Invasive Species

CISR: Asian Long-horned Beetle

Anonymous — Mon, 20 Jan 2020 21:34:26 +0000

CISR: Asian Long-horned Beetle Anonymous (not verified) Mon, 01/20/2020 - 13:34 More Blog Posts CISR Team May 23, 2009

The Situation: An exotic long-horned beetle was first discovered attacking ornamental trees in New York City and Chicago. Detections of this pest have since been made in most states in the northeastern portion of the United States as well as in California beginning in 1996. Their route of entry into the USA appears to have been in untreated wooden packing crates originating in China. The Asian Long-Horned Beetle (ALB) is native to Asia, where it kills many species of trees, including poplars, maples, elms and mulberries. These beetles are large, conspicuous insects, readily recognized by their horns or antennae.

Damage: Oviposition cavities chewed out by females are found in tree trunk bark and branch junctions, or on the trunk itself. As larvae mature, they enter the heartwood of the tree, destroying the quality of the wood, while feeding by large numbers of beetle larvae can kill trees by girdling them. Adult beetles emerge in the summer through 3/8″ diameter holes in the bark. Sap flows heavily from these large wounds and infested trees are prone to secondary attack by other diseases and insects. This beetle adversely affects the human environment by killing valuable shade and park trees, as well as injuring or even killing forest trees of economic value (e.g., sugar maples in the northeast USA). Structural weakening of trees by tunneling larvae also poses a physical danger to pedestrians and vehicles from falling limbs or trees during wind and/or ice storms.

Economic Impact: The primary impact of ALB has been on street trees in several infected sites. These trees require removal, treatment to destroy all life stages present (e.g., chipping), and replacement, at a cost of several hundred dollars per infestation. If this pest enters a forest ecosystem, the economic impact could be far greater than eradication and containment costs and could adversely impact export markets for various hardwood products such as veneers. For California, the damage to street and park trees could be immense if this pest becomes established in urban areas. California forests could also be severely impacted if this pest were introduced as many native tree species are likely to be vulnerable to attack.

Distribution: This beetle is widely distributed in China, Japan and Korea. It causes severe damage from 21-43½ north latitude and 100-127½ east longitude, especially in wooded populations. In the USA the beetle is well known in the states of New York, New Jersey, and Illinois. In Canada the beetle attacks trees in Toronto and Ontario. However, this beetle has been intercepted widely at warehouse and ports all over the USA and it is likely to continue its continental spread.

Research: Much of the research on this pest has been done outside of the U.S. by scientists in countries that have been experiencing the effects of this pest for a quite a long period of time. Studies on other species of borer beetles could prove useful in dealing with this pest. There has been some research done on the effect of natural enemies, including entomopathogenic nematodes, which could become effective biological control agents of this insect. Studies have also been conducted to find more resistant species of trees that could be used as replacements for infected trees. Improved quarantine methods are needed to halt the immigration of this pest into uninfested areas of the United States (e.g., California).

Research: Much of the research on this pest has been done outside of the U.S. by scientists in countries where ALB is native (e.g., China). Cooperative studies between Chinese scientists and USDA-ARS researchers are ongoing and are focusing in part on finding biological control agents. There has been research on the effect of several kinds of natural enemies on ALB larvae and adults, including entomopathogenic nematodes and fungi, which could be effective biological control agents of this insect if environmental conditions are appropriate. Foreign exploration for parasitoids that attack eggs and larvae of ALB are being conducted in China. Studies have also been conducted to find more resistant species of trees that could be used as replacements for susceptible tree species in urban environments. Improved quarantine methods are needed to halt the accidental movement of this invasive pest into uninfested areas of the United States (e.g., California).

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CISR: The Light Brown Apple Moth

Anonymous — Mon, 20 Jan 2020 21:33:25 +0000

CISR: The Light Brown Apple Moth Anonymous (not verified) Mon, 01/20/2020 - 13:33 More Blog Posts CISR Team May 24, 2009

The Light Brown Apple Moth,

The situation: Light brown apple moth (LBAM) is a tortricid leafroller approximately ¼ inch in length that roll leaves into shelters. LBAM is native to Australia and has established in New Zealand, Hawaii, Ireland, New Caledonia and Great Britain. In March 2007, the presence of LBAM was confirmed in California and shipments of plant material have been restricted from California to other states in the USA and also within California from infested counties where LBAM has been detected to non-infested areas in California. The California Department of Food and Agriculture (CDFA) considers LBAM to be a Class A pest and has implemented an eradication program which primarily involves mating disruption pheromones and insecticide treatments.

