The official USDA response to invasive pest snails: two recent case histories
David G. Robinson Ph.D. USDA APHIS National Malacology Laboratory The Academy of Natural Sciences of Drexel University Philadelphia, PA 19103 USA 1. Introduction
With increased globalization of international trade, the threat of invasive snails and slugs is becoming apparent to most governments in the world (or should be …) In the USA, the responsibility for keeping pests, and animal and plant diseases out of the country rests with the agency: USDA APHIS (United States Department of Agriculture, Animal and Plant Health Inspection Service)
In 1995, the agency began to increase its focus on snail and slug pests, hiring its first malacologist 2. Prevention of pest introduction
Continuing analysis of tens of thousands of interceptions of snails and slugs over the last 20 years, and detailed pathway analysis, indicate the focus of inspections For example, due to high numbers of quarantine-significant snails associated with ceramic tiles and quarry products from Italy (high risk pathway), up to 100% of those containers may be inspected For lower risk pathways, on commodities where snails are rarely found, or from adjacent countries (e.g. México and Canada), only 2-5% are inspected All importation of live snails from abroad requires a permit All interstate movement of live snails requires a permit Illegal importation of snails results in confiscation and/or fines 2. Prevention of introduction (continued)
There are more than 350 airports, seaports, and land border crossings into the country The US Department of Homeland Security employs thousands of inspectors at all entry points into the country
USDA APHIS currently has hundreds of safeguarding officers, as well as specialists in entomology, plant pathology, nematology, and malacology at the 33 largest ports, and operates 17 Plant Inspection Stations at the ports that handle the greatest volume of imports and numbers of passengers
Miami Plant Inspection Station I. Temperate terrestrial snails and slugs
Snails belonging to the family Helicidae are native to Europe and temperate Asia Many species native to the Mediterranean climate are serious pests They are routinely smuggled in air passenger baggage, as well as transported as hitchhikers on containers The best-known is the Brown garden snail, Cornu aspersum (Müller)(= Helix aspersa, Cryptomphalus aspersus, Cantareus aspersus), feeding a wide variety of agricultural crops, including Citrus and grapes Agricultural damage and suppression programs for Cornu aspersum cost $8-12 million annally in California alone California ships plants (and snails) all over the country; Pennsylvania, New Jersey and North Carolina currently have eradication programs for introduced Cornu aspersum Cornu aspersum (Müller) I. Temperate terrestrial snails and slugs (continued)
Snails belong to the families Helicidae, Hygromiidae and Cochlicellidae are native to temperate Eurasia - especially the Mediterranean Basin, often display massing behaviour; potentially they can be introduced into higher altitudes in the tropics Under certain conditions, the massing of immense numbers of these snails can interfere with the cultivation of crops, and more importantly, with their harvest These species may not necessarily be plant feeders; rather their pest status is attributed to their behavior and their staggering reproductive capacity under ideal conditions
Theba pisana and Prietocella barbara on a fence post in South Australia (photo: M. Leyson) Three different species of snail massing on a twig in southern France (photo: J. Copeland) I. Temperate terrestrial snails and slugs (continued)
A white snail - Theba pisana (Müller) (family Helicidae), is considered to be one of the most serious snail pests, in terms of its massing behavior as well as being a voracious plant feeder on numerous economically important crops This is one the most commonly intercepted snail species from the Mediterranean Basin
Theba pisana in South Australia
Theba pisana on wheat stubble Theba pisana on wheat Theba pisana on fence post (photo: M. Leyson) (photo: J. Copeland) (photo: M. Leyson) I. Temperate terrestrial snails and slugs (continued)
Cernuella virgata from Tacoma, Washington (photos: P. Marquez)
Cernuella virgata Cernuella virgata on wheat in South Australia Introduced to Washington (photo: J. Coupland) (eradication in progress), and reported from California (status unknown)
Cernuella virgata (da Costa) (family Hygromiidae), a species that has been introduced into port areas in the state Washington (USA), is considered by Australian authorities as serious a pest as Theba pisana (family Helicidae). Both are called “White snails” and their numbers can reach such high levels as to cause total losses to affected wheat fields during some years in Australia I. Temperate terrestrial snails and slugs (continued)
