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The use of artificial diets for rearing natural enemies is an expensive technique with negative implications in the development of parasitoids. The aim of this study was to determine the effects on the development of the parasitoid Chelonus insularis Cresson (Hymenoptera: Braconidae) using as the host Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) larvae reared on castor bean (Ricinus communis L.) and maize (Zea mays L.) leaves. Twenty-five egg masses of S. frugiperda were exposed to adult parasitoids of C. insularis. One hundred twenty-three larvae were fed with castor bean leaves and 309 larvae with maize. Survival of S. frugiperda larvae and emergence of healthy adults of C. insularis were recorded. Durations of the developmental stages, weight per parasitoid, length of the radial cell, and total length of the forewing also were recorded. No significant differences were determined between the two host plants with respect to survival of S. frugiperda larvae or the emergence of healthy adults of C. insularis. Durations of the developmental stages of the parasitoid were longer on castor bean leaves than on maize. The length of the radial cell and the total length of the forewing were greater on parasitoids that emerged from castor bean-reared larvae than those reared on maize for both females and males. The weight per parasitoid did not differ. Chelonus insularis can be maintained in S. frugiperda larvae reared on castor and maize leaves but, based on these results, the use of castor bean leaves favors the size of the parasitoid.

Resistance to Spodoptera frugiperda (Lepidoptera: Noctuidae) damage has been documented in some Mexican maize races and teosintes. There are approximately 31 races of native maize and three races of teosinte in Oaxaca state, but little is known about their resistance to insect damage. This study compared the development and fecundity of S. frugiperda fed on native maize and the teosinte Zea luxurians, from Oaxaca, Mexico. No significant differences were determined in the development parameters of males and females according to the host plant types, except the pupal weight of males, which was higher on teosinte (0.189 g) than on native maize (0.174 g). Duration from hatching to adult emergence was 28.96 to 30.17 d on native maize and 28.51 to 30.34 d on teosinte. Females emerged before males in both host plant types. The sex ratio was approximately 0.5 for both sexes. Larval weight was higher on teosinte (0.451 to 0.459 g) than on native maize (0.442 to 0.454 g). According to the fecundity parameters, no significant differences in the duration of oviposition, the number of eggs per egg mass, eggs per female, and eggs per host plant types were determined. Fitness Index was positively correlated with the pupal weight of both sexes and the fecundity parameters of S. frugiperda females. Our results demonstrated that larval feeding on native maize and teosinte did not affect the development parameters and fecundity of S. frugiperda. Constitutive defenses in native maize leaves were similar to those of teosinte.

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