Category Archives: Target Pests

Helicoverpa Species

Source: Gyorgy Csoka, Hungary Forest Research Institute, Bugwood.org

Common Name: American Bollworm, Cotton Bollworm, Corn Earworm, Tomato Fruitworm
Latin Name: Helicoverpa armigera, Helicoverpa zea, Helicoverpa punctigera
Order: Lepidoptera
Family: Noctuidae

Main Host(s): Field and row crops, e.g. cotton, corn, and fruiting vegetables such as tomato, lettuce, beans, pigeon pea, cowpea, sorghum, etc.

Life Cycle

Helicoverpa zea is known by numerous different common names including Cotton Bollworm or Corn Earworm, and many others specific to the crop on which it can be found. This damaging pest is native to North America. In Europe, Asia, Africa, and Australia the species is Helicoverpa armigera. While Helicoverpa armigera is a problem in many parts of the (old) world, it is a particularly difficult pest in Australia and India, where it is the number-one pest of cotton, and in Southeast Asia, where it is the most significant pest on vegetables. Regardless, Helicoverpa species worldwide have numerous host plants.

Adult moths of Helicoverpa species are vigorous flyers moving into the colder regions in the summer. The number of generations can vary from 1-2 in the colder regions and up to 7 in warmer climates. They hone in on the best host plant (be it an agricultural crop or weedy plant, depending on the part of the season) for egg laying and larval feeding. Eggs are laid singly and hatch in 3-4 days.

Larvae of Helicoverpa species can have from 5-6 instars or up to 7-8 depending on environmental/host conditions. They have a tendency to feed and bore preferentially into a crop’s flowering or fruiting structures or into clusters of leaves (as in lettuce).

Impact & Damage

The larvae feeding behavior of boring into plant structures makes Helicoverpa pests very destructive. For example, one larvae in a corn ear render it unmarketable. Infestations of flower buds of cotton (squares) will also have a great impact on yield. This feeding behavior is also challenging for many insecticides to provide optimal control.

Recommended Control

Pheromone traps are available for monitoring adult Helicoverpa pest populations in high value vegetable crops. Helicoverpa species have developed resistance to several insecticides, such as pyrethroids and insect growth regulators. For this reason, a program using DiPel^® (and/or XenTari^®) is an important means to control these destructive pests.

References & Sources:

http://www.biorationalapproach.com/
www.daff.qld.gov.au/26_8147.htm
entnemdept.ufl.edu/creatures/veg/corn_earworm.htm
www.ipm.ucdavis.edu/PMG/r783300111.html
edis.ifas.ufl.edu/pdffiles/PP/PP11700.pdf
ipm.ncsu.edu/Production_Guides/Tomatoes/AG-405Web.pdf

European Grapevine Moth

Source: Jack K. Clark, University of California IPM Statewide Program

Common Name: European Grapevine Moth (EGVM)
Latin Name: Lobesia botrana
Order: Lepidoptera
Family: Tortricidae

Main Host(s): Preferred host is grape, but occurs on kiwi, raspberry, apple, pomegranate and wild hosts such as Virginia creeper, etc.

Life Cycle

Long an important pest in grape production throughout Europe, European grapevine moth (EGVM) (Lobesia botrana) made its way into Chile and the premium wine grape areas of California for the first time in 2009, causing great concern. In Europe, EGVM can be found together with another grape berry moth, i.e. Eupocilia (Clysia) ambiguella.

There are generally two to four generations of EGVM per year. The first generation occurs between early April and mid-May in the U.S. The second (adult moth flight) appears in mid-June to late July, and the third and most critical generation appears in late August until late September.

The female lays single eggs 2-3 at a time on flower buds and fruiting structures. When the eggs develop, the black head of the developing larvae can be seen through the translucent egg covering (blackhead stage). The eggs hatch in 3-10 days depending on temperature. The final larval generation pupates for overwintering in the soil or under bark.

Impact & Damage

The first larval generation of EGVM is usually of no concern as feeding occurs on flower buds. Damage by the second larval generation feeding on small berries can become economically impactful, but the third generation larvae cause the greatest damage. This generation feeds on berries after veraison, exposing berries and clusters to bunch rot (Botrytis cinerea) and other secondary fungi.

Recommended Control

Monitoring for EGVM eggs in the vineyard should begin immediately after moths are observed in sex pheromone monitoring traps. Beneficial insect predators and parasites can play a significant role in first generation EGVM control. Despite the threat from later larval generations, growers have learned that through careful scouting and judicious application of the Bacillus thuringiensis (Bt) insecticide DiPel^®, the pest’s potentially serious damage could be limited. All generations can be controlled using DiPel alone or in tank mix or rotation with chemical insecticides. DiPel can also be used with pheromone dispensers used in mating disruption programs. DiPel application should occur when the majority of the eggs are at the blackhead stage with a second application 7-10 days after the first, if necessary.

