Bugs for Growers

Biological and Cultural methods to control imported cabbageworms

The cabbage butterfly is commonly called as imported cabbageworm, Artogeia rapae (Pieris rapae). This is one of the most important pests of many Cole crops including broccoli, cabbage, collard greens, cauliflower, kale and turnip.  Butterflies are easy to identify as they have whitish colored fore-and hind-wings with one and two black spots on the top of each of fore wings of males and females, respectively.  Also, both males and females have a black spot on the outer front margin of each hind wing.  Females lay singly yellow colored and oblong eggs on the either side of the leaves and depending on the temperature eggs hatch within a week. Mature larvae are velvety green in color with a narrow orange stripe down the middle of the back and a yellowish stripe along each side of the body (Fig. 1.)  The pupae are green to light brown in color, attached to bottom leaves and adults generally emerge from these pupae within 2 weeks of pupation. Cabbage butterflies overwinter as pupae in previous crop plant debris in the garden. [caption id="attachment_644" align="aligncenter" width="300" caption="Fig. 1. Severe damage caused by Imported Cabbageworms near growing point of a collard green plant"][/caption] Generally cabbage butterfly larvae feed voraciously near to the growing point of the host plants (Fig. 2) but they can also feed indiscriminately by chewing large irregular holes on both young and mature leaves of different host plants including broccoli, cabbage, cauliflower, collard greens, kale and turnip (Figs. 1 and 2). [caption id="attachment_645" align="aligncenter" width="200" caption="Fig. 2. Larva of an imported cabbageworm feeding by chewing large irregular holes on a collard green mature leaf"][/caption] Since chemical insecticides cannot be used in organic vegetable gardens, growers have to rely on the cultural and biological methods to manage populations of imported cabbageworm.

Cultural Methods

For small or large vegetable gardens, best cultural practice is hand picking and killing of all the larval stages of imported cabbageworm. Although this practice is laborious and time consuming, it works and reduces the damage caused by this economically important insect pest. Also, at the end of the fall season remove all the previous crop plant debris so that there will be less protected areas available for overwintering imported cabbage worms, which in turn will reduce the populations of adults in the next spring.  This low number of adult emergence means there will be less numbers of eggs to hatch into larvae meaning there will be less larval incidence to cause the damage to the crop in the spring.

Biological Methods

Biological methods include use of natural enemies/biological control agents to control cabbage butterflies. Three well known biological control agents including Bacillus thuringiensis (Bt), entomopathogenic nematodes and wasps have a potential to manage imported cabbageworm population in the vegetable gardens.

Bacillus thuringiensis kurstaki (Bt):

This bacterium is recognized as a bacterial insecticide but it is not harmful to the humans, animals or the environment. This is a very effective biopesticide on young larval stages as compared to the mature larval stages of cabbage butterflies.  This microbial biocontrol agent is commercially available and can be applied using traditional sprayers. For the effective control of imported cabbageworms, Bacillus thuringiensis kurstaki should be applied at every seven day interval after noticing the first incidence of pest.

Entomopathogenic nematodes:

Currently, entomopathogenic nematodes are used as effective biological control agents against many different kinds of soil-dwelling insect pests of many economically important crops and turfgrasses. These nematodes are commercially available and are not harmful to humans, animals and even beneficial insects like honeybees. Canadian researchers have demonstrated that the entomopathogenic nematodes including Steinernema carpocapsae, S. feltiae and S. riobrave can cause 76 to 100% mortality of imported cabbageworms Artogeia rapae if applied at temperatures ranging from 25 to 30 °C and their LC50 values were ranged from 4 to 18 infective juveniles (Bélair et al., 2003). Mahar et al (2005) also reported that in addition to the above stated species of entomopathogenic nematodes, Heterorhabditis bacteriophora and H. indica nematodes can infect and kill both larvae and pupae of cabbage butterflies. Recently, another insect-parasitic nematode, Rhabditis blumi also been shown to be effective against imported cabbageworm (Park et al., 2012).

Wasps:

Following four species of parasitic wasps can serves as effective biological control agents against imported cabbage worm.

