Wing Deformities in Monarch Butterflies in New Zealand: The Role of a Parasite and the Climate

Monarch butterflies can be infected by a parasite called OE. Butterflies with OE may not complete their development or, if they do, the adult butterflies might have deformed wings. We found that the proportion of adult butterflies with wing deformities increased further south in New Zealand, where the weather is colder. In contrast, the number of butterflies infected with the OE parasite decreased further to the south. No OE was observed in butterflies from the coldest, southernmost location of Dunedin, while all butterfly samples from the warmest, northernmost site at the top of the North Island were infected. The OE parasite seems to vary on a north-south gradient, with more OE in the north and less in the south. Our analysis showed that being parasitised by OE did not mean butterflies were more likely to have wing deformities. We think that the colder temperatures in the south of the country limit the development of the OE parasite and independently cause the wing deformities seen in the adult butterflies

Invasion success and management strategies for social vespula wasps

Three species of Vespula have become invasive in Australia, Hawailsquoi, New Zealand, and North and South America and continue to spread. These social wasp species can achieve high nest densities, and their behavioral plasticity has led to substantial impacts on recipient communities. Ecologically, they affect all trophic levels, restructuring communities and altering resource flows. Economically, their main negative effect is associated with pollination and the apicultural industry. Climate change is likely to exacerbate their impacts in many regions. Introduced Vespula spp. likely experience some degree of enemy release from predators or parasites, although they are exposed to a wide range of microbial pathogens in both their native and introduced range. Toxic baits have been significantly improved over the last decade, enabling effective landscape-level control. Although investigated extensively, no effective biological control agents have yet been found. Emerging technologies such as gene drives are under consideration

A citizen science project reveals contrasting latitudinal gradients of wing deformity and parasite infection of monarch butterflies in New Zealand

1. Host–parasite interactions represent complex relationships among species, often with considerable spatial variation. We examined latitudinal variation in the prevalence of monarch butterfly (Danaus plexippus) infection by the protozoan parasite Ophryocystis elektroscirrha via a citizen science project in New Zealand. Parasitism by O. elektroscirrha can result in incomplete development causing mortality, or adult butterflies with deformed wings and reduced fitness. 2. We established the existence of counter-latitudinal clines of wing deformities and parasite prevalence in monarchs, which in New Zealand are non-migratory. The prevalence of wing deformities increased with increasing latitude, whereas the prevalence of parasite infections decreased with increasing latitude. No parasitism was observed in our highest latitudinal location, while all butterfly samples were infected in the warmest and lowest latitudinal site. The prevalence of parasitism or wing deformity did not vary with the butterfly sex. 3. Cold temperatures appear to independently affect the parasite and host butterfly development, with lower temperatures limiting parasite development and inducing wing deformities in butterflies. Other protozoan parasites display similar latitudinal clines that are thought to be temperature related. 4. Environmental factors appear to independently influence insect populations through different mechanistic pathways. The high prevalence of parasite infections may affect butterfly fitness in warmer regions, but the cooler conditions at higher latitudes manifest as a major fitness cost, deformed wings. Monarch butterflies in New Zealand and around the world may perform better where it is not too hot (and optimal for these parasites), but not cold (where the pupae experience developmental issues)

Bioclimatic modelling identifies suitable habitat for the establishment of the invasive european paper wasp (Hymenoptera: Vespidae) across the southern hemisphere

Species distribution models (SDMs) are tools used by ecologists to help predict the spread of invasive species. Information provided by these models can help direct conservation and biosecurity efforts by highlighting areas likely to contain species of interest. In this study, two models were created to investigate the potential range expansion of Polistes dominula Christ (Hymenoptera: Vespidae) in the southern hemisphere. This palearctic species has spread to invade North and South America, South Africa, Australia, and more recently New Zealand. Using the BIOCLIM and MAXENT modelling methods, regions that were suitable for P. dominula were identified based on climate data across four regions in the southern hemisphere. In South America areas of central Chile, eastern Argentina, parts of Uruguay, and southern Brazil were identified as climatically suitable for the establishment of P. dominula. Similarly, southern parts of South Africa and Australia were identified by the model to be suitable as well as much of the North Island and east of the South Island of New Zealand. Based on outputs from both models, significant range expansion by P. dominula is possible across its more southern invaded ranges

