Asian long horned beetle

Taxonomy and description

Common names for Anoplophora glabripennis in Asia are the starry sky beetle, basicosta white-spotted longicorn beetle, or smooth shoulder-longicorn, and it is called the Asian long-horned beetle (ALB) in North America.

Adults are very large insects with bodies ranging from 1.7 to 3.9 cm (0.67 to 1.54 in) in length and antennae which can be as long as 4 cm (1.6 in) or 1.5–2 times longer than the body of the insect. They are shiny black with about 20 white spots on each wing cover and long antennae conspicuously banded black and white. These beetles can fly, but generally only for short distances, which is a common limitation for Cerambycidae of their size and weight. The upper sections of the legs of the adults are whitish-blue. ALB can be distinguished from related species by the markings on the wing covers and the pattern of the antennae.

Range and habitat

Asian long-horned beetle is native to eastern Asia, primarily in eastern China, Korea, and Japan. It is invasive outside its native range.

In its native range, ALB primarily infest trees maple, poplar, willow, and elm. In the United States, ALB has completed development on species of these genera and also Aesculus, Albizia, birch, katsura, ash, planes, and Sorbus. In Canada, complete development has been confirmed only on maple, birch, poplar, and willow, although oviposition has occurred on other tree genera. Maple is the most commonly infested tree genus in North America, followed by elm and willow. In Europe, complete development has been recorded on maple, Aesculus, alder, birch, hornbeam, beech, ash, planes, poplar, Prunus, willow, and Sorbus. The top five host genera infested in Europe, in decreasing order, are maple, birch, willow, Aesculus, and poplar. Not all poplar species are equally susceptible to ALB attack.

In North America, established populations were first discovered in August 1996 in Brooklyn, New York and has since been found in other areas of New York, New Jersey, Massachusetts, Illinois, Ohio, and Ontario in Canada. However, it has also been eradicated from some regions within these states and provinces.

Established populations have also been found in Europe in Austria, Belgium, England, France, Germany, Italy, Switzerland, and the United Kingdom., though the beetle has also been intercepted in areas it has not established through inspection of international trade goods such as wood packaging.

Life cycle

Adult females lay 45–62 eggs in their lifetime by chewing a small pit through the bark of the host tree to the cambium and lay one 5–7 mm (0.20–0.28 in) long egg underneath the bark in each pit. Eggs hatch in 13–54 days depending on temperature. Eggs that have not developed enough, such as those laid in late summer or early fall, will overwinter and hatch the following season.

Larvae are cylindrical and elongate and can be 50 mm (2.0 in) long and 5.4 mm (0.21 in) wide. Larvae first create a feeding gallery in the cambial region, but more mature larvae tunnel to the heartwood as they feed. Larvae go through at least five instars over 1–2 years; which can vary due to host or temperature conditions. Larvae expel frass from their tunnels near the original oviposition site. A larva can consume up to 1,000 cubic cm of wood in its lifetime. Asian long-horned beetle larvae do not pupate before they reach a critical weight, so additional larval instars can occur.

Pupation usually occurs in spring at the end of the larval tunnel in the sapwood, eclosion occurs 12–50 days later, and adults will chew out of the tree approximately one week after eclosion. Adults feed on leaf petioles and can chew through bark on small branches to feed on the vascular cambium. Eggs, larvae or as pupae can overwinter within the tree. In their overwintering phase, ALB are inactive and development does not occur. They resume their life cycle when temperatures are above 10 °C (50 °F).

Upon emergence, adult females can copulate, although an obligatory maturation period is required for feeding after emergence for ovarian maturation. Laboratory studies have estimated the female maturation period lasts 9–15 days. Adult males have mature spermatozoa before emergence, and feeding is necessary only to sustain their normal activity. Adults typically lay eggs on the plant they developed on during immature stages rather than colonizing new plants unless population density is high or the host plant is dead. However, when they do disperse, they can travel up to approximately 2.5 km (1.6 mi) from their host tree in a growing season in search of new hosts, although in a mark-recapture experiment about 98% of adults were recaptured within 1 km (0.62 mi) of their release point. Adults will typically infest the crown and main branches first and will begin to infest the trunk as the crown dies. Adult longevity and fecundity are influenced by conditions such as the larval host plant and temperature. Laboratory reared males and females can live up to 202 and 158 days, respectively.