References & Sources:

www.biorationalapproach.com
www.grapes.msu.edu/grapeberrymoth.htm
www.ipm.ucdavis.edu/PMG/selectnewpest.grapes.html
www.ipm.ucdavis.edu/EXOTIC/eurograpevinemoth.html
www.inra.fr/hyppz/RAVAGEUR/6eupamb.htm

Diamondback Moth

Source: Russ Ottens, University of Georgia, Bugwood.org

Common Name: Diamondback moth
Latin Name: Plutella xylostella
Order: Lepidoptera
Family: Plutellidae

Main Host(s): Cole crops (cruciferous plants)

Life Cycle

Diamondback Moths occur worldwide, but populations are sparse in cold climates. Diamondback Moth larvae are relatively small — about one-third of an inch when full grown — compared to other caterpillars found in Brassica vegetable crops, Their rapid 30-day life cycle can cause serious crop damage.

This pest has many generations per year, five to seven in moderately warm climates with an even higher number in (sub)-tropical regions. Diamondback Moth generations can quickly start overlapping, especially in warmer climates, meaning that eggs, larvae, and pupae can all be found in the same field at the same time.

XenTari in Soft Chemistry DBM Control Program Chart

Females will lay about 100 eggs over a two-day period, generally on the undersides of leaves. The eggs will hatch in five to six days and four larval stages follow, which combined, last between 21-25 days. The larvae will initially burrow into the leaf and mine it during the first and second instars. Then, toward the end of the second larval stage, it will exit and start feeding on the underside of the leaf. Pupa can be found in small cocoons attached to leaf surfaces.

Impact & Damage

The Diamondback Moth has developed resistance to more than 40 insecticides since the 1960s, with the demonstrated ability to develop insecticide resistance in only 2-4 years. It has done so especially in tropical countries such as Malaysia, Taiwan, Thailand, etc., where Brassica crops are grown in a continuous cropping cycle. This makes DBM a perfect target for an integrated control program featuring biorational products.

Recommended Control

Close scouting of the fields, followed by pinpoint applications of DiPel^® or XenTari^® and using a rotation of chemical insecticides, should provide an effective IPM program that avoids problems with resistance. As with most pests controlled by Bt, it’s best to control the Diamondback Moth in its early larval stages. Since feeding begins on the underside of the leaves, it’s critical that the spray application fully covers the foliage. It’s typically best to use sex pheromone traps to predict moth population peaks and is critical to begin applications when larvae are young before the pest reaches older larval stages.

References & Sources:

www.biorationalapproach.com
web.entomology.cornell.edu/shelton/diamondback-moth/
www.ent.uga.edu/veg/colecrops.htm
www.ipm.ucdavis.edu/PMG/r108301311.html
www.scentosociety.org/Volumes/JAUE/v21/171.pdf
ento.psu.edu/extension/factsheets/diamondback-moth

Colorado Potato Beetle

Source: Whitney Cranshaw, Colorado State University, Bugwood.org

Common Name: Colorado Potato Beetle
Latin Name: Leptinotarsa decemlineata
Order: Coleoptera
Family: Chrysomelidae

Main Host(s): Potato, eggplant, tomato

Life Cycle

Colorado Potato Beetle (CPB), Leptinotarsa decemlineata has long been a major pest of potato. In addition to potato, the pest also feeds on eggplant and tomato. It can be found in most potato growing regions in the U.S., Europe, as well as some parts of Asia.

Adult beetles emerge in the spring and they move rapidly by walking or flying to a suitable host plant for feeding, mating and egg laying. The beetles have a life span of 4-5 weeks, which includes a lengthy egg laying period of several weeks. Both adults and larvae of various ages can be found on their host plant. Up to three generations per year are possible depending on the climate. Summer generations have a pupal stage of 5-10 days in the soil while shorter day length will trigger the fall generation to pupate for overwintering.

The female of this species deposits hundreds of orange-yellow eggs in clusters of 30-40 eggs on the underside of leaves. The eggs hatch in 4-10 days depending on temperature, followed by four larval instars over a 21-day duration. All life stages can easily be detected and indentified.

Impact & Damage

Both the immature and adult stages of this beetle can be present at the same time and since the older larvae and the adults are vigorous feeders, the population can do considerable damage to host plant foliage. In potato, defoliation of up to 15-20% can be tolerated, but CPB populations should be kept low throughout the season.

Recommended Control

This pest has developed resistance to virtually every conventional insecticide that growers have tried. The list includes organophosphates, carbamates, pyrethroids and since 2006 the first cases of resistance to neonicotinoids are known. Novodor^® (Bacillus thuringiensis subspecies tenebrionis) is a logical choice for CPB control because the Bt mode of action is different from any conventional insecticide and no cross-resistance has ever been reported. Novodor is a highly specific, highly effective product for controlling CPB. In particular, it is one of very few options for CPB control for growers of organic potatoes.

References & Sources:

www.biorationalapproach.com
entnemdept.ufl.edu/creatures/veg/leaf/potato_beetles.htm
www.potatobeetle.org/overview.html
www.hort.uconn.edu/ipm/veg/htms/cpbipm.htm
www.umaine.edu/umext/potatoprogram/Fact%20Sheets/cpb.pdf

Cabbage Looper

Common Name: Cabbage Looper
Latin Name:Trichoplusia ni
Order: Lepidoptera
Family: Noctuidae

Main Host(s): Cole crops but also lettuce, celery, tomato and a wide range of other vegetables.