1. The egg parasitic wasp, Trichogramma spp.: This is a very tiny parasitic wasp known for parasitizing eggs of imported cabbageworms. These wasps are commercially available and can be mass released when lots of adult butterflies are present in the garden and already started laying eggs on the leaves.  This will prevent the hatching of eggs into larvae thus preventing damage caused by imported cabbageworm larvae to Cole crops (Oatman et al., 1968).
2. The brachonid wasp, Cotesia glomerata: This gregarious wasp parasitizes the larvae of the imported cabbageworms. This wasp species is not commercially available but it can naturally occur (Herlihy et al., 2012) and capable of suppressing the populations of cabbage butterflies in the vegetable gardens and fields. This wasp lays eggs inside the young caterpillars of imported cabbageworms. The eggs hatch and the larvae develop inside the developing imported cabbageworm larvae, then emerge as mature larvae and pupate in yellow silken cocoons outside the host, which dies during the process of the emergence of wasp larvae. If this wasp is present in the fields, which are infested with imported cabbageworms or other insect hosts, it can parasitize and kill over 60% of their insect host larvae.
3. The solitary wasp, Cotesia rubecula:  This naturally occurring parasitic wasp is known to its specificity to the members of genus Pieris especially imported cabbageworms. Although C. rubecula wasp parasitizes all the stages of imported cabbageworms, it prefers last instar of imported cabbageworms, which is the most damaging stage. This is the most studied parasitic wasp of imported cabbageworms and found to be distributed throughout the US (Herlihy et al., 2012).
4. The pteromalid wasp, Pteromalus puparum: This tiny wasp specifically parasitizes pupae of imported cabbageworms and other lepidopterous insects.  Since this wasp parasitoid kills only pupae of its insect host, it does not reduce the larval feeding damage caused before pupation but it certainly reduces the emergence of the next generation of adults. This means there are less number of egg laying females that results in the less number of eggs and therefore, less larval incidence to cause severe damage to the crop.

 

Literature:

Bélair, G., Fournier, C.Y. and Dauphinais, N. 2003. Efficacy of Steinernematid nematodes against three insect pests of Crucifers in Quebec.  Journal of Nematology 35: 259–265. Cai, J., Ye, G.Y. and Hu, C. 2004.  Parasitism of Pieris rapae (Lepidoptera: Pieridae) by a pupal endoparasitoid, Pteromalus puparum (Hymenoptera: Pteromalidae): effects of parasitization and venom on host hemocytes. Journal of Insect Physiology 50:315-322. Cameron, P.J. and Walker, G.P. 1997.  Host specificity of Cotesia rubecula and Cotesia plutellae, parasitoids of white butterfly and diamondback moth. Proceedings of 50th N.Z. Plant Protection Conference: 236-241 Herlihy, M.V., Van Driesche, R.G., Abney, M.R., Brodeur, J., Bryant, A.B., Casagrande, R.A., Delaney, D.A., Elkner, T.E., Fleischer, S J., Groves, R.L., Gruner, D.S., Harmon, J.P., Heimpel, G.E., Hemady, K., Kuhar,T.P., Maund, C.M., Shelton, A.M., Seaman, A.J., Skinner, M., Weinzierl, R., Yeargan, KV. And Szendrei, Z. 2012. Distribution of Cotesia rubecula (Hymenoptera: Braconidae) and its displacement of Cotesia glomerata in Eastern North America.  Florida Entomologist, 95:461-467. Mahar, A.N., Jan, N.D., Chachar, Q.I., Markhand, G.S., Munir M. and Mahar, A.Q. 2005. Production and infectivity of some entomopathogenic nematodes against larvae and pupae of Cabbage Butterfly, Pieris brassicae L. (Lepidoptera:Pieridae). Journal of Entomology 2: 86-91. Oatman, E. R.; Platner, G. R.; Greany, P. D. 1968. Parasitization of imported cabbageworm and cabbage looper eggs on cabbage in Southern California, with notes on the colonization of Trichogramma evanescens. Journal of Economic Entomology 61: 724-730. Park, H.W., Kim, H.H., Youn, S.H., Shin, T.S., Bilgrami, A.L., Cho, M.R. and Shin, C.S. 2012. Biological control potentials of insect-parasitic nematode Rhabditis blumi (Nematoda: Rhabditida) for major cruciferous vegetable insect pests. Applied Entomology and Zoology 47: 389-397.

