Biomass and biodiversity of nocturnal aerial insects in an Adelaide City park and implications for bats (Microchiroptera)

Abstract

Temporal variation of insect communities in urban environments is poorly known and mechanisms driving these changes are unclear, as are the implications for insectivorous predators. We examined the relationships between season and nocturnal aerial insect biomass and biodiversity, and between temperature and insect biomass in the Adelaide zoological gardens from December 2005 to September 2006. We also compared the effectiveness of two insect trap types and used a bat detector to assess bat activity in relation to insect biomass. During the study, 9,939 insects from 13 orders were collected at the Adelaide zoo with a Malaise trap and a light trap. Mass and diversity of insects were highest during warm months, as was bat activity, and bat activity was positively correlated with insect biomass. Winter-active insects consisted predominantly of Diptera and Lepidoptera, which may provide an important winter food resource for insectivorous bats. The Malaise trap attracted fewer insect orders and biomass than did the light trap, and insects congregated within 6 m of artificial lights, so bats that forage at lights may have an advantage in urban areas. A strong need for the inclusion of urban insects to biodiversity inventories exists in the context of bat conservation.

Prey availability and foraging activity of grassland bats in relation to urbanization

“…Among-zone variation in hourly foraging activity of Myotis spp. corresponded to among-zone variation in insect biomass, as expected (Scanlon and Petit 2008). The lack of this relationship for E. fuscus/L.…”

Patterns of Insect Abundance and Distribution in Urban Domestic Gardens in Bangalore, India

“…Urban ecology is a relatively new field of research in most developing countries, and the information available has tended to have a predominant focus on plants [28,37,38]. Yet, it is critical to understand the factors shaping the abundance and diversity of insects, which provide a range of supporting ecosystem functions in urban ecosystems [6,39], support other, insectivorous taxa, such as birds and bats [40], and constitute sensitive indicators of changes in management practices and habitat characteristics impacting overall biodiversity [4].…”

Urbanization affects the trophic structure of arboreal arthropod communities

“…Although assessments of the ecological consequences of urbanization have historically been survey-based, with a strong bias towards vertebrates and dominant plants, there has been a recent shift in focus to determine the responses of terrestrial invertebrates (Nuckols and Connor 1995;Niemelä et al 2002;Clarke et al 2007;Scanlon and Petit 2008) as a means to understanding how urbanization affects ecosystem function. Invertebrate responses to urbanization have been found to be highly variable across taxa and are often linked to disruptions of ecological processes (Hatcher and Ayres 1997;McIntyre and Hostetler 2001;Rickman and Connor 2003;Christie and Hochuli 2009).…”