As an invasive species

Due to high tree mortality caused by larval feeding outside its native range, ALB can change both forest and urban ecosystems. In the United States, it can potentially destroy 30.3% of urban trees and cause $669 billion in economic loss. Early detection is used to manage infestations before they can spread.

Monitoring

Tree infestation can be detected by looking for exit holes 3/8 to 3/4 inches in diameter (1–2 cm) often in the larger branches of the crowns of infested trees. Sometimes sap can be seen oozing from the exit holes with coarse sawdust or "frass" in evidence on the ground or lower branches. Dead and dying tree limbs or branches and yellowing leaves when there has been no drought also signal ALB infestation. Traps can also be used containing a pheromone and a plant kairomone to attract nearby adults. Some acoustic sensors can also differentiate larval feeding within trees. Dogs can also be trained to detect the smell of frass on trees.

Workers in warehouses in CA, FL, IL, IN, MA, MI, NC, NJ, NY, OH, PA, SC, TX, WA, and WI in the United States, and in the Greater Toronto Area in Ontario, Canada. After an aggressive containment program and with the last confirmed sighting in 2007, Canada declared itself free of the beetle on April 5, 2013 and lifted restrictions on the movement of tree materials.

Quarantine

Quarantines have been established around infested areas to prevent accidental spread of ALB by people. The use of Solid Wood Packing Materials (SWPM) for maritime shipping is regulated for adequate treatment methods at certain ports. US customs regulations were changed on September 18, 1998 to require wooden packing materials from China be chemically treated or kiln-dried to prevent further infestations of the Asian long-horned beetle from arriving. Pest inspection, new rules, and public awareness are the key steps to prevention of the spread of the Asian long-horned beetle.

Management

All infested trees are removed and chipped in place. The stumps of infested trees are ground to below the soil level. All tree removal is done by certified tree care personnel to ensure that the process is completed properly. New York and Chicago began this eradication process in 1997 with thousands of dollars in effort to complete the project.

Insecticides such as imidacloprid, clothianidin, dinotefuran have been used to target adult beetles in canopies or as trunk injections to target larvae. Insecticides within the tree may not translocate evenly, which causes some ALB to survive treatments. Combined with efficacy concerns, high cost, and non-target effects on other insects, widespread prophylactic treatment of trees in an infestation area concerns scientists.

Over 1,550 trees in Chicago have been cut down and destroyed to eradicate ALB from Chicago. In New York, over 6,000 infested trees resulted in the removal of over 18,000 trees; New Jersey's infestation of over 700 trees led to the removal and destruction of almost 23,000 trees, but infested trees continue to be discovered.

Some resistant trees have been developed that quickly fill oviposition pits with sap or produce callous tissue that encases and kills eggs. Non-host species are typically used to replace removed trees.

Biological control has also been considered in some areas such as China. Fungi such as Beauveria brongniartii can increase mortality in larvae and adults while Metarhizium brunneum and Beauveria asiatica can reduce adult survival time. Most parasitoids in the native range of ALB have a broad host range, and are not suitable as classical biological control agents. Woodpeckers can also be a significant source of mortality. Countries working towards eradicating ALB typically do not initially utilize biological control.

Eradication

In areas such as North America where infestations are small, ALB can potentially be eradicated. As trees are removed or treated, all host trees on public and private property located within an established distance from an infested area are surveyed by trained personnel. Infested areas are re-surveyed at least once per year for 3–5 years after the last beetle or infested tree is found.

As of 2015, ALB has been eradicated from Islip, Manhattan, and Staten Island in New York, Jersey City in New Jersey, Chicago in Illinois, and Boston in Massachusetts. It was also declared eradicated in Toronto, Ontario, but it was re-discovered there in 2013.