Vegetable: Colorado Potato Beetle, Management, UMass Center for Agriculture, Food and the Environment
Colorado Potato Beetle, Management
- 1 Colorado Potato Beetle, Management
- 2 Monitoring & Thresholds:
- 3 Cultural Controls & Prevention:
- 4 Biological Controls:
- 5 Chemical Controls & Pesticides:
- 6 Avoiding Pests and Disease in the Garden
- 7 Controlling disease
- 8 Cooperative Extension Publications
- 9 Bulletin #2424, Insecticide Resistance in Colorado Potato Beetles
Colorado potato beetle is a key pest of potato and eggplant throughout the Northeast and requires a combination of cultural, biological and chemical strategies for effective control. It is important to understand the life cycle of any pest you are trying to control — for information on Colorado potato beetle identification, life cycle, and crop injury, please see our main Colorado Potato Beetle article.
Monitoring & Thresholds:
See scouting sheets for potato and eggplant at the bottom of this page. These can be used for a range of insects and diseases in each crop.
Scout beetles on 30-50 plants (or later in the season, stalks). One recommended procedure is to walk the field in a V-shaped pattern and stop at 10 sites across the field. Randomize your selection of sites using a set number of paces (e.g. stop every 10 paces) depending on field size. At each location, select 3-5 plants if plants are less than 12-18” tall; if plants are larger, select 3-5 stalks. Alternatively, select 30-50 plants or stalks individually at random across the field.
Count adults, large larvae (greater than half-grown) and small larvae (less than half-grown) separately. Take note of the presence of orange-yellow egg masses on undersides of leaves — eggs will hatch into larvae 7-10 days after being laid. Record percent defoliation of each plant/stalk.
A treatment should be considered if the number of adults or larvae or defoliation levels reach one of these thresholds:
- 10% defoliation
- Adults: 25 beetles/50 plants
- Small larvae: 4/plant
- Large larvae: 1.5/plant or stalk, based on a count of 50 plants/stalks
Scout weekly. If population pressure may be on the rise, such as when new eggs are hatching or larvae are small, scout again in 3-4 days, especially if numbers are above the following thresholds: 15 adults, 75 small larvae or 30 large larvae per 50 plants/stalks.
Potatoes can tolerate 20% defoliation without reduction in yield (or even more, depending on time of the season and cultivar). Damage by adults in rotated fields may not be significant, so you can wait for egg hatch to kill both adults and larvae. In contrast, damage to eggplant seedlings from adult feeding is often severe enough to warrant control of the adults.
Cultural Controls & Prevention:
- Crop rotation. Rotate to fields at least 200 yards from previous year’s fields. Barriers such as roads, rivers, woodlands, and fields with non-host crops are helpful. This single practice delays and reduces colonization by adults, and reduces subsequent egg and larval populations.
- Healthy seed. Plant only healthy seed and practice good crop nutrition to help plants grow well and withstand feeding injury.
- Early planting. Green sprouting, also know as chitting, prepares whole seed potatoes to emerge rapidly, gaining about 7-10 days to harvest. This early start makes it easier for the crop to put on growth and size before CPB adults and larvae arrive. While it won’t avoid damage altogether, it may reduce the need for insecticides.
- Late planting. Planting after mid-June and using a short season variety often avoids CPB damage, as adults that do not find food will leave the field in search of greener pastures. This practice may eliminate the need for controls.
- Mulch potato and eggplant with straw to reduce number of adults settling on plants. This can be accomplished in larger plantings by strip planting in a rye mulch, then mowing and pushing the rye straw over the plants after they emerge. For smaller plots, straw may be carried in.
- Use mechanical barriers such as trench traps, trap crops, and straw mulch to delay and reduce infestation. Install plastic-lined trench traps next to overwintering sites at least one week before adults emerge. Trenches should be 1′ to 2′ deep and 6″ to 24″ wide at the top. They can be U- or V-shaped with side walls sloping at angles between 65° and 90°. Beetles walking from field borders fall into the trench and cannot fly out.
