Japanese Beetle

The Japanese beetle (''Popillia japonica'') is a species of scarab beetle. The adult measures in length and in width, has iridescent copper-colored elytra and a green thorax and head. It is not very destructive in Japan (where it is controlled by natural predators), but in North America and some regions of Europe is a noted pest to roughly 300 species of plants, including rose bushes, grapes, hops, canna, crape myrtles, birch trees, linden trees, and others.

The adult beetles damage plants by skeletonizing the foliage (i.e., consuming only the material between a leaf's veins) as well as, at times, feeding on a plant's fruit. The subterranean larvae feed on the roots of grasses.

Description

Adult ''P. japonica'' measure in length and in width, with iridescent copper-colored elytra and green thorax and head. A row of white tufts (spots) of hair project from under the wing covers on each side of the body.

Distribution

''Popillia japonica'' is native to Japan, but is an invasive species in North America and Europe.

The first written evidence of the insect appearing within the United States was in 1916 in a nursery near Riverton, New Jersey bulbs prior to 1912, when inspections of commodities entering the country began. As of 2015, just nine western states of the United States were considered free of Japanese beetles. Beetles have been detected in airports on the west coast of the United States since the 1940s.

The first Japanese beetle found in Canada was inadvertently brought by tourists to Yarmouth, Nova Scotia by ferry from Maine in 1939. During the same year, three additional adults were captured at Yarmouth and three at Lacolle in southern Quebec.

Japanese beetles have been found in the islands of the Azores since the 1970s. In 2014, the first population in mainland Europe was discovered near Milan in Italy. In 2017, the pest was detected in Switzerland, most likely having spread over the border from Italy. Swiss authorities are attempting to eradicate the pest.

Only three were found in Washington State, USA in 2020, but then from late June to September 3, 2021 there were over 20,000 found in Grandview alone.

Lifecycle

Ova are laid individually, or in small clusters near the soil surface. Within approximately two weeks, the ova hatch, the larvae feeding on fine roots and other organic material. As the larvae mature, they become c-shaped grubs which consume progressively coarser roots and may do economic damage to pasture and turf at this time.

Larvae hibernate in small cells in the soil, emerging in the spring when soil temperatures rise again. Within 4–6 weeks of breaking hibernation, the larvae will pupate. Most of the beetle's life is spent as a larva, with only 30–45 days spent as an imago. Adults feed on leaf material above ground, using pheromones to attract other beetles and overwhelm plants, skeletonizing leaves from the top of the plant downward. The aggregation of beetles will alternate daily between mating, feeding, and ovipositing. An adult female may lay as many as 40–60 ova in her lifetime.

Throughout the majority of the Japanese beetle's range, its lifecycle takes one full year, however in the extreme northern parts of its range, as well as high altitude zones as found in its native Japan, development may take two years.

Control

Phenological models might be useful in predicting the timing of presence of larvae or adults of the Japanese beetle. Model outputs can be used to support the timely implementation of monitoring and control actions against the pest, thus reducing its potential impact.

Owing to its destructive nature, traps have been invented specifically to target Japanese beetles. These comprise a pair of crossed walls with a bag or plastic container underneath and are baited with floral scent, pheromone, or both. However, studies conducted at the University of Kentucky and Eastern Illinois University suggest beetles attracted to traps frequently do not end up in the traps, instead, they land on plants in the vicinity and cause more damage along the flight path and near the trap than may have occurred if the trap were not present.

During the larval stage, the Japanese beetle lives in lawns and other grasslands, where it eats the roots of grasses. During that stage, it is susceptible to a fatal disease called milky spore disease, caused by a bacterium called milky spore, ''Paenibacillus'' (formerly ''Bacillus'') ''popilliae.'' The USDA developed this biological control and it is commercially available in powder form for application to lawn areas. Standard applications (low density across a broad area) take from one to five years to establish maximal protection against larval survival (depending on the climate), expanding through the soil through repeated rounds of infection.

On field crops such as squash, floating row covers can be used to exclude the beetles, but this may necessitate hand pollination of flowers. Kaolin sprays can also be used as barriers.

Research performed by many US extension service branches has shown pheromone traps attract more beetles than they catch. Traps are most effective when spread out over an entire community, and downwind and at the borders (i.e., as far away as possible, particularly upwind), of managed property containing plants being protected.

