Degradative succession of the insects in small rodents in subtropical systems

We evaluated the insect succession in small rodent carcasses on the soil extracts (surface vs. buried) in two areas (riparian vs. agricultural) and two seasonal periods (spring vs. summer). Daily, the rodent carcasses were weighed and the insects present were collected in them for counting and family level identification. We also measured the air and soil temperature daily, in addition to the physical and chemical characteristics of the soil. The total of 11,059 individuals from 28 taxa was collected. The most abundant taxa were Calliphoridae (70%), Formicidae (20%), Muscidae (2%), and Sarcophagidae (2%). Insect richness was higher in spring in riparian vegetation areas; however, decomposition and insect abundance were greater in spring in agricultural areas by the high temperature measured. Vespidae, Sarcophagidae, Muscidae, and Calliphoridae decreased over time with abundance peaks respectively at 3, 7, 7, and 8 days in riparian vegetation areas. Calliphoridae decreased abundance over time with a peak at five days, but Armadillidiidae increased with peak at 6-9 days in agricultural areas. Decay and insect abundance was high in agricultural areas, mainly on the soil surface. Insect richness was high in riparian vegetation areas, especially on the soil surface. Only the superficial layers of soil presented taxon indicators and all decreased over time with abundance peaks of Calliphoridae, Sarcophagidae, and Muscidae at 5-8, 7, and 7 days, respectively. This abundance peak of insect families help to understand the degradative succession of the insect community in small rodents in subtropical systems of the neotropical region.

Activity Pattern and Correlation between Bat and Insect Abundance at Wind Turbines in South Sweden

We present data on species composition and activity of bats during two years at three different wind- turbines, located in south Sweden, both at the base and nacelle height. To test the hypothesis that bats are attracted to wind turbines because of feeding opportunities, insects were sampled at nacelle height at one wind turbine using a suction trap, simultaneously as bat activity were measured. At this wind turbine, we also compared two different technical systems for ultrasound recordings and collect meteorological data. The variation in bat activity was high between nights and between wind turbines. In addition to the expected open-air foraging species (Pipistrellus, Nyctalus, Vespertilio and Eptesicus), some individuals of unexpected species (Myotis, Barbastella, and Plecotus) were found at nacelle height. There was a weak but significant positive relation between bat activity and insect abundance, so the hypothesis could not be rejected, suggesting there might be other factors than insect abundance explaining the frequency of bat visits at the nacelle. We found a strong correlation between bat passes and weather conditions. A reasonable way to mitigate collisions is with stop-regulation. However, this study highlights some of the problems with defining the limits for stop-regulation based on weather conditions.

Effect of Indoor Climate and Habitat Change on Museum Insects during COVID-19 Closures

COVID-19 spread globally and, as there was little immunity, quarantine, isolation, and social distancing became widely practiced. As people were restricted to their homes in many countries, public venues, such as museums, galleries, and historic houses, were typically closed. This allowed insect abundance, under changed conditions, to be explored using traps from the Technical Museum, Schönbrunn Palace, Hofburg Museum, and Weltmuseum in Vienna. The trap contents reveal an increase in Lepisma saccharinum, the common silverfish, as well as in the Zygentoma Ctenolepisma longicaudatum and C. calvum at some museums. Other insects such as Tineola bisselliella, Anthrenus verbasci, and Attagenus smirnovi, though found in reasonable numbers, did not increase. Museum interiors were likely a little cooler and drier during lockdown, but this difference is too small to explain the increased silverfish activity. The larger rooms were certainly quieter, which allowed insects freedom to range more widely. Nevertheless, museums did not observe increased damage to collections from the larger numbers. The infestations during the closures suggest a need for low level cleaning and regular inspections, with an initial focus examining those areas frequented by insects in the past.

Citizen Science for Quantification of Insect Abundance on Windshields of Cars Across Two Continents

The abundance and the diversity of insects in Europe have declined considerably during recent decades, while it remains unclear whether similar changes may also have occurred elsewhere. Here we used citizen science for quantifying the abundance of flying insects on windshields of cars across Europe and to a smaller extent in China. We used the abundance of insects killed against windshields of cars during 3,530 transects for a total distance of 83,019 km made by 50 observers as estimates of insect abundance. A total of 124,606 insects were recorded, or approximately 1.5 insect per km. The abundance of insects killed against windshields was highly repeatable among days for the same locality, showing consistent estimates of abundance. The main determinants of insect abundance were features of cars (driving speed and car model that can be considered noise of no biological significance), local weather (temperature, cloud cover and wind speed) and variation across the season and the day. We tested for differences in the abundance of flying insects killed on windshields of cars predicting and finding (1) a reduction in insect abundance in areas with ionizing radiation at Chernobyl compared to uncontaminated control sites in the neighborhood, (2) a reduction in the abundance of flying insects in Western compared to Eastern Europe, (3) a reduction in the abundance of flying insects killed on windshields from southern to northern Europe compared to latitudinal samples of insects from southern to northern China, and (4) a difference in abundance of insects killed on windshields of cars in Spain with a significant interaction between Spain and Denmark. Thus a number of abiotic and biotic factors accounted for temporal and spatial heterogeneity in abundance of insects, providing a useful tool for monitoring and studying determinants of spatial and temporal patterns of insect abundance. This also implies that our estimate of insect abundance may be relevant for the study of competition and for interactions at higher trophic levels.