- Plant perimeter trap crops to attract beetles before the main crop emerges. Trap crops can also be planted between overwintering sites and this season’s crop. Flame, vacuum or spray border crop before beetles move into the main crop. Another approach is to plant three to five rows of potatoes treated with a systemic insecticide in a perimeter around the field; this treated border will kill up to 80% of the colonizing beetles. Straw mulch around the host crop has been shown to reduce beetle numbers. Late planting may cause beetles to leave the field before potatoes emerge, resulting in lower beetle numbers.
- Flame crops under 3-4 inches high to kill colonizing adult beetles. Move rapidly using a tractor mounted or hand-held flamer. The goal is to scorch beetles, as injury to antennae and legs render them unable to orient and climb plants. at this early stage, healthy emerging potatoes have sufficient reserves to regrow foliage and establish well.
There are numerous predators and parasitoids that attack CPB adults (a tachinid fly), larvae (12-spotted ladybeetle, spined soldier bug, ground beetles), and eggs. These can significantly reduce CPB populations as well as keeping aphids in check. If sprays are needed, selective products will conserve beneficial insects.
Chemical Controls & Pesticides:
Scout to determine whether or not a damaging population is present. When using products that control only larvae or only small larvae, scout for eggs, note egg hatch and apply controls before larvae reach third instar to avoid the worst feeding injury. For materials that control all stages, you may wait and scout for adults and larvae to determine the need to apply insecticides.
Resistance management. Colorado potato beetles rapidly develop resistance to insecticides. The population on a single farm may develop resistance in response to management practices on that farm, meaning that it is up to each farmer to manage resistance on their own farm.
Pesticides are assigned a group number, based on their mode of action. Group numbers can be found on labels and in the New England Vegetable Management Guide. Resistance can develop whenever insecticides with the same mode of action are used multiple times against the same population in the same and succeeding years. Any insecticide used repeatedly on the same population of CPB will lose its efficacy in less than 5 years. For a table of insecticide groups with products registered for use on Colorado potato beetle, please see the attachment at the bottom of this page.
Growers should avoid using pesticides in the same group twice in one year, or even better, once every other year. Newer chemistries should be used first. For conventional growers, there are enough products to keep a two-year rotation that will effectively control CPB while delaying resistance to any one product. For organic growers, there are fewer products available, and cultural control practices should be followed to avoid dependency on a product.
Do not try to kill every beetle in the field. Potato crops can withstand 15-20% defoliation without affecting yields; eggplant can withstand 10% defoliation. In potatoes, avoid spraying the beetle in late season, as food reserves in the foliage two weeks prior to senescence add little to final tuber bulking.
Organic control (OMRI listed). Spinosad and azadiractin are the main options. Beauvaria bassiana (Mycotrol O) has been shown to suppress CPB populations, though it does not provide immediate control. Cultural controls are key to reducing dependence on a limited number of products.
Products registered for Colorado potato beetle include:
To prevent resistance, alternate among classes of insecticides in each generation, and throughout the season. The following insecticides each have a different mode of action and provide good options for alternate insecticides that provide effective control:
Abamectin (AgriMek 0.15EC, Abba) is mainly a contact material, which controls larvae. It may be best used early in the season, when good coverage is easier to obtain. Rates of 5-6 fl oz per acre gave effective control in commercial fields in trials on Long Island. The lowest labeled rate is 8 fl oz.
Azadiractin (Neemix, Aza-Direct). Insect growth regulator for immature stages of insects including CPB. OMRI listed. Neem products have shown efficacy against CPB in trials and is rated as ‘good’ efficacy in the Ohio Vegetable Production Guide. This may provide an alternative to spinosad for organic growers.
Chlorantraniliprole (Coragen) received a federal label in 2008. A new class of chemistry (group 28) that disrupts the calcium balance of muscles. It can be applied as a foliar (translaminar) or systemic (soil uptake) at planting or transplanting or through drip irrigation. Effective against catperpillars, including difficult ones like beet armyworm, CPB (allstages), and leafminer; labeled in potato, brassicas, leafy greens, cucurbits, fruiting crops, and sweet corn. Active ingredient also known as Rynaxypyr.
Cyromazine (Trigard). Insect growth regulator for small larvae just after egg hatch. Does not control adult beetles. Low rate will provide suppression only.
