Pests and Pest Control
Japanese Beetle is the most dreaded pest on roses in Midwestern and Eastern parts of the USA and Canada. The beetle's unique life cycle, reproductive capacity, ability to colonize more than one host, and migrate from one country to the other crossing vast expanses of water helped the beetle to successfully colonize North America. Undetected by agriculture inspectors at Airports or Seaports, they move from country to country with travelers and their baggage. Being voracious feeders, the larvae (caterpillars, grubs) and the adult beetles cause heavy damage to plant parts and heavy financial losses to farmers, flower growers, and orchard owners.
Japanese Beetle poses a severe threat to roses and other members of the Family Rosaceae (apples, cherries, etc.). Adult Japanese Beetles infest hundreds of plant species that include shade and fruit trees, ornamental shrubs, small fruits, garden crops, weeds, and field crops. The grubs are serious pests of lawns and nursery stocks. (Photo of Japanese Beetles devouring rose leaves by Dr. Sridharan)
History
Japanese Beetle poses a severe threat to roses and other members of the Family Rosaceae (apples, cherries, etc.). Adult Japanese Beetles infest hundreds of plant species that include shade and fruit trees, ornamental shrubs, small fruits, garden crops, weeds, and field crops. The grubs are serious pests of lawns and nursery stocks. (Photo of Japanese Beetles devouring rose leaves by Dr. Sridharan)
History
Japanese Beetle ( Popillia japonica ), a native of Japan, Korea and China probably first found its way from Asia to Europe and then into the USA through plant smuggling. The beetle arrived first in Southern New Jersey in 1916. The beetle population moved to Maine and other coastal states in the east, and westwards to a number of Midwestern States. Ferries transporting passengers between the coastal Maine and coastal Canadian Provinces helped in the onward migration and successful establishment of the beetle in Canada.
Favorable climatic conditions and gardening practices of homeowners helped the beetles to successfully establish themselves in North America. Almost every home in North America has a lawn. Adult females hide under the lawns and lay eggs. When eggs hatch, the hungry grubs feed on turf grass roots. Roses and fruit trees provide food for adult beetles.
Biology
Japanese Beetle (Popillia japonica (Newman)) is a member of insect Family Scarabaeidae, and the order, Coleoptera. The ovoid adult beetles, both male and female are beautiful with a shiny metallic green body and coppery brown fore wings. A row of 5 lateral brushes of white hairs on each side of the lower surface of the last abdominal segment distinguishes the Japanese beetle from the rest of beetle family.
Life Cycle
Metamorphosis is characteristic of all insects' life cycle. During its life cycle, the beetle passes through four developmental stages -- egg, larva (grub), pupa and adult. Each stage has its own characteristic morphological, and anatomical features very different from the succeeding stage. The beetle does extensive damages to plant life as a grub and as an adult. During the pupal stage, it may appear to be sleeping; however it undergoes dramatic changes invisible to the naked eyes of a gardener to emerge later as a fully developed beetle. Fortunately for the roses, the beetle has only one generation per year.
Favorable climatic conditions and gardening practices of homeowners helped the beetles to successfully establish themselves in North America. Almost every home in North America has a lawn. Adult females hide under the lawns and lay eggs. When eggs hatch, the hungry grubs feed on turf grass roots. Roses and fruit trees provide food for adult beetles.
Biology
Japanese Beetle (Popillia japonica (Newman)) is a member of insect Family Scarabaeidae, and the order, Coleoptera. The ovoid adult beetles, both male and female are beautiful with a shiny metallic green body and coppery brown fore wings. A row of 5 lateral brushes of white hairs on each side of the lower surface of the last abdominal segment distinguishes the Japanese beetle from the rest of beetle family.
Life Cycle
Metamorphosis is characteristic of all insects' life cycle. During its life cycle, the beetle passes through four developmental stages -- egg, larva (grub), pupa and adult. Each stage has its own characteristic morphological, and anatomical features very different from the succeeding stage. The beetle does extensive damages to plant life as a grub and as an adult. During the pupal stage, it may appear to be sleeping; however it undergoes dramatic changes invisible to the naked eyes of a gardener to emerge later as a fully developed beetle. Fortunately for the roses, the beetle has only one generation per year.