Damage: LBAM has been recorded from over 2,000 different types of plants, encompassing 50 plant families. Host plants include deciduous tree fruits, subtropical fruits, berry fruits, ornamentals, and forest and shade trees. LBAM larvae feed on leaves and buds reducing photosynthetic rate, deforming growth patterns, which leads to general plant weakness and disfigurement. In grapes, apples, kiwifruit, plums, avocados, and citrus, LBAM larvae can feed directly on the fruit, and resulting feeding damage renders fruit unmarketable. Because of the economically important effects of larval feeding, LBAM has a high pest status in New Zealand and Australia because of zero tolerance requirements for presence in produce destined for the export markets.

Economic Impact: To date, the LBAM program has spent approximately $70 million in CDFA and USDA funds. If eradication is unsuccessful and LBAM establishes in California, the impact on increased production costs and crop losses for LBAM hosts could be over $133 million per year (as estimated by CDFA). Additionally, quarantine restrictions and export trade barriers will likely be devastating to some commodity industries. For example, Mexico and Canada implemented restrictions on a number of commodities from quarantined California counties in May and June 2007, respectively. Furthermore, LBAM has not established in any of the other states of the continental U.S, outside of California, therefore, other U.S. states would likely impose restrictions on the movement of potentially infested produce from California. These restrictions could severely impact the domestic marketing of California-grown agricultural products.

Distribution: In March 2007, LBAM was found in Alameda County in California. Infestations have since been found in thirteen counties located in California’s Central Coast and Bay Area communities, which are therefore under quarantine: Alameda, Contra Costa, Marin, Monterey, Napa, San Benito, San Francisco, San Mateo, Santa Barbara, Santa Clara, Santa Cruz, Solano and Sonoma.

Research: Foreign exploration efforts for LBAM natural enemies in southeastern Australia (the home range for this pest) commenced in November of 2007. Dr. N. Mills is currently conducting host specificity testing of two Australian parasitoids for potential release in California. Concurrent with this effort, UC and CDFA researchers have been monitoring LBAM populations to identify ongoing parasitism by egg, larval and pupal parasitoids presently occurring in California. It has been determined that LBAM eggs are being parasitized by two species of Trichogramma (Trichogramma fasciatum and Trichogramma platneri ), and larvae are being parasitized by several species of parasitoids. Additional work by Dr. K. Daane (UC Berkeley) is being done to determine what other leafroller species in the region are supporting these larval and pupal parasitoids that are presently parasitizing LBAM.

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CISR: The Glassy-Winged Sharpshooter

Anonymous — Mon, 20 Jan 2020 21:32:46 +0000

CISR: The Glassy-Winged Sharpshooter Anonymous (not verified) Mon, 01/20/2020 - 13:32 More Blog Posts CISR Team May 25, 2009

The Situation: The glassy-winged sharpshooter (GWSS), likely introduced from the southeastern U.S. as eggs on nursery stock, was first observed in Orange and Ventura counties in California in 1989. It has a large plant-host range and is especially abundant on citrus.

Damage: GWSS feeds on plants through straw-like mouthparts inserted into the xylem tissue which conducts water throughout the plant. Because nutrients are diluted in xylem fluid, GWSS must process large volumes to meet nutritional needs. Thus, this pest produces copious amounts of watery excreta and are a social nuisance as the liquid rains down from large populations feeding on ornamental trees. In infested citrus orchards, tree canopies take on a white-washed appearance by mid-summer due to the buildup of residues after the evaporation of this watery excreta. Even more important is the capacity for the GWSS to acquire and spread a plant pathogenic bacterium, Xylella fastidiosa. Different strains of this bacterium induce severe diseases in many agricultural and ornamental plants. The best known of these maladies is Pierce’s disease of grapevines. In southern California, GWSS spreads the Pierce’s disease bacterium and a new strain of X. fastidiosa that induces a lethal disease of oleander named oleander leaf scorch. Other crops at risk include almonds (almond leaf scorch), and alfalfa (alfalfa dwarf), which are infected by the same strain of X.f. that induces Pierce’s disease, and potentially other ornamental and fruit trees.

Economic Impact: Currently, GWSS is responsible for outbreaks of Pierce’s disease in several wine-grape growing areas of California, including Temecula, Bakersfield, Ontario, and Coachella. In ornamental horticulture, an important part of the landscape in the southwest will be lost if oleander leaf scorch continues to spread and resistant oleander varieties are not found. Oleander is found in 20% of all home gardens in California, and is a mainstay of landscapes in shopping centers, parks and golf courses. The California Department of Transportation (Caltrans) maintains oleander in over 2,100 miles of freeway median. It is estimated that Caltrans alone stands to suffer at least a $52 million loss if oleander on highway plantings is lost. In the city of Tustin (Orange County), approximately $200,000 was requisitioned to pay for removal of oleanders maintained on city greenbelts and for replanting other ornamental species. Another huge economic problem lies in the transport of ornamentals by wholesale nurseries as this industry is subjected to rigorous inspections and mandatory insecticide applications to minimize the accidental shipment of GWSS into uninfested areas of California.

