Leucothyreus alvarengai Frey (Coleoptera: Melolonthidae: Rutelinae) samples were obtained from sugarcane (Saccharum officinarum L.) (Poaceae) fields in the municipalities of Naviraí and Nova Andradina, Mato Grosso do Sul, Brazil. Adults were collected with the aid of light traps, whereas immatures were sampled by opening two trench sizes (30 x 30 x 30 cm and 80 x 50 x 40 cm) in the soil, beside the plants. The collected larvae were reared in laboratory conditions, fed by sugarcane seedlings. The biological cycle of L. alvarengai was completed in 230 days, displaying three larval instars with mean size of the cephalic capsule of 1.68, 2.46, and 3.00 mm for the first, second, and third instar, respectively. Adults were collected in greater numbers in December 2012, and first-instar larvae were observed as of January 2013. Conversely, pupae were observed in the field from July 2012 to January 2013. This is the first record of larvae and adults of L. alvarengai in sugarcane fields in Mato Grosso do Sul state, contributing with the knowledge about its biology and temporal distribution in the field.
Subject(s)
Coleoptera , Saccharum , Animals , Poaceae , Brazil , Larva , Edible GrainABSTRACT
The genus Diabrotica has over 400 described species, the majority of them neotropical. However, only three species of neotropical Diabrotica are considered agricultural pests: D. speciosa, D. balteata, and D. viridula. D. speciosa and D. balteata are polyphagous both as adults and during the larval stage. D. viridula are stenophagous during the larval stage, feeding essentially on maize roots, and polyphagous as adults. The larvae of the three species are pests on maize, but D. speciosa larvae also feed on potatoes and peanuts, while D. balteata larvae feed on beans and peanuts. None of these species express a winter/dry season egg diapause, displaying instead several continuous, latitude-mediated generations per year. This hinders the use of crop rotation as a management tool, although early planting can help in the temperate regions of the distribution of D. speciosa. The parasitoids of adults, Celatoria bosqi and Centistes gasseni, do not exert much control on Diabrotica populations, or show potential for inundative biocontrol plans. Management options are limited to insecticide applications and Bt genetically modified (GM) maize. Other techniques that show promise are products using Beauveria bassiana and Heterorhabditis bacteriophora, semiochemical attractants for monitoring purposes or as toxic baits, and plant resistance.
ABSTRACT
Liogenys suturalis Blanchard is one of the main soil pests associated to corn, wheat and oat crops in the Southern Mato Grosso do Sul State. This work aimed to investigate the bioecological and behavioral aspects of this pest. The study was carried out in several municipalities of Mato Grosso do Sul State under field and laboratory conditions from August 2004 to December 2006. In the laboratory, we studied the incubation period and egg viability, the number of instars, and pupal and adult sex-related traits. The insect distribution was determined yearly, as well as the period of insect flying and some behavioral aspects during mating. Egg viability averaged 81.7 percent, with an incubation period of 22.8 ± 4.32 days. Liogenys suturalis took the whole year to complete its life cycle, developing through three different instars. The highest larval feeding activity and development occurred in February and June, and adult flight activities were between the second fortnight of September and December. Sex dimorphism was observed in both pupae and adults. Flights were concentrated from 7:00 to 8:00 PM. The average time for mating was 9.82 min. The observed adult sex ratio was 0.63.
Liogenys suturalis Blanchard é uma das principais pragas de solo associada às culturas do milho, do trigo e da aveia no Sul do Mato Grosso do Sul. O objetivo deste trabalho foi estudar aspectos bioecológicos e comportamentais dessa praga. A pesquisa foi executada em vários municípios do estado, em condições de campo e laboratório, entre agosto de 2004 e dezembro de 2006. No laboratório foram determinados o período de incubação e a viabilidade dos ovos, o número de ínstares e caracteres sexuais de pupas e adultos. Foram estudadas a distribuição temporal do inseto ao longo do ano, o período de revoada e aspectos comportamentais da cópula. A viabilidade média dos ovos foi de 81,7 por cento e o período médio de incubação de 22,8 ± 4,32 dias. Liogenys suturalis completou o ciclo de vida no período de um ano passando por três instares. A fase em que a maioria das larvas estava mais desenvolvida e consumindo as raízes das plantas ocorreu entre os meses de fevereiro a junho e o período de revoada de adultos ocorreu da segunda quinzena de setembro até dezembro. Observou-se dimorfismo sexual em pupas e adultos. A maior porcentagem de adultos em revoada foi observada no horário entre 19:00h e 20:00h. A cópula teve duração média de 9,8 min. A razão sexual observada para adultos foi de 0,63.