Genetic strain diversity of multi-host RNA viruses that infect a wide range of pollinators and associates is shaped by geographic origins

Emerging viruses have caused concerns about pollinator population declines, as multi-host RNA viruses may pose a health threat to pollinators and associated arthropods. In order to understand the ecology and impact these viruses have, we studied their host range and determined to what extent host and spatial variation affect strain diversity. Firstly, we used RT-PCR to screen pollinators and associates, including honey bees (Apis mellifera) and invasive Argentine ants (Linepithema humile), for virus presence and replication. We tested for the black queen cell virus (BQCV), deformed wing virus (DWV), and Kashmir bee virus (KBV) that were initially detected in bees, and the two recently discovered Linepithema humile bunya-like virus 1 (LhuBLV1) and Moku virus (MKV). DWV, KBV, and MKV were detected and replicated in a wide range of hosts and commonly co-infected hymenopterans. Secondly, we placed KBV and DWV in a global phylogeny with sequences from various countries and hosts to determine the association of geographic origin and host with shared ancestry. Both phylogenies showed strong geographic rather than host-specific clustering, suggesting frequent inter-species virus transmission. Transmission routes between hosts are largely unknown. Nonetheless, avoiding the introduction of non-native species and diseased pollinators appears important to limit spill overs and disease emergence

Gut microbial communities and pathogens infection in New Zealand bumble bees (Bombus terrestris, Linnaeus, 1758)

The gut microbiome is an important component of bee health. Previous research around the globe indicated that bee gut microbiome can be affected by the presence of pathogens. We surveyed for the presence of three specific pathogens in populations of the buff-tailed bumble bee, Bombus terrestris (Linnaeus, 1758), across New Zealand. The pathogen Crithidia bombi was the most prevalent and widespread pathogen across the studied sites, with prevalence ranging from 30 to 100% of the bees examined. Nosema bombi was, however, only found in North Island sites. The Deformed wing virus was detected in bumble bees at all the sites except one (Twizel in the South Island) with prevalence ranging from 0 to 60%. The B. terrestris gut microbiome and the associated pathogens from two contrasting locations were studied. Bacteria such as Snodgrassella alvi and Lactobacillales were observed. We also found that infections with C. bombi were associated with more diverse, distinct gut microbiome perhaps indicating disruptions of gut microbe communities that contribute to impair bumble bees’ health

Novel biotechnologies for eradicating wasps: seeking Māori studies students’ perspectives with Q method

© 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. Aligned with the New Zealand government’s ‘Predator-Free 2050’ target for Aotearoa New Zealand, National Science Challenge: Our Biological Heritage supports research into five distinct ‘novel biotechnological controls’ of exotic wasps. A framing question within this project is which controls are considered ‘socially acceptable’ and thus suitable for further development to control and potentially eradicate introduced wasps? How can the public answer this question without first engaging with complex technologies? Can they develop and express an informed view that still reflects their ‘gut’ reactions and unique positions? To model and explore the views of an ‘informed public’, university students in Māori studies engaged in reflection, writing and mapping activities; choice and ranking exercises; Q Method; and focus group interviews. Amongst the interviewees, Q Method analysis distinguished three ‘factors’, describing unique viewpoints: those who see the potential of biotechnologies, those who are in doubt about them and those in a position of trust in scientists. Overall, the group see potential in new biotechnologies for wasps but are wary of political, economic and social decision-making mechanisms

The management and financial implications of variable responses to grapevine leafroll disease