Distribution: Since its initial introduction, the numbers of GWSS and associated problems have increased as the insect spreads throughout southern California. The GWSS can now be found in high populations in areas of San Diego, Orange, Riverside, San Bernardino, Los Angeles, Ventura, Kern and Santa Barbara counties. GWSS has successfully invaded French Polynesia (1999), Hawaii (2004), Easter Island (2005), and the Cook Islands (2007).

Research: At the University of California on the Riverside, Davis and Berkeley campuses, and at the county level through Cooperative Extension, research is under way to manage GWSS population densities and curtail the potential devastation of GWSS-spread diseases. Studies are aimed at developing better detection methods for the pathogens and reducing vector pressure in affected areas by managing pathogen and vector source hosts. In addition, efforts are concentrating on providing short-term strategies to slow the spread of these diseases while long-term solutions are developed. Short-term strategies include the use of systemic insecticides and behavior modifiers that disrupt acquisition and transmission of the pathogen by GWSS. Long term solutions involve the introduction of biological control agents that attack the eggs of GWSS, techniques that insert genes into host plants that confer resistance or tolerance to X. fastidosa, or other xylem-limited bacteria that interfere with the pathogen’s reproduction, movement, and vector transmission.

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CISR: Blue Gum Galling Wasp

Anonymous — Mon, 20 Jan 2020 21:32:07 +0000

CISR: Blue Gum Galling Wasp Anonymous (not verified) Mon, 01/20/2020 - 13:32 More Blog Posts CISR Team May 26, 2009

The Situation: Since 1850, eucalyptus trees of >90 species have been imported as seed from Australia into California for a wide range of ornamental and other uses. Eucalyptus are now an ubiquitous plant in urban areas in southern California, and these plants are becoming increasingly more common in California’s natural areas too where some species are considered to be invasive weeds. In urban areas, these native Australian trees are valued for their fast growth and tolerance of poor soils and drought. Consequently, eucalyptus is considered by many a valuable landscape, shade, and windbreak tree. For more than a century, these species remained virtually pest free. However, beginning in the 1980s, a series of eucalyptus-feeding insects invaded the region, beginning with the borer Phoracantha semipunctata (Coleoptera: Cerambycidae), which was first detected in California in 1984. Since then about 15 other species of eucalypt herbivores have invaded California, including another Phoracantha species (in 1995), the leaf feeding weevil Gonipterus scutellatus (in 1994), the chrysomelid leaf beetle Trachymela sloanei (in 1998), and at least six species of psyllids, including the blue gum psyllid (Ctenarytaina eucalypti) and two lerp physllids (Glycaspsis brimblecombei and Eucalyptolyma maideni).

Selitrichodes globulus is thought to be native to Australia, although it has not been found in this country. Other species of gall forming eulophids native to Australia have successfully invaded other areas of the world in addition to California. For example, Ophelimus maskellioccurs naturally on Eucalyptus in New South Wales, Australia and is an invasive species in the Mediterranean region. Heavy galling of leaves by O. maskelli results in premature shedding of the leaves. The impact of high wasp populations on the canopy of Eucalyptus in Israel is very serious, and heavily damaged trees exhibit desiccation throughout large parts of their crowns. The adult galling wasps cause health problems to people during mass emergence from galls. Industrial areas surrounded by ornamental eucalyptus trees produce clouds of wasps during peak emergence periods and can be a human nuisance. A biological control program against O. maskelli in Israel has been conducted using a parasitic wasp, Closterocerus chamaeleon, and it appears to be providing good levels of control. It is possible that in Australia natural enemies of S. globulus exist and these could be used in a biological control program against this pest in California.

Damage: In November 2008, in Monrovia Los Angeles County, California, a homeowner discovered unusual gall like growths on branches of a backyard blue gum (Eucalyptus globulus complex). Additional infestations were found in Arcadia in Los Angeles County. This pest appears to be quite host specific, having only been recorded from blue gum eucalyptus. Ironically, this host specificity may lend itself to possible biological control of invasive blue gums, particularly in sensitive wilderness areas where these plants are not wanted.

