Intraspecific variation in the ability ofMicroctonus aethiopoides(Hymenoptera: Braconidae) to parasitiseSitona lepidus(Coleoptera: Curculionidae)

Abstract

Sitona discoideus (Coleoptera: Curculionidae), a pest of lucerne (Medicago sativa), is controlled in New Zealand by the introduced parasitoid Microctonus aethiopoides (Hymenoptera: Braconidae). Unfortunately, a second Sitona species, S. lepidus (=flavescens), which has recently invaded New Zealand and has become a pest of white clover (Trifolium repens), is not parasitised by M. aethiopoides. Previous experiments have shown that New Zealand M. aethiopoides will attack S. lepidus, but its eggs appear to be killed by the host immune response. In contrast, M. aethiopoides has been observed to successfully parasitise S. lepidus in Europe. It is possible either A02010; that New Zealand S. lepidus has a more effective immune response to M. aethiopoides than European S. lepidus, or that New Zealand M. aethiopoides is less able to evade the S. lepidus immune system than European M. aethiopoides. An experiment was conducted to compare the suitability of French and New Zealand S. lepidus as hosts for French M. aethiopoides. This provided no evidence of S. lepidus intraspecific variation in host suitability for parasitism. Furthermore, amplification of inter simple sequence repeat (ISSR) regions of M. aethiopoides DNA demonstrated clear genetic differences between French and New Zealand M. aethiopoides. It was concluded that intraspecific variation in the ability of M. aethiopoides to evade the immune response of S. lepidus is the reason for the low levels of parasitism observed in New Zealand compared with Europe. Development rate data for M. aethiopoides larvae and pupae are reported.

British‐based search for natural enemies of the clover root weevil,Sitona lepidusin Europe

“…The M. aethiopoides collected were able to be continuously laboratory-reared on New Zealand as well as British-sourced populations of S. lepidus. This contrasted with an inability to rear New Zealand M. aethiopoides on New Zealand S. lepidus (Barratt et al 1997) and was consistent with the results of Phillips et al (2002) who demonstrated genetic differentiation between French and New Zealand M. aethiopoides, while finding no difference in host suitability for French M. aethiopoides parasitising French and New Zealand S. lepidus. The different geographical populations of M. aethiopoides were forwarded to New Zealand containment facilities where efforts have continued to maintain genetic diversity (Goldson et al 2001).…”

“…Both are solitary endoparasitoids attacking the adult weevil, and there was initial hope that these parasitoids could be useful in suppressing S. lepidus. However, subsequent experimentation demonstrated that M. aethiopoides and M. hyperodae were ineffective as parasites of New Zealand populations of S. lepidus (Barratt et al 1997); a conclusion further supported by the research of Phillips et al (2002). Consequently, in 1998, a search for suitable agents was commenced in the United States and Europe.…”

Population Genetic Structure of the Grasshopper Eyprepocnemis plorans in the South and East of the Iberian Peninsula

“…In insects, ISSR markers have been employed to characterize different lineages in Bombyx mori [23] and Antheraea mylitta [24], as well as in studies on hybridization [25], genetic diversity [26]–[28], and conservation genetics [29].…”

Virus-like particles in the ovaries of Microctonus aethiopoides Loan (Hymenoptera: Braconidae): Comparison of biotypes from Morocco and Europe

“…so it is not possible to deduce anything about genetic diVerences based on VLPs. Using ampliWcation of inter simple sequence repeat (ISSR) regions of M. aethiopoides DNA, Phillips et al (2002) showed that the degree of genetic diVerentiation between Moroccan and European M. aethiopoides was insuYcient to infer diVerentiation to the extent of species or subspecies. Iline and Phillips (2003) examined allozyme variation between Moroccan and European M. aethiopoides specimens, and of nine enzyme systems and 11 general proteins, only esterase (known to be amongst the most variable of enzmes) was polymorphic in this comparison.…”