Invasive : Risks and Pathways Project WESTERN

UPDATED: JUNE 2019

Invasive insects are a huge biosecurity challenge. We profile some of the most harmful invaders overseas to show why we must keep them out of .

Species Western yellowjacket / pensylvanica.

Main impacts Reduces native insect populations, competes with pollinating and predatory insects, disrupts pollination. Damages fruit crops; disrupts fruit, timber and honey industries; stings people. Native range Canada, USA, Mexico.1 Invasive range .1

Main pathways of global spread As a contaminant on traded plants and as a stowaway in shipping containers.2 WHAT TO LOOK OUT FOR ENVIRONMENTAL Western are about 1.5 cm long and have a distinctive, complete yellow eye ring around each compound eye. IMPACTS OVERSEAS Photo: Ken Schneider Flickr CC BY-NC 2.0 In Hawaii the western yellowjacket is having dramatic impacts. It preys on a wide range of insects and ‘at virtually zero over the course of the HUMAN AND and can exert very high predation day’6. As well as competing with pressure with perennial hives sometimes for nectar, the prey on them at a ECONOMIC IMPACTS containing more than half a million ‘surprisingly high’ frequency7. Because OVERSEAS wasps (far more than the annual-only yellowjackets thermoregulate, they may In its native range in the western USA the 3 hives in their native range) . In Hawaii attack while the bees are sluggish from western yellowjacket is a serious human 7 Volcanoes and Haleakala national parks, low temperatures . Native bees ( nuisance. Every few years population the yellowjackets depress densities ) and introduced honeybees avoid outbreaks associated with warm, dry 3 by 36% and caterpillar densities by 86% . flowers defended by the wasps, their springs create severe problems for people Endemic picture-wing have also visits to ohia flowers greatly increasing recreating outdoors and harvesting 6 declined. Other insects hunted include when yellowjackets are removed . Native timber and fruit8. People are often stung Nesodynerus crickets, bugs, tipulid flies and bees, all wasps also suffer from when they disturb in houses, in endemic Hawaiian genera, as well as yellowjackets, which compete with them gardens and parks and suffer serious , and cockroaches3,4 (3, 4). 7 for both ohia nectar and caterpillar prey . swelling and blisters8. The wasps gather The native wasps avoid nesting in areas Western yellowjackets are aggressive at picnics and food dispensing facilities to with yellowjacket nests, becoming far ‘nectar thieves’, reducing seed production scavenge sweet foods and meat. They can more common when these nests are by Hawaii’s dominant tree, ohia be serious pests in fruit-growing regions, removed. (Metrosideros polymorpha), by taking its sometimes halting harvesting operations nectar without spreading the pollen, and when workers are stung8. The wasps also by displacing the insects that do provide damage fruit, feeding on grapes and pollination services5,6. The wasps drain the removing the juices, and piercing pears, nectar crop each morning and it remains peaches and other fruits. Several growers

INVASION WATCH: Western yellowjacket in Oregon and Washington have reported losing nearly half their red grape crop8. Beekeepers lose hives to attacks from yellowjackets, which harvest the bees until none remain, and in surviving hives honey harvesting is disrupted by stings8.

AUSTRALIAN CONCERNS Australia already has two invasive Vespula wasps, the European wasp (V. germanica) and the English wasp (V. vulgaris), and the impacts of these are sufficient reason to fear a third. In Tasmania’s highlands they threaten the endangered Ptunarra brown butterfly Oreixenica( ptunarra), which declined when the wasps invaded their habitat, and recovered slightly 9 at sites where wasps were poisoned . Western yellowjackets are aggressive hunters. Here, one has captured a honey . Scientists fear the wasps are the breaking Photo: TJ Gehling | Flickr CC BY-NC-ND 2.0 point for this species9. In one area near Hobart the wasps have greatly reduced all 9. Potter-Craven J, Kirkpatrick JB, McQuillan PB, insects10. They successfully invade native The ohia trees whose nectar it depletes Bell P (2018): The effects of introduced vespid forests11. In , English wasps in Hawaii are in the same family as Australia’s eucalypts, paperbarks and wasps ( and V. vulgaris) are implicated in the decline of common Oreixenica teatrees. Its overseas distribution, on threatened native butterfly ( native birds in New Zealand honeydew ptunarra) populations in Tasmania. Journal of 12 from northern Mexico to Canada and beech forest . Sustained by honeydew Insect Conservation. 22: 521–532. from a scale insect, the wasps in these including Hawaii, suggests that a wide distribution could be achieved in 10. Spradbery J, Maywald G (1992): The forests can achieve a biomass four times distribution of the European or German wasp, Australia. greater than the combined biomass Vespula germanica (f) (, ), of birds and introduced rodents and in Australia – past, present and future. stoats (also predators) and outnumber SOURCES Australian Journal of Zoology. 40: 495–510. native wasps by one or two orders of 11. Matthews RW, Goodisman M a. D, Austin 1. Global Invasive Species Database (2009): 13 AD, Bashford R (2000): The introduced English magnitude . Species profile: . Invasive wasp (L.) (Hymenoptera : Species Specialist Group, IUCN. Retrieved Vespula wasps are pests on Australian Vespidae) newly recorded invading native from http://www.iucngisd.org/gisd/species. fruit farms. A strawberry farmer reported forests in Tasmania. Australian Journal of php?sc=174. losing 20% of his crop, and winegrowers Entomology. 39: 177–179. 14 2. Invasive insects: risks and pathways. have reported losses of 10–25% . 12. Elliott GP, Wilson PR, Taylor RH, Beggs JR Unpublished data (2019): Monash University The wasps also sting fruit pickers and (2010): Declines in common, widespread native and Invasive Species Council. harvesters, and rob commercial beehives birds in a mature temperate forest. Biological and kill bees14. They aggregate in 3. Wilson EE, Mullen LM, Holway DA (2009): Conservation. 143: 2119–2126. history plasticity magnifies the ecological fruit-processing plants and in fruit and 13. Thomas CD, Moller H, Plunkett GM, Harris effects of a social wasp invasion.Proceedings confectionary shops14. They are a serious RJ (1990): The prevalence of introduced of the National Academy of Sciences. 106: Vespula vulgaris wasps in a New Zealand beech concern for the Tasmanian forestry 12809–12813. industry, for they attack and disrupt work forest community. New Zealand Journal of 4. Gambino P (1992): Yellowjacket (Vespula when nests are disturbed by bulldozers Ecology. 13: 63–72. pensylvanica) predation at Hawaii Volcanoes 15 14. Bashford R (2001): The spread and or workers . Backpackers in Southwest and Haleakala national parks: identity of prey impact of the introduced vespine wasps National Park have complained of large items. Proceedings, Hawaiian Entomological 14 Vespula germanica (F.) and Vespula vulgaris numbers of wasps at remote campsites . Society. 31: 157–164. (L.) (Hymenoptera: Vespidae: ) in The two species of Vespula in Australia 5. Hanna C, Foote D, Kremen C (2013): Invasive Tasmania. Australian Entomologist. 28: 1–12. species management restores a plant- to some extent complement each other, 15. Bashford R (2010): Development of an pollinator mutualism in Hawaii. Journal of with European wasps favouring open insecticide baiting system applicable for the Applied Ecology. 50: 147–155. and partly shaded sites and English control of exotic Vespula (Hymenoptera: wasps also occupying shaded forests14. 6. Hanna C, Foote D, Kremen C (2014): Vespidae) wasp species in Tasmanian forestry The arrival of English wasps in Tasmania Competitive impacts of an invasive nectar thief operation sites. Australian Entomologist. 37: on plant–pollinator mutualisms. Ecology. 95: some decades after the appearance of 163–169. 1622–1632. European wasps prompted the comment that the ‘additive effects of the arrival 7. Wilson EE, Holway DA (2010): Multiple mechanisms underlie displacement of solitary ABOUT THIS PROJECT of a second species of social wasp in Hawaiian Hymenoptera by an invasive social The Invasive Insects: Risks and Tasmania will dramatically increase wasp. Ecology. 91: 3294–3302. Pathways Project is a partnership the potential for ecological damage, 8. Akre RD, Greene JF, MacDonald PJ, between Monash University and the Invasive particularly in World Heritage Areas’11. Landolt PJ, Davis HG (1980): Yellowjackets of Species Council. To find out more visit The western yellowjacket would be an America North of Mexico. U.S. Department of invasives.org.au/risks-and-pathways. additional source of ecological harm. Agriculture Handbook No. 552.

INVASION WATCH: Western yellowjacket