scholarly journals Density-Dependent Recruitment and Diapause in the Spring-Feeding Generation of Hemlock Woolly Adelgid (Hemiptera: Adelgidae) in Western North America

2016 ◽  
Vol 45 (6) ◽  
pp. 1352-1359 ◽  
Author(s):  
Aaron S. Weed ◽  
Joseph S. Elkinton ◽  
Nina K. Lany
Keyword(s):  
North America ◽  
Hemlock Woolly Adelgid ◽  
Western North America ◽  
Density Dependent

EVIDENCE FOR MORTALITY IN ADDITION TO SUCCESSFUL PARASITISM OF NEEDLEMINING LARCH CASEBEARER (LEPIDOPTERA: COLEOPHORIDAE) LARVAE BY AGATHIS PUMILA (RATZ.) (HYMENOPTERA: BRACONIDAE)

1988 ◽  
Vol 120 (11) ◽  
pp. 1035-1036
Author(s):  
R.B. Ryan
Keyword(s):  
North America ◽  
Biological Agents ◽  
Dependent Manner ◽  
Western North America ◽  
Partial Explanation ◽  
Density Dependent ◽  
Coleophora Laricella ◽  
Insect Parasites

In an attempt to control the larch casebearer, Coleophora laricella (Hübner), in western North America with biological agents, insect parasites from Europe and Japan were introduced (Denton 1972, 1979; Ryan et al. 1987). The braconid Agathis pumila (Ratz.) has become widely established and apparently has been responsible for markedly reduced casebearer densities (Ryan 1983, 1986; Ryan et al. 1987). Parasitization by it in many research plots reached 80-95% (unpublished data), then declined following reductions in the casebearer populations in a typically delayed density-dependent manner. I present here a partial explanation for why casebearer densities declined so drastically, to levels even lower than could perhaps be explained by parasitization at such high levels.

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