JOURNAL OF INSECT CONSERVATION

First field-based estimates of bumblebee diapause survival rates showcase high survivorship in the wild
Pugesek G, Thuma JA and Crone EE
Bumblebee ( spp.) queens overwintered in artificial settings tend to have low survival rates, raising concerns that diapause may be a particularly sensitive life cycle stage for this ecologically and economically valuable group of pollinators. However, it remains unclear whether lab-based estimates of diapause survival are comparable to survival rates of natural populations. In this study, we monitored the survival of queens overwintering in the field in Ipswich, MA, and conducted a meta-analysis of studies that estimate queen diapause survival in the lab to compare our field-based estimates of survival to those of lab-based studies. We found that queen had relatively high rates of overwintering survival after about six months (> 60%), especially when compared to estimates of six-month survival from lab studies (< 10%). We also observed a trend that broadly corroborates many lab studies of bumblebees, in that overwinter survival of queens was related to colony origin. In addition to providing the first estimate of diapause survival for bumblebee queens in nature, our study emphasizes the need to verify patterns observed in the lab to field-based studies.
Effects of vineyard inter-row management on the diversity and abundance of plants and surface-dwelling invertebrates in Central Romania
Fiera C, Ulrich W, Popescu D, Bunea CI, Manu M, Nae I, Stan M, Markó B, Urák I, Giurginca A, Penke N, Winter S, Kratschmer S, Buchholz J, Querner P and Zaller JG
Vineyard inter-rows are important biodiversity hotspots within agricultural landscapes, especially when they are covered with vegetation. However, little is known on the effects to management intensity on a broad range of surface-dwelling invertebrates and their interaction with vegetation. We assessed the diversity and activity density of ants, beetles, millipedes, mites, spiders, springtails and woodlice using pitfall traps in vineyards with either high management intensity (HI) consisting of frequently tilled inter-rows or low management intensity (LO) with alternating tillage in every second inter-row. The study was performed in the Târnave wine region in Central Romania. We wanted to know whether, (i) vineyard management intensity affects the diversity of plants and invertebrates, and (ii) local habitat characteristics affect species richness of different functional guilds and taxa. Species richness of some invertebrate taxa (Coleoptera, Araneae, Formicidae) did significantly differ between HI and LO vineyards. Only phytophages (some Coleoptera) increased in species richness and activity density with vegetation cover. Vineyard soil properties (organic matter content, pH, P, and K) did not significantly differ between HI and LO vineyards. We conclude that vineyard inter-row management can affect both the conservation of biodiversity and the provision of biodiversity-driven ecosystem services.
Transfer of invertebrates with hay during restoration operations of extensively managed grasslands in Switzerland
Stöckli A, Slodowicz D, Arlettaz R and Humbert JY
Hay transfer from a speciose donor meadow to a species-poor receiver grassland is an established method to restore species-rich grassland plant communities. However, it has rarely been investigated to which extent invertebrates can be transferred with hay during such operations, which was the aim of this study.
Consistent oviposition preferences of the Duke of Burgundy butterfly over 14 years on a chalk grassland reserve in Bedfordshire, UK
Hayes MP, Ashe-Jepson E, Hitchcock GE, Knock RI, Lucas CBH, Bladon AJ and Turner EC
The Duke of Burgundy butterfly () is known to have specific habitat requirements for its larval foodplants. However, no studies have yet investigated whether these preferences vary over time or in relation to climate, and there is a paucity of data on whether management on reserves can replicate preferred conditions. Here, we build upon existing research to confirm which characteristics Duke of Burgundy prefer for their larval foodplants, whether preferences remain consistent across years, and whether conservation management on reserves can replicate these conditions. Fieldwork was carried out at Totternhoe Quarry Reserve, a chalk grassland site in Bedfordshire, UK. Confirming previous research, we found that large plants in dense patches were chosen for oviposition, but that once chosen there was no preference to lay eggs on a plant's largest leaf. Chosen foodplants were also more sheltered and in closer proximity to scrub than their controls. However, at a finer scale, we found little evidence for any preference based on differences in microclimate, or vegetation height immediately surrounding the plants. This suggests features that alter microclimatic conditions at a larger scale are relatively more important for determining the suitability of oviposition sites. Nearly all preferences remained consistent over time and did not vary between years. Management of scrub on the reserve was able to reproduce some preferred habitat features (high plant density), but not others (large plant size).
