Biodiversity Guide - The Intertwine

egional conservation strategybiodiversity guideChapter 5 Fish and Wildlife of the RegionTable 5-2Examples of Exotic Terrestrial Macroinvertebrates of the Greater Portland-Vancouver RegionExotic Crop PestsSpecies or GroupTerrestrial Flatworm, Bipalium sp.;Predator slug, Testacella haliotideaExotic Slugs and SnailsExotic EarthwormsChinese Mantid, Tenodera aridifolia sinensisBedbug, Cimex lectulariusBrown Marmorated Stink Bug, Halyomorpha halysSeed Bugs (e.g., Metapoplax ditomoidesand Raglius alboacuminatus)European Gazelle Beetle, Nebria brevicollisBark and Ambrosia Beetles (e.g., Anisandrus dispar,Scolytus multistriatus, & Scolytus rugulosus)Cabbage White Butterfly, Pieris rapaeCherry Bark Tortrix, Enarmonia formosanaEuropean Crane Flies (Tipula oleracea & T. paludosa)Mosquito, Ochlerotatus japonicusHousefly, Musca domesticaSpotted Wing Drosophila, Drosophila suzukiiExotic Ants (e.g., Odorous House Ant,Tapinoma sessile, and Pavement Ant,Tetramorium caespitum)EffectsEconomic loss; increased pesticide use; introduction of exotic, generalist biocontrol agentsPredators of native and exotic slugs, snails, and earthwormsCrop and ornamental damage, increased pesticide use, competitors of native slugs and snails,vetors of novel pathogens and parasites (affecting vertebrates and humans as well)Change soil structure favoring exotic weeds and detrimental to native earthworms; competitorsof native earthworms; vectors of novel pathogens and parasites of native earthworms; supporthigh populations of exotic and native predators that also eat native earthwormsGeneralist predator of native insects, including beneficials and pollinatorsMajor nuisance, increased pesticide useMajor nuisance pest, is becoming a major crop and ornamental plant pest, increasedpesticide useSignificant nuisance pests, increased pesticide useCompetitor of native carabid beetles, possible novel predator of non-adult stages of threatenedand endangered butterfliesDamage, stress, or kill crop, ornamental, and forest shrubs and trees; increased pesticide usePest of cabbage, lettuce, etc.; increased pesticide useKills orchard and ornamental cherries, plums, etc.; increased pesticide use; costs associatedwith biocontrol implementationCrop, ornamental, and turf damage; increased pesticide useDisease vector, nuisance, increased pesticide useDisease vector, nuisance, increased pesticide useCrop pest increased pesticide useNuisance, crop damage by protecting sap-sucking insects from predators and parasites,competitors of native ants, predators of native soil terrestrial invertebrates, increasedpesticide usePesticidesPesticides, which include insecticides and herbicides,harm invertebrates. Insecticides not onlykill insects outright, but sublethal doses can affecttheir foraging and nesting behaviors. Pesticidesintended for a specific target often harm a host ofother species.Herbicides can kill plants on which insectsdepend, thus reducing the amount of foraging oregg-laying resources. The broadcast applicationof a non-selective herbicide can indiscriminatelyreduce flowers, caterpillar host plants, or nestinghabitat, causing a decline in pollinators and otherinvertebrates.Insecticides are widely used in urban areasthroughout the United States to control bothnative and non-native species. These chemicalsare designed to kill insects and their allies, andthere is little doubt that they have led to significantdecline of both terrestrial and aquaticinsects. Their use should be avoided whereverpossible.Conservation Issues and Threats inAquatic HabitatsPortland’s urban drainages are characterized bystorm-driven runoff patterns, soil erosion andsedimentation, chemical pollutants from lawnfertilizers and pesticides, channelization, and,in some areas, steep eroding banks and generalchannel instability. These influences harminvertebrates through toxicity, reduced oxygenin the water, habitat loss, habitat simplification,and habitat alteration. (For more information, seeChapter 7, “Threats and Challenges”).ChannelizationThe process of channelization destroys pools andriffles, cuts off meanders, reduces stream length,deepens channels, and destroys riparian vegetation.Loss of pools and riffles reduces habitatdiversity for aquatic organisms. Loss of riparianvegetation can increase water temperature, destabilizebanks (thus causing erosion), and affectaquatic invertebrate food resources.DewateringDewatering activities influence rivers and streamsby altering the channel, flow, water temperature,and water chemistry, all of which in turn affectaquatic organisms. Freshwater mussels, which canlive for decades, have been documented in severalurban streams. Dewatering can eliminate entirepopulations of this long-lived invertebrate, evenif the dewatering is for a short period of time forrestoration purposes.SiltationDevelopment reduces water quality for invertebratesin two primary ways: by increasingsedimentation loads during construction and byincreasing flow after storms. Sedimentation canaffect aquatic insect respiration, rendering thehabitat unsuitable for many organisms.Fertilizers and PesticidesThe application of fertilizers and pesticides andtheir subsequent runoff in the greater Portland-Vancouver region is highly destructive to invertebratelife. Chemically polluted streams are generallycharacterized by high densities of midgesand worms and a lack of sensitive species such asstoneflies, mayflies, and caddisflies. In many casesthe volume of pesticides and fertilizers used peracre on urban lawns and gardens is greater thanthat used on agricultural crops.74 75