Host range expansion by British moths onto introduced conifers

Abstract

1. Over 2% of British angiosperm-feeding moths (Lepidoptera) have been recorded feeding on conifers introduced to Britain, and may be undergoing host range expansion.2. We compared some of the life-history traits and ecological characteristics of fifty such species, originally exploiting angiosperms and now recorded feeding on conifers, with those of 400 non-shifting angiosperm-feeding moths, to identify those factors linked with host shifting.3. Shifting species attack a wider range of angiosperms than non-shifting species, their original hosts tend to be woody tress and shrubs, and they hatch from the egg earlier in the year. 4. Comparisons with the random control samples suggest that larval feeding habit and overwintering stage are also important (species with less intimate relations with the host plant, and those overwintering as eggs are more likely to shift); these trends persisted when the taxonomic distribution of the shift species was controlled for, though were no longer significant.5. Moth species in habitats and on host plant families which are associated with conifer afforestation in upland Britain are more likely to shift, suggesting that ecological opportunity is an important factor in host range expansion.

Colonisation of native and exotic conifers by indigenous bark beetles (Coleoptera: Scolytinae) in France

“…Newly introduced conifers are often more colonised than native species but opposite conclusions have been reported as well (Bejer, 1981;Delplanque et al, 1987;Evans, 1987;da Ros et al, 1993;Fraser and Lawton, 1994;Lindelö w and Bjö rkman, 2001;Dalin and Bjö rkman, 2006;Lieutier, 2006;Roques et al, 2006).…”

“…These factors are often linked to plant characteristics: abundance (Neuvonen and Niemelä , 1981), geographical range (Strong, 1974), age of introduction (Kennedy and Southwood, 1984), tree size and structural complexity (Lawton and Schroder, 1977), taxonomical or resource proximity (Ehrlich and Raven, 1964;Connor et al, 1980) and defence mechanisms (Lieutier, 2006). Insect characteristics, such as host specificity (Fraser and Lawton, 1994), the degree of intimacy with the host tree (Lieutier, 2006) and lack of natural enemies (Keane and Crawley, 2002) can also affect host shift ability. Among these different factors, tree taxonomic proximity among natural and novel hosts and insects' host specificity often have a strong influence on insect establishment on new conifer species, with some variations depending on sites and species studied (Evans, 1987;Lindelö w and Bjö rkman, 2001;Dalin and Bjö rkman, 2006;Lieutier, 2006;Roques et al, 2006).…”

Establishment and expansion of a Thaumetopoea pityocampa (Den. & Schiff.) (Lep. Notodontidae) population with a shifted life cycle in a production pine forest, Central-Coastal Portugal

“…Singer et al, 1993;Groman and Pellmyr, 2000;Feder et al, 2003), illustrating the potential for these species to evolve over human time scales. This has economic importance, since many of these insects are economically significant crop pests (Funk et al, 2002), which also imposes problems in forest ecology and management (Baltensweiler et al, 1977;Fraser and Lawton, 1994). These examples are based on host shifts as the driving force in diversification.…”

An old adaptive radiation of forest dung beetles in Madagascar

“…The shift to cattle dung is nonetheless an interesting phenomenon, which has important consequences for the focal species and for the structure of the dung beetle community in open areas in Madagascar, with a mixture of endemic and introduced species. A shift in resource use potentially allows range expansion of species entering enemy and competition free space (Fraser and Lawton, 1994;Murphy, 2004 …”