The Japanese beetle
adult--an attractive pest.
Japanese beetle
larva.
A typical cluster of
Japanese beetle eggs.
Japanese beetle
pupa.
Adult females emerge from the pupae on the ground in June. There is plenty of plant food available in spring and summer for the emerging beetles to feed on. The emergence peaks in July and August. The hungry beetles start feeding in huge congregations on all host plants (roses and hundreds of other plant species) around. The females signal that they are ready to mate by releasing the insect hormone, pheromone. The insects are extremely perceptive to odor and can detect pheromone from long distances. The males fly in the direction of females wherever they are -- on the ground or above the ground on the host plants. They feverishly mate several times. The more the mating, the hungrier the females get and devour the host plants for a day or two after mating. The females then return to the ground in the afternoons and burrow in the soil to lay eggs. After laying a few eggs, the females return to the roses to feed and mate again. By the time the mating cycle is over, each female has laid about 40 to 60 eggs. By mid-August, the females complete egg laying. The white oval eggs are usually about 1/16 inch (1.5 mm) long and 3/64 inch (1.0 mm) wide. They absorb the moisture in the soil and become more roundish.
Temperature regulates egg hatching and further development. As the soil temperature rises (80-90°F) in autumn, the eggs hatch into larvae within eight to nine days after they have been laid. At lower temperatures (65°F), the hatching may take about thirty days. The larvae are typical white grubs that can be separated from other soil dwelling white grubs by the presence of a V-shaped series of bristles on the raster. First instar larvae are about 1/16 inch (1.5 mm) long while the mature third instars are about 1-1/4 inch (32 mm) long. The grubs (first instar larvae) dig into moist soil, eat plant roots, and complete their development within two to four weeks. The first instar larvae develop into second instars. At higher temperatures (78°F) the second instar completes its development in less than twenty days and at lower temperatures (68°F), it may take eight weeks. As grubs tunnel into the soil feeding on the roots, the temperatures decrease; however, the soil is still warm enough for the survival of grubs. They dig deeper and deeper into the ground eating away the plant roots and organic matter. They hibernate under the ground until spring arrives. The grubs return to the surface in the spring when the surface soil temperatures are about 60°F, usually in mid-April. The grubs continue their development in the spring and the few second instars seem to mature in time to pupate along with the third instars. The mature grubs form a pre-pupa in early June. The pre-pupa voids its gut contents and has a translucent appearance. The pupa is formed in the split skin of the pre-pupa in an earthen cell 1-to-3 inches down in the soil. The grubs metamorphose into cream-colored pupae, which later become light reddish-brown with age. The average pupa is about 1/2 inch (14 mm) long and 1/4 inch (7 mm) wide.
Plant Damage
Adults feed on the upper surface of foliage of most plants, consuming the soft tissues between the veins; as a result the leaves look skeletonized. Beetle-damaged leaves turn brown and die. The dead leaves fall. Defoliation drastically reduces photosynthesis, as leaves are the photosynthesizing centers. Defoliation reduces the availability of food material for a healthy growth of roses. The hips are smaller. The beetle also attacks the hips eating the flesh.
The vicious attack of the beetle does not stop with roses. The beetle will destroy other hosts that are in the landscape. The voracious grubs damage the turf grass.
Control Strategies
Fortunately, a few control measures such as preventing unauthorized entry of beetles into an area from a beetle infested area, changing gardening practices or controlling the beetle population with biological or chemical controls minimize the beetle damage on plants.
Quarantine
Japanese beetles do not pose a threat to fruit trees in California as the State USDA-APHIS has imposed a strict quarantine on importing plants from neighboring states and other countries. All over the USA the USDA has similar guidelines for nurserymen and sod producers for shipping plant material with soil out of Japanese Beetle infested areas. Educating gardeners about introducing pests by smuggling plants from infested areas is important in preventing new infestations.