The potential for parasite spill-back from commercial bumblebee colonies: a neglected threat to wild bees?
Martin CD, Fountain MT and Brown MJF
Commercially-reared bumblebee colonies provide pollination services to numerous crop species globally. These colonies may harbour parasites which can spill-over to wild bee species. However, the potential for parasites to spread from wild to commercial bumblebees, which could then lead to parasite spill-back, is poorly understood. To investigate this, parasite-free commercial colonies, which are used commercially for strawberry pollination, were placed into seasonal strawberry crops for either 6- or 8-week blocks across two key time periods, early spring and early summer. Bumblebees were removed from colonies weekly and screened for the presence of parasites. In the early spring placement, only one parasite, the highly virulent neogregarine , was detected at a low prevalence (0.46% across all bees screened). In contrast, all colonies placed in the crop in the early summer became infected. A trypanosome, , and were the most prevalent parasites across all samples, reaching peak prevalence in screened bees of 39.39% and 18.18% respectively at the end of the experimental period. The prevalence of was greater than most UK records from wild bumblebees, suggesting that commercial colonies could enhance levels of infection in wild bees through spill-back. Studies on larger geographical scales with different commercial colony densities are required to fully assess spill-back risk. However, seasonal management, to minimise spill-back opportunities, and treatment of commercial colonies to prevent infection, could be implemented to manage the potential risks of parasite spill-back to wild bees. Our results show that commercial bumblebee populations do pick up infections, most likely from wild bees, and that these infections can reach prevalences where they may pose a threat to wild bees via parasite spill-back. More research is required to clarify the extent of this potential threat.
Oviposition behaviour and emergence through time of the small blue butterfly () in a nature reserve in Bedfordshire, UK
Ashe-Jepson E, Bladon AJ, Herbert G, Hitchcock GE, Knock R, Lucas CBH, Luke SH and Turner EC
Climate change affects butterflies in many ways, influencing the timing of emergence and reproduction, habitat preferences, and behaviour. The small blue ( Fuessley, 1775) is highly specialised in its host plant requirements, feeding on the seeds of a single species, kidney vetch (), on which the larvae occur singly to avoid cannibalism. The butterfly is likely to be vulnerable to temperature-related changes in oviposition, adult emergence, and host plant flowering times, and is, therefore, a good model species for investigating climate change-related impacts. Using 26 years of data from the national UK Butterfly Monitoring Scheme (1993-2019) from one nature reserve, and 4 years of targeted egg searches (2006, 2007, 2008, 2020) from three reserves in Bedfordshire, UK, we investigated the effects of local temperature on small blue emergence date and total abundance, whether flowerhead or local environmental characteristics predicted small blue oviposition behaviour, and whether this changed between years. Small blue adults emerged on earlier dates over time, and earlier in years with higher maximum February temperatures. Total adult abundance was not predicted by monthly temperatures or total abundance in the previous year. Oviposition behaviour was broadly consistent across years, with egg presence more likely and egg abundance higher on kidney vetch flowerheads that were taller than the surrounding vegetation, and surrounded by taller vegetation and fewer mature flowerheads. The effect of solar radiation differed between years, with a negative effect on the probability of egg presence in 2007 and 2008, but a positive effect in 2020. Egg abundance per flowerhead was highly variable between years, with 2006 having four times more eggs per flowerhead than other years. This was likely driven by high adult abundance in 2006, which could have increased competition for flowerheads.
Flower plantings promote insect pollinator abundance and wild bee richness in Canadian agricultural landscapes
Van Drunen SG, Linton JE, Kuwahara G and Ryan Norris D
Global declines in pollinator populations are an ongoing concern from biodiversity and food security viewpoints. A growing conservation initiative in agricultural landscapes is the establishment of wildflowers on marginal lands to provide floral resources and habitat for pollinators. However, the effectiveness of such conservation and restoration efforts are not always assessed. We assessed the effectiveness of a private sector pollinator conservation initiative by (1) comparing insect abundance and richness between planted flower plots and control plots and (2) assessing changes between years. Over two years, planted flower plots and control plots (i.e. out-of-production farm areas) located in Canada were surveyed for insects using visual observation, netting, and pan trapping methods. Significantly more pollinators, especially wild bees, and higher wild bee richness were found in planted plots than control plots. Plot size had no effect on insect abundance and richness indicating that even small-scale flower plantings can provide benefits to pollinator communities. While pollinator, predator, and herbivore arthropod abundance and richness were stable or declined between years, likely due to adverse weather conditions in the second year of the study, wild bee abundance and richness increased over the same period. Our results support that flower plantings can be a successful conservation tool to increase pollinator and wild bee abundance and biodiversity within agricultural landscapes.
Floral enhancement of arable field margins increases moth abundance and diversity
Blumgart D, Botham MS, Menéndez R and Bell JR
Moth populations have declined across large parts of north-western Europe since the mid-20th century due, in part, to agricultural intensification. Agri-environment schemes (AES) are widely implemented across Europe to protect biodiversity in agricultural landscapes. Grass field margins enriched with wildflowers typically out-perform grass-only margins in terms of increasing insect abundance and diversity. However, the effect of wildflower enrichment on moths remains largely unstudied. Here, the relative importance of larval hostplants and nectar resources for adult moths within AES field margins are investigated. Two treatments and a control were compared: (i) a plain grass mix, the control, (ii) a grass mix enriched with only moth-pollinated flowers, and (iii) a grass mix enriched with 13 wildflower species. Abundance, species richness and Shannon diversity were up to 1.4, 1.8 and 3.5 times higher, respectively, in the wildflower treatment compared to plain grass. The difference in diversity between treatments became greater in the second year. There was no difference in total abundance, richness or diversity between the plain grass treatment and grass enriched with moth-pollinated flowers. The increase in abundance and diversity in the wildflower treatment was due primarily to the provision of larval hostplants, with nectar provision playing a smaller role. The relative abundance of species whose larval hostplants included sown wildflowers increased in the second year, suggesting colonisation of the new habitat. We show that, at the farm scale, moth diversity can be greatly enhanced and abundance moderately enhanced by sowing diverse wildflower margins, providing these insects with both larval hostplants and floral resources, compared to grass-only margins.
Habitat associations of day-flying Lepidoptera and their foodplants within nature reserves in Bedfordshire, UK
Ashe-Jepson E, Anderson J, Hitchcock GE, Wallis S, Wingader K, Bladon AJ and Turner EC
Species often associate with specific habitat characteristics, resulting in patchy distributions, whereby they only occupy a proportion of available habitat. Understanding which characteristics species require is a valuable tool for informing conservation management. We investigated the associations of eleven species of day-flying Lepidoptera larvae and their foodplants with habitat characteristics within calcareous grassland reserves in Bedfordshire, UK, across two scales relevant to land managers and target species: the reserve (cardinal aspect, vegetation type) and foodplant patch scale (foodplant height and density). We investigated whether ecological traits (habitat specialism, as defined at a national-scale, and overwintering life stage) influenced the strength of associations. At the reserve scale, we found variation in associations with habitat characteristics across species, with species that overwinter at non-adult life stages having more restricted associations, indicating that they may be more vulnerable to environmental change. Associations were generally stronger with vegetation type than aspect, which can be manipulated more easily by land managers. Seven species had similar associations with habitat characteristics to their foodplants, implying that management to benefit foodplants will also benefit larvae. However, the remaining four species had different associations to their foodplants, and may require alternative management approaches. At the foodplant patch scale, four species were associated with foodplant characteristics, which could be used to inform effective fine-scale management.
Hayes MP, Ashe-Jepson E, Hitchcock GE, Clark R, Hellon J, Knock RI, Bladon AJ and Turner EC
Climate change is set to become one of the leading causes of biodiversity loss worldwide, with extreme weather events projected to increase in frequency. Ectothermic animals such as insects are at particular risk, especially when they are isolated and unable to move through the landscape to track suitable climate. To protect such taxa, it is important to understand how they are impacted by extreme weather events and whether management could provide effective microclimate refuges. However, potential management interventions remain untested for many species. Here, we show that the extreme high temperatures experienced in the UK on 19th July 2022 resulted in a community of butterflies becoming inactive, but that shaded areas, including artificial slopes created as part of conservation management for climate change, provided a refuge during this period. Our results indicate that future high temperatures could force butterflies to shelter in the shade, potentially being unable to fly, feed or mate during these periods, with possible long-term impacts, particularly if multiple consecutive high temperature days are experienced.