Performance of  Sirex noctilio ’s biocontrol agent  Deladenus siricidicola , in known and predicted hosts

Nahrung, Helen F.; Ramsden, M.; Hayes, R. Andrew; Francis, Lesley; Griffiths, M.W.

doi:10.1016/j.biocontrol.2016.08.003

Cited by 7 publications

(3 citation statements)

References 28 publications

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“…Parasitism of S. noctilio by D. siricidicola within a tree is subject to influence by several factors such as wood moisture content, competition between A. areolatum and other fungi (Hurley et al 2008, and differential A. areolatum growth in different Pinus spp. or hybrids (Nahrung et al 2016). Consequently, a perfect overlap between the in vitro and in vivo results should not be expected.…”

Section: Discussionmentioning

confidence: 99%

Population variation in traits of Deladenus siricidicola that could influence the biocontrol of Sirex noctilio in South Africa

Mlonyeni

Wingfield

Greeff

et al. 2018

International Journal of Pest Management

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Deladenus siricidicola is the primary biocontrol agent of the invasive woodwasp, Sirex noctilio.The nematode is mass-reared in culture on the S. noctilio symbiotic fungus, A. areolatum, but can also be induced to convert into its infective form in culture. The aim of this study was to explore the level of variation among a collection of D. siricidicola strains to convert into the infective form in culture. In addition, we measured variation in growth of the nematode on a strain of A. areolatum that is commonly used for laboratory rearing. Both traits could influence laboratory rearing and efficiency in the field. The 22 strains from three countries showed significant variation in the frequency of conversion into the infective form in culture. Even genetically uniform strains from South Africa displayed a range of variation in this trait. There was also significant variation in the growth of D. siricidicola on A. areolatum. These results emphasise the importance of considering variation in traits in D. siricidicola that could influence a biological control program. They also provide tools that could be used to screen larger collections of D. siricidicola for variation in traits linked to virulence and reproduction.

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Section: Discussionmentioning

confidence: 99%

Population variation in traits of Deladenus siricidicola that could influence the biocontrol of Sirex noctilio in South Africa

Mlonyeni

Wingfield

Greeff

et al. 2018

International Journal of Pest Management

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“…The impact of tree species for this host/parasite system is not known. However, Nahrung et al (2016) found that tree species can impact performance of D. siricidicola on S. noctilio in Australia. In the present study, the Arkansas sites were in highlands or mountains, and >450 km from the Louisiana site, which was in the south‐central plains.…”

Section: Discussionmentioning

confidence: 99%

Association of the native parasitic nematode Deladenus proximus with individuals and populations of the native woodwasp Sirex nigricornis

Nouhuys

Harris

Stephen

et al. 2022

Agri and Forest Entomology

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Parasitic stages of the North American native dimorphic nematode Deladenus proximus develop within larvae of the native North American siricid Sirex nigricornis and sterilize many of the eggs in adult females. Sirex nigricornis were reared from felled trees or trapped in Arkansas and Louisiana in 2017–2019 and parasitism by D. proximus was evaluated. Deladenus proximus parasitized 0.16–0.43 of S. nigricornis individuals, among sites and years. Parasitized males were smaller than healthy males, and more males were parasitized than females emerging from the same trees. Rate of parasitism increased with increasing S. nigricornis density per tree, and, as per tree density increased, so did the proportion that was male. Egg sterilization (woodwasp eggs killed and inhabited by nematodes) was partial, with an average proportion of 0.66–0.88 woodwasp eggs sterilized by D. proximus per female S. nigricornis, differing significantly by site. As the numbers of eggs in a female increased, the proportion of eggs sterilized declined. Comparing data from this study with others, a trend is reported for variable levels of egg sterilization in Sirex females, with 0 or 100% sterilization often occurring in novel host/parasite associations and partial (averages between 50% and 100%) sterilization occurring when host/parasite associations have co‐evolved.

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“…Variation in populations of A. areolatum found in this study could impact on the Sirex biological control programme in South Africa. Mass production of D. siricidicola depends on A. areolatum , as does the reproduction of the nematode within trees (Nahrung, Ramsden, Hayes, Francis, & Griffiths, ). The strain of the fungus, however, has a major influence on the productivity of D. siricidicola (Morris et al., ).…”

Section: Discussionmentioning

confidence: 99%

Genetic diversity of Amylostereum areolatum, the fungal symbiont of the invasive woodwasp Sirex noctilio in South Africa

et al. 2018

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Amylostereum areolatum is a wood‐decaying homobasidiomycete fungal symbiont of Sirex noctilio. Together, they cause serious damage to pine plantations in the Southern Hemisphere. The fungus reproduces asexually and is vertically transmitted by S. noctilio females, which results in extensive spread of clones. Specific A. areolatum clones are often dominant in areas invaded by the wasp. This is in contrast with the high diversity and complex invasion pattern of S. noctilio in most of these regions. In South Africa, for example, nuclear and mitochondrial ribosomal loci and vegetative compatibility group (VCG) markers on a small number of isolates have shown that only one genotype is present in the country. The aim of this study was to develop microsatellite markers for A. areolatum and determine the genetic diversity and structure of a relatively large collection of isolates of the fungus in South Africa. From five sequenced A. areolatum genomes, a total of 233 microsatellite primer pairs were designed, of which 57 were polymorphic among the genomes. Eleven of these polymorphic markers were then used in a population genetics study including 55 South African isolates. In a surprising manner, nine multilocus genotypes were found among these isolates, and with no population structure among different regions across South Africa. The single VCG previously identified for isolates from the country clearly do not correspond to a clone. The detected A. areolatum variation has relevance for the biology of the Sirex‐Amylostereum symbiosis, its introduction history into South Africa and its management through biocontrol. The microsatellite primers and data emerging from them also provide powerful tools for the study of A. areolatum populations in other parts of the world.

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Performance of Sirex noctilio ’s biocontrol agent Deladenus siricidicola , in known and predicted hosts

Cited by 7 publications

References 28 publications

Population variation in traits of Deladenus siricidicola that could influence the biocontrol of Sirex noctilio in South Africa

Population variation in traits of Deladenus siricidicola that could influence the biocontrol of Sirex noctilio in South Africa

Association of the native parasitic nematode Deladenus proximus with individuals and populations of the native woodwasp Sirex nigricornis

Genetic diversity of Amylostereum areolatum, the fungal symbiont of the invasive woodwasp Sirex noctilio in South Africa

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