Long-Term Coexistence of Two Invasive Vespid Wasps in NW Patagonia (Argentina)

In Patagonia (Argentina) two non-native vespid wasps became established in the last decades. Vespula germanica was first detected in 1980 while V. vulgaris arrived some 30 years later. Both species can have a strong negative impact on agriculture, natural environment and on outdoor human activities. Invasion success -the establishment and spread of a species- may be influenced negatively by the degree of interaction with the resident native community, and alien species already present. The sequential arrival of these two wasps allows us to understand key questions of invasion ecology. Additionally, recognizing the outcome of the invasion by vespids in Patagonia -a region lacking native social wasps-, may help plan species-focused mitigation and control strategies. We explored long term species coexistence through the deterministic Lotka-Volterra competition model, using site-specific field data on prey captured (to estimate niche overlap) and current nest densities in sites. Food items carried by workers were similar but there is some degree of segregation. V. germanica nest density in shared sites, and in sites without coexistence, were 3.14 and 3.5 respectively, being higher for V. vulgaris with 4.71 and 5.33. The model predicts stable co-existence of both species in the invaded range, yet a higher abundance of V. vulgaris should be expected. Added to evidence on other foraging behavioral attributes of both wasp species and the invasion patterns observed in other regions, it is likely that the prior presence of V. germanica does not contribute significantly to the biotic resistance of the invaded range for V. vulgaris

Microbiota of an Invasive Wasp Vespula vulgaris and Hymenopteran relatives: Interpreting the microbiome

<p>Invasive species represent a critical threat to ecosystems and ecological communities, causing changes through overwhelming predation as well as competing with native species for resources. Understanding the mechanisms behind invasive success is essential for understanding why they invade and the consequences of their invasions. Furthermore, invasive species, like all macroscopic organisms, harbour symbiotic and pathogenic microbes that constitute their microbiomes, which could explain invasive success. The complex ecological interaction networks within the microbiome can have a positive or negative impact on host abundance and dominance. These interactions may be significant for invasive species, where microbial influences acting on an exotic host can potentially drive the ecological success of an invasive population to the detriment of recipient communities. This thesis explores the microbiota of one of the most globally invasive species, the common wasp Vespula vulgaris, with the overall aim to investigate and characterise the microbiome of V. vulgaris, using metagenomics, bioinformatics and molecular techniques. The initial comparative microbiota study focused on three distinct life stages (larvae, worker and queen), from two ranges. This analysis revealed a core bacteriome community present in V. vulgaris. There was evidence of higher microbial diversity in wasp larvae compared with workers and queens. The Queen (gyne) microbiome revealed a more specific microbiome with absences of certain microbiota found in larvae and workers from the same nest, indicating a more distinctive microbiome. Interestingly, analysis of life stages between ranges showed significant dissimilarity in microbiomes, with microbiota loses, and acquisitions in the introduced New Zealand range. Using the same techniques, the microbiota of V. vulgaris and four hymenopteran hosts (Apis mellifera, Bombus terrestris, Vespula germanica and Linepithema humile), were comparatively analysed. The analysis investigated both shared microbiota and host specific microbiota. This analysis indicated the polyphagous V. vulgaris as having a diverse microbiome varying between nests and sites, indicating less specific microbiota in comparison to other hymenopteran hosts in this study. Vespid wasp colonies are known to occasionally crash in the presence of diseases; however, there is a lack of reliable evidence indicating pathogenic micro-organisms play an essential role in wasp colony dynamics. Incorporating knowledge gained in previous analyses, the next aim was to investigate V. vulgaris nests symptomatic of an infectious agent to discover the cause of pathology. Through molecular techniques, such as Illumina RNA-Seq, PCR and Sanger sequencing, the potential cause of infection and decline of diseased nests was examined. The metatranscriptomic comparison of diseased and healthy larvae highlighted five putative infectious agents. The bacteria Moellerella wisconsensis, Moku virus, Kashmir Bee Virus, Aspergillus and the microsporidian Vavraia culicis floridensis found in infected larvae, potentially causing pathology in the host. The first known instance of Moku virus, and potentially V. culicis floridensis and M. wisconsensis was documented as potential pathogens of V. vulgaris present in New Zealand. To test for potential virulence of these putative infectious agents, an infection study was carried out. Vespula vulgaris nests and larvae were orally infected in the lab using homogenised infected larvae. Subsequently, test and control larvae were sampled to conduct and quantify a time series analysis of infection using RT-qPCR using designed primers. This dissertation provided the first insight into the microbiome of V. vulgaris in the native and introduced range providing a baseline for further research. This analysis and the subsequent microbiota identified may play a role in wasp population dynamics, giving a better understanding of the observed thriving V. vulgaris population dynamics in New Zealand.</p>

Microbiota of an Invasive Wasp Vespula vulgaris and Hymenopteran relatives: Interpreting the microbiome