Subject(s)
Animals , Female , Male , Coleoptera , Behavior, Animal , Brazil , Coleoptera/anatomy & histology , Coleoptera/physiologyABSTRACT
Liogenys suturalis Blanchard is one of the main soil pests associated to corn, wheat and oat crops in the Southern Mato Grosso do Sul State. This work aimed to investigate the bioecological and behavioral aspects of this pest. The study was carried out in several municipalities of Mato Grosso do Sul State under field and laboratory conditions from August 2004 to December 2006. In the laboratory, we studied the incubation period and egg viability, the number of instars, and pupal and adult sex-related traits. The insect distribution was determined yearly, as well as the period of insect flying and some behavioral aspects during mating. Egg viability averaged 81.7%, with an incubation period of 22.8 + or - 4.32 days. Liogenys suturalis took the whole year to complete its life cycle, developing through three different instars. The highest larval feeding activity and development occurred in February and June, and adult flight activities were between the second fortnight of September and December. Sex dimorphism was observed in both pupae and adults. Flights were concentrated from 7:00 to 8:00 PM. The average time for mating was 9.82 min. The observed adult sex ratio was 0.63.
Subject(s)
Behavior, Animal , Coleoptera , Animals , Brazil , Coleoptera/anatomy & histology , Coleoptera/physiology , Female , MaleABSTRACT
O objetivo do trabalho foi, através de medidas de consumo e utilização de alimento, determinar, entre 25 e 30ºC, qual a temperatura mais adequada para criação de Spodoptera frugiperda (J.E. Smith), Diatraea saccharalis (Fabr.) e Heliothis virescens (Fabr.) em dieta artificial. Foram estudadas 50 lagartas por espécie, individualizadas em recipientes de vidro de 8,5 cm de comprimento x 2,5 cm de diâmetro e mantidas a 25 e 30ºC, UR de 60±10 por cento e fotofase de 14h. Foram determinados, com base em matéria seca, o peso de lagarta no máximo desenvolvimento, do alimento consumido e das fezes eliminadas, e os índices nutricionais: taxa de consumo relativo (RCR), taxa de crescimento relativo (RGR), taxa metabólica relativa (RMR), digestibilidade aparente (AD), eficiência de conversão do alimento ingerido (ECI) e eficiência de conversão do alimento digerido (ECD). Para S. frugiperda a condição térmica mais adequada foi a de 30ºC, por proporcionar maior peso no máximo desenvolvimento, maior ganho de peso, maior razão de crescimento, maior ECI, maior ECD e menor custo metabólico. Por outro lado, tanto para H. virescens como para D. saccharalis, não houve diferença nos índices nutricionais, avaliados nas duas condições térmicas. Assim, por uma geração, e baseando-se em índices nutricionais, a temperatura mais elevada é recomendada para manutenção de S. frugiperda em laboratório. Para as outras espécies, é indiferente criá-las a 25 ou a 30ºC.
The goal of this work was to determine the most suitable temperature for rearing Spodoptera frugiperda (J.E. Smith), Diatraea saccharalis (Fabr.) and Heliothis virescens (Fabr.) in artificial diet, by means of measures of food intake and utilization between 25 and 30ºC. Fifty worms per species, individualized and kept in 8.5 cm long and 2.5 cm diameter glass containers were studied at the temperatures mentioned, 60±10 percent RH, and 14 hour photophase. Based on dry matter, one determined worm weight at maximum development, food consumed and feces eliminated at both conditions (25 and 30ºC) and the nutritional ratios: relative consumption ratio (RCR), relative growth ratio (RGR), relative metabolic ratio (RMR), approximate digestibility (AD), efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD). The most suitable temperature for S. frugiperda was 30ºC since it provided higher weight at the maximum development, higher weight gain, higher growth ratio, higher ECI, higher ECD, and lower metabolic cost. On the other hand, no differences regarding nutritional rates were observed for either H. virescens or D. saccharalis evaluated at both thermal conditions. Thus, for one generation and based on nutritional rates, the highest temperature (30ºC) is recommended for laboratory maintenance of S. frugiperda. As for the other species, rearing at 25 or 30ºC is indifferent.
