Foraging in a pathogen reservoir can lead to local host population extinction: a case study of a Lepidoptera-virus interaction |
| |
Authors: | Andrew Richards Jennifer Cory Martin Speight Trevor Williams |
| |
Institution: | (1) Natural Environment Research Council, Institute of Virology and Environmental Microbiology, Oxford, UK, GB;(2) Department of Zoology, Oxford University, South Parks Road, Oxford, UK, GB |
| |
Abstract: | In 1990, natural infestations of the polyphagous vapourer moth, Orgyia antiqua (Lepidoptera: Lymantriidae) in lodgepole pine plantations in northern Scotland, were studied to ascertain the role of host
foraging behaviour on the prevalence of nucleopolyhedrovirus (NPV; Baculoviridae) infection in the population. Aerial dispersal
of early instar larvae (L1–L3) from the tree canopy onto heather foliage at the forest understorey, with subsequent relocation
back onto the tree as late-instar larvae (L4–L6) appeared to play a significant role in the development of a widespread virus
epizootic in which approximately 80% of L4–L6 individuals succumbed to disease. Bioassays of foliage 1 year later showed that
the distribution of NPV followed a pronounced vertical gradient through the forest canopy culminating in high concentrations
of virus in the forest understorey. Experimental systems comprising potted pine trees positioned above heather bases showed
that NPV infections could be acquired by early stage larvae following dispersal from the tree and feeding on the undercanopy
vegetation, then translocated to the tree component for secondary transmission to susceptible tree-feeding individuals. Behavioural
studies indicated that the tendency for first-, second- and third-instar larvae to disperse to the understorey was probably
not influenced by larval density on the tree but was strongly dependent on larval instar. In contrast, the tendency for larvae
to relocate from the understorey heather to the tree was affected by both larval density and larval instar, suggesting that
both these factors may significantly affect virus acquisition, translocation and transmission in the host population. In the
present study, the heather understorey appeared to act as a pathogen reservoir in which virus could persist between host generations.
Spatial heterogeneity in virus distribution combined with host foraging behaviour (dispersal and feeding) resulted in the
pathogen playing a major role in host population dynamics over an extended time period (3 years). The reservoir theory is
supported by the observation that similar dynamics were not observed in O. antiqua populations at neighbouring sites which lacked understorey food plants.
Received: 8 June 1998 / Accepted: 5 October 1998 |
| |
Keywords: | Nucleopolyhedrovirus Dispersal Foraging Transmission Pathogen reservoir |
本文献已被 SpringerLink 等数据库收录! |
|