Host preferences and reproductive performance of the juniper bark beetle, Phloeosinus bicolor (Brulle), on logs from different parts of the bole of indigenous Cupressus sempervirens L. (Cupressaceae) and exotic C. arizonica Greene and C. sempervirens var. atlantica (Gaussen) Silba were experimentally studied in the field and laboratory in Tunisia. Attack densities were around 1/dm2 in the field, fecundity was 10–25 eggs per female's gallery, with a sex ratio close to 1. There was no effect of cypress taxon or log category on host selection or attack parameters (attack density, density of systems, density of galleries, rate of successful attacks), although values for C. sempervirens tended to be higher than those for C. arizonica. Reproductive performance (gallery length and fecundity) was highest in C. arizonica and lowest in C. sempervirens var. atlantica, with C. sempervirens in an intermediate position; egg densities did not differ. Gallery length and fecundity showed a significant linear correlation but were lower in C. sempervirens var. atlantica than in the other two taxa. Thus there seems to be no relationship between host preference and host suitability in P. bicolor: its ability to choose and oviposit in various cypress taxa fits with its polyphagous status.
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1 November 2009
Host Selection and Reproductive Performance of Phloeosinus bicolor (Coleoptera: Curculionidae: Scolytinae) in Indigenous and Exotic Cupressus in Tunisia
Mohamed Lahbib Ben Jamaa,