Novaluron (Rimon) is a relatively new pesticide chemical belonging to the class of insecticides called insect growth regulators> (IGR). IGRs slowly kill the insects over a period of a few days by disrupting the normal growth and development of immature insects. Novaluron acts as an insecticide mainly by ingestion, but has some contact activity. IGR insecticides are comparatively safer to beneficial insects and environment. Target applications to the beginning of egg hatch when larvae are small. Use higher rates for larger larvae. Does not control adults.
Spinetoram (Radiant 2SC) has the same type of active ingredient and mode of action as spinosad. New liquid formulation. Target small larvae. May be applied with chemigation.
Spinosad (Entrust, OMRI listed; Spintor 2SC is no longer on the market though stocks can be used) gives control of all stages of CPB at a 3.5 to 4.5 fl oz rate. Will also control European corn borer.
Nicotinoid insecticides may be soil or trickle applied (Admire, Platinum, Venom), foliar applied (Actara, Assail, Leverage,Provado, or Venom), or applied to seed pieces (Cruiser, Gaucho MZ). In the Connecticut Valley, there are fields whereCPB resistance to imidacloprid (Admire) is 300 times that of susceptible populations. Control of CPB requires higher rates, does not last as long, or has been lost completely. There is cross-resistance among products in the nicotinoid group. For resistance management, do not use a product in this group on more than one generation per year. A single foliar application is less likely to cause resistance than a soil applied systemic, because it only affects part of the population and only one generation.
In summary: If adults are the predominant stage, the following neonicotinoids are labeled but should not be used if an at planting neonicotinoid was applied: Actara, Assail, Leverage, Provado (imidacloprid), or Venom. These materials should provide control as long as beetles are not resistant to this class of chemistry. Once eggs hatch and larvae are present, the previous materials as well as Avaunt + PBO, Agri-mek (abamectin), Coragen, cryolite, Radiant, Rimon, or Spintor have provided control.
-R Hazzard; (sources include: D Ferro (UMass Amherst), J. Mishanec (NYS), J Boucher (CT), J. Whalen (DE), T. Kuhar(VA), G. Ghidhu (NJ), New England Vegetable Management Guide, Ohio Vegetable Production Guide)
Avoiding Pests and Disease in the Garden
Colorado Potato Beetle
Rather than reach for a product that’s likely to destroy every bug in sight, try to target the specific pest with a specific product. Paul recommends BT for caterpillars; Neem oil helps eliminate Colorado potato beetles from gardens without hurting insects that are beneficial to the garden.
Photo by: Shutterstock/Oleksandrum
«Whenever I take people on a tour of my landscape,» says master gardener Paul James, «they’re invariably amazed at how few pest and disease problems I have despite the fact that I rarely use any type of organic controls and, for nearly 30 years, I’ve never used any synthetic products.»
To maintain his relatively-pest-free landscape, Paul never uses broad-spectrum insecticides. «They’re formulated to destroy virtually every bug they come in contact with. Such products, however popular, will invariably backfire on you. And in many cases, they’re also toxic to humans as well as other critters like birds and bees.» And, he says, even nontoxic pest controls like garlic and pepper sprays can backfire on you as well.
Broad-spectrum insecticides backfire because they destroy beneficial insects as well as problem pests, and as a result, they upset the natural balance of bugs in the landscape. It’s the balance between good and bad bugs that’s critical to achieving the biodiversity that allows both kinds of insects to coexist.
«In other words, it’s okay to have bugs that prey on your plants as long as you also have bugs that prey on them,» he says. «When — and only when — the population of problem pests gets out of control should you even consider control measures, and even then, you might want to think twice before spraying or dusting.»
The population of beneficial insects can’t rebound at the same rate of problem pests. Nature designed the system that way to make sure there would always be an adequate food supply — or plant-eating bugs for the beneficial insects to consume. So if, for example, you spray a broad-spectrum pesticide on a plant plagued by aphids, you may actually do more harm than good. You might destroy 80 percent of the aphids, but you would almost certainly destroy 100 percent of the lady beetles that were busily eating all those aphids. And what’s more interesting is that aphids don’t have to mate during the growing season. In fact, female aphids are likely carrying unborn females that are already pregnant. The lady beetles, on the other hand, are at a distinct disadvantage. They must find a mate and reproduce in the more familiar sense, which takes time. And in the meantime, the aphids have a huge jump-start on whatever plant you’ve just sprayed.