Cultural Controls
Change gardening practices that encourage the development and proliferation of the beetle. Do not grow roses in the vicinity of a lawn. Since warm temperatures and moisture in the soil provide favorable conditions for hatching of eggs into larvae and further development of grubs, do not irrigate during the time the eggs and first instar larvae are developing.
In a rose garden, do not plant trees and shrubs such as Japanese and Norway maple, birch, pin oak, horse chestnut, Rose of Sharon, sycamore, ornamental apple, plum, cherry, mountain ash, willows, lindens, elms and Virginia creeper that serve as hosts to the adults.
Biological Controls
Insect Parasites (Tiphia popilliavora and T. vernalis): Nature has its own ways of handling pest populations. For every pest, there is a predator or a parasite capable of destroying the pest. The parasitic wasps, Tiphia popilliavora (native to Japan, Korea and North China) and T. vernalis (native to Korea and China), have been imported and released in this country. T. popilliavora from Japan was first released in New Jersey in 1921-22, where they quickly established. By the end of 1950 their progeny and strains from Korea and China were distributed over the infested areas of 10 states . The Korean strain adapted better to American conditions. T. vernalis was first released in New Jersey in 1925, and by 1953 over 2,000 colonies of this species were distributed over 15 states. T. vernalis is more effective in controlling Japanese beetle population than T. popilliavora.
One-quarter-inch-long shiny black adult wasps emerge during May and early June and feed on aphid honeydew. The female wasp stings the overwintering third instar Japanese beetle larva in the soil, and temporarily paralyzes it. The female wasp deposits a single egg on the beetle larva. Each female wasp may deposit up to 25 eggs during 25-30 days. The wasp egg hatches in a few days, and feeds on the host consuming the entire body, except the head and legs of the host, which eventually dies. The wasp completes its life cycle on the dead host. The wasps thrive when plenty of food supply is available. Umbelliferous plants (for example carrot, fennel, anise, etc.) provide the food for the adult wasps. When the Japanese beetles die of milky disease, the wasp population decreases as the beetle grubs that serve as food for the developing wasp larvae are no longer there. This has more damaging effect on T. popilliavora because soil temperatures at the time of parasitic activity (fall) are more favorable to the rapid development of the disease than in the spring when T. vernalis is active. Unfortunately, the wasps do not seem to reduce the beetle population below the damaging levels.
Predators
Invite birds into the landscape. Starlings, grackles, robins and other birds feed on large numbers of grubs, especially during early spring and fall. Small animals such as moles, skunks and raccoons also feed on the grubs. Birds and mammals considerably reduce Japanese beetle grub populations, however, they damage turf grass in the process of digging for the grubs.
Bacterial Milky Disease
Japanese beetles are susceptible to bacterial milky diseases, caused by Bacillus popilliae Dutky and B. lentimorbus Dutky. Milky diseases control grub populations in some areas in the eastern United States. The spores are commercially available (Fairfax Biological Laboratory, Inc. Clinton Corners, New York 12514, and Reuter Laboratories, Gainesville, Virginia 22065). Commercial formulations of spore product like 'Doom' require about 4 years after applications to become effective and can be active against grubs for 20 years. Apply 2 grams of spores at 5-10 foot intervals on turf with high populations of grubs. Do not use any other insecticides when using bacterial spores as the bacteria needs to complete its life cycle on the beetle.
Entomophagous Nematodes
Nematodes that parasitizes on insects (Entomophagous Nematodes) offer another solution for controlling Japanese Beetles. One such parasitic nematode is Steinernema (Neoaplectana) glaseri Steiner. The nematode was used before 1940 for controlling the Japanese beetles. Despite its potential as an effective control agent, it is no longer in use because of the expenses involved in developing it. Currently the commercially available preparations containing Heterorhabditis spp. appear to be effective in the control of Japanese beetle. Xenorhabdus spp., a pathogenic bacterium symbiotically associated with the nematode Heterorhabditis is responsible for the killing of grubs. The bacteria reside in the intestine of the infective juvenile stage of nematodes. The nematode penetrates an insect host and moves to the haemocoel (spaces in insects through which blood circulates) where it dumps the bacteria. The bacteria proliferate, kill the host and establish suitable conditions for reproduction of the nematodes by providing nutrients and inhibiting the growth of other bacteria. Apply the nematodes when the white grubs are in the second instars. Irrigate the soil before and after nematode applications to increase the efficacy of the nematodes.