© 2021, Società Italiana di Patologia Vegetale (S.I.Pa.V.). Grapevine leafroll-associated virus 3 (GLRaV-3) is a worldwide pathogen of Vitis negatively affecting wine production. In red berry cultivars grown in New Zealand, the foliar changes to GLRaV-3-infected vines inform decisions on vine removal (roguing). However, roguing does not always contain GLRaV-3 spread in the presence of an insect vector like the mealybug, Pseudococcus calceolariae. Virus incidence and mealybug abundance data collected annually over 7 years were modelled under differing scenarios to ascertain support for roguing. In a simulated 1 ha vineyard planted in 2500 mature Merlot vines, simulations over 20 years evaluated the effectiveness of roguing, ‘rogue 1 + 2’ (concurrent roguing of symptomatic plus both within-row neighbouring vines), inefficient roguing (50% of symptomatic vines rogued), and ‘no-action’. The model used variable initial GLRaV-3 incidence (0.4, 5, 10, 15 and 20%), and low, median and high vector densities (6, 26 and 75 mealybugs per 100 vine leaves, respectively). Roguing was the optimal response to GLRaV-3, independent of the initial incidence, but results were vector density dependent. At a low vector density, roguing relative to the other responses tested, sustained the lowest annual GLRaV-3 incidence, the least need to plant replacement vines and the lowest estimated average annual costs plus loss of income. At median and high vector densities, roguing remained the most favourable response but virus control was less effective and the costs incurred were higher. Thus, for vineyards affected by GLRaV-3, achieving economic sustainability relies on integrating efficient roguing with effective vector management

Population genetics of the invasive wasp Vespula germanica in South Africa

The German wasp (Vespula germanica) is a highly successful invader on a global scale. These wasps were first observed in the Western Cape region in South Africa in 1972, and they have the potential to expand their range and cause significant damage to the native biodiversity. Our study used nuclear (DNA microsatellites) and mitochondrial DNA (mtDNA) from 42 wasp colonies to analyse the population genetics of V. germanica in their invaded South African range. We sequenced three mitochondrial genes; cytochrome c oxidase I, cytochrome b and cytochrome c oxidase II. We found six mtDNA haplotypes present in South Africa. Although only a single fertilized queen is sufficient for the establishment of a wasp nest, the probability of a single introduced queen to successfully establish a nest and a population is very small. If multiple queens were introduced at the same time, the probability for more than one haplotype being transferred to the new population increases. Therefore, the true number of queen introductions occurred in South Africa can be inferred to be between two and six. We examined nine microsatellite loci and found weak-to-no genetic sub-structuring, likely due to high dispersal rates. We concluded that German wasps in South Africa maintain a homogenous population with movement of individuals between localities

Gene silencing for invasive paper wasp management: Synthesized dsRNA can modify gene expression but did not affect mortality

Invasive paper wasps such as Polistes dominula are a major pest and problem for biodiversity around the globe. Safe and highly targeted methods for the control of these and other social wasp populations are needed. We attempted to identify potentially-lethal gene targets that could be used on adult paper wasps in a gene silencing or RNA interference (RNAi) approach. Double-stranded RNA (dsRNA) was designed to target genes for which silencing has proven lethal in other insects. dsRNA was provided either orally to foragers or directly injected into the wasps. We also provided the dsRNA unprotected or protected from degradation by gut nucleases in two different forms (lipofectamine and carbon quantum dots). The effects of oral delivery of 22 different gene targets to forager wasps was evaluated. The expression of five different genes was successfully reduced following dsRNA ingestion or injection. These gene targets included the FACT complex subunit spt16 (DRE4) and RNA-binding protein fusilli (FUSILLI), both of which have been previously shown to have potential as lethal targets for pest control in other insects. However, we found no evidence of significant increases in adult wasp mortality following ingestion or injection of dsRNA for these genes when compared with control treatments in our experiments. The methods we used to protect the dsRNA from digestive degradation altered gene expression but similarly did not influence wasp mortality. Our results indicate that while many of the same gene targets can be silenced and induce mortality in other insects, dsRNA and RNAi approaches may not be useful for paper wasp control