caa a22 4500 397571550 CHVBK 20180308164843.0 cr unu---uuuuu 161202e19961001xx s 000 0 eng 10.1093/ee/25.5.1002 doi (NATIONALLICENCE)oxford-10.1093/ee/25.5.1002 Natural Causes and Rates of Early Larval Mortality in Gypsy Moths (Lepidoptera: Lymantriidae) Sampled from Field Populations in Different Density States [Elektronische Daten] [Ellen H. Yerger, Marycarol Rossiter] There was significant variation in early survival among gypsy moth, Lymantria dispar (L.), populations across the northeastern United States. The test individuals were collected as new eggs from field populations representing 5 regions, which differed in their history of gypsy moth establishment. Within each region, 2 populations were sampled: one in the building phase and the other in the outbreak phase of the gypsy moth population density cycle. We measured hatch success and incidence of early death (up to day 12 after feeding initiation) and identified the cause of death (viral, fungal, or poor quality). These data were used to test the following 2 hypotheses: (1) young larvae from high density populations experience greater mortality because of disease and poor quality than those from building populations, and (2) early stage survival is greater at the leading edge of gypsy moth range expansion than in populations from established regions. We found that mortality patterns differed in relation to density of the sampled population: populations in the outbreak stage were of poorer quality, showing lower hatch success and higher mortality among hatchlings. Mortality caused by a nucleopolyhedrosis virus was greatest among neonates from outbreak populations relative to neighboring building populations in all regions where there was no history of Entomophaga maimaiga (Humber) fungal infection. Despite the presence of E. maimaiga infection in field populations of several regions before the egg laying period, there was no evidence of infection by the fungus E. maimaiga in neonates hatched from any field collected egg masses. In neonates who were collected as eggs from populations with a history of E. maimaiga infection, the virus was curiously absent, despite its characteristic presence in building and outbreak populations and usual role in ending an outbreak. These results suggest that it is important to determine whether this fungus interferes with replication and transmission of the virus and inadvertently prevents the initiation or development of a viral epizootic. Finally, regions with the longest history of gypsy moth establishment had lower overall early survival. However, this relationship may be confounded by the presence of the new fungal microbe, E. maimaiga, in the 2 regions of oldest establishment. In these 2 regions, 48% of the egg masses had very poor hatch compared with 9% for the other 3 regions. But, if only post-hatch survival is considered, there was no relationship between early stage mortality and time after gypsy moth establishment in a region. © 1996 Entomological Society of America Population Ecology nationallicence Lymantria dispar nationallicence Entomophaga maimaiga fungus nationallicence nucleopolyhedrosis virus nationallicence population quality nationallicence population dynamics nationallicence density dependence nationallicence Yerger Ellen H. Department of Entomology, Pennsylvania State University, University Park, PA 16802 aut Rossiter Marycarol Department of Entomology, Pennsylvania State University, University Park, PA 16802 aut Environmental Entomology Oxford University Press 25/5(1996-10-01), 1002-1011 0046-225X 25:5<1002 1996 25 ee https://doi.org/10.1093/ee/25.5.1002 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1093/ee/25.5.1002 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Yerger Ellen H. Department of Entomology, Pennsylvania State University, University Park, PA 16802 aut NATIONALLICENCE 700 1- Rossiter Marycarol Department of Entomology, Pennsylvania State University, University Park, PA 16802 aut NATIONALLICENCE 773 0- Environmental Entomology Oxford University Press 25/5(1996-10-01), 1002-1011 0046-225X 25:5<1002 1996 25 ee Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford