Multiple invasions of a generalist herbivore-Secondary contact between two divergent lineages of Nezara viridula Linnaeus in Australia

Diversity and distribution of cytochrome oxidase I (COI) haplotypes of the brown marmorated stink bug, Halyomorpha halys Stål (Hemiptera, Pentatomidae), along the eastern front of its invasive range in Eurasia

The arrival, establishment and pest status of Halyomorpha halys in Europe and non-native countries in Asia have been well-documented, with thorough characterisation of the genetic diversity and occurrence of cytochrome oxidase I (COI) haplotypes in Switzerland, France, Hungary, Italy and Greece. However, a number of gaps exist in terms of the characterisation of the haplotype diversity and occurrence of H. halys along the invasion front that covers eastern Europe, western and central Asia. To contribute towards filling this gap, the COI haplotype diversity and distribution were investigated for H. halys collected in Serbia, Ukraine, Russia, Georgia and Kazakhstan. A total of 646 specimens were analysed and five haplotypes were found (H1, H3, H8, H33 and H80). Haplotype H1 was present in all five countries investigated and was the only haplotype detected amongst > 500 specimens collected from Ukraine, Russia and Georgia. H1 (82%) was the dominant haplotype found in Kazakhstan, alongside H3 (18%). In contrast to the low or no diversity observed in these four countries, Serbia had higher haplotype diversity and was represented by five haplotypes. Although H3 was dominant (47%) in Serbia, H1 was also prevalent (40%); the remaining haplotypes (H8, H33 and H80) were minor contributors (1–11%) to the haplotype composition. The results are discussed in context with other known populations in neighbouring countries and patterns of haplotype diversity indicate the movement of successful invasive populations in Europe to generate secondary invasions along the eastern front of the invasion in Eurasia. Possible scenarios regarding the spread of particular haplotypes in these regions are discussed, along with suggestions for future research to fill existing gaps.

Examination of population genetics of the Coconut Rhinoceros Beetle (Oryctes rhinoceros) and the incidence of its biocontrol agent (Oryctes rhinoceros nudivirus) in the South Pacific Islands

Recently, incursions of the Coconut rhinoceros beetle (CRB), Oryctes rhinoceros, have been detected in south Pacific countries that were previously free of the pest. It has been suggested that this range expansion is related to an O. rhinoceros haplotype that is reported to show reduced susceptibility to the well-established classical biocontrol agent, Oryctes rhinoceros nudivirus (OrNV). We investigated O. rhinoceros population genetics and the OrNV status of specimens collected in Fiji, New Caledonia, Papua New Guinea (PNG), Samoa, Solomon Islands, Tonga, Vanuatu and the Philippines. Based on the sequence of the mitochondrial CoxI gene, we found three major mitochondrial haplotype groups (CRB-G, CRB-PNG and CRB-S) across the region. Haplotype diversity varied between and within countries and a high incidence of OrNV infection was detected in all haplotypes wherever they occurred. The O. rhinoceros population in some countries was monotypic and all individuals tested belonged to a single haplotype group. However, in Samoa we detected CRB-S and CRB-PNG and in Solomon Islands we detected all three haplotype groups. Genotyping-by-Sequencing (GBS) showed genetic differentiation in the O. rhinoceros nuclear genome across populations on different islands and provided evidence for gene flow, resulting in a well-mixed population, despite the presence of different CoxI haplotypes in Solomon Islands. Evidence of admixture was also detected on both islands of Samoa. The current CoxI based method is not a reliable diagnostic marker for phenotypic traits, especially in countries such as Solomon Islands where the mitochondrial haplotypes have come back into sympatry and are mixed. To identify possible mechanisms of resistance to OrNV, further molecular analyses O. rhinoceros in response to virus infection is required. To improve biological control of O. rhinoceros, such analyses will need to be combined with an improved understanding of the population genetics of the pest and the evolutionary history of OrNV in the region.