The Milk Snail (Otala lactea (Müller)) (family Helicidae) is a potential serious pest if it reaches agriculturally-productive areas
Otala lactea massing in Ranchos Palos Otala lactea massing in San Pedro, Los Verdes, Los Angeles County Angeles County (photo: G. Bartman) I. Temperate terrestrial snails and slugs (continued)
Ceramic tiles, at a plant in packed for export, attract numerous snails living in the adjacent waste ground. The snails are drawn into the high humidity environment within the plastic wrapping and under the wooden pallets
A cursory survey (about 20 minutes) at this site yielded 16 quarantine significant snail species
Tiles and quarry products from circum- Medterranean countries represent the principal pathway of pest Helicidae, Hygromiidae and Cochlicellidae into other countries I. Temperate terrestrial snails and slugs (continued)
Many of the larger ports in the United States receive thousands of containers of tiles every year I. Temperate terrestrial snails and slugs (continued)
The US imports 3½ - 4 million metric tons of tiles every year mainly from Italy and Spain, but increasingly from China and Brazil
5-25% of tiles and quarry products are infested with quarantine-significant snails I. Temperate terrestrial snails and slugs (continued)
Slugs (snails with internal shells) are pests of particular concern. In the cooler climates, slugs of European origin are considered to be the most damaging of mollusk pests. The most serious cooler-climate slug pest is the Gray field slug, Deroceras (Agriolimax) reticulatum (Müller)
I. Temperate terrestrial snails and slugs (continued)
The Gray field slug – Deroceras reticulatum Extended length up to 5 cm (photos: P. Marquez (at left) and I. Richling (at right))
The Gray field slug of particular concern in Europe and North America, attacking field corn, causing severe defoliation and stunting, and soybean, causing plant stand reduction I. Temperate terrestrial snails and slugs (continued)
Others slug species affecting lettuce, cabbage, corn, soybean, alfalfa, etc., as well as being serious greenhouse pests:
The Greenhouse slug - Lehmannia valentiana (Férussac) (upper left): extended length up to 7 cm; the Dusky slug – Arion subfuscus Draparnaud) (lower left): extended length up to 7 cm; the Leopard slug – Limax maximus (Linné) (right): extended length up to 20 cm
These European invasive slug species are all well-established in temperate North America II. Tropical and subtropical terrestrial species
The best known tropical snail pests are the giant African snails, four of which are frequently intercepted at U.S. airports and maritime ports
Achatina (Lissachatina) fulica (GAS) from originally East Africa; established southern and eastern Asia, throughout the Indian and Pacific Basins, including Hawaii; South America and the West Indies II. Tropical and subtropical terrestrial species (continued)
The giant African snail (GAS ) - Lissachatina fulica, is routinely confiscated from tourists’ baggage leaving the Hawaiian Islands and increasingly from the Neotropics; it is a serious pest of over 500 economically important plant species worldwide, including agricultural, horticultural and medicinal plants a principal vector of cerebral angiostrongyliasis, affecting humans and livestock an important element of an illegal pet trade
Lissachatina fulica confiscated by SITC in Wisconsin, USA (photo: R. Zimmerman) II. Tropical and subtropical terrestrial species (continued)
Total # # Snails State During 2004 and early 2005, the USDA seizures seized Smuggling Interdiction and Trade Wisconsin 75 1364 Compliance (SITC) unit conducted a giant African snail (GAS ) “blitz”, targeting Michigan 18 1553 illegal breeding and distribution networks Ohio 5 3139 6871 live snails were confiscated and Illinois 8 98 incinerated, plus tens of thousands of eggs destroyed Indiana 5 300
GAS were found in pet stores, swap meets, Pennsylvania 1 170 and schools, as well as private homes Virginia 3 143 Several cases of GAS –vectored angiostrongyliasis were diagnosed because West Virginia 1 102 of the associated with “pet” snails New Jersey 1 1 We are currently involved in a case of Puerto Rico 1 1 smuggled GAS in Hialeah, Florida, for “religious purposes” III. Impact of invasive snails and slugs
Invasive mollusk species have the potential to:
Directly impact agriculture, by destroying the crops through feeding damage
Or by reaching such high numbers as to make the harvest of such crops impossible
Modify and disrupt natural ecosystems, including direct and indirect effects on native species
Raise quarantine issues for agricultural and other exports