Mechanical Control
Insect traps containing pheromone, though available, do not offer an effective control over the beetle population. In addition, traps may attract other beetles that would damage the turf.
Chemical Controls
If and when you decide to use chemical controls, make sure that the Department of Agriculture has approved them for use in your area. Assess risks and benefits of pesticide of your choice. Follow manufacturers' instructions strictly for use and disposal. Use Sevin (carbaryl), Malathion, Rotenone and Orthene (acephate) for the control of adult Japanese beetles. Use Imidacloprid (Merit™ Insecticide for turf; Marathon™ for nursery use), Bendiocarb, Isofenphos, Chlorpyrifos or Diazinon on grubs. In heavy infestations, use a 5-7 day spray schedule in July and early August on sensitive ornamentals and fruit trees.
Treat turf grass as the grass provides food and hiding place for the grubs. Apply the product, Merit™ (imadichloprid) for larval control prior to the emergence of adult beetles and during grub infestations. Timing of applications of insecticide is crucial in the control. Apply insecticide when grubs are smaller as it is difficult to kill larger grubs. Apply appropriate pesticides starting May through July, when eggs are first hatching and grubs are beginning to feed. Use rescue treatments in August and September. Use of pesticides on grubs prior to pupations will not be effective as they do not feed for long before they pupate.
Follow the manufacturers' instructions for applications and disposals of insecticides. Use necessary precautions to protect from the harmful effects of insecticides. Wear long pants, long sleeved shirts, rubber gloves and closed rubber boots, masks and protective goggles when handling any insecticide. Be aware of the potential hazards to other creatures in the landscape. It is better to use cultural or biological controls than chemical controls.
Reference:
Control of Japanese Beetle Adults and Grubs in Home Lawns, http://ohioline.osu.edu/hyg-fact/2000/2001.html
Managing Adult Japanese Beetles, L. H. Townsend, www.uky.edu/Ag/Entomology/entfacts/trees/ef409.htm
Biology and Management of the Japanese Beetle, Daniel A. Potter and David W. Held, Annual Review of Entomology Vol. 47: 175-205 (Volume publication date January 2002)
R.-U. EHLERS, 1996, Insect Biocontrol with Non-endemic Entomopathogenic Nematodes (Steinernema and Heterorhabditis spp.): Conclusions and Recommendations of a Combined OECD and COST Workshop on Scientific and Regulatory Policy Issues, Biocontrol Science and Technology Biocontrol Science and Technology, Volume 6, Number 3
Temperature regulates egg hatching and further development. As the soil temperature rises (80-90°F) in autumn, the eggs hatch into larvae within eight to nine days after they have been laid. At lower temperatures (65°F), the hatching may take about thirty days. The larvae are typical white grubs that can be separated from other soil dwelling white grubs by the presence of a V-shaped series of bristles on the raster. First instar larvae are about 1/16 inch (1.5 mm) long while the mature third instars are about 1-1/4 inch (32 mm) long. The grubs (first instar larvae) dig into moist soil, eat plant roots, and complete their development within two to four weeks. The first instar larvae develop into second instars. At higher temperatures (78°F) the second instar completes its development in less than twenty days and at lower temperatures (68°F), it may take eight weeks. As grubs tunnel into the soil feeding on the roots, the temperatures decrease; however, the soil is still warm enough for the survival of grubs. They dig deeper and deeper into the ground eating away the plant roots and organic matter. They hibernate under the ground until spring arrives. The grubs return to the surface in the spring when the surface soil temperatures are about 60°F, usually in mid-April. The grubs continue their development in the spring and the few second instars seem to mature in time to pupate along with the third instars. The mature grubs form a pre-pupa in early June. The pre-pupa voids its gut contents and has a translucent appearance. The pupa is formed in the split skin of the pre-pupa in an earthen cell 1-to-3 inches down in the soil. The grubs metamorphose into cream-colored pupae, which later become light reddish-brown with age. The average pupa is about 1/2 inch (14 mm) long and 1/4 inch (7 mm) wide.