Examination of these galls by County Entomologists revealed the presence of small internally feeding larvae which were responsible for the observed damage. Larvae were being reared to adulthood to confirm the association of adult galling wasps with observed galls. The life cycle of this pest may take up to five months to complete. Initial identifications tentatively placed with this wasp in the genus Ophelimus, but this identification was changed by specialists who work on this group of insects who recognized it as a species new to science. It is likely that in the absence of host specific natural enemies S. globulus will spread quickly throughout California and may cause considerable damage to vulnerable eucalyptus species. It is possible that this pest may invade other countries, such as Bolivia, China, Colombia, Ethiopia, India, Peru and Spain which grow blue gums commercially for fuelwood, pulpwood, and eucalyptus oil.

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CISR: Asian Citrus Psyllid

Anonymous — Mon, 20 Jan 2020 21:31:31 +0000

CISR: Asian Citrus Psyllid Anonymous (not verified) Mon, 01/20/2020 - 13:31 More Blog Posts CISR Team May 26, 2009

The Situation: Asian citrus psyllid (ACP) is an efficient vector of the bacterial citrus disease huanglongbing (HLB), previously called citrus greening disease, which is one of the most destructive diseases of citrus worldwide. In the United States, the psyllid vector is found in Florida, Mexico, Louisiana, Georgia, South Carolina, Cuba, Belize and the Yucatan peninsula of Mexico. A federal quarantine restricts all movement of citrus and Rutaceae from into California in order to prevent introduction of the psyllid or the disease. The psyllid is under eradication in Southern California. If the psyllid and the disease were to become established in California, the disease would devastate the citrus industry.

Damage: ACP nymphs can only surive on the new flush tips of citrus. Because they produce a toxin, the flush tips die back or become twisted and the leaves do not expand normally. This problem can be reduced through pesticide control of the psyllid population or releases of natural enemies. A more important consequence of the introduction of ACP into California is its ability to vector the bacterial disease HLB. HLB causes assymetrical blotchy mottling of leaves (in contrast to Zinc deficiency that causes symmetrical blotching). Fruit from HLB-infected trees are small, lopsided, poorly colored, and contain aborted seeds. The juice from affected fruit is low in soluble solids, high in acids and abnormally bitter. The fruit retains its green color at the navel end when mature, which is the reason for the name citrus greening disease. The fruit is of no value because of poor size and quality. There is no cure for the disease and rapid tree removal is critical for prevention of spread.

Economic Impact: HLB is one of the most devastating diseases of citrus and since its discovery in Florida in 2005, citrus acreage in that state has declined significantly. Since the psyllid arrived in Southern California in 2008, the citrus nursery industry is rapidly moving its production under screenhouses. If the psyllid were to become established in citrus growing region, pesticide treatments for the psyllid would be instituted resulting in a direct cost of greatly increased pesticide use (3-6 treatments per year) and indirect costs due to disruption of the integrated pest management program. If the disease were to appear in California, a costly eradication program would need to be instituted to remove infected trees in order to protect the citrus industry.

Distribution of ACP and HLB: ACP is found in Asia, parts of the Middle East, South and Central America Mexico and the Carribean. Asian citrus psyllid was first detected in backyard citrus in Southern California in August 2008. Surveys have found infestations in areas of San Diego and Imperial counties. ACP is also found in Florida, Louisiana, Georgia, South Carolina, Texas and Hawaii. HLB is present in China, eastern and southern Africa, the Indian subcontinent, Madagascar, Mauritius, Reunion, the Saudi Arabian peninsula, and southeast Asia. In 2005, HLB was found in Florida and it is now known to occur in Cuba, Belize, and Eastern Mexico The presence of HLB in Mexico increases the risk for introduction of the disease into California via psyllids or infected plant material.

Research: Research centers on characterization of the bacteria, development of HLB detection methods, and control of the disease and the psyllid. To date, control of the disease is based on planting HLB-free citrus germplasm, eradication of infected citrus plants, and control of the vector with systemic insecticides. Countries with HLB learn to manage the disease so that they can still produce citrus. In California, the best strategy to keep this disease out is to continue to prevent spread of the psyllid into citrus growing regions through insecticide treatments and support both the federal and state quarantine regulations and the University of California’s Citrus Clonal Protection Program, which provides a mechanism for the safe introduction of pest and disease-free citrus germplasm into California.

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CISR: Caulerpa taxifolia

Anonymous — Mon, 20 Jan 2020 21:30:51 +0000

CISR: Caulerpa taxifolia Anonymous (not verified) Mon, 01/20/2020 - 13:30 More Blog Posts CISR Team May 27, 2009

The Situation: Caulerpa taxifoliais an invasive alga that is causing serious environmental problems in the Mediterranean Sea. This invasive weed was discovered in southern California and New South Wales, Australia in 2000. Caulerpa taxifolia was officially eradicated from southern California in 2006.

