In 2013, the presence of Helicoverpa armigera (Hübner) was reported in cotton, soybean, corn and weeds in diverse regions of Brazil. We studied the biology and the fertility life table of this pest when reared on cotton (293 cv. CNPA RF), soybean (cv. Brasmax Power), corn (cv. BRS 1010), wheat (cv. BR 18) and on an artificial diet. Caterpillars were reared using the vegetative and reproductive structures of the hosts, under laboratory conditions (temperature 25 ± 1°C; relative humidity (RH) 70 ± 10%; photoperiod =14 h). The experimental design was completely randomized, with five treatments (four host plants and artificial diet) and 17 replications. Significant effects were verified for the different types of hosts tested on the growth of the insect as well as on fecundity and laying rate. The results showed that cotton and soybean had higher viability at the stages of growth, higher rate of survival of adult females in the reproductive period than the other host crops, and similar values for insects reared on an artificial diet, which reveals that cotton and soybean can be appropriate for rearing H. armigera on a natural diet. Corn and wheat showed high larval and pupal mortality and low biotic potential.

DANOS CAUSADOS POR LARVAS E ADULTOS DETermos para indexação: vaquinha, praga de milho, ecologia, comportamento, hospedeiros. DAMAGES CAUSED BY LARVAE AND ADULTS OF DIABROTICA SPECIOSA (COLEOPTERA: CHRYSOMELIDAE) IN CORNABSTRACT -Diabrotica speciosa (Germar, 1824) is traditionally a polyphagous pest during the adult phase although with some preference for bean and soybean leaves. In the past years, however, the larval phase of this chrysomelid achieved the pest status likewise other species of the genus in the USA causing severe damages to the root system of corn. The aim of this research was to evaluate the damages caused by different population levels of D. speciosa to corn roots and by adults to corn, soybean, bean and rice leaves. A significant decrease in the dry weight of corn roots, in the dry weight of the upper part, and in plant height in comparison with the control plant was observed even in small larvae population densities. The economic threshold level was less than 40 larvae per plant. The adults had significant preference for bean and soybean leaves while corn and rice were less consumed.

Biological Notes and Behavior of Liogenys suturalis Blanchard (Coleoptera: Melolonthidae) in Mato Grosso do Sul State, BrazilABSTRACT -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 fi eld 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 sexrelated traits. The insect distribution was determined yearly, as well as the period of insect fl ying and some behavioral aspects during mating. Egg viability averaged 81.7%, 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 fl ight 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.

RESUMO

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Avaliou-se o efeito do regulador de crescimento de insetos lufenuron (Match CE) sobre a fecundidade dos adultos e a viabilidade de ovos de Diabrotica speciosa (Germar) (Coleoptera: Chrysomelidae), em laboratório. Adultos recém-emergidos da criação foram separados por sexo, colocando-se um casal por gaiola de acrílico transparente. Quinze casais foram alimentados com folhas de feijão (Phaseolus vulgaris L.) tratadas com lufenuron, durante 13 dias após o acasalamento. Após esse período, os insetos foram alimentados com folhas de feijoeiro não tratadas. O mesmo número de casais foi alimentado com folhas de feijoeiro não tratadas com o inseticida. A fecundidade e a viabilidade dos ovos obtidos foram avaliadas, a cada três dias, persistindo até o 34º dia após o acasalamento. O número médio de ovos colocados por fêmea (177,5) e a viabilidade dos ovos obtidos dos casais tratados com lufenuron (19,8%) foi significativamente inferior ao dos casais alimentados com folhas não tratadas, os quais apresentaram fecundidade média de 375,4 ovos/fêmea e viabilidade dos ovos de 68,7%. Aparentemente, o produto ingerido pela fêmea, foi transferido transovarianamente para o embrião, afetando o seu desenvolvimento e impedindo a eclosão da larva. Os resultados obtidos mostram a possibilidade do emprego do inseticida lufenuron visando a redução da progênie de D. speciosa, quando os adultos se alimentarem em plantas tratadas com o produto.

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Studies related to the feeding behavior of pest insects provide information that will aid the development of control tactics. Leaf consumption by Diabrotica speciosa adults fed on bean, corn, potato and soybean was determined in the laboratory under free-choice (multiple or double-choice) and no-choice (confinement) conditions. In the multiple-choice tests leaf circles were randomly arranged in a circular pattern (arena) inside Petri dishes. The degree of preference for the hosts was determined under double-choice conditions, where common bean was considered the standard host and the remaining plants (soybean, potato and corn) as test hosts. In all trials, two Diabrotica speciosa couples were released and maintained within the dish for 24 hours; the leaf area consumed by the insects was determined after this feeding period. Food type (host) influenced leaf area consumption by D. speciosa adults both in free-choice and in no-choice tests (P < 0.05). Under freechoice conditions, the insects preferred to feed on bean rather than on soybean, potato or corn, with no differences among these last three host plants (P > 0.05). As to the no-choice test, the consumption was higher for corn than for potato, probably to compensate the low nutritional quality of the first host. Key words: insect, root worm, host plant, food preference, food intake CONSUMO FOLIAR POR ADULTOS DE Diabrotica speciosa (COLEOPTERA: CHRYSOMELIDAE) EM DIFERENTES HOSPEDEIROSRESUMO: Estudos relacionados ao comportamento alimentar dos insetos-pragas, podem fornecer informações que auxiliam no desenvolvimento de táticas visando seu controle. Foi determinado, em laboratório, o consumo foliar por adultos de Diabrotica speciosa, quando alimentados com folhas de feijoeiro, milho, batata e soja, sob condições de livre escolha (múltipla e dupla escolha) e sem chance de escolha (confinamento). Nos testes de múltipla escolha, círculos foliares foram dispostos, ao acaso, num arranjo circular (arena) em placas de Petri. O grau de preferência dos hospedeiros foi determinado em condições de dupla escolha, considerandose o feijoeiro a espécie padrão e os demais hospedeiros (soja, batata e milho) como plantas testes. Para todos os testes, dois casais de D. speciosa foram liberados no interior da placa e aí mantidos por 24 horas, determinadose, após esse período, a área foliar consumida pelos insetos. O tipo de alimento (hospedeiro) oferecido aos adultos de D. speciosa influenciou o grau de consumo foliar tanto nos testes de livre escolha como nos de confinamento (P < 0.05). Nos testes de livre escolha, os insetos preferiam se alimentar de folhas de feijoeiro em relação às de batata, soja e milho, sem diferir significativamente entre estas últimas. Em condições de confinamento o consumo foliar é maior em milho do que em batata, provavelmente como compensação pela baixa qualidade nutricional da gramínea em relação às leguminosas.