PALAVRAS-CHAVE: Insecta, insecticida, percevejo, plantio direto, tratamento de sementes ABSTRACT -Results of field evaluations indicated that the neotropical pentatomid Dichelops melacanthus (Dallas) is associated with wheat, Triticum aestivum L. In the no-tillage cultivation system, adults and nymphs were mostly found on the soil, near the plant stems and underneath crop residues of the preceding summer crop, usually soybean, Glycine max (L.) Merrill, or corn, Zea mays L. Wheat grown under the conventional cultivation system showed minimal bug attack. D. melacanthus caused substantial damage to no-tillage wheat plants, particularly to seedlings. Bug attack reduces the number of seed heads of up to 34%. Seed yield was reduced in 31% due to the bugs' feeding, compared to plants free of damage. All developmental phases of the wheat plant were susceptible to the attack of D. melacanthus, and the greatest yield reduction occurred from stem elongation (26.5%) to milky grain stage (33.1%). Seed treatment using insecticides was efficient, greatly reducing the grain production losses.

The influence of the photoperiod on the biology and seasonal morphs of Dichelops melacanthus (Dallas, 1851) was studied in the laboratory. Four different photoperiods (11, 12, 13, and 14 hL = hours of light) were tested, keeping the temperature at 25 +/- 1 masculine C and the relative humidity at 65 +/- 5%. Nymph developmental time tended to be longer under shorter photophases (11 and 12 hL). The 14-hour photophase (long day) resulted in lower nymph mortality rates. Females maintained at 13 and 14 hL showed greater weight gain (1st-28th day) than females under 12 hL. D. melacanthus showed reproductive oligopause induced by short photophases, especially when exposed to 11 hL. Under 13 and 14 hL, 85% and 65% of females oviposited, respectively, in comparison to 10% and 15% of females ovipositing under 11 and 12 hL, respectively. Fecundity (number of egg masses and number of eggs/female) was greater in the longer than under the shorter photophases. Seasonal dimorphism induced by photoperiod was observed in D. melacanthus adults. Under short-day conditions (11 and 12 hL), adults showed short and rounded shoulder spines, grayish brown abdomen (mainly in 11 hL), high lipid contents, and lower percentage of mature reproductive organs. Under long-day conditions (13 and 14 hL), the stink bugs showed greatly developed shoulder spines, green abdomen, low lipid contents, and mature reproductive organs.

Biologia de Ninfas e de Adultos de Dichelops melacanthus (Dallas) (Heteroptera: Pentatomidae) Alimentando-se de Plantas Cultivadas e Não-Cultivadas RESUMO -A biologia do pentatomídeo Dichelops melacanthus (Dallas) em plantas cultivadas e não-cultivadas foi estudada em laboratório. A mortalidade ninfal variou de ≈ 60% em milho (semente madura) a 77% em trigo (espiga imatura); nenhuma ninfa sobreviveu em plântulas de milho ou trigo. O desenvolvimento ninfal em soja, milho ou trigo (semente, vagem ou espiga) variou de 25,5 a 32,8 dias. O peso dos adultos na emergência foi menor em espiga de trigo. As ninfas alimentaram-se preferencialmente de soja (vagem imatura). Nas plantas não-cultivadas, as ninfas tiveram mortalidade de 73% em crotalária (vagem imatura); e 100% em trapoeraba (ramo). O desenvolvimento ninfal foi mais lento em crotalária ou trapoeraba do que em soja. A sobrevivência dos adultos decresceu com o tempo na maioria dos alimentos, com ≈50% dos adultos vivos no 30º dia. Em plântulas de milho e trigo ≈80% dos adultos estavam mortos no 20º dia. A longevidade total dos adultos variou de 31-43 dias, exceto em plântulas de milho e trigo (< 15 dias). A % de fêmeas que ovipositou foi maior (≈76%) em soja (vagem ou semente imatura) e menor (≈9%) em espiga imatura de trigo; as fêmeas não reproduziram em plântulas de milho ou trigo. O período de pré-oviposição foi menor (≈12 dias) em soja (vagem ou semente imatura) e maior (≈37 dias) em trigo (espiga imatura). A fecundidade foi semelhante e maior em todos os alimentos do que em trigo (espiga imatura). O ganho de peso ocorreu em todos os alimentos, menos plântulas de milho e trigo. Os adultos alimentaram-se preferencialmente em soja (vagem imatura e semente madura); plântula de trigo foi o alimento menos preferido.PALAVRAS-CHAVE: Insecta, alimento, planta hospedeira ABSTRACT -The biology of the pentatomid Dichelops melacanthus (Dallas) feeding on cultivated and non-cultivated plants was studied in the laboratory. Nymph mortality varied from ≈ 60 on corn (seed mature) to 77% on wheat (ear immature); no nymphs survived on seedlings of corn or wheat. Nymph developmental time on soybean, corn or wheat (seed, pod or ear) varied from 25.5 to 32.8 days. Body weight at adult emergence was similar and greater on most foods than on wheat ear. Nymphs fed preferentially on soybean (pod immature). On non-cultivated hosts, nymphs showed high mortality (73%) on crotalaria (pod immature); on tropical spiderwort (stem) all nymphs died. Nymphs took longer time to develop on crotalaria and/or on spiderwort than on soybean. Body weight at adult emergence did not differ on crotalaria or soybean. Survivorship decreased with time on most foods, with ≈50% of adults alive at day 30. On corn and wheat seedlings ≈80% of adults were dead on day 20. Adult longevity ranged 31-43 days, except on corn and wheat seedlings < 15 days. Females % ovipositing peaked (≈76%) on soybean (pod or seed immature), and was minimum (≈9%) on wheat ear (immature); no females reproduced on seedlings of corn or wh...

Damage of the green belly stink bug 'BR 18' and 'BRS 193', in

ResumoEstudo referente à biologia de ninfas do percevejo barriga verde, Dichelops melacanthus (Dallas, 1851), sob três diferentes temperaturas (15, 20