Caulerpa taxifolia is native in tropical waters with populations naturally occurring in the Caribbean, Gulf of Guinea, Red Sea, East African coast, Maldives, Seychelles, northern Indian Ocean, southern China Sea, Japan, Hawai‘i, Fiji, New Caledonia and tropical/sub-tropical Australia. A cold water strain of this attractive tropical alga, possibly developed from plants that initially originated from Australia, was selected for by aquarium managers at the Wilhelma Zoo in Stuttgart, Germany in 1980. By 1984, this coldwater strain of Caulerpa had been released into the Mediterranean Sea by the Oceanographic Museum of Monaco where it established.

Currently, Caulerpa has colonized thousands of hectares of sea bottom in the Mediterranean and it is found from France to Croatia and its range in the Mediterranean will likely to continue to expand. The invasive strain of Caulerpa can tolerate low sea water temperatures and can survive out of water, in moist conditions, for up to 10 days. This alga can colonize most kinds of substrates including rock, sand, mud, and seagrass beds from depths ranging from less than 1 m to ~12 m.

Caluerpa is capable of rapid growth and reproduction of the invasive strain is asexual and dispersal occurs through fragmentation. Fragments as small as 1 cm give raise to viable plants. Long distance spread occurs via ballast water discharge from transoceanic boats and illegal dumping of aquaria plants. More localized dispersal occurs through the unintentional movement of plant material on boats, anchors, or fishing gear, or via algal fragments being dispersed by sea currents.

The Problem: The invasive strain of Caulerpa in the Mediterranean Sea smothers other algal species, seagrasses and sessile invertebrate communities. It does this by either out-competing species for food and light or due to the toxic effects of caulerpenyne compounds that are contained in its foliage. Large meadows of Caulerpa have vastly reduced native species diversity and fish habitat. Native fish which are able to eat Caulerpa, such as Mediterranean bream, accumulate caulerpenyne toxins in their flesh which makes these fish unsuitable for human consumption.

The appearance of Caluerpa in southern California in 2000 was most probably caused by an aquarium owner improperly dumping the contents of a marine fish tank into a storm water system that fed into Agua Hedionda Lagoon in Carlsbad where this weed was first discovered. California has since passed a law forbidding the possession, sale or transport of Caulerpa taxifolia within the state. There is also a federal law under the Noxious Weed Act forbidding interstate sale and transport of the aquarium strain Caulerpa.

When first detected the populations of Caulerpa in southern California were small enough for eradication to be feasible. To eradicate underwater populations of Caulpera, patches were covered with tarpaulins which were held down with sandbags which sealed the edges. Chlorine was poured under the sealed tarpaulins which trapped the chlorine. Chlorine in this instance acted as a pesticide and killed living organisms trapped under the tarpaulins, including Caulerpa. The unintentional killing of fish, invertebrates, and plants while not desirable was deemed necessary and preferable to letting Caulpera spread unchecked.

Economic Impact: Small infestations found in Agua Hedionda Lagoon in Carlsbad near San Diego and Huntington Beach near Los Angeles, took six years to eradicate at a cost of more than $7 million (US). So far no other infestations of the cold water strain of Caulerpahave been located in the USA. In the Mediterranean commercially important fisheries have been adversely affected because fewer fish live in areas with heavy Caulerpa infestations.

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CISR: New Zealand Mud Snail

Anonymous — Mon, 20 Jan 2020 21:28:39 +0000

CISR: New Zealand Mud Snail Anonymous (not verified) Mon, 01/20/2020 - 13:28 More Blog Posts CISR Team May 27, 2009

The Situation: As the common name indicates, this invasive pest is native to New Zealand. New Zealand mud snail has had a long invasion history. It was first found in the United Kingdom in 1859, the western Baltic in Europe in 1887, the Mediterranean and eastern Europe were invaded in the 1950’s. The snail has also established Australia and Japan. In 1987, New Zealand mud snail was found in Idaho (the Snake River). It has since spread through Yellowstone National Park, and is now found in Wyoming, Montana, and Oregon (1994). The Great Lakes were invaded in 1991. Genetic analyses suggest that the source population in the Great Lakes likely originated from Europe and invaders were introduced into the Great Lakes in ballast water discharged from transoceanic ships that came from Europe. The snail was found in British Columbia Canada in 2007, and the first record of this pest in California was from the Owens River which was officially confirmed in 2000. All western US states, except New Mexico, now have permanent populations of New Zealand mud snail.

