Nymph and adult biology of Euschistus heros (Hemiptera : Pentatomidae) andits abundance related to planting date and phenological stages of sunflower

The Neotropical brown stink Lug Euschistus heros (F.) was found to feed and reproduce on sunflower, Helianthus annuus L., in northern Parana state, Br azil. In the laboratory, 37.5% of nymphs feeding on sunflower fruits reache d adulthood, compared with 65.0% on fruits of the preferred host soybean, G lycine max (L.) Merrill. Nymph developmental time was significantly longer on sunflower (1.5 d longer for females and 3.2 d longer for males) than on soybean. At adult emergence, female nymphs attained similar weight on both foods, but male nymphs were 7.2% heavier on soybean than on sunflower. On b oth foods, females were heavier than males. Adult longevity, reproduction, and body weight gain was similar on both foods, with an overall tendency of better performance on soybean compared with sunflower. Tn the field, E her os adults were captured on sunflower in greater number during April-May at the 2nd planting date, when plants were developing seeds (R7-R8),compared w ith December-January at the Ist planting date, when plants were blooming (R 5-R6). On sunflower plants, bugs were preferably found on heads, and on the front side, feeding on seeds, compared with stems or leaves.