Hybrid vigor in the biological control agent, Longitarsus jacobaeae

Abstract

Hybridization is an important evolutionary mechanism that can increase the fitness and adaptive potential of populations. A growing body of evidence supports its importance as a key factor contributing to rapid evolution in invasive species, but the effects of hybridization have rarely been assessed in intentionally introduced biological control agents. We investigated hybrids between a Swiss and an Italian population of the beetle, Longitarsus jacobaeae, a biological control agent of Jacobaea vulgaris, by reciprocally crossing individuals in the laboratory. Phenological traits of F1 and F2 hybrid lineages showed intermediate values relative to their parental populations, with some maternal influence. Fitness of the F2 generation, measured as lifetime fecundity, was higher than that of the Italian parent in one of the lineages and higher than that of either parent in the other hybrid lineage. The increased fecundity of hybrids may benefit tansy ragwort biological control by increasing the establishment success and facilitating a more rapid population buildup in the early generations. Even though the long-term consequences of hybridization in this and other systems are hard to predict, intentional hybridization may be a useful tool in biological control strategies as it would promote similar microevolutionary processes operating in numerous targeted invasive species.

Multiple introductions and recombination in Cryphonectria hypovirus 1: perspective for a sustainable biological control of chestnut blight

“…Such a beneficial effect can be compared to the positive effect that hybridization can have on the fitness of herbivorous insects used as biocontrol agents (Szucs et al. ) or to the effect of genetic recombination on the adaptive potential of introduced invasive species (Lavergne and Molofsky ; Keller and Taylor ).…”

An evolutionary ecology perspective to address forest pathology challenges of today and tomorrow

“…Genetic analyses of CHV1 populations in western and southern Europe have demonstrated that establishment and spread of the mycovirus are associated with a few recombinant virus lineages (Feau et al 2014). These results, together with the known effect of hybridization on vigor of biological control agents (Szucs et al 2012), the high rate of beneficial recombinations in viruses (Vuillaume et al 2011), and the demonstrated high cost of bacterial resistance in coevolution with multiple phage viruses (Koskella et al 2012) suggest to use several hyperparasite lineages in biological control strategies, especially in areas where releases of hyperparasites have failed until now. Coinfection strategies should be thoroughly studied in experimental systems prior to deployment, since the coexistence of different strains of a mycovirus within one host may not only lead to homologous recombinations but also result in the selection of more virulent strains, with lower transmission efficiency (Frank 1996;Mosquera and Adler 1998). 6 The tree microbiota: a rapidly evolving trait that will allow trees to face anthropogenic environmental change?…”

Population admixture and high larval viability among urban toads

“…First or early-generation hybrids sometimes show outbreeding depression due to a disadvantage in heterozygosity or genetic incompatibility, which leads to lower fitness. However, recent long-term studies on the effect of hybridizations revealed that few strains of hybrid in a population can recover outbreeding depression and produce higher fitness in F2 and later generations than parental (Erickson and Fenster 2006; Hwang et al 2011; Szűcs et al 2012). These are really complicated problems in urban ecology.…”