The color of the snail shell is variable, and can range from gray and dark brown to light brown. The snail is usually 4-6 mm in length in areas that have been invaded, but snails can grow to almost twice this size, up to 12 mm, in New Zealand where populations are much lower. New Zealand mud snail is a nocturnal grazer that feeds on plant and animal detritus, algae, and diatoms. Invasive populations have an unusual mode of reproduction. New Zealand mud snails can reproduce asexually and female snails are born with developing embryos inside them. Consequently, all populations consist of genetically identical clones. In New Zealand, native mud snail populations consist of sexually reproducing populations (the males make up less than 5% of the populations) and asexually reproducing females. Each snail can produce around 230 offspring a year, and reproduction typically occurs during the spring and summer.

The Problem: New Zealand mud snail has likely been introduced into new areas by fishermen who have not properly cleaned equipment such as waders, wading boots, nets, and other gear. Because New Zealand mud snails are so small they are easily overlooked on fishing gear, and they are very resistant to desiccation. Snails can live for 24 hrs without water, and for up to 50 days on damp surfaces. This level of hardiness provides ample time for inadvertent movement of hitchhikers before they die. The snail is also tolerant of estuarine conditions and can live at depths of up to 45 m on solid and silty substrates. Once introduced into a new area, New Zealand mud snails can reach densities exceeding 500,000 per square meter. The exact implications of these incredibly high population densities are not certain. However, it is thought that such high snail populations probably have a negative affect on populations of other aquatic organisms, especially native snails and the insects and fish that feed on them. It is likely that freshwater ecosystems are adversely affected by such high populations of an invasive snail.

The highest concentration of New Zealand mud snails ever reported was in Lake Zurich, Switzerland, where the species colonized the entire lake within seven years to a density of 800,000 per square meter. Interestingly, these massive populations were not sustained, and a population crash due to unknown causes occurred. Consequently, New Zealand mud snails are not as common as they once were in Lake Zurich. A similar event was apparently observed in Denmark.

There are no known specialized natural enemies of New Zealand mud snail that have accompanied this invader as it has moved globally. Lack of predators, parasites, and pathogens has almost certainly promoted the invasion success of this pest. In New Zealand, the mud snail is attacked by 11 species of trematode, a type of parasitic flatworm, which sterilizes infected snails. This parasite may be important for regulating mud snail populations in New Zealand thereby preventing them reaching the incredible densities seen overseas. It is possible that host specific trematodes exist in New Zealand and these may be used to control pest populations of New Zealand mud snail if they can be shown to pose no risk to desirable native snail populations in areas that have been invaded by this pest.

Control of the New Zealand Mud Snail: Since there are no feasible eradication technologies, the first line of defense against New Zealand mud snail is containment. Since spread appears to be strongly associated with recreational freshwater fishing and wading gear, there are several recommended ways to reduce the risk of spreading New Zealand mud snail throughout California. Some suggested ways to decontaminate fishing gear include freezing overnight, or treating with chemicals known to be toxic to New Zealand mud snail. Many freshwater fishing websites have decontamination recipes for cleaning gear of New Zealand mud snail.

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CISR: Quagga & Zebra Mussles

Anonymous — Mon, 20 Jan 2020 21:27:58 +0000

CISR: Quagga & Zebra Mussles Anonymous (not verified) Mon, 01/20/2020 - 13:27 More Blog Posts CISR Team May 28, 2009

The Situation: Quagga and zebra mussels are aquatic invasive species that are native to eastern Europe. The quagga mussel originated from Dnieper River drainage of Ukraine. The zebra mussel was first described from the lakes of southeast Russia and its natural distribution also includes the Black and Caspian Seas. Quagga and zebra mussels get their common names from the zebra-type striping on the shells. Both mussel species are small and typically grow to the size of a fingernail. They are prolific breeders and these mussels can attach to both hard and soft surfaces in freshwater ways.

Zebra mussels have a long history of invasion and have successfully established in Great Britain (1824), The Netherlands (1827), The Czech Republic (1893), Sweden (1920), Italy (1973), the Great Lakes in the USA (1988), and California (2008). Quagga mussels were first found in the USA in the Great Lakes in 1989, Nevada in 2007, and California in 2008. Ballast water discharge from transoceanic ships is thought to be responsible for the long distance spread of zebra and quagga mussels from their original home ranges in eastern Europe. Short distance spread between fresh waterways within countries most likely occurs via the movement of recreational boats. This occurs when boats are not cleaned and dried adequately and contaminated watercraft are then moved from infested waterways to pristine water bodies where mussels are accidentally introduced. These mussels can survive for 3-5 days out of water without suffering lethal desiccation.

