Alexander Wild (all) Virtual Entomology for Master Naturalists Rivanna Master Naturalists 8 April 2020 Linda S. Fink Duberg Professor of Ecology Sweet Briar College Many of today’s beautiful images were taken by Alex Wild (https:// www.alexanderwild.com/) Goals for Insect Day Understand 1. features that characterize arthropods in general, insects specifically 2. how much variation there is in all aspects of insect biology 3. ecological importance of insects Feel prepared to 4. participate in insect projects as Master Naturalists • children's and school programs • pollinator and foodplant gardening • monitor native insect populations, stream health, exotic insects • measure biodiversity (e.g. bioblitz, NABA butterfly count) • citizen science (e.g. Journey North, Monarch Watch) 5. learn more about insects Structure of the presentation PowerPoint 1. Introduction to arthropods and insects break PowerPoint 2. Why are insects so successful? break PowerPoint 3. The seven largest groups of insects Insects are the dominant multicellular life form on the planet A “species scape” • Number of species • Numbers of individuals • Biomass Why learn about insects? "the insects are so numerous that if they were divided equally among each one of the earth's 6 billion human inhabitants, each of us would be allotted 1 x 1018 insects -- that's a billion billion -- 1,000,000,000,000,000,000." J. Myers, some years ago mayflies locusts monarch butterflies Why learn about insects? Human requirements Agriculture and food production beneficial and harmful Health and disease human, livestock, companion animals, plants Scientific discovery Culture Economics Why learn about insects? Ecological roles pollination phytophagy seed dispersal fungal dispersal nutrient cycling predators and parasites prey Bumblebee buzz pollinating a tomato blossom Peponapis squash bee Andrenid bee on an apple blossom Why learn about insects? Ecological roles pollination phytophagy seed dispersal fungal dispersal stem borer nutrient cycling predators and parasites phyto- plant prey fruit pest phag(o)- eat leaf miner phloem feeder Why learn about insects? Ecological roles pollination phytophagy seed dispersal fungal dispersal nutrient cycling predators and parasites prey But the best reason to study insects is... But the best reason to study insects is... they are amazing Alex Wild But the best reason to study insects is... they are amazing Alex Wild But the best reason to study insects is... they are amazing Alex Wild But the best reason to study insects is... they are amazing Alex Wild 2018 headlines Hallman, C.A. et al. 2017. More than 75 percent decline over 27 years in total flying insect biomass in protected areas. PLoS ONE 12(10): e0185809. Sanchez-Bayo, F. and K.A.G. Wyckhuys. 2019. Worldwide decline of the entomofauna: A review of its drivers. Biol Cons 232: 8-27. F. Sánchez-Bayo, K.A.G. Wyckhuys Proportion of terrestrial insect species in decline or locally extinct A) Terrestrial taxa decline <30% vulnerable endangered exnct 1 0.9 0.8 0.7 0.6 0.5 on of species 0.4 0.3 Propor 0.2 0.1 0 B) Aquac taxa 0.8 Sanchez-Bayo & Wyckhuys. 2019. Biological Conservation 232: 8-27. 0.7 0.6 0.5 exnct 0.4 endangered on of species vulnerable 0.3 decline <30% Propor 0.2 0.1 0.0 Ephemeroptera Odonata Plecoptera Trichoptera Fig. 3. Proportion of insect species in decline or locally extinct according to the IUCN criteria: vulnerable species (> 30% decline), endangered species (> 50% decline) and extinct (not recorded for > 50 years). A) terrestrial taxa; B) aquatic taxa. Davis et al., 2004 ; Kreutzweiser et al., 2007 ). services, but it's unclear to what extent natural ecosystems can sustain While countless insect species are disappearing, few others are oc- their overall ecological resilience (Memmott et al., 2004 ). cupying vacant niches and expanding their distribution. In terrestrial Species extinctions equally impact the overall biomass of entire ecosystems, most of the occupying species are generalists with diverse ecosystems, as insects form the base that supports intricate food webs. ecological preferences (e.g., Bombus impatients, Plusia putnami, Indeed, the essential role that insects play as food items of many ver- Laemostenus terricola and Hippodamia variegata). In aquatic environ- tebrates is often forgotten. Shrews, moles, hedgehogs, anteaters, lizards, ments, species replacement is also mediated by ecological traits such as amphibians, most bats, many birds and fish feed on insects or depend degree of tolerance to pollutants (e.g. Sympetrum striolatum, Brachyptera on them for rearing their offspring. Even if some declining insects might risi and Potamyia flava), with communities thus becoming more uniform be replaced with others, it is difficult to envision how a net drop in and less diverse in composition (Houghton and Holzenthal, 2010). overall insect biomass could be countered. The large declines in insect Species replacement may help retain the delivery of certain ecosystem biomass observed in Europe (Hallmann et al., 2017 ) and Puerto Rico Proportion of declining insect species F. Sánchez-Bayo, K.A.G. Wyckhuys Box Mean line Mild outliers (agriculture) and manufacture goods (industrialisation) at the expense 1 n = 34 n = 11 n = 15 n = 9 of various natural habitats. Among Coleoptera, Lepidoptera and 0.9 Hymenoptera, land-use change and landscape fragmentation is surely the main cause of species declines (Fig. 5), with agricultural conversion 0.8 and intensification for food production listed in 24% of the reports 0.7 (Fig. 6). Urbanisation, by contrast, is reported in 11% of cases, while 0.6 deforestation appears in 9% of reports. 