Introduce snail-vectored human and livestock diseases, including cerebral and abdominal angiostrongyliasis,
Introduce these diseases to native species and other invasive species that are already present
Laboratory studies indicate that diseases such as those that affect recognized vectors (such as GAS and veronicellid slugs) can be introduced into native snail and slug populations, increasing the threat to Public Health III. Impact of invasive mollusks (continued)
Facilitate the spread of other diseases not normally associated with mollusks For example, large accumulations of dead GAS shells filling with rain water can provide an ideal breeding environment for mosquito larvae – producing more mosquitoes and perhaps facilitating the spread of malaria, dengue fever and yellow fever Plant pathogens such as Phytophtora spp. , not usually associated with molluscs, can also be vectored by snails including GAS
Dead shells along roadside in Barbados (photo: A. Fields) III. Impact of invasive mollusks (continued)
The association of invasive, synanthropic snails and slugs with human habitation brings snails and slugs, if populations are high enough, into direct contact with people Directly impact urban and suburban householders, leaving slime trails, piles of feces and dead, rotting snails in homes and gardens This may also impact tourism
Example: GAS on golf courses, in hotels in hotel gardens, floating dead in swimming pools, etc. in the Antilles Reports of cases of cerebral angiostrongyliasis in tourists and local people in Jamaica and the Hawaiian Islands is of considerable concern to their governments IV. Public Health and Veterinary Perspectives
Several of the invasive species are known to be vectors of a serious disease that affects humans and livestock, including: the giant African snail (GAS ) – Lissachatina fulica the Cuban slug – Veronicella cubensis the Southeast Asian semi-slug – Parmarion martensi the Asian tramp snail – Bradybaena similaris
The disease, known as eosinophilic angiostrongyliasis, is caused by a parasitic nematode worm, Angiostrongylus cantonensis – the Rat Lungworm. It can be contracted by consuming improperly cooked snail meat (in the case of the giant African snail), freshwater crustaceans, or by accidentally ingesting tiny snails, slugs and crustaceans that are infected by the larval cercaria. Infected snails and slugs can also contaminate water supplies with the nematode if they fall into drinking water, drown and decompose. We now understand that the slime of these gastropods left on uncooked fruits and vegetables may also transmit the disease Symptoms include severe headaches, nausea, vomiting, neck stiffness, sensitivity to light and contact, seizures, and neurological abnormalities, lasting several weeks In addition to humans, the disease has also been reported in monkeys, horses, and other livestock. Therefore it has considerable veterinary importance, as well as a public health threat Death can occur in especially healthy young adults Disease prevention relies on handling all snails and slugs with latex gloves, and thorough washing of hands with hot soap and water afterwards IV. Public Health and Veterinary Perspectives (continued)
Watch the video: http://animal.discovery.com/videos/ monsters-inside-me-the-rat- lungworm.html
Source: Centers for Disease Control, Atlanta, Georgia, USA
Infected patients at rural clinic in Ecuador
Angiostrongylias cantonensis V. Control / suppression / eradication (continued)
Current snail eradication and suppression programs in the USA Successful eradication programs Case history No. 1 – Part A
In 1966 GAS was introduced into Miami, Florida in by young boy returning from a holiday in Hawaii, carrying 3 live snails in his baggage The USDA and Florida Department of Agriculture killed 18,000 snails and enumerable eggs; 1973 declared successfully eradicated; 1975 eradication costs determined to be almost $1 million (approximately $3 million in today’s $$’s) V. Control / suppression / eradication (continued)
Introductions into the USA: Lissachatina fulica Case history No. 1 – Part B
In late 2009, a young girl was admitted to hospital suffering from symptoms resembling eosinophilic angiostrongyliasis Interviews with her and her parents indicated she has been taking part in a religious ritual of a “fringe religious group” Members of this group would break the apex of the snails, and drink the body fluids The snails, consisting of two achatinid snails species, Lissachatina fulica and Archachatina marginata, were being kept at the residence of the religious group’s leader All the snails were confiscated, and surrounding properties surveyed for escaped snails, but none were found Case history No. 1 – Part C (or B continued ?)