Plant Damage
Adults feed on the upper surface of foliage of most plants, consuming the soft tissues between the veins; as a result the leaves look skeletonized. Beetle-damaged leaves turn brown and die. The dead leaves fall. Defoliation drastically reduces photosynthesis, as leaves are the photosynthesizing centers. Defoliation reduces the availability of food material for a healthy growth of roses. The hips are smaller. The beetle also attacks the hips eating the flesh.
The vicious attack of the beetle does not stop with roses. The beetle will destroy other hosts that are in the landscape. The voracious grubs damage the turf grass.
Control Strategies
Fortunately, a few control measures such as preventing unauthorized entry of beetles into an area from a beetle infested area, changing gardening practices or controlling the beetle population with biological or chemical controls minimize the beetle damage on plants.
Quarantine
Japanese beetles do not pose a threat to fruit trees in California as the State USDA-APHIS has imposed a strict quarantine on importing plants from neighboring states and other countries. All over the USA the USDA has similar guidelines for nurserymen and sod producers for shipping plant material with soil out of Japanese Beetle infested areas. Educating gardeners about introducing pests by smuggling plants from infested areas is important in preventing new infestations.
Cultural Controls
Change gardening practices that encourage the development and proliferation of the beetle. Do not grow roses in the vicinity of a lawn. Since warm temperatures and moisture in the soil provide favorable conditions for hatching of eggs into larvae and further development of grubs, do not irrigate during the time the eggs and first instar larvae are developing.
In a rose garden, do not plant trees and shrubs such as Japanese and Norway maple, birch, pin oak, horse chestnut, Rose of Sharon, sycamore, ornamental apple, plum, cherry, mountain ash, willows, lindens, elms and Virginia creeper that serve as hosts to the adults.
Biological Controls
Insect Parasites (Tiphia popilliavora and T. vernalis): Nature has its own ways of handling pest populations. For every pest, there is a predator or a parasite capable of destroying the pest. The parasitic wasps, Tiphia popilliavora (native to Japan, Korea and North China) and T. vernalis (native to Korea and China), have been imported and released in this country. T. popilliavora from Japan was first released in New Jersey in 1921-22, where they quickly established. By the end of 1950 their progeny and strains from Korea and China were distributed over the infested areas of 10 states . The Korean strain adapted better to American conditions. T. vernalis was first released in New Jersey in 1925, and by 1953 over 2,000 colonies of this species were distributed over 15 states. T. vernalis is more effective in controlling Japanese beetle population than T. popilliavora.
One-quarter-inch-long shiny black adult wasps emerge during May and early June and feed on aphid honeydew. The female wasp stings the overwintering third instar Japanese beetle larva in the soil, and temporarily paralyzes it. The female wasp deposits a single egg on the beetle larva. Each female wasp may deposit up to 25 eggs during 25-30 days. The wasp egg hatches in a few days, and feeds on the host consuming the entire body, except the head and legs of the host, which eventually dies. The wasp completes its life cycle on the dead host. The wasps thrive when plenty of food supply is available. Umbelliferous plants (for example carrot, fennel, anise, etc.) provide the food for the adult wasps. When the Japanese beetles die of milky disease, the wasp population decreases as the beetle grubs that serve as food for the developing wasp larvae are no longer there. This has more damaging effect on T. popilliavora because soil temperatures at the time of parasitic activity (fall) are more favorable to the rapid development of the disease than in the spring when T. vernalis is active. Unfortunately, the wasps do not seem to reduce the beetle population below the damaging levels.
Predators
Invite birds into the landscape. Starlings, grackles, robins and other birds feed on large numbers of grubs, especially during early spring and fall. Small animals such as moles, skunks and raccoons also feed on the grubs. Birds and mammals considerably reduce Japanese beetle grub populations, however, they damage turf grass in the process of digging for the grubs.
