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Plants have evolved a diverse array of defensive mechanisms against biotic and abiotic stresses, which can be either constitutive or inducible. Variation in plant-intrinsic factors such as the genotype and the leaf position coupled with insect herbivory can affect the expression of resistance to insects. We investigated if soybean defense induction triggered by Spodoptera cosmioides herbivory varies in function of the genotype and leaf position. This hypothesis was tested in two bioassays using leaf discs or entire leaflets collected from the upper and lower trifoliates of S. cosmioides-injured and uninjured V3-V4 soybean plants. We used one genotype that was constitutively resistant and one that was constitutively susceptible to S. cosmioides based on previous screening. Third-instar larvae were fed one of the treatments and assayed for leaf consumption, larval growth, and efficiency of conversion of ingested food. Genotype and leaf position significantly interacted with herbivory and affected soybean-induced resistance to S. cosmioides. Negative responses on S. cosmioides larvae consumption and growth rates were only observed when leaf material was originated from the upper soybean trifoliate. The susceptible soybean genotype did not exhibit induced resistance characteristics. Food offered as leaf disc was better at demonstrating induced resistance in previously injured soybean, whereas offering entire leaflet the induced effects were less pronounced. Here we provide new findings on soybean resistance by demonstrating that resistance induction to S. cosmioides herbivory is dependent on the plant genotype and leaf position where injury took place, with negative effects better evinced in bioassays using leaf discs than entire leaflets.

Advances in techniques for rearing insects on artificial diets are fundamental to solving issues of basic and applied entomology. In this study, we evaluated the development of Spodoptera albula (Walker) (Lepidoptera: Noctuidae) on three artificial diets used for other species of Lepidoptera, at three larval densities, and two densities of adult couples housed in oviposition cages of two sizes, with the aim of optimizing methodology for rearing S. albula in the laboratory. Biological parameters were recorded from S. albula, and a fitness index was calculated based on the larval survival and duration and weight of pupae. The total and daily oviposition was recorded using 5 or 10 adult couples of S. albula housed in two cage sizes. Concentrations of total nitrogen and protein in the tested diets were determined. Development of S. albula was completed in all artificial diets; however, the diet used for rearing Anticarsia gemmatalis (Hübner) larvae was the most suitable for S. albula, yielding intermediate development time and higher survival relative to the other diets. Individualization of larvae favored S. albula development by producing overall greater weights of larvae and pupae, higher survival rates, and longer adult longevity. Cage size and number of couples per cage did not influence S. albula fecundity in the experiment conditions. Spodoptera albula can be satisfactorily reared on the artificial diet used for A. gemmatalis, using one larva per tube, and either density of adults at any cage size. Additional amendments are needed in the rearing methodology to achieve optimal conditions for larval development to adulthood.

ResumoEste trabalho teve como objetivos avaliar a atratividade, não preferência para alimentação e antibiose em cultivares de amendoim de hábitos de crescimento ereto e rasteiro a Stegasta bosquella (Chambers). Avaliaram-se oito cultivares, sendo quatro de hábito de crescimento ereto (IAC Tatu, IAC 22, IAC 8112 e IAC 5) e quatro de hábito rasteiro (IAC Runner 886, IAC 147, IAC 125 e IAC 503). Foram realizados testes de não preferência para alimentação com e sem chance de escolha, utilizando-separes de discos foliares sobrepostos de 1,0 cm de diâmetro, os quais foram dispostos em placas de Petri onde foram liberadas lagartas de terceiro instar de S. bosquella. Avaliou-se a atratividade das lagartas em tempos pré-estabelecidos, além da massa seca consumida. No teste de antibiose, foram avaliados os parâmetros biológicos: período e viabilidade larval, de pré-pupa, pupal e total, pesos de lagartas e pupas, razão sexual e longevidade. Nenhuma das cultivares de amendoim de hábito de crescimento rasteiro apresentaram resistência do tipo não preferência para alimentação. Dentre as cultivares de hábito de crescimento ereto, IAC 5 e IAC 22 foram as menos atrativas e consumidas no teste de não preferência para alimentação com chance de escolha, e IAC 5 e IAC 8112 foram as menos atrativas no teste sem chance de escolha. As cultivares de hábito rasteiro IAC 147 e IAC Runner 886 afetaram a sobrevivência larval de S. bosquella, apresentando resistência do tipo antibiose. Para as cultivares de hábito ereto, IAC 22 e IAC 8112 afetaram a viabilidade larval, apresentando resistência do tipo antibiose. As cultivares de hábito de crescimento rasteiro e ereto não influenciaram os parâmetros biológicos de peso de pupa, razão sexual e longevidade de S. bosquella. Palavras-chave: Arachis hypogaea, lagarta-do-pescoço-vermelho, oleaginosas, resistência de plantas a insetos AbstractThis work aimed to evaluate the attractiveness, non-preference for feeding and antibiosis in straight and runner growth habit peanut cultivars to Stegasta bosquella (Chambers). Eight cultivars were evaluated, four of straight growth habit (IAC Tatu, IAC 22, IAC 8112 and IAC 5) and four of runner growth habit (IAC Runner 886, IAC 147, IAC 125 and IAC 503). Free-choice and no-choice feeding tests were performed, using pairs of overlapped leaf discs with 1.0 cm diameter, which were placed in Petri dishes where third instar larvae of S. bosquella were released. The attractiveness to the larvae was assessed

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