Effects of Host Plant and Larval Density on Intraspecific Competition in Larvae of the Emerald Ash Borer (Coleoptera: Buprestidae)

Abstract

Competition for food, mates, and space among different individuals of the same insect species can affect density-dependent regulation of insect abundance or population dynamics. The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is a serious invasive pest of North American ash (Fraxinus spp.) trees, with its larvae feeding in serpentine galleries between the interface of sapwood and phloem tissues of ash trees. Using artificial infestation of freshly cut logs of green ash (Fraxinus pennsylvanica Marshall) and tropical ash (Fraxinus uhdei [Wenzig] Lingelsh) with a series of egg densities, we evaluated the mechanism and outcome of intraspecific competition in larvae of A. planipennis in relation to larval density and host plant species. Results from our study showed that as the egg densities on each log (1.5-6.5 cm in diameter and 22-25 cm in length) increased from 200 to 1,600 eggs per square meter of surface area, larval survivorship declined from ≍68 to 10% for the green ash logs, and 86 to 55% for tropical ash logs. Accordingly, larval mortality resulting from cannibalism, starvation, or both, significantly increased as egg density increased, and the biomass of surviving larvae significantly decreased on both ash species. When larval density was adjusted to the same level, however, larval mortality from intraspecific competition was significantly higher and mean biomasses of surviving larvae was significantly lower in green ash than in tropical ash. The role of intraspecific competition of A. planipennis larvae in density-dependent regulation of its natural population dynamics is discussed.

Cannibalism among same-aged nymphs of the omnivorous predator Dicyphus errans (Hemiptera: Miridae) is affected by food availability and nymphal density

“…It was signifi cantly longer in the treatment with 8 nymphs, which indicates a more adverse effect of intermediate numbers of nymphs on development. An adverse effect of cannibalism is slower development (Lima, 1998;Chapman et al, 1999;Duan et al, 2013). It is likely that when there are few nymphs (i.e.…”

A new forest pest in Europe: a review of Emerald ash borer (Agrilus planipennis) invasion

“…; Duan et al. ), but also depends on when the eggs were laid during the summer months (Cappaert et al. ; Wang et al.…”

“…Besides climatic parameters, host condition seems also to be important for the duration of the life cycle. Larval development takes longer in healthy or newly infested trees (Tluczek et al 2011;Duan et al 2013), but also depends on when the eggs were laid during the summer months (Cappaert et al 2005;Wang et al 2010a, b). The semivoltine cycle seems to slow down EAB population growth in newly established, low-density populations .…”

Drivers of aggregation in a novel arboreal parasite: the influence of host size and infra-populations

“…In turn, host saturation reduces host quality (Kaplan and Denno, 2007). Infrapopulation size scales negatively with parasite body size in most host-parasite interactions (see Ikeda, 1979;Rankin and Borden, 1991;Poulin, 1999Poulin, , 2007Barber, 2005;Lagrue and Poulin, 2008;Neuhäuser et al, 2010;Duan et al, 2013;Blasco-Costa and Poulin, 2013). We found A. virescens intensity varied remarkably between hosts, ranging from 1 to 19 (median = 2) feeding scars with parasites present.…”