Bacterial Milky Disease
Japanese beetles are susceptible to bacterial milky diseases, caused by Bacillus popilliae Dutky and B. lentimorbus Dutky. Milky diseases control grub populations in some areas in the eastern United States. The spores are commercially available (Fairfax Biological Laboratory, Inc. Clinton Corners, New York 12514, and Reuter Laboratories, Gainesville, Virginia 22065). Commercial formulations of spore product like 'Doom' require about 4 years after applications to become effective and can be active against grubs for 20 years. Apply 2 grams of spores at 5-10 foot intervals on turf with high populations of grubs. Do not use any other insecticides when using bacterial spores as the bacteria needs to complete its life cycle on the beetle.
Entomophagous Nematodes
Nematodes that parasitizes on insects (Entomophagous Nematodes) offer another solution for controlling Japanese Beetles. One such parasitic nematode is Steinernema (Neoaplectana) glaseri Steiner. The nematode was used before 1940 for controlling the Japanese beetles. Despite its potential as an effective control agent, it is no longer in use because of the expenses involved in developing it. Currently the commercially available preparations containing Heterorhabditis spp. appear to be effective in the control of Japanese beetle. Xenorhabdus spp., a pathogenic bacterium symbiotically associated with the nematode Heterorhabditis is responsible for the killing of grubs. The bacteria reside in the intestine of the infective juvenile stage of nematodes. The nematode penetrates an insect host and moves to the haemocoel (spaces in insects through which blood circulates) where it dumps the bacteria. The bacteria proliferate, kill the host and establish suitable conditions for reproduction of the nematodes by providing nutrients and inhibiting the growth of other bacteria. Apply the nematodes when the white grubs are in the second instars. Irrigate the soil before and after nematode applications to increase the efficacy of the nematodes.
Mechanical Control
Insect traps containing pheromone, though available, do not offer an effective control over the beetle population. In addition, traps may attract other beetles that would damage the turf.
Chemical Controls
If and when you decide to use chemical controls, make sure that the Department of Agriculture has approved them for use in your area. Assess risks and benefits of pesticide of your choice. Follow manufacturers' instructions strictly for use and disposal. Use Sevin (carbaryl), Malathion, Rotenone and Orthene (acephate) for the control of adult Japanese beetles. Use Imidacloprid (Merit™ Insecticide for turf; Marathon™ for nursery use), Bendiocarb, Isofenphos, Chlorpyrifos or Diazinon on grubs. In heavy infestations, use a 5-7 day spray schedule in July and early August on sensitive ornamentals and fruit trees.
Treat turf grass as the grass provides food and hiding place for the grubs. Apply the product, Merit™ (imadichloprid) for larval control prior to the emergence of adult beetles and during grub infestations. Timing of applications of insecticide is crucial in the control. Apply insecticide when grubs are smaller as it is difficult to kill larger grubs. Apply appropriate pesticides starting May through July, when eggs are first hatching and grubs are beginning to feed. Use rescue treatments in August and September. Use of pesticides on grubs prior to pupations will not be effective as they do not feed for long before they pupate.
Follow the manufacturers' instructions for applications and disposals of insecticides. Use necessary precautions to protect from the harmful effects of insecticides. Wear long pants, long sleeved shirts, rubber gloves and closed rubber boots, masks and protective goggles when handling any insecticide. Be aware of the potential hazards to other creatures in the landscape. It is better to use cultural or biological controls than chemical controls.
Reference:
Control of Japanese Beetle Adults and Grubs in Home Lawns, http://ohioline.osu.edu/hyg-fact/2000/2001.html
Managing Adult Japanese Beetles, L. H. Townsend, www.uky.edu/Ag/Entomology/entfacts/trees/ef409.htm
Biology and Management of the Japanese Beetle, Daniel A. Potter and David W. Held, Annual Review of Entomology Vol. 47: 175-205 (Volume publication date January 2002)
R.-U. EHLERS, 1996, Insect Biocontrol with Non-endemic Entomopathogenic Nematodes (Steinernema and Heterorhabditis spp.): Conclusions and Recommendations of a Combined OECD and COST Workshop on Scientific and Regulatory Policy Issues, Biocontrol Science and Technology Biocontrol Science and Technology, Volume 6, Number 3