Organic Garlic Production

1. Preparation of Land for Garlic Planting:

Garlic is generally planted in late fall and harvested in late spring. Garlic can be grown in partially sunny areas but it thrives best in full sun. Clean the selected area by removing all the previous plant and weed debris. This can be used to make compost (Fig. 1). [caption id="attachment_610" align="aligncenter" width="300"] Fig. 1. A pile of previous plant and weed debris used for making compost[/caption] Then loosen the soil with a tiller or a shovel and level it with a rake (Fig. 2). [caption id="attachment_600" align="aligncenter" width="300"] Fig. 2. The selected area should be leveled before planting.[/caption] After leveling the soil, cover the whole area with old newspapers. This will block out sunlight and help prevent germination of weed seeds, which in turn will save the trouble of weeding when the garlic is growing (Fig. 3) [caption id="attachment_601" align="aligncenter" width="300"] Fig. 3. Old newspapers are easily available and can be used as a organic weed control in the garlic field.[/caption] Secure the newspapers with 6" wooden planks (Figs. 4 and 5) or any other available heavy material so that the papers do not fly away with the wind (Figs. 3 and 4). Using 6" planks allows a desirable distance of 6" to be maintained between two planting rows. While laying the planks on the newspaper, leave 3- 4 inch gap between the planks. In this way, planting rows will be formed automatically between the planks (Fig. 4). [caption id="attachment_608" align="aligncenter" width="300"] Fig. 4. Wooden planks used to secure newspapers and for forming rows for planting garlic.[/caption] After arranging wooden planks in each row, make holes with a metal rod or a wooden stick in the soil by ripping newspaper in a circular fashion at every 6 inches for planting garlic cloves (Fig. 5). [caption id="attachment_602" align="aligncenter" width="242"] Fig. 5. A hole was made in the soil using a small metal rod to plant a garlic seed clove[/caption] In this way a standard distance of 6 inches would be maintained between two garlic plants and between two rows.  Note that the process described above (wooden planks and newspapers) is only feasible for a small garden and not for large acreage.

2. Planting Garlic:

After the above preparations are completed, break a garlic bulb into individual cloves (Fig. 6). Select comparatively large sized cloves for planting as large sized cloves will produce large sized garlic bulbs (Fig. 7). [caption id="attachment_604" align="aligncenter" width="278"] Fig. 6. Garlic cloves are separated from bulbs and individual clove used as garlic seeds. Each clove produces a garlic bulb.[/caption] [caption id="attachment_605" align="aligncenter" width="253"] Fig. 7. Large size garlic cloves were selected for planting because they generally produce large size garlic bulbs.[/caption] Store these cloves in a cool place until you are ready tor plant, generally the beginning of November to the end of December is an ideal time here in Georgia. In the colder parts of the country, garlic should be planted 3-4 weeks before the ground freezes. The timing of planting is important to let the garlic cloves produce a good root system before winter sets in. When optimum moisture (at field capacity) is present in the soil, plant a single selected large sized clove with pointed end up in the hole at least 1.5 to 2.0 inches deep and cover it with a thin layer of soil (Fig. 8). [caption id="attachment_595" align="aligncenter" width="237"] Fig. 8. As shown in the picture insert a single clove, with pointed end up, in the hole and cover it with a thin layer of soil.[/caption] Depending on the moisture in the ground and environmental temperature, garlic cloves will sprout within 7- 10 days of planting (Fig. 9). [caption id="attachment_606" align="aligncenter" width="260"] Fig. 9. Sprouted garlic clove 10 days after planting.[/caption] Allow garlic plants to grow until garlic plants show typical symptoms of their readiness to harvest. Fig. 10. shows growth of garlic 3 months after planting. [caption id="attachment_607" align="aligncenter" width="244"] Fig. 10. The growth of garlic crop three months after planting[/caption] Generally garlic bulbs are ready when the lower leaves turn yellowish or brownish in color and top leaves are still greenish in color (Fig. 11).  However, if you wait until all the leaves turn brown or become dry then it is too late to harvest the garlic. You will notice that all bulbs are divided (split) into separate cloves and they will not have enough leaf sheathes to wrap all the cloves together into an intact bulb, which in turn affects the storage life of garlic bulbs.  Also, there is a possibility that these divided bulbs can become targets for infection by fungus or any other disease causing organisms.

