Hitchhikers Not on Plant Material

Bill Crowe

Hitchhikers are generally categorized as organisms carried or transported by chance, i.e., unintentionally. Major economic pests are regularly intercepted at quarantine borders around the world, hitchhiking on a variety of goods. The presence of such pests is usually difficult to detect and even harder to predict. Nevertheless, quarantine authorities worldwide are continually searching for better methods of detection, prevention, and/or treatment of hitchhikers. At Australian borders, AQIS regularly intercepts many serious economic pests of plants and animals, including humans. In the following paper I will attempt to highlight several important hitchhikers that are intercepted in quarantine, and provide possible solutions to their detection, prevention, and control.

The majority of insects intercepted hitchhiking on goods entering Australia are stored product pests, such as flour beetles, weevils, grain beetles, etc. Most of these are intercepted in empty shipping containers that contain some form of residue from a previous consignment. The majority of species are now considered to be cosmopolitan in distribution but the question of pesticideـresistant strains still concerns some scientists. However, there are a significant number of other plant and animal pests intercepted hitchhiking on a wide range of goods each year. There have been more than 5,500 invertebrates (mainly insects and snails) found hitchhiking on nonplant products by AQIS since 1995 (current at 1/12/00 - source: AQIS Pest and Disease Interception Database). While many of these are considered to be of a low quarantine risk, there are some serious risk pests (Table 1).

Table 1. Quarantine Hitchhikers on Nonplant Products

The risks associated with these pests varies and depends on a number factors, including relative numbers found, availability of suitable host material at the point of discharge, their stage of development, and their condition. These factors are in turn influenced by variables, such as host commodity and method of import. For example, those found hitchhiking on or in goods imported by airfreight are likely to be in better condition due to their short transit time.

Shipping containers provide a method of transport for many hitchhiking pests, and two surveys have recently been conducted in Australia and New Zealand. Pathogenic species of Fusarium (a fungus found in soil) and two Asian gypsy moth (AGM), (Lymantria dispar L.) egg masses were among the quarantinable contaminants detected during the New Zealand external container survey (Gadgil et. al. 1999, unpublished data). The survey concluded that between 10 and 68% (depending on origin) of containers carried quarantinable contaminants on their outside surfaces. Another survey, conducted by the University of Queensland (Stanaway, et. al. 1996, unpublished data), concentrated on the internal examination of containers. Of the 3,001 containers examined, 7,966 insects were found in 1,166 (39%). The more notable detections included Sirex wasps (Sirex juvencus L. and Urocerus gigas L.), musk beetles (Aromia moschata L.), and several different species of exotic auger beetles (e.g., Heterobostrychus aequalis Waterhouse). Exotic ants, scarab beetles, bees, and moths were also detected. The survey concluded that shipping containers were a high-risk method of introducing exotic pests.

Figure 1. Asian gypsy moth egg mass (in car wheel arch from Japan).

Asian gypsy moth is arguably the number one forest pest likely to enter Australia. The egg masses (Fig. 1) are regularly found by New Zealand quarantine authorities on cars from Japan (66 egg masses found in 1999; 15 viable), ships (8 egg masses on ships from Russia in 1996), and containers (79 egg masses since 1996; 19 viable). Other interesting items that AGM has been intercepted from include used tires, a pallet of ceramic glaze, and a lawn mower (Ken Glassey, personal communication). Other hitchhiking forestry pests intercepted by quarantine officers include white spotted tussock moth (Orgyia thyellina Butler), termites (e.g., in cardboard boxes), burnt pine longhorn beetle (Arhopalus ferus Mulsant) (e.g., on ships, paper, etc.), auger beetles (e.g., in paper) and Monterey pine aphid ( Essigella californica Essig) found in cardboard boxes of avocadoes from New Zealand.

Shipping containers also provide a transportation medium for many different species of snails, some of which are exotic pests of agricultural significance. Giant African snail (Achatina fulica Bowdich) is regularly intercepted hitching a ride on containers, machinery, and decks of ships. Since 1995 it has been intercepted on 227 occasions; mostly on the outsides of containers (current at 1/12/00 - source: AQIS Pest and Disease Interception Database). Many of these interceptions included numerous specimens. Recently, in Gladstone (Queensland) in excess of 120 snails were detected on a container vessel from Popua, New Guinea. Golden apple snail (Pomacea canaliculata) is another pest species that is regularly intercepted on containers. Live aestivating snails are also collected by air passengers for inclusion in shell collections.

Ships also provide a popular mode of transport for many hitchhikers that travel around the world. Some of the more important hitchhikers include, AGM, honey bees (e.g,. Apis cerana Fabricius, A. dorsata Fabricius, and A. mellifera L., vectors of devastating parasitic bee mites; http://www.aqis.gov.au/docs/pr/
ayatqpub7.htm, and burnt pine longhorn beetle. Burnt pine longhorn is regularly intercepted from New Zealand on a variety of goods (ship decks, paper, timber, etc.) during its summer flight season. During the summer months, Australia now demands mandatory preshipment fumigation of all timber from New Zealand ports where the beetle occurs.

Aircraft disinfection procedures appear to take care of many of the insects that blunder into aircraft holds during loading, but some have been found alive when inspections are conducted in Australia and New Zealand. Recently, in Brisbane, giant honey bee (A. dorsata) was found on top of a shrink­wrapped pallet of machinery parts from Malaysia. Asiatic rhino beetle (Oryctes rhinoceros L.), a serious pests of palms, has been found alive in an aircraft hold and also in a polystyrene box containing tissue culture flasks from South East Asia.

Other interesting insect hitchhiking finds include mosquitoes (Aedes albopictus Skuse and Aedes aegypti L. as resistant eggs on machinery), khapra beetle (Trogoderma granarium Everts http://www.aqis.gov.au/docs/pr/ayatqpub4.htm in cardboard boxes, hessian bags, etc.), paper wasps and yellow jackets (on machinery and similar items) and lesser auger beetle (Heterobostrychus aequalis Waterhouse, found in a cardboard box containing a chocolate cake).

A number of strategies may be employed to counteract the risks posed by hitchhikers. These include:

Increased public awareness: Quarantine authorities are unable to check all cargo, so we must educate freight handlers, stevedores, and the general public to recognize the major quarantine pests and report them accordingly. Hitchhikers are regularly found on goods not normally subject to quarantine (e.g., new computers in cardboard boxes). Posters, leaflets, field guides (e.g., Forests and Timber-“A Guide to Exotic Pests and Diseases”, <http://www.aqis.gov.au/docs/border/fieldguide.htm>) are a great way of getting the quarantine message across. This process may be taken one step further to incorporate coregulation activities, where industry groups can become accredited under a quality- assurance arrangement to inspect certain products on behalf of quarantine authorities.

Targeted inspection and surveillance efforts: Concentrate our efforts on proven pest pathways (i.e., high-risk cargo from high-risk origins). This would include trapping and surveillance systems around ports for high-risk pests and pathogens (e.g., in Australia we conduct port surveillance for bees, AGM, snails, mosquitoes, culicoides, and screw worm fly (Chrysomia bezziana Villeneuve, http://www.aqis.gov.au/docs/pr/ayatqpub5.htm).

Preshipment or on-arrival treatments for high-risk goods: In Australia we now require mandatory permethrin treatment of machinery from East Timor capable of holding water. AQIS also requires that timber from New Zealand be fumigated during the flight season of burnt pine longhorn beetle. Aircraft disinfection is another example of a treatment that is employed to mitigate a known hitchhiker risk.