Where quagga and zebra mussels co-exist, quagga mussels appear to outcompete zebra mussels, and quagga mussels can colonize to depths greater than those achieved by zebra mussels and are more tolerant of colder water temperatures. For example, in Lake Michigan, zebra mussels made up 98.3% of mussels in 2000, by 2005 quagga mussels represented 97.7% of collected mussels. Zebra mussels were found at densities of around 899 per square meter, but quagga mussels now dominate at 7,790 mussels per square meter. Quagga mussels have been found at depths of up to 540 feet in Lake Michigan where they filter feed year round.Consequently, quagga mussels may end up being the more problematic of these two mussel species in California.

The Problem: Quagga and zebra mussel invasions have had catastrophic impacts in the ecosystems in which they have established. These organisms clog water intake structures (e.g., pipes and screens), which greatly increases maintenance costs for water treatment and power plants. Recreational activities on lakes and rivers are adversely affected as mussels accumulate on docks, buoys, boat hulls, anchors, and beaches can become heavily encrusted.

The shells of both mussel species are sharp and can cut people, which forces the wearing of shoes when walking along infested beaches or over rocks. Mussels adhering to boat hulls can increase drag, affect boat steering, and clog engines, all of which can lead to overheating and engine malfunctions. Ecological problems also result from mussel invasions. Zebra and quagga mussels can kill native freshwater mussels in two ways: (1) attachment to the shells of native species can kill them, and (2) these invasive species can outcompete native mussels and other filter feeding invertebrates for food. This problem has been particularly acute in some areas of the USA that have a very rich diversity of native freshwater mussel species.

The encrusting of lake and river bottoms can displace native aquatic arthropods that need soft sediments for burrowing. In the Great Lakes this had lead to the collapse of amphipod populations that fish rely on for food and the health of fish populations has been severely affected.

These mussels have been associated with avian botulism outbreaks in the Great Lakes which have caused the mortality of tens of thousands of birds. Because of their filter feeding habit, it has been estimated that these mussels can bioaccumlate organic pollutants in their tissues by as much as 300,000 times when compared to concentrations in the water in which they are living. Consequently, these pollutants can biomagnify as they are passed up the food chain when contaminated mussels are eaten by predators (e.g., fish and crayfish), who in turn are eaten by other organisms (e.g., recreational fishermen who eat contaminated fish.) High mussel populations can increase water acidity and decrease concentrations of dissolved oxygen.

Interestingly, invasions by quagga and zebra mussels have been documented as having some positive affects on receiving ecosystems. For example, filtration of water by mussels as they extract food removes particulate matter. This filtration has improved water clarity, and reduced the eutrophication of polluted lakes. In some instances these improvements may have benefited local fishing industries. Conversely, improved water clarity allows penetration of light to greater depths which can alter the species composition of aquatic plant communities and associated ecosystems. This improved water quality is thought to aid algal blooms that get washed ashore where they rot making recreational beaches unusable. Further, the highly efficient removal of phytoplankton can deprive other aquatic species of food.

Invasion success in some areas of California may be affected by water chemistry. Waterways around the Sierra Nevada mountains may have insufficient calcium (an element needed for shell growth) and some lakes in northeast California may be too salty for mussel survival. However, the general consensus is that most freshwater ways in California will be accommodating to zebra and quagga mussels.

Economic Impact and Management: Zebra and quagga mussel invasions create an immense financial burden because of the need to continuously and actively manage these pests. It has been estimated that it costs over $500 million (US) per year to manage mussels at power plants, water systems, and industrial complexes, and on boats and docks in the Great Lakes. Similar yearly management costs are anticipated for California. For example, a recent estimate (2009) by the Army Corps of Engineers indicates that quagga mussels could cause annual loses of $22 million to the Lake Tahoe region should they establish there. The report details potential damage to tourism, reduced property values, and increased maintenance costs. Management of problematic mussel populations may be achieved in different ways in California. Water draw downs in canals and aqueducts could be used to kill mussels by drying them out. Poisons such as chlorine and copper sulfate which are toxic to quagga and zebra mussels could be employed under certain conditions.