Life Cycle

Cabbage Loopers are native to North America and only overwinter in the warmest Southern areas, such as Florida.
The adults can travel great distances, migrating in the springto Northern regions and arriving even in Canada in July and August.

Female Cabbage Looper moths lay pale green eggs, singly or in small clusters of half a dozen mostly on the undersides of leaves but some on upper leaf areas. The eggs hatch in 3 to 4 days, but even as they go through the five larval stages over the next 18-25 days, the larvae generally remain on the undersides of leaves because they are photosensitive. The larvae move in a looping motion, hence the name “Looper”.

Pupation occurs in the fall and the pupae overwinter followed by emergence in the Spring.

Impact & Damage

In warm climates, Cabbage Loopers can have up to seven generations a year and can cause tremendous damage to vegetable crops. Due to easy identification and determination of feeding damage, the Cabbage Looper is a designated standard for assessing caterpillar pest presence and the timing of insecticide applications.

Alton N. Sparks, Jr., University of Georgia, Bugwood.org

Egg Stage
Source: Whitney Cranshaw, Colorado State University, Bugwood.org

Recommended Control

Scouting and early detection of Cabbage Loopers is particularly critical. Many growers use sex pheromone traps to monitor incoming adults. After adults have been found, scouting for eggs begins. Both DiPel^®, with Bt subspecies kurstaki, and XenTari^®, with Bt subspecies aizawai as active ingredient are excellent strategies against the Cabbage Looper. Feeding damage assessment during the course of the growing season is important to know when to initiate spray applications. Bt should be applied when egg masses are mature and insects are beginning to hatch. Significant feeding begins with the second instar, not the first, so most growers find that if they apply a thorough coverage of a Bt within a couple of days of egg hatch, they can avoid serious economic damage.

Used properly, DiPel performance against Cabbage Looper
is on par with the leading diamide chemistries.

References & Sources:

www.biorationalapproach.com
www.uri.edu/ce/factsheets/sheets/cabbagelooper.html
www.ipm.ucdavis.edu/PMG/r108301011.html
www.omafra.gov.on.ca/english/crops/facts/99-035.htm
entnemdept.ufl.edu/creatures/veg/leaf/cabbage_looper.htm
www.vegedge.umn.edu/vegpest/colecrop/looper.htm
westernfarmpress.com/controlling-beet-armyworms-cabbage-loopers

Armyworm

Common Name: Armyworm
Latin Name:Spodoptera spp., e.g. exigua, frugiperda, littoralis, Pseudoletia unipuncta
Order: Lepidoptera
Family: Noctuidae

Main Host(s): Field and row crops, e.g. cotton, soybean, cole crops, leafy and fruiting vegetables

Life Cycle

Larval Stage

Source: Frank Peairs, Colorado State University, Bugwood.org

Armyworm includes several species including the Beet Armyworm (Spodoptera exigua), Fall Armyworm (S. frugiperda) and Southern Armyworm (S. eridania) in the U.S. Various species are a problem in many parts of the world: in Africa, S. exempta; in Asia, S. litura; in the Mediterranean area, S. littoralis. The designation of “true” Armyworm is reserved for Pseudoletia unipunctata. The adult moths of the Armyworm are strong flyers and migrate to the cooler parts of the regions they inhabit.

Impact & Damage

Females generally lay white to yellow eggs in several rows on the undersides of leaves in lower canopy of the plant. Armyworm larvae hatch from large egg masses and then forage in groups, hence their name. Three generations per year are possible. Following egg hatch, many larvae will be grouped in a mass within a small concentrated area. Larger larvae are enormously destructive. Armyworms begin feeding near where they hatch, and begin to spread out as they grow. Because they feed at night, armyworms can be difficult to control. Pupation occurs in the soil.

Armyworm species feed on a host of field and row crops, from cotton, soybeans to grains such as rice, wheat, sorghum, as well as vegetables including cole crops, leafy and fruiting vegetables. Since most larvae will grow to large size insects they can do considerable damage.

Recommended Control

VBC’s XenTari^® is highly effective against Armyworm pests. An excellent time to spray XenTari is when larvae are young and concentrated in small areas. At early developmental stages armyworms are most susceptible to Bt. It is strongly recommended that growers apply XenTari within the first week after egg hatch to ensure the pest is controlled while the populations are concentrated and remain in the first or second instar.

Early application of Bt requires knowledge of insect development and scouting. Pheromone traps are available for monitoring adult flight to help discover early when eggs may be laid.

Typically, higher rates of XenTari are used when controlling this pest.

Used properly, XenTari performance against Armyworm pests is on par with the leading diamide chemistries.

References & Sources:

http://www.biorationalapproach.com
entnemdept.ufl.edu/creatures/field/true_armyworm.htm
extension.missouri.edu/webster/webster/agric/armyworms-field.html
ipm.illinois.edu/fieldcrops/insects/armyworm/
ipm.ncsu.edu/ag295/html/armyworm.htm
bugguide.net/node/view/67373/bgimage
www.europe-aliens.org/pdf/Spodoptera_littoralis.pdf