3. Harvesting of Garlic:

Harvesting garlic is a very easy process but you still need to take care to avoid bruising or injuring the bulbs so that their storage life will be enhanced.  Garlic bulbs sunburn easily and some varieties' flavor will change when exposed to the sun so select a cloudy day to harvest garlic. Th ground should also be soft (i.e. a few days after moderate amount of rain) for easy uprooting.  It is always advisable to loosen the soil beside the plant with a shovel or fork and then lift the plant (Fig. 11). This way the bulbs are not injured and remain intact with the stems/leaves, which are required for the process of proper curing. [caption id="attachment_592" align="aligncenter" width="300"] Fig. 11. For easy uprooting, first loosen the soil beside the plant with a shovel or fork and then lift the plant. along with garlic bulb[/caption] Then leave the harvested plants on the ground (if day is cloudy) for a couple of hours to dry the soil attached to the bulbs (Fig. 12). [caption id="attachment_596" align="aligncenter" width="300"] Fig. 12. Harvested garlic laid to dry out soil[/caption]

4. Curing of Garlic:

Shake the garlic plants to remove any extra dry soil from the bulbs and take them to the curing barn. For better curing, the curing barn should be a well-ventilated and warm but not hot.  For curing purposes, tie the stems/leaves of four plants together (Fig. 13) and then hang them on a stick or on the rope to form a single layer for easy drying/curing (Fig. 14). [caption id="attachment_598" align="aligncenter" width="195"] Fig. 13. Several bunches of four harvested garlic plants that tied together for hanging on a stick for proper curing[/caption] [caption id="attachment_594" align="aligncenter" width="300"] Fig. 14. For better curing, hang garlic plants in a single layer on a stick in the curing barn[/caption]

5. Storage of Garlic:

This process of curing generally takes several weeks. After curing, brush any remaining soil and loose leaf sheathes off of the bulbs, clip the roots, remove the stems and store the bulbs in mesh or paper bags (Fig. 15) in a well-ventilated and cool place. [caption id="attachment_593" align="aligncenter" width="179"] Fig. 15. Store properly cured garlic in a mesh or paper bags in a well-ventilated and cool place.[/caption]    

Biological control of squash bug

The squash bugs (Anasa tristis) are the economically important pests of many plants in the Cucurbitae family. Adult bugs are grayish in color and about 5/8 inch long. [caption id="attachment_457" align="aligncenter" width="300" caption="The adult squash bug found on zucchini leaf"][/caption] Female bugs lay yellowish orange or reddish colored eggs on the underside of leaves or on stems. [caption id="attachment_458" align="aligncenter" width="300" caption="Squash bugs generally lay eggs in a group of 20- 25 on the underside of leaves but they can also lay eggs on the uppersurface of leaf"][/caption] Immediately after hatching from eggs, nymphs start feeding on the leaves, leaf stalks and stems, and become mature by going through five nymphal stages. [caption id="attachment_456" align="aligncenter" width="300" caption="Single Squash bug nymph feeding on a zucchini leaf"][/caption] [caption id="attachment_551" align="aligncenter" width="300" caption="Squash bug nymphs feeding on Zucchini leaf stalks"][/caption] Both adults and nymphs suck cell sap from leaves and leaf stalks using their sucking piercing types of mouth parts. Heavy infestation causes wilting of leaves and eventually killing the entire plant. There are several species of predatory and parasitic insects that feed on the both mature and immature stages, and eggs of squash bugs. For example, predatory insects including the bigeyed bug (Geocoris punctipes), Pagasa fusca and the damsel bug (Nabis sp) directly munch on the all the stages of squash bugs whereas the feather-legged fly (Trichopoda pennipes) adults parasitizes both the nymphal and adult squash bugs but adults of the scelionid wasp (Gyron pennsylvanicum)parasitizes eggs of squash bugs. Thus these beneficial insects have a potential to keep populations of squash bugs below economic threshold level in your garden. Therefore, if you want to have presence of more of these beneficial insects in your organic garden, you need to plant specific types of attractive plants that will serve as food source for their adults to hang around in your garden. For example, the adult feather-legged flies that parasitize and kill the squash bugs in your organic garden are attracted to plants such as carrot, dill and parsley. [caption id="attachment_552" align="aligncenter" width="300" caption="Dill flowers can attract both predatory and parasitic insects to your organic garden"][/caption] The predatory bigeyed bugs are attracted to sunflowers whereas damsel bugs are attracted alfalfa, clover and radish flowers.