0.5 As agricultural crops comprise about 12% of the total land surface 0.4 on the planet (FAO, 2015), farming directly affects a considerable on of declining species declining of on 0.3 proportion of insect species (Dudley and Alexander, 2017). In Europe 0.2 and North America, the expansion of the agricultural frontier took place fi Propor mostly in the rst half of the 20th century, whereas in South America, 0.1 Africa and Asia occurred mainly in the second half of the century (Foley 0 et al., 2005; Gibbs et al., 2010). In its wake, rare species associated with Europe U.K. N America other pristine ecosystems and natural habitats either retreated or were en- Fig. 4. Proportion of declining insect species in different regions of the world. tirely lost (Grixti et al., 2009; Ollerton et al., 2014). Major insect de- clines occurred, however, when agricultural practices shifted from traditional, low-input farming style to the intensive, industrial scale (Lister and Garcia, 2018) inevitably lead to a starvation of dependent Sanchez-Bayo & Wyckhuys. 2019. production brought about by the Green Revolution (Bambaradeniya vertebrates (Hallmann et al., 2014; Lister andBiological Garcia, Conservation 2018; Poulin 232: 8-27. and Amerasinghe, 2003; Ollerton et al., 2014). The latter practices did et al., 2010; Wickramasinghe et al., 2003). This kind of cascading effect not necessarily involve deforestation or habitat modification (e.g., was first observed with grey partridge (Perdix perdix) populations in grassland conversion, drainage of wetlands) but rather entailed the England since 1952, and was ascribed to reproductive failure. The ul- planting of genetically-uniform monocultures, the recurrent use of timate cause of the partridge collapse was a combined use of in- synthetic fertilisers and pesticides, the removal of hedgerows and trees secticides and herbicides in agricultural land, leading to insufficient in order to facilitate mechanization, and the modification of surface insect numbers to feed the chicks (Potts, 1986). Equally, in the U.K. the waterways to improve irrigation and drainage. Monocultures led to a diversity and abundance of bats in intensive agricultural landscapes is great simplification of insect biodiversity among pollinators, insect considerably lower than on organic farms because of a reduction in natural enemies and nutrient recyclers, and created the suitable con- insect biomass caused by pesticide use in the former settings ditions for agricultural pests to flourish. A quarter of the reports in- (Wickramasinghe et al., 2004), and direct insecticide exposure through dicate these agriculture-related practices as the main driver of insect the bats' prey items (Mispagel et al., 2004; Stahlschmidt and Bruhl, declines in both terrestrial and aquatic ecosystems (Wilcove et al., 2012). 1998). The susceptibility of specialist pollinators to land-use changes (in- 4.1. Drivers of the declines volving loss of floral resources, nesting and hibernation sites), appears to be a determining factor in the decline of many bumblebees and wild A large proportion of studies (49.7%) point to habitat change as the bees (Williams and Osborne, 2009). For specialist ground beetles, the main driver of insect declines, a factor equally implicated in global bird loss of hedgerows and trees likely triggered their decline (Brooks et al., and mammal declines (Chamberlain and Fuller, 2000; Diamond, 1989). 2012). Declines in moths are tied to the fate of their overwintering Next on the list is pollution (25.8%) followed by a variety of biological larval host plants: forbs for species overwintering as larvae, and trees factors (17.6%), whereas few studies (6.9%) indicate climate change as for those overwintering as egg, pupa, or adult. The combined removal triggering the losses (Fig. 5; Table S2). of weeds and trees in intensive agricultural settings may thus explain the decline of moth species overwintering as larvae (Fox, 2013; Mattila 4.1.1. Habitat change et al., 2006; Merckx et al., 2009; Pocock and Jennings, 2008). Con- Habitat change is an immediate consequence of human activities. Its versely, the change from intensive farming to organic farming has led to global pace and scope has been expanding over the past centuries, with increases in abundance and diversity of moths (Taylor and Morecroft, increasing amounts of land being transformed to provide dwellings, 2009), while the abandonment of grazing land has allowed the recovery facilitate transportation and enable tourism (urbanisation), grow food of some common butterflies (Kuussaari et al., 2007).