Demographic processes in the root-borer Agrilus hyperici (Coleoptera: Buprestidae): A biological control agent of St John's wort
Titel:
Demographic processes in the root-borer Agrilus hyperici (Coleoptera: Buprestidae): A biological control agent of St John's wort
Auteur:
Briese, D. T.
Verschenen in:
Biocontrol science and technology
Paginering:
Jaargang 1 (1991) nr. 3 pagina's 195-206
Jaar:
1991
Inhoud:
Oviposition pattern and larval survival of the root-borer Agrilus hyperici, a biological control agent for Hypericum perforatum, were estimated from dissections of the host plant collected at several sites in its native range in southern France. The distribution of eggs per flowering stem was random, though there was evidence of greater attraction to more vigorous plants. This led to greater attack on larger multistemmed plants, better able to support larval development. Survival of the larvae within roots was negatively density dependent and, where there was more than one larva per plant, was positively correlated to root size. Laboratory experiments, conducted at 'summer' temperatures, showed a net reproductive rate of 66.5 eggs per female, produced at a rate of 1-2 per day. Fertility was 77.7%. These results were combined with the field survival data to produce tentative life-tables for A. hyperici at four sites. Generation increases varied from 3.8- to 11.7-fold. A. hyperici was found to have lifehistory characteristics of a K-strategist'; it is adapted to maximizing carrying capacity rather than reproduction. The stability of the A. hyperici-H. perforatum system is discussed in this context.
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