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

Abstract

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.

Computational Interaction Analysis of Sirex noctilio Odorant-Binding Protein (SnocOBP7) Combined with Female Sex Pheromones and Symbiotic Fungal Volatiles

“…Until now, S. noctilio in China has been distributed mainly in the northeast and parts of Inner Mongolia, which is consistent with the highly suitable area predicted by the CLIMEX model [26]. In countries where invasive S. noctilio colonization has occurred, parasitic wasps and nematodes have achieved good control effects [27]. However, the implementation of biological control is greatly affected by environmental factors.…”

Circumventing regulatory safeguards: Laricobius spp. and biocontrol of the hemlock woolly adelgid

“…The importance of accurate identification of released biocontrol species and avoidance of contamination of cultures with similar species has long been recognised (Rosen, 1986), and appropriate procedures to minimise this risk are well known (e.g., Paterson et al, 2016). Further, inferences about similarities at the genus or species level are giving way to comparisons of important variation in genotypes of biocontrol agents (e.g., Mlonyeni et al, 2018), of their target pests or weeds (e.g., Wardill et al, 2005), of hosts of targeted pests (e.g., Krstin et al, 2017), and at the community level (reviewed in Whitham et al, 2012). Fischer et al (2014) developed a non-lethal mitochondrial DNA, RFLP assay to distinguish and filter L. naganoensis from L. osakensis colonies.…”