On 8 September 2011, the USDA was notified by Florida Department of Agriculture of possible Giant African snail (Lissachatina fulica) = “GAS ”
USDA initiated field operations and confirmed the identification of the GAS on 9 September 2011 Initial Response:
Activation of the Incident Command System
elimitation surveys throughout southern Florida, especially in Dade County, where Miami is located
A Cooperative Agreement Established with by Florida Department of Agriculture in order to coordinate all activities and for the Federal USDA to provide funding (Sept-December 2012 of US$ 3 million)
A major Outreach Campaign to the general public, including TV, Radio, newpspapers, blogs, and outreach to all schools in the areas
CAPS surveys are now being conducted throughout the state of Florida Infestation • Miami-Dade County only- Area = 2,431.26 square miles [=6.296,9 km2) • Furthest cores- roughly 30 miles apart [=41,8 km] • As of April 2015- 28 defined cores (27 in Dade County, 1 in Broward) • As of 10 April 2015 - over 156,800 GAS from 666 positive properties, dissected and destroyed • No detections to date at nurseries or stock dealers • One case of disease caused by GAS , but not angiostrongyliasis – disease remains undiagnosed • The USDA maintains phone banks to receive reports of GAS from the general public
Program Coordination • Weekly conference calls with USDA and Florida Department of Agriculture
Outreach to Impacted Areas – Important for core ID • Snail blog • Look For It! Report It! Campaign • Bus signs • Billboards • Radio and newspaper ads • Schools are being encourgaed to participate in the Junior Detective Program” Giant African Land Snail Junior Detectives Junior detectives are partnering with their parents to look for and report giant African land snails! If you are a 5th grader in Miami-Dade County and are interested in more information about becoming a Junior Detective, ask your science teacher about the program. If you are a 5th grade science teacher in Miami-Dade County and are interested in more information about the Junior Detective Program, call 888-397-1517 or contact: Denise Feiber Public Information Director Florida Department of Agriculture and Consumer Services Division of Plant Industry [email protected] 352-395-4779 Dogs trained specifically for detection of GAS in container yards, … and in other environments, including gardens and empty lots an
House-to-house interviews are conducted regularly in all the cores where the Lissachatina fulica is known to be established Outreach (continued) • Legislative & Public Affairs (LPA) • Pest alerts • Identification cards • Posters • Videos • Activity Sheets • Blogs • So far $11 million spent Case history No. 2
Since 2001, the USA has had two infestations of Xerolenta obvia, the “Eastern Heath snail” The species is originally from southeastern Europe, especially Greece, Bulgaria and also in Turkey
It was recently reported as established in the southern third of Scandinavia (T. von Proschwitz pers. com.) It has been established in Canada (the Windsor Peninsula in southern Ontario) since the 1970s in non-agricultural land 4. Control / suppression / eradication (continued)
The first eradication in the USA of Xerolenta obvia In August of 2001, a large population of the southeastern European species of Xerolenta obvia was found in a series of rail yards in the city of Detroit, Michigan As this species is a potential pest of wheat production, the USDA, the Michigan Department of Agriculture and owners of the rail yards agreed to cooperate, and activated the Incident Command System Initial Response: Delimitation surveys were initiated immediately and infested areas identified Molluscicide treatment using iron phosphate and metaldehyde began almost immediately (disturbed area with few or no native species) Where vegetation was thick (in abandoned yards, and along highways, herbicides were applied to remove all food sources for the snails Control / suppression / eradication (continued)
Populations of Xerolenta obvia in the Detroit area, Michigan, currently being eradicated