<p>Invasive species represent a critical threat to ecosystems and ecological communities, causing changes through overwhelming predation as well as competing with native species for resources. Understanding the mechanisms behind invasive success is essential for understanding why they invade and the consequences of their invasions. Furthermore, invasive species, like all macroscopic organisms, harbour symbiotic and pathogenic microbes that constitute their microbiomes, which could explain invasive success. The complex ecological interaction networks within the microbiome can have a positive or negative impact on host abundance and dominance. These interactions may be significant for invasive species, where microbial influences acting on an exotic host can potentially drive the ecological success of an invasive population to the detriment of recipient communities. This thesis explores the microbiota of one of the most globally invasive species, the common wasp Vespula vulgaris, with the overall aim to investigate and characterise the microbiome of V. vulgaris, using metagenomics, bioinformatics and molecular techniques. The initial comparative microbiota study focused on three distinct life stages (larvae, worker and queen), from two ranges. This analysis revealed a core bacteriome community present in V. vulgaris. There was evidence of higher microbial diversity in wasp larvae compared with workers and queens. The Queen (gyne) microbiome revealed a more specific microbiome with absences of certain microbiota found in larvae and workers from the same nest, indicating a more distinctive microbiome. Interestingly, analysis of life stages between ranges showed significant dissimilarity in microbiomes, with microbiota loses, and acquisitions in the introduced New Zealand range. Using the same techniques, the microbiota of V. vulgaris and four hymenopteran hosts (Apis mellifera, Bombus terrestris, Vespula germanica and Linepithema humile), were comparatively analysed. The analysis investigated both shared microbiota and host specific microbiota. This analysis indicated the polyphagous V. vulgaris as having a diverse microbiome varying between nests and sites, indicating less specific microbiota in comparison to other hymenopteran hosts in this study. Vespid wasp colonies are known to occasionally crash in the presence of diseases; however, there is a lack of reliable evidence indicating pathogenic micro-organisms play an essential role in wasp colony dynamics. Incorporating knowledge gained in previous analyses, the next aim was to investigate V. vulgaris nests symptomatic of an infectious agent to discover the cause of pathology. Through molecular techniques, such as Illumina RNA-Seq, PCR and Sanger sequencing, the potential cause of infection and decline of diseased nests was examined. The metatranscriptomic comparison of diseased and healthy larvae highlighted five putative infectious agents. The bacteria Moellerella wisconsensis, Moku virus, Kashmir Bee Virus, Aspergillus and the microsporidian Vavraia culicis floridensis found in infected larvae, potentially causing pathology in the host. The first known instance of Moku virus, and potentially V. culicis floridensis and M. wisconsensis was documented as potential pathogens of V. vulgaris present in New Zealand. To test for potential virulence of these putative infectious agents, an infection study was carried out. Vespula vulgaris nests and larvae were orally infected in the lab using homogenised infected larvae. Subsequently, test and control larvae were sampled to conduct and quantify a time series analysis of infection using RT-qPCR using designed primers. This dissertation provided the first insight into the microbiome of V. vulgaris in the native and introduced range providing a baseline for further research. This analysis and the subsequent microbiota identified may play a role in wasp population dynamics, giving a better understanding of the observed thriving V. vulgaris population dynamics in New Zealand.</p>

Identifying Priorities, Targets, and Actions for the Long-term Social and Ecological Management of Invasive Non-Native Species

Formulating effective management plans for addressing the impacts of invasive non-native species (INNS) requires the definition of clear priorities and tangible targets, and the recognition of the plurality of societal values assigned to these species. These tasks require a multi-disciplinary approach and the involvement of stakeholders. Here, we describe procedures to integrate multiple sources of information to formulate management priorities, targets, and high-level actions for the management of INNS. We follow five good-practice criteria: justified, evidence-informed, actionable, quantifiable, and flexible. We used expert knowledge methods to compile 17 lists of ecological, social, and economic impacts of lodgepole pines (Pinus contorta) and American mink (Neovison vison) in Chile and Argentina, the privet (Ligustrum lucidum) in Argentina, the yellow-jacket wasp (Vespula germanica) in Chile, and grasses (Urochloa brizantha and Urochloa decumbens) in Brazil. INNS plants caused a greater number of impacts than INNS animals, although more socio-economic impacts were listed for INNS animals than for plants. These impacts were ranked according to their magnitude and level of confidence on the information used for the ranking to prioritise impacts and assign them one of four high-level actions—do nothing, monitor, research, and immediate active management. We showed that it is possible to formulate management priorities, targets, and high-level actions for a variety of INNS and with variable levels of available information. This is vital in a world where the problems caused by INNS continue to increase, and there is a parallel growth in the implementation of management plans to deal with them.

Spatio–Environmental Analysis of Vespula germanica Nest Records Explains Slow Invasion in South Africa

Investigating the distributions of invasive species in marginal habitats can give clues to the factors constraining invasive spread. Vespula germanica is the most widely distributed of all the invasive Vespids, which in the Southern Hemisphere typically have large extensive invasive populations. In contrast, the invasion into South Africa has been slow and is still confined to a small geographic area. Here we analyse the distribution of all recent nest records in South Africa (n = 405). The distance to main rivers, mean annual rainfall, summer normalised difference moisture index (NDMI) values, and mean annual temperatures (average, minimum, maximum, and summer maximum temperature) was measured for every nest. We find that value ranges of these variables are different between the value ranges recorded for nests, the general distribution area of the wasp, and the area of absence. Optimised Hot Spot Analysis was used to quantify spatial structure in the measured climatic variables. Generally, factors related to moisture stress set the environmental limits of V. germanica’s landscape distribution. Due to the strong preference of nesting sites close to river courses, for higher rainfall conditions, medium to medium-high NDMI values, and lower mean annual temperatures, it is unlikely that V. germanica will be able to spread uniformly where it is currently found in South Africa.