title: Overwintering survival and spring emergence of Helicoverpa armigera (Lepidoptera: Noctuidae) in northern Greece.
abstract: Overwintering survival of Helicoverpa armigera (Hübner) was studied under field conditions during the winter of 2004-2005 and 2005-2006 to clarify whether a local population of this insect is established in northern Greece. Additionally, the postdiapause eclosion  times of the overwintering generation was compared with adult male dynamics using pheromone traps. Our study supplies strong evidence that part, if not all, of the late-season generation of H. armigera overwinters as diapausing pupa in northern Greece, suggesting that a local population  exists in this area. Pupae enter diapause during September and October in response to declining temperatures and photoperiod. A limited number of degree-days in autumn prevented part of the population from developing to the diapausing pupal stage. Larvae of H. armigera that were placed  in field conditions late in October were not able to pupate and died. The termination of diapause and the eclosion of adults in the following spring were determined by the local soil temperatures. Diapause terminated between mid-April and early May, and adult emergence occurred within a 4-  to 6-wk period from late April to early June. Females emerged slightly earlier than the males. The emergence of 10, 25, 50, 75, and 90% of adults required 153, 199, 252, 303, and 347 DD, respectively. Differences in timing and degree of overlap between adult emergence from the experimental  population and pheromone trap catches suggests that the spring population of this species also includes immigrants.
authors: Aristotle University of Thessaloniki, Faculty of Agriculture, Laboratory of Applied Zoology and Parasitology, 54124 Thessaloniki, Greece.
authors: G K
authors: GK
authors: Mironidis
authors: D C
authors: DC
authors: Stamopoulos
authors: M
authors: M
authors: Savopoulou-Soultani
mesh_terms: D000818:Animals; D005260:Female; D006115:Greece; D008297:Male; D008675:Metamorphosis, Biological; D008954:Models, Biological; D009036:Moths / Q000254:growth & development*; D012621:Seasons; D012724:Sex Attractants; D012987:Soil; D013696:Temperature
chemical_list: D012724:Sex Attractants; D012987:Soil