Literature:

Decker, K.B. and Yeargan, K.V. 2008. Seasonal phenology and natural enemies of the squash bug (Hemiptera : Coreidae) in Kentucky. Environmental Entomology 37: 670-678. Olson, D.L., Nechols, J.R. and Schurle, B.W. 1996.   Comparative evaluation of population effect and economic potential of biological suppression tactics versus chemical control for squash bug (Heteroptera: Coreidae) management on pumpkins. Journal of Economic Entomology 89: 631-639. Pickett, C.H. Schoenig, S.E. and Hoffmann, M.P.  1996. Establishment of the squash bug parasitoid, Trichopoda pennipes Fabr (Diptera: Tachnidae), in northern California. Pan-pacific Entomologist 72: 220-226. Vogt, E.A. and Nechols, J.R. 1993. Responses of the squash bug (Hemiptera, Coreidae) and its egg parasitoid, Gryon-pennsylvanicum (Hymenoptera, Scelionidae) to 3 cucurbita cultivars. Environmental Entomology 22: 238-245.

1. Flea beetles are called as flea beetles because they jump like fleas. Flea beetles are metallic black, blue, bronze or brown in color and about 1/16-1/8^th inch long.
2. Life cycle of flea beetles is very simple containing egg, larval and adult stages.  Flea beetles overwinter as adults by hiding under shelters including dry debris of plants (leaves and stems) left over from your garden crops or weeds. Early in the spring when temperature rises to about 50 F, the overwintering beetles become active and start feeding on the leaves of young plants. While feeding, they mate and lay eggs in the soil cracks around the root system of host plants or weeds in your garden or surrounding areas . Eggs hatch within 1-2 weeks and immediately larvae starts feeding on the roots of young host plants (see below) or weed hosts until they become mature. Then mature larvae pupate in the soil for 1-2 weeks; then emerge as adults and the life cycle continues. Generally this insect completes 2-3 generations in a year.
3. Flea beetles are known to cause economic damage to many different vegetable crops including beans, broccoli, Brussels sprouts, cabbage, cauliflower, Chinese cabbage, collards, corn, eggplant, kale, lettuce, melons, mustard,  peppers, potatoes, radishes, red Russian kale, rutabaga, spinach, squash, sunflowers, tomatoes, turnips and several species of weeds.
4. Adults are the most damaging stage of flea beetles. They generally feed on foliage by chewing small holes through leaves and their heavy infestation gives a sieve-like appearance to the plant leaves thus reducing their marketable value especially leafy vegetables. Also, the heavy infestation of flea beetles can kill young seedlings.
5. Flea beetle larvae feed on the plant roots but they do not cause a considerable economic damage to crop.
6.  As temperature starts declining in the fall, adult flea beetles start looking for a shelter to hide and overwinter. Therefore, the process of management of flea beetles should begin in the fall to target overwintering beetles to reduce their incidence and outbreak in the next spring. The management of flea beetles should include both cultural and biological methods. Although the chemical insecticides could be more effective than other methods in controlling flea beetles, their use in the organic gardens should be avoided due to their detrimental effects on the human/animal health and environmental pollution.
7. As a cultural control practice, keep your garden and its surrounding clean in the fall by removing all the plant debris including dry leaves and stems of harvested crops, weeds and other trash that may serve as the possible shelter for overwintering beetles.
8.  Biological control method includes use of entomopathogenic nematodes (also called as insect-parasitic or beneficial nematodes) to target and kill larval and pupal stages of flea beetles in the spring.  Entomopathogenic nematodes can also attack and kill flea beetle adults if they come in contact in the soil.  Application of entomopathogenic nematodes such as Steinernema carpocapsae, Heterorhabditis bacteriophora and Heterorhabditis indica in the mid-late spring in your garden can kill both larval and pupal stages of flea beetles and thus reduce the emergence second generation adults, which are the most damaging to your crop.
9. For the optimal rates and appropriate methods of application of entomopathogenic nematodes, read our blog at http://blog.bugsforgrowers.com/natural-predators/entomopathogenic-nematodes/beneficial-nematodes/how-to-deploy-your-nematode-army-and-kill-insect-pests/