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Invasive Species

CISR: Tipu Psyllid

Anonymous — Mon, 20 Jan 2020 21:27:17 +0000

CISR: Tipu Psyllid Anonymous (not verified) Mon, 01/20/2020 - 13:27 More Blog Posts CISR Team May 30, 2009

The Situation: The rosewood tree, Tipu, or “Pride of Bolivia”,Tipuana tipu (Fabaceae), is native to South America (South Brazil, Argentina, Uruguay, Paraguay, Bolivia) and is widely grown as a landscape ornamental and shade tree in southern California and elsewhere in the world (e.g., Egypt, Portugal, and Israel.) Tipu trees are popular because they are drought and frost tolerant, are thornless, exhibit moderate height at maturity (~10m), and have attractive pinnate green leaves, and clusters of bright yellow flowers. Seeds are winged and look strikingly similar to those produced by maples. In October 2008, the Tipu psyllid, a new pest record for California, was found feeding on this urban plant in San Diego County.

Damage: Tipu psyllid nymphs and adults nymphs are tiny insects that feed on phloem. All life stages (except eggs which are non-feeding) attack young leaves and branches of Tipu trees. Extensive feeding causes the leaves on host plants to curl and drop prematurely. Nymphs produce pelletized wax-like residue. Adults and nymphs produce copious amounts of honeydew which fosters the growth of black sooty mold on leaves and branches. The wax pellets produces by nymphs are very similar to those seen in the Eugenia psyllid, an exotic pest from Australia that attacks Eugenia and Syzigium in California. Tipu psyllids feed exposed, without the protection of flocculent waxes or pit like depressions in leaves.

This pest was first detected in October 2008 in Carlsbad in San Diego County in California. Interestingly, this insect has recently emerged as a serious pest of Tipu trees in Curibita Brazil. Pest populations in Curibtia are very high, trees are being defoliated, excessive honey dew excretion is fouling concrete sidewalks and vehicles parked under Tipu trees. Tipu psyllid populations in several southern California communities have produced similar fouling of objects and sidewalks beneath infested trees. In Curitiba, high density pest populations are attacked by lady bug beetles (Coleoptera: Coccinellidae) which provide some control of outbreaks. In the absence of natural enemies (e.g., predators, parasites, or pathogens) or insecticidal controls, the establishment of Tipu psyllid in California poses a significant threat to the health and value of Tipu tree plantings in California landscapes.

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CISR: Bagrada Bug

Anonymous — Mon, 20 Jan 2020 21:25:09 +0000

CISR: Bagrada Bug Anonymous (not verified) Mon, 01/20/2020 - 13:25 More Blog Posts CISR Team May 31, 2009

The Situation: The Bagrada bug (also called painted or harlequin bug) was first found in June 2008 in Los Angeles Co. California, and is now widely distributed in LA and Orange Counties. Establishment of Bagrada bug in California is a new USA and Western Hemisphere record.

Damage: Bagrada bug is a major pest of crop plants in the Brassicaceae (Cruciferae), which includes important foods like cabbage, kale, turnip, cauliflower, mustard, broccoli, and radish. The Bagrada bug has also been recorded attacking papaya, potato, maize, sorghum, cotton, capers, and some legumes. Damage is inflicted on host plants when adults and nymphs insert their needle-like mouth parts and suck juices from the plant. Feeding results in large stippled or wilted areas on leaves. Often the growth of newly formed central shoots or heads of plants become stunted. Populations can build up quickly reaching damaging densities that require control. Heaviest infestations are typically observed in organic farms, community gardens, and residential vegetable gardens were little or no pesticides are used. Local residents, not familiar with this new stink bug, often think they have beneficial lady bugs, because Bagrada adults and larger nymphs are about same the size and have a similar bright coloration.

Identification: Adult Bagrada bugs are 5-7 mm long, and have black, shield-shaped bodies with distinctive white and orange markings. Adult females are larger than males. Nymphs are wingless and pass through 5 instars or developmental stages. Over the course of shedding the exoskeleton and growing, the wings gradually develop. First instar Bagrada bugs have reddish-brown heads and thoraxes and bright red abdomens. Later instars become darker (adding black color to their body) and develop wing pads. Eggs are oval, creamy-white, and turn orange as they age. Females lay eggs in the soil beneath host plants, but may also oviposit on leaves. Usually all life stages are present together on plants and adults are commonly observed in copulation.

Distribution: Bagrada bug is found in East and Southern Africa, Egypt, Zaire and Senegal. The global distribution of this pest also includes southern Asia and southern Europe (Malta and Italy). This pest is only known from Southern California in the USA.

Research: Very little is known about the identity and impact of biological control agents, in particular parasitoids, that attack eggs, nymphs, and adult Bagrada bugs. Despite the importance of this pest in many countries the biology, ecology, and population dynamics of this insect are not very well understood. Some progress in Europe has been made on chemical communication between Bagrada bugs.

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Invasive Species