Enhancement of the Diversity of Pollinators and Beneficial Insects in Intensively Managed Vineyards

(1) Modern, intensive agricultural practices have been attributed to the loss of insect biodiversity and abundance in agroecosystems for the last 80 years. The aim of this work is to test whether there are statistically significant differences in insect abundance between different zones and over time on the vineyard field. (2) The study was carried out in five intensive wine farms in Spain over a three-year period (2013–2015). Each field was divided into two zones, one where cover plants were planted, and another remained unchanged (without cover). (3) A clear trend to increase the average number of insect species and individuals throughout the years in all farms was observed. Moreover, the zones with cover plants showed a significant difference with respect to the zones without. (4) The use of permanent cover plants allows creating areas of refuge for the insects favouring their conservation and reducing the agriculture impact in the insect decline.

Seasonal prey availability and diet composition of Lesser Asiatic Yellow House Bat Scotophilus kuhlii Leach, 1821

Diet is an important factor in understanding bat ecology and conservation. This study assessed seasonal prey availability and diet composition of the Asiatic Lesser Yellow House Bat Scotophilus kuhlii in various districts of Uttar Pradesh between January 2016 to December 2018. Fecal and insect samples were collected seasonally using sweep nets between 1800 and 1900 h. From each location 20 fecal pellets were selected for analysis and searched for taxonomically recognizable remnants. The analysis revealed that S. kuhlii fed on Coleoptera, Diptera, Hymenoptera, Isoptera, Orthoptera, Odonata, Blattodae, Lepidoptera, and Hemiptera, identified from legs, antennae and wings/elytra in fecal pellets. Seasonal variation in the presence of isolated insect remnants and insect abundance at foraging grounds was observed. Thus S. kuhlii is a voracious feeder and plays an important role as a pest control agent.

Taxon-specific temporal shifts in pollinating insects in mass-flowering crops and field margins in Ireland

In intensively cropped agricultural landscapes, the vegetation in edges and hedges (henceforth “field margins”) represents an important semi-natural habitat providing fundamental resources for insect pollinators. We surveyed the pollinating insects associated with two mass-flowering crops, apple and oilseed rape, and compared the insect fauna of the main crop with that in the field margins in the grass-dominated agricultural landscapes of Ireland. Different insect groups responded differently to the presence of the flowering crop, with honey and bumble bees more abundant in crops than margins during crop flowering, but more hover flies and butterflies in margins throughout. The composition of the insect assemblage also shifted over time due to taxon-specific changes in abundance. For example, solitary bees were most abundant early in the season, whereas hover flies peaked, and butterflies declined, in mid-summer. The temporal shift in insect community structure was associated with parallel changes in the field margin flora, and, although we found no relationship between insect abundance and abundance of field margin flowers, Bombus abundance and total insect abundance were positively correlated with floral diversity. After the crop flowering period, floral abundance and diversity was maintained via margin plants, but by late summer, floral resources declined. Our results confirm the importance of field margins for insect pollinators of entomophilous crops set within grass-dominated landscapes, even during the crop flowering period, and provide additional support for agri-environment schemes that protect and/or improve field margin biodiversity. The results also demonstrate that although shifts in insect and plant communities may be linked phenologically there may not always be simple relationships between insect and floral abundance and richness.

What is happening to insect numbers, and what does it mean?

Reports of declines in abundance of a number of insect species have been increasing over the last two decades. These have variously been attributed to climate change, urbanisation, deforestation, agricultural intensification, habitat fragmentation and pesticide usage. The picture has been complicated by the fact that not all insect groups have shown the drastic declines reported for others, flawed methodology, paucity of long-term studies, the lack of data from the tropics with most long-term studies emanating from Europe and North America. In addition, the number of insect groups studied has largely been restricted to charismatic species such as Hymenoptera, Lepidoptera, Coleoptera and Odonata. Despite this, the evidence for long-term declines in insect abundance is incontrovertible. To aid in our understanding of the problem we need to set up more globally coordinated studies, use past data in innovative ways and convince policy makers and governments to support these studies.

Landscape and Local Drivers Affecting Flying Insects along Fennel Crops (Foeniculum vulgare, Apiaceae) and Implications for Its Yield

Agricultural landscapes are increasingly characterized by intensification and habitat losses. Landscape composition and configuration are known to mediate insect abundance and richness. In the context of global insect decline, and despite 75% of crops being dependent on insects, there is still a gap of knowledge about the link between pollinators and aromatic crops. Fennel (Foeniculum vulgare) is an aromatic plant cultivated in the South of France for its essential oil, which is of great economic interest. Using pan-traps, we investigated the influence of the surrounding habitats at landscape scale (semi-natural habitat proportion and vicinity, landscape configuration) and local scale agricultural practices (insecticides and patch size) on fennel-flower-visitor abundance and richness, and their subsequent impact on fennel essential oil yield. We found that fennel may to be a generalist plant species. We did not find any effect of intense local management practices on insect abundance and richness. Landscape configuration and proximity to semi-natural habitat were the main drivers of flying insect family richness. This richness positively influenced fennel essential oil yield. Maintaining a complex configuration of patches at the landscape scale is important to sustain insect diversity and crop yield.