What are Japanese beetles?

As name implies Japanese beetles, Popillia japonica are native to Japan but in the United States, they were first accidentally introduced into New Jersey in 1916. Currently, Japanese beetles have been distributed throughout the United State and causing economic loss to many agricultural and horticultural crops, and reducing aesthetic values of many ornamental plants. Japanese beetle adults are shiny and attractive metallic-green in color, oval shaped and about 1.5 inch long (Fig. 1.). These beetles cause a severe damage to leaves (Fig. 1), flowers (Fig.2) and ripening fruits of different plant species.  In case of severe infestation, adult Japanese beetles can completely skeletonize all the leaves (Fig. 3) and eventually defoliate the whole plants.  Larvae (also called grubs) of Japanese beetle make C- shape when they are disturbed (Fig. 4) and they possess three pairs of thoracic legs. They are whitish in color with yellowish-brown colored head capsule. Japanese beetle grubs generally feed on the roots of turf grass and many ornamental plants. The damage caused by Japanese beetle grubs to turf grass is easily recognized.   [caption id="attachment_483" align="aligncenter" width="179" caption="Fig.1. Japanese Beetles feeding on rose leaves"][/caption] [caption id="attachment_485" align="aligncenter" width="179" caption="Fig. 2. Adult Japanese beetles are feeding on the rose flowers"][/caption] [caption id="attachment_484" align="aligncenter" width="179" caption="Fig.3. Rose leaves are completely skeletonized by Japanese beetle adults"][/caption] [caption id="attachment_486" align="aligncenter" width="300" caption="Fig. 4. Japanese beetle larvae or grubs feed on the turfgrass roots."][/caption]

Signs of Japanese beetle infestation and damage to lawns and golf courses.

• At the beginning of infestation in your lawn, you will notice localized patches of dead turf grass, which is always confused with the symptoms of water stress.
• As the feeding activity of grubs on turf roots increases, small patches of dead turf are enlarged and joined together to form the large areas of dead turf.
• This dead turf is generally loose and can be easily picked up with hand like a piece of carpet.
• The most important sign of presence of Japanese beetle grubs in your lawn is that the infested areas of lawn is destroyed by digging animals such as raccoons and skunks or by birds that are looking for grubs to feast on them.

Life cycle of Japanese beetle:

For Japanese beetles, it takes about one year to complete egg to egg life cycle.  For example, adults of Japanese beetles emerge from pupae in the late June through July and start feeding on leaves, flowers and fruits. While feeding they mate and lay eggs in the soil near grass root zone at the depth of 1-2 inches. The eggs hatch within 1-2 weeks (i.e. in August) and first instar grub immediately starts feeding on grass roots and organic matter.  Grubs develop into two more instars August through October by continuously feeding on grass roots. In September and October they start moving deep into soil for overwintering.  When weather warms in April, grubs move back into the turf root-zone, start feeding on turf roots again and continue to develop and early in the June they pupate into the soil.  Then adults of Japanese beetles emerge from pupae in the late June, then they mate, lay eggs and life cycle continues.

What are entomopathogenic nematodes?

Entomopathogenic nematode are also called as insect-parasitic nematodes, which are defined as thread-like microscopic, colorless and un-segmented round worms. These round worms are the members of both Steinernematidae and Heterorhabditidae families and currently used as an excellent biological control agents against many soil dwelling insect pests of many economically important insect pests including Japanese beetles.  Entomopathogenic nematodes are sold when they are in the infective juvenile stage that also called as dauer juveniles. These infective juveniles always carry mutualistically associated symbiotic bacterial cells in their gut. Since these bacteria are pathogenic and capable of causing a disease to a variety of insect hosts, they are called as entomopathogenic nematodes.

Which species of entomopathogenic nematodes are effective against Japanese beetles?

Following species of entomopathogenic nematodes have been considered to be the most effective species against Japanese beetle grubs (see below for the optimum rates of nematodes).

• Heterorhabditis bacteriophora nematodes
• Heterorhabditis zealandica
• Heterorhabditis indica nematodes
• Steinernema scarabaei
• Steinernema carpocapsae nematodes
• Steinernema rivobrave

Why fall is the time to apply nematodes and reduce existing populations to prevent future outbreaks of Japanese beetles.

As we know that Japanese beetles overwinter in their larval stages. To do this, they will start moving deep into the soil in September and October (depending on the temperature). In some places the temperature has already started declining, which is an important cue for Japanese beetle larvae to get ready for winter weather.  Therefore, it is time to apply entompopathogenic nematodes which can target the Japanese beetle larvae that start going deep into the soil for overwintering.

What stages of Japanese Beetles can be targeted?

• All the immature stages of Japanese beetles are susceptible to entomopathogenic nematodes.
• Adults of Japanese beetles are also susceptible to entomopathogenic nematodes.

How can Entomopathogenic Nematodes kill Japanese beetle larvae?

When the infective juveniles of entomopathogenic nematodes are applied to the soil surface or thatch layer, they start looking for their hosts including Japanese beetle grubs. Once a grub has been located, the nematode infective juveniles penetrate into the Japanese beetle grub body cavity via natural openings such as mouth, anus and spiracles. Then these infective juveniles enter grub’s body cavity where they release symbiotic bacteria (Xenorhabdus spp. for Steinernematidae and Photorhabdus spp. for Heterorhabditidae) from their gut in grub blood. When in the grub’s blood, multiplying nematode-bacterium complex causes septicemia and kills Japanese beetle grubs usually within 48 h after infection.  Nematodes generally feed on multiplying bacteria, mature into adults, reproduce and then emerge as infective juveniles from the cadaver to seek new Japanese beetle grubs or other insect host that present in the soil.

When, how and how many entomopathogenic nematodes should be applied for the effective control of Japanese beetles?

For details read our blog

Literature:

Grewal, P.S., Koppenhofer, A.M., and Choo, H.Y., 2005.  Lawn, turfgrass and Pasture applications. In: Nematodes As Biocontrol Agents. Grewal, P.S. Ehlers, R.-U., Shapiro-Ilan, D. (eds.). CAB publishing, CAB International, Oxon. Pp 147-166. Koppenhofer, A.M., Fuzy, E.M., Crocker, R.L., Gelernter, W.D. and Polavarapu, S. 2004. Pathogenicity of Heterorhabditis bacteriophora, Steinernema glaseri, and S. scarabaei (Rhabditida : Heterorhabditidae, Steinernematidae) against 12 white grub species (Coleoptera : Scarabaeidae). Biocontrol Science and Technology. 14: 87-92. Maneesakorn, P., An, R., Grewal, P.S.and Chandrapatya, A. 2010. Virulence of our new strains of entomopathogenic nematodes from Thailand against second instar larva of the Japanese Beetle, Popillia japonica (Coleoptera: Scarabaeidae). Thai Journal of Agricultural Science.43: 61-66. Mannion, C.M., McLane, W., Klein, M.G., Moyseenko, J., Oliver, J.B. and Cowan D. 2001. Management of early-instar Japanese beetle (Coleoptera : Scarabaeidae) in field-grown nursery crops. Journal of Economic Entomology. 94: 1151-1161.