Studies on insect food intake and utilization are important for determining the degree of insect/plant association and host species’ resistance, and also for helping design pest management programs by providing estimates of potential economic losses, techniques for mass breeding of insects, and identifying physiological differences between species. We studied the feeding and development of fall armyworm, Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae), on transgenic (Bt) and non‐transgenic (non‐Bt) cotton. The larvae of S. frugiperda fed on Bt cotton had a longer development period (23.0 days) than those fed on non‐Bt cotton (20.2 days). Survivorship of S. frugiperda larvae fed on Bt cotton (74.1%) was lower than that of larvae fed on non‐Bt cotton (96.7%). Pupal weight of larvae fed on Bt cotton (0.042 g) was lower than that of larvae fed on non‐Bt cotton (0.061 g). The cotton cultivar significantly affected food intake, feces production, metabolization, and food assimilation by S. frugiperda larvae. However, it did not affect their weight gain. Intake of Bt‐cotton leaf (0.53 g dry weight) per S. frugiperda larva was lower than the intake of non‐Bt‐cotton leaf (0.61 g dry weight). Larvae fed on Bt‐cotton leaves produced less feces (0.25 g dry weight) than those fed on non‐Bt‐cotton leaves (0.37 g dry weight). Weight gain per S. frugiperda larva fed on Bt‐cotton leaves (0.058 g dry weight) was similar to the weight gain for larvae fed on non‐Bt‐cotton leaves (0.056 g dry weight). The cotton cultivar significantly affected the relative growth, consumption, and metabolic rates, as well as other nutritional indices: the figures were lower for larvae fed on Bt‐cotton leaves than for larvae fed on non‐transgenic cotton leaves.

The study investigated the development, survivorship, and food intake of cotton leafworm Alabama argillacea (Hübner) fed on three cotton cultivars with colored fibers. Significantly shorter larval life-span and higher pupal weight as well as higher survival rates were observed in A. argillacea fed on leaves of BRS Safira and BRS Rubí cotton cultivars compared with the BRS 200 cultivar (BRS = Brazil). Weight gain, feces, and food intake were higher in A. argillacea fed on leaves of BRS Safira compared with the BRS 200 cultivar. The cotton cultivar significantly affected all larval food intake and utilization indices for A. argillacea. The larvae of A. argillacea were more efficient (higher efficiency in converting ingested (ECI) and digested (ECD) food) when fed on leaves of the BRS Safira cultivar in comparison to the BRS 200 cultivar, since the larval phase was shortened and food intake was higher, resulting in a higher growth rate (RGR). However, A. argillacea larvae fed on the leaves of the BRS 200 cultivar, with lower ECI and ECD, exhibited a compensatory response, extending the duration of the larval phase and increasing food intake, resulting in a higher relative metabolic rate. We conclude that BRS Safira provides the best food quality for A. argillacea, BRS 200 the worst, and BRS Rubi plants of intermediate quality.

Quantitative analysis of the consumption and use by herbivore pest's of the host plant is a common tool used for studying the interaction between insects and plants. Our goals were to quantify cotton leafworm, A/a¿)ama argillacea (Hübner) (Lepidoptera: Noctuidae), larval consumption rate in three cotton, Qos.njpium hirsutum L., cultivars that produce colored cotton fibers, and the effects of the consumption rate on A. argillacea pupal weight in greenhouse conditions. Larvae consumed a maximum of 0.69-1.03 g of leaf tissue over a 24-h period in all cultivars tested. Total consumption by A. argillacea larvae was highest when fed with 'BRS 200' leaves (2.89 g) and the lowest when fed with leaves from 'BRS Safira' (2.26 g). The regression analysis showed significant relationships between the quantity of leaf tissue consumed and pupal weights for each cotton cultivar. A. argillacea larvae fed on BRS 200 demonstrated a longer developmental period (14.84 d) than larvae fed on 'BRS Rubi' leaves (11.62 d) or BRS Safira (11.14 d). We concluded that BRS Safira presents the best quality food source for A. argillacea, BRS 200 is the worst, and BRS Rubí is intermediate. The longer developmental times of A. argillacea on BRS 200 may allow longer windows of opportunity for the use of biological control agents to reduce the damage caused by this pest and also would complete less generations per phenological cycle of the cotton crop.

The effects of photoperiod on nymphal development, growth and adult size in Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) were studied. Predators were collected in cotton fields in Patos (7°S, 37°W), Paraíba State, Brazil. A randomized block experimental design was used, with treat-