Insects can, and very often do, develop a resistance to certain garden chemicals, and the results of such genetic resistance can be even more devastating. Each time you apply a pesticide, a few pests will survive. In the next generation that they produce, the offspring may develop a genetic resistance to that pesticide. And genetic resistance can occur very quickly in the insect population because insects are capable of producing many generations over a short period of time. In mammals, genetic changes may take thousands, perhaps even millions, of years.
«This is all reason enough to avoid the use of garden chemicals,» Paul says, «but I am willing to admit that there are times when you need to control pests.» He offers some tips:
Don’t panic at the first signs of attack. Realize that plants can sustain a fair amount of pest damage — up to 50 percent of their leaf surface — before the pest needs to be controlled. Instead, monitor the damage for a day or two, and then develop your own plan of attack. For aphids, first try a strong blast of water from the hose. While the water blast works amazingly well, it’s something you’ll have to repeat every other day or so until the aphids are gone. If that doesn’t solve the aphid problem, then consider using insecticidal soap. This concoction is highly effective against all soft-bodied insects — including aphids — as well as mites and whiteflies, but it won’t harm mature, beneficial insects. And finally, consider releasing beneficial insects — in this case, lady beetles to control the aphids.
Rather than reach for a product that’s likely to destroy every bug in sight, try to target the specific pest with a specific product. Paul recommends BT for caterpillars; Neem for cucumber and Colorado potato beetles; horticultural oil or insecticidal soap for scale, mites and aphids. In fact, with BT, Neem, horticultural oil and insecticidal soap, you can control virtually any and every pest problem, he says.
Disease control is a slightly different situation than pest control, but aggressive intervention isn’t always the answer. Plant diseases, especially fungal diseases, are very often the result of factors you can actually control:
Proper placement. Site plants so they get plenty of air circulation around them to prevent fungal spores from attaching to leaf surfaces. Planting too close to the house or crowding plants will set the stage for fungal invasion.
Good landscape sanitation. If you have a plant that’s prone to fungal disease, be sure to remove and discard fallen leaves from the base of the plant on a regular basis to prevent the spread of the disease. More importantly, take steps to prevent the onset of fungus. Once a fungal disease arrives, it’s likely to stick around for a while.
Practice prevention. To prevent fungus, water the bases of plants rather than the leaves, unless of course you’re trying to control aphids. Apply fresh mulch now and then throughout the growing season to prevent spores from bouncing back onto leaf surfaces. And use horticultural oils, baking soda solutions — perhaps even milk — to prevent fungal diseases from attacking plants in the first place.
Finally, the most important thing you can do to prevent pests and disease problems is to give your plants optimum growing conditions — the particular type of light, water and soil that each plant needs. And maintaining healthy soil is important too.
«Make no mistake, healthy plants are far more able to withstand attack by pests and diseases than unhealthy ones are,» Paul says. «So don’t skimp on the compost; it can do more to maintain healthy soil and produce healthy plants than most people realize.»
Cooperative Extension Publications
Bulletin #2424, Insecticide Resistance in Colorado Potato Beetles
Developed by Associate Professor Andrei Alyokhin, Extension Professor James Dwyer, and Assistant Extension Professor Andrew Plant.
For information about UMaine Extension programs and resources, visit extension.umaine.edu.
Find more of our publications and books at extensionpubs.umext.maine.edu.
Table of Contents:
The Colorado Potato Beetle, Leptinotarsa decemlineata, is the most significant insect pest of the solanaceous family of plants, which includes potatoes, tomatoes, and eggplant. Both adults and larvae feed on plant foliage. In the absence of control measures, Colorado potato beetle damage can result in complete defoliation of potato fields.
Colorado Potato Beetle
Colorado potato beetles overwinter in the soil as adults, often aggregating in woody areas adjacent to the fields in which they have spent the previous summer. Starting in late May, the overwintered beetles dig themselves out of the soil and mate. Then they colonize potato fields, feed for several days, and start laying eggs. If fