Oviposition behaviour and emergence through time of the small blue butterfly (Cupido minimus) in a nature reserve in Bedfordshire, UK

Abstract Climate change affects butterflies in many ways, influencing the timing of emergence and reproduction, habitat preferences, and behaviour. The small blue (Cupido minimus Fuessley, 1775) is highly specialised in its host plant requirements, feeding on the seeds of a single species, kidney vetch (Anthyllis vulneraria), 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. Implications for insect conservation Our results indicate that management for greater availability of taller kidney vetch amongst taller vegetation would encourage small blue oviposition on a greater number of flowerheads, providing a possible means of reducing competition and increasing larval survival, and that this would be effective despite variation in adult abundance between years. The high level of competition we observed in the year with the highest adult abundance indicates that higher numbers of host plants should be encouraged to reduce competition and larval cannibalism in peak years, increasing the likelihood of long-term population persistence and growth.

Effects of Adult Biomass and Environmental Conditions on Bigheaded Carp Reproductive Output

Bighead Carp Hypothalmichthys nobilis and Silver Carp Hypothalmichthys moltrix (hereafter collectively referred to as Bigheaded Carp) have spread throughout the majority of the Mississippi River since the 1970s. The current northern invasion edge of Bigheaded Carp in the Upper Mississippi River (UMR) spans between Pools 14 and 20 because of limited passage at Lock and Dam (LD) 19. Mechanisms limiting adult Bigheaded Carp abundance above LD19 are unknown but may be due in part to lack of reproductive success influenced by adult abundance and environmental factors. Our objective was to investigate how relative adult biomass and river temperature and discharge affect maximum annual Bigheaded Carp larval production in the UMR using a Ricker stock-recruitment model. Adult Bigheaded Carp relative biomass (kg/h) was estimated annually with boat electrofishing and larvae were collected every 10 d between May and August 2014–2017 in Pools 14–20 in the UMR. Adult relative biomass ranged from 0.0 to 880.9 kg/h, whereas maximum annual larval densities ranged from 0.0 to 2,869.4 larvae/m3. After accounting for variability among pools and years, the most supported linear Ricker stock-recruitment model indicated the number of recruits per spawner decreased with increasing adult relative biomass and increased with mean discharge. Our results highlight the importance of adult biomass and river discharge conditions for reproduction of Bigheaded Carp along leading edges of invasion. Management strategies that aim to maintain low adult abundance where reproduction is not yet occurring could help limit population increases via reproduction, whereas reducing high adult biomass (e.g., commercial harvest, barriers) may result in greater Bigheaded Carp reproductive output in the UMR.

STRUKTUR KOMUNITAS PARASITOID YANG BERASOSIASI DENGAN PENGOROK DAUN TANAMAN BAWANG MERAH DI BALI

The existence of a type of parasitoid in an area with a certain height is largely determined by several factors, including the physical environment, space, feed sources, the presence of other parasites and human intervention. The purpose of this study was to determine the community structure of parasitoid associated with stone leek leafminer including abundance index, diversity index and dominance index in several locations of onion planting in Bali. Field surveys are conducted regularly during one planting season. On the location of onion plantations with an altitude of<500 m asl, covering the Badung Regency and Gianyar Regencies, on the onion planting area at that location no parasitoid was found (abundance index R1 = 0.00; diversity index H’= 0.00; dominance index D = 0.00). In locations with a height of ≥500-1000 m asl, covering several locations in Tabanan Regency, there were 2 types of parasitoid, Hemiptarsenus varicornis as many 3 adult (abundance index R1 = 0.6213; diversity index H’ = 0.2544; dominance index D = 0.0100) and Opius sp. 22 adult (abundance index R1 = 6.5239; diversity index H’= 0.1125; dominance index D = 0.7700). In locations with an altitude of ≥1000 m asl, covering several locations in Tabanan Regency and Bangli Regency, there were also 2 types of parasitoid namely H. varicornis 5 adult (abundance index R1 = 1.2941; diversity index H’ = 0.3380; dominance index D = 0.0433) and Opius sp. 17 adult (abundance index R1 = 5.1763; diversity index H’= 0.2013; dominance index D = 0.5887).

Damselfly (Odonata: Calopterygidae) Population Decline in an Urbanizing Watershed

Reduction of terrestrial vegetation and degradation of water quality are among the factors driving insect population decline in growing cities. In this study, we investigated the extent of habitat deterioration, behavioral and physiological responses, and fitness of a damselfly [Hetaerina americana (F.)] population in a semitropical region in central Mexico. The study population was located in a riverine area that crosses a small urban area (Tehuixtla city). We related two habitat variables (tree/shrub covered area and numbers of wastewater outlets) to presumable damselfly responses (larval and adult abundance, duration of adults exposed directly to sunlight, lipid content and muscle mass, and egg survival) over the years 2002 and 2016. We detected a reduction in terrestrial vegetation cover, an increase in wastewater outlets, and a decrease in larval and adult abundance. Adults were more exposed to sunlight in 2016 than in 2002 and showed a reduced lipid content and muscle mass in 2016. Egg survival also decreased. Although correlative, these results suggest impairment of damselfly condition (via lipid and muscle reduction) and fitness as urbanization increases.

Microclimate and larval habitat density predict adult Aedes albopictus abundance in urban areas

ABSTRACTThe Asian tiger mosquito, Aedes albopictus, transmits several arboviruses of public health importance, including chikungunya and Zika. Since its introduction to the United States in 1985, the species has invaded over forty states, including temperate areas not previously at risk of Aedes-transmitted arboviruses. Mathematical models incorporate climatic variables in predictions of site-specific Ae. albopictus abundances to identify human populations at risk of disease. However, these models rely on coarse resolutions of environmental data that may not accurately represent the climatic profile experienced by mosquitoes in the field, particularly in climatically-heterogeneous urban areas. In this study, we pair field surveys of larval and adult Ae. albopictus mosquitoes with site-specific microclimate data across a range of land use types to investigate the relationships between microclimate, density of larval habitat, and adult mosquito abundance and determine whether these relationships change across an urban gradient. We find no evidence for a difference in larval habitat density or adult abundance between rural, suburban, and urban land classes. Adult abundance increases with increasing larval habitat density, which itself is dependent on microclimate. Adult abundance is strongly explained by microclimate variables, demonstrating that theoretically derived, lab-parameterized relationships in ectotherm physiology apply to the field. Our results provide support for the continued use of temperature-dependent models to predict Ae. albopictus abundance in urban areas.

Importance of philopatry and hydrodynamics in the recruitment of bioeroding sponges on Indonesian coral reefs

Increasingly frequent large-scale coral mortality events are occurring across the globe, leading to a rise in available reef substrata and promoting an increase in the abundance of other benthic taxa. One such group are bioeroding sponges, which can benefit considerably from reef degradation. However, the occupation of new substrates is partially reliant upon larval recruitment, and currently little is known about the factors affecting bioeroding sponge recruitment. In this study we investigated the potential drivers of bioeroding sponge recruitment using a 2-year deployment of experimental calcareous substrates across seven reefs in the Wakatobi region of Indonesia. Recruitment was observed for five bioeroding sponge species, namely Cliona orientalis, Cliothosa cf. aurivillii, Cliothosa hancocki and two presently unidentified brown clionaids, Cliona aff. viridis sp. A and Cliona aff. viridis sp. B. Recruits were present on 69% of the experimental substrates but had a low mean (±s.e.m.) spatial coverage of just 0.42±0.13%. Total recruitment and species assemblage structure were correlated with local adult abundance, water flow and substrate cues. Our results suggest that any proliferation of bioeroding sponges on newly available substrate following coral mortality is likely to be conditional on local adult abundance and hydrodynamics.

Proceedings of the First International Snakehead Symposium

<em>Abstract.</em>—The U.S. Congress directed the U.S. Fish and Wildlife Service (USFWS) to identify, contain, and eradicate Northern Snakehead <em>Channa argus </em>in the United States. Later, the Mississippi River Basin Panel on Aquatic Nuisance Species requested that the Aquatic Nuisance Species Task Force develop a management plan to include additional snakehead species (Channidae) that are, or have the potential to become, invasive in United States waters. Objectives of the snakehead management and control plan, which was developed by USFWS and collaborators, include developing long-term adaptive management and control methods. We developed a Ricker stock-recruit model using Northern Snakehead population data collected in four northern Virginia tidal tributaries during 2009–2015 to inform management and control efforts. The resulting model functional relationship explained 93% of recruitment variability using adult stock size (mean electrofishing catch/h [CPUE] of adults) and mean river flow during May. Recruitment was quantified using boat electrofishing CPUE of age-2 fish lagged for two years, because age-0 and even age-1 fish did not appear to be fully recruited to the gear. Seventy-six percent of recruitment variation was explained by adult abundance, while an additional 17% was explained by mean river flow during May (inverse relationship). Model predictions indicated management efforts to reduce adult stock size, from the optimum of 2–4 fish/h to <0.5 fish/h, should be the most effective tool to reduce recruitment and resulting adult abundance over the long term. That level of adult abundance (approximately 12% of the mean during 2009–2015) should be the target maximum for Northern Snakehead control efforts in the study areas.

Larval Food Limitation in a Speyeria Butterfly (Nymphalidae): How Many Butterflies Can Be Supported?

For herbivorous insects the importance of larval food plants is obvious, yet the role of host abundance and density in conservation are relatively understudied. Populations of Speyeria butterflies across North America have declined and Speyeria adiaste is an imperiled species endemic to the southern California Coast Ranges. In this paper, we study the link between the food plant Viola purpurea quercetorum and abundance of its herbivore Speyeria adiaste clemencei to better understand the butterfly’s decline and aid in restoration of this and other Speyeria species. To assess the degree to which the larval food plant limits adult abundance of S. a. clemencei in 2013, we compared adult population counts to population size predicted from a Monte Carlo simulation using data for number of V. pur. quercetorum plants, number of leaves per plant, and leaf area per plant, with lab estimates of leaf area consumed to reach pupal stage on the non-native host V. papilionacea. Results indicated an average estimate of 765 pupae (median = 478), with 77% of the distribution being <1000 pupae. However, this was heavily dependent on plant distribution, and accounting for the number of transect segments with sufficient host to support a pupa predicted 371 pupae. The adult population empirical estimate was 227 individuals (95% CI is 146 to 392), which lies near the first quartile of the simulated distribution. These results indicate that the amount of host available to larvae was more closely linked to adult abundance than the amount of host present, especially when considering assumptions of the analyses. The data also indicate that robust populations require host density well in excess of what is eaten by larvae, in combination with appropriate spacing, to mitigate factors such as competition, starvation from leaving host patches, or unrelated to food plant, such as mortality from drought, predators, parasites, or disease.