Eradication programs, using iron phosphate and metaldehyde formulations, have been applied for 9 years , over an area of 45 hectares V. Control / suppression / eradication (continued)
Two current mollusk eradications in the USA of Xerolenta obvia As Montana is the third most important state for wheat production in the USA, the response to the presence of Xerolenta obvia needed to be immediate The infestation was first detected on 28 July 2012, identified 2 days later, and delimitation surveys conduct daily in the infested county and all surrounding counties by federal and state officers Incident Command System activated 10 August 2012
Wheat already harvested is currently being tested for degree of contamination Contaminated hay bales are incinerated
Xerolenta obvia infestation is concentrated along Belt Creek and around the town of Belt, with some outliers along some roads (red, yellow, and green – positive points; blue – negative points)
Extent of infestation 25 miles [= 42,2 km] long, and 6 miles [= 9,66 km] wide at the maximum
The two populations of Xerolenta obvia, in Detroit, Michigan and in Belt Montana, are genetically and morpholoically distinct – these are therefore two separate introductions All points where surveys for Xerolenta obvia have been done as of 31st of August; the infested area may have to be quarantined The use of molluscicides is considered a control method of last resort, due to concerns of the effects to native snails species and to livestock Controlled burns (currently being done in Australia for snail pests) are not feasible in Montana due to the drought affecting the area – already there are many natural fires Mechanical crushing is currently being done along road sides and infested fields, using metal rollers weighing over 23,818 lb [= 10.43 kg] Conclusions
Invasive (non-native) snail and slugs species are a serious and ongoing threat to every country’s food supply, natural environment, native species, and public health Invasive snails and slugs can be serious agricultural pests and disease carriers; however, the presence of native snails are usually indicators of a healthy natural environment and should be protected Invasive species can originate from any climate and usually can adapt to a greater environmental diversity than where they originate from Detection, identification, and official response needs to be immediate and involve federal, state and local authorities with, most importantly, an effective public outreach and involvement Interception, detection, suppression, control, and eradication programs are very costly, but the cost to agriculture, the environment, tourism, and public health is much greater and the damage is irreversible More malacologists need to become involved in agriculture; research and publication about mollusk pests will encourage governments to pay more attention to them, and will provide the funding and jobs Conclusions (continued)
The best “control program” for invasive species is to prevent them from being introduced in the first place !
Theba pisana on wheat stubble Theba pisana on wheat Theba pisana on fence post (photo: M. Leyson) (photo: J. Copeland) (photo: M. Leyson) Theba pisana infestation of wheat in southern Australia Acknowledgements
Richard Hoenisch (WPDB) at U.C. Davis Laurie Morales, Geraldo Gonzalez, Nathan Cotrell, Shi-Yih Hung, Marwan Kharboutli, Eric Johnson, Mark Segall, and George Nash (USDA APHIS PPQ (Texas)) Suzete Gomes, Samanta Singh and Eduardo Colley (USDA National Malacology Laboratory) Eduardo Varona (USDA State Operations Support Office) in Miami, Florida Greg Bartman, Patrick Marquez, William Tang and Frederick Zimmerman (USDA Port Identifiers / Malacology Specialists) Paul Hornby (USDA SPHD Florida) Gary Adams (USDA SPHD Montana) Brian Sullivan (USDA Safeguarding Specialist Detroit, Michigan) Ian Foley, Cam Lay amd Donna Rise (Montana Department of Agriculture) Trevor Smith (Florida DPI) The hundreds of USDA and State agricultural officers involved in the control of pest snails
Lissachatina fulica massing in Saint Lucia Lesser Antilles (photo: D. G. Robinson)