When present in small numbers, the beetles may be manually controlled using a soap-water spray mixture, shaking a plant in the morning hours and disposing of the fallen beetles, or simply picking them off attractions such as rose flowers, since the presence of beetles attracts more beetles to that plant.

Several insect predators and parasitoids have been introduced to the United States for biocontrol. Two of them, '' Istocheta aldrichi'' and ''Tiphia vernalis'', are well established with significant but variable rates of parasitism.

Host plants

While the larvae of Japanese beetles feed on the roots of many genera of grasses, the adults consume the leaves of a much wider range of hosts, including these common crops: bean, cannabis, strawberry, tomato, pepper, grape, hop, rose, cherry, plum, pear, peach, raspberry, blackberry, corn, pea, okra, and blueberry.

List of adult beetle hostplant genera

* ''Abelmoschus''
* '' Acer'' (maple)
* ''Aesculus'' (horse chestnut)
* ''Alcea''
* ''Aronia''
* ''Asimina'' (pawpaw)''
* ''Asparagus''
* ''Aster''
* ''Buddleja''
* ''Calluna''
* ''Caladium''
* '' Canna''
* ''Cannabis sativa''
* ''Chaenomeles''
* '' Castanea'' (sweet chestnut)
* ''Cirsium'' (thistle)''
* ''Cosmos''
* ''Dahlia''
* ''Daucus'' (carrot)
* '' Dendranthema''
* ''Digitalis''
* '' Dolichos''
* ''Echinacea'' (coneflower)
* ''Hemerocallis''
* ''Heuchera''
* ''Hibiscus''
* ''Humulus'' (hop)
* ''Hydrangea''
* ''Ilex'' (holly)
* ''Impatiens''
* ''Ipomoea'' (morning glory)
* ''Iris''
* ''Juglans'' (walnut)
* ''Lagerstroemia''
* ''Liatris''
* ''Ligustrum'' (privet)
* ''Malus'' (apple, crabapple)
* ''Malva'' (mallow)
* ''Mentha'' (mint)
* ''Myrica''
* ''Ocimum'' (basil)
* ''Oenothera ''(evening primrose)''
* ''Parthenocissus''
* '' Phaseolus''
* ''Phlox''
* '' Physocarpus''
* ''Pistacia''
* ''Platanus'' (plane)
* ''Polygonum'' (Japanese knotweed)
* ''Populus'' (poplar)
* ''Prunus'' (plum, peach)
* ''Quercus'' (oak)
* ''Ribes'' (gooseberry, currants, etc.)
* ''Rheum''
* ''Rhododendron''
* ''Rosa'' (rose)
* ''Rubus'' (raspberry, blackberry, etc.)
* ''Salix'' (willows)
* ''Sambucus'' (elder)
* ''Sassafras''
* ''Solanum'' (nightshades, including potato, tomato, eggplant)
* ''Spinacia'' (spinach)
* ''Syringa'' (lilac)
* ''Thuja'' (arborvitae)
* ''Tilia'' (basswood, linden, UK: lime)
* ''Toxicodendron'' (poison oak, poison ivy, sumac)
* ''Ulmus'' (elm)
* ''Vaccinium'' (blueberry)
* ''Viburnum''
* ''Vitis'' (grape)
* '' Weigelia''
* ''Wisteria''
* '' Zea''
* ''Zinnia''

Gallery

File:Jblarva.jpg, Japanese beetle larva (grub)
File:Jbpupa.jpg, Japanese beetle pupa
File:Jbadult.jpg, Japanese beetle adult
File:Japanese Beetle Feeding on Peach Tree.jpg, Adult Japanese beetles feeding on peach tree
File:Japanese Beetles, Ottawa.jpg, Mating, Ottawa, Ontario, Canada
File:Japanese Beetles on Pasture Rose, Ottawa.jpg, Feeding, Ottawa
File:FullSizeRender 36.jpg, Japanese beetle feeding on calla lily, Ottawa, Ontario, Canada

References

External links

Japanese beetle
on the UF/ IFAS Featured Creatures Web site

Japanese Beetle
Canadian Food Inspection Agency



Species Profile – Japanese Beetle (''Popillia japonica'')
National Invasive Species Information Center, United States National Agricultural Library.

{{Taxonbar, from=Q1683382

Beetles described in 1841
Beetles of Asia
Grape pest insects
Insect pests of ornamental plants
Taxa named by Edward Newman
Insects in culture
Rutelinae