Invasive Land Snails of Hawaii National Plant Diagnostic Network Malacology Workshop UC Davis 16-18 June 2015 Kenneth A. Hayes Howard University, Department of Biology Washington, DC Introduction of land snail species in Hawaii 98 introduced land snail species recorded (45 established) Geographical origins of the established Cumulative number of land snail introduced land snail species in Hawaii species introduced to Hawaii Europe (7) Holarctic (3) New World Asia/Australasia (11) (9) Africa (6) Pacific Islands (1) Unknown (1) Christmas trees Recent Interceptions of Cornu aspersum • Maui and Big Island • Texas floral shipment to Safeway, Oahu (Valentine’s Day) • Fencing shipment Hawaii to Oahu Invasive Snails in Hawaii’s nurseries • Number of islands: 6 largest MHI • Number of facilities surveyed: 62 • Number of species recorded: 41 • Number of species at each facility: 1–17 • Number of new species records for Hawaii: 8 Unidentified • Number of new island records: 27 (17 species) philomycid Hayes et al. 2007. Bishop Museum Occasional Papers Cowie et al. 2008. International Journal of Pest Management Hayes et al. 2012. Bishop Museum Occasional Papers Christensen et al. 2014 Bishop Museum Occasional Papers Unidentified charopid 100 of World’s Worst Invasive Species • Non-Marine Molluscs – Giant African Land Snail (Achatina fulica) – Cannibal Snail (Euglandina rosea) – Apple Snail (Pomacea canaliculata) 22% in Hawaii Elevational Distribution of Alien Land Snails in Hawaii’s Nurseries V. cubensis Lamellidea oblonga Achatina fulica 500 m Liardetia doliolum Parmarion martensi Gonaxis sp. Gulella bicolor Allopeas clavulinum Tropical Opeas hannense Paropeas achatinaceum Species Subulina octona Succinea costaricana Succinea tenella Laevicaulis alte Veronicella cubensis Gastrocopta servilis Deroceras laeve Deroceras reticulatum Arion spp. Ovachlamys fulgens Cornu aspersum Allopeas kyotoense Lehmannia valentiana Non- Limacus flavus Limax maximus Tropical Milax gagates Species Polygyra cereolus Euglandina rosea Hawaiia minuscula D. reticulatum Oxychilus alliarius 200 400 600 800 1000 1200 1400 1600 1800 Mann-Whitney U (P = 0.015) Elevation (m) Most Widespread Alien Land Snails V. cubensis Lamellidea oblonga P. achatinaceum Achatina fulica 500 m Liardetia doliolum Parmarion martensi Gonaxis sp. Gulella bicolor Allopeas clavulinum Tropical Opeas hannense Paropeas achatinaceum Species Subulina octona Succinea costaricana Succinea tenella Laevicaulis alte Veronicella cubensis Gastrocopta servilis Deroceras laeve Deroceras reticulatum Arion spp. Ovachlamys fulgens Cornu aspersum D. laeve Allopeas kyotoense Lehmannia valentiana Non- Limacus flavus Limax maximus Tropical Milax gagates Species Polygyra cereolus Euglandina rosea O. alliarius Hawaiia minuscula Oxychilus alliarius 200 400 600 800 1000 1200 1400 1600 1800 Elevation (m) Snail Assemblages in Hawaii’s Nurseries (high vs. low elevation sites) H = High elevation H H (> 500 m) L = Low elevation L L (< 500 m) L HH L L L H H L H H L L LL L H H H L LL HH H L L H L L L L H H L L L H H H L L L H L L L H MDS ordination of sites based on Bray-Curtis similarity values; Stress: 0.13 ANOSIM; P < 0.001 Invasive “slugs” Limacidae • Laevicaulis alte Veronicellidae • Veronicella cubensis • Deroceras laeve • Deroceras reticulatum Agriolimacidae • Arion intermedius • Lehmannia valentiana • Limax flavus • Limax maximus Milacidae • Milax gagates • Meghimatium striatum • Meghimatium bilineatum Philomycidae • Philomycidae sp. Arionidae • Parmarion martensi Ariophantidae Disease Vectors Species No. tested No. (%) positive Non-native species Lissachatina fulica 62 7(11) Cyclotropis sp. 13 1(8) Deroceras reticulatum 61 2(3) Euglandina rosea 39 8(21) Laevicaulis alte 44 13(30) Lehmannia valentiana 11 1(9) Limax maximus 11 3(27) Ovachlamys fulgens 10 1(10) Oxychilus alliarius 69 10(14) Parmarion martensi 19 13(68) Paropeas achatinaceum 73 3(4) Pomacea canaliculata 56 1(2) Subulina octona 54 2(4) Veronicella cubensis 159 4(3) Habitat Restoration - Outplanting Outplanting Infestation V. cubensis S. tenella L. maximus D. laeve Z. arboreus Sanitation Guidelines • Clean and tidy facility – Minimize hiding places for snails • Buffer area (3-4 m wide) • Monitoring • Physical + chemical barriers Decontaminating materials Conclusions • Many alien snails in Hawaii are horticultural pests, vectors of diseases, food source for invasive predators • New species continue to be introduced, resulting in continuing new state and island records • Nurseries may act as a reservoir for invasive snails and slugs Conclusions • Many of these alien species occupy high elevation areas which are the last refugia of many native Hawaiian snails • Preventing the introduction of temperate species should be a high conservation priority on tropical islands • Continued vigilance, ongoing monitoring and impact assessments are needed.