Nymph biology of Dichelops furcatus (F.) and of Dichelops melacanthus (Dallas) (Heteroptera: Heteroptera: Pentatomidae) on different food sources

Laboratory studies were conducted to evaluate the nymph biology of Dichelops furcatus (F.) and of D. melacanthus (Dallas) on pods of green bean, Phaseolus vulgaris L., on seeds, pods and seedlings of soybean, Glycine max (L.) Merrill, and on seeds and seedlings of corn, Zea mays L. and of wheat, Triticum aestivum L. Thirty nymphs were used for each food, each nymph individualized in plastic Petri dish (6.0 x 1.5 cm for seeds and pods) or in plastic box (11.0 x 11.0 x 3.5 cm for seedlings wrapped in wet cotton), placed at random in an environmental chamber (25 ± 1°C, 65 ± 5% RH and 14hL photoperiod). Results indicated that the best food for both species was soybean pods (70% nymph survivorship). No nymphs survived on seed/seedlings of corn and on seedlings of soybean and wheat. Nymph developmental time (2nd to 5th instar) varied from 19 to 26 days for both species on seeds of wheat, seeds or pods of soybean, or on pods of green beans. Fresh body weight of females at emergence for D. furcatus was greater on soybean pods (68.8 mg) and smaller on wheat seeds (42.7 mg); for males it varied from 50.3 mg on wheat seeds to 62.6 mg on soybean pods. Females D. melacanthus showed greater body weight on soybean pods (53.5 mg) and smaller on wheat seeds (37.9 mg); males showed greater body weight on green bean pods (53.3 mg) and smaller on wheat seeds (34.3 mg). Results demonstrate that soybean pods were the most suitable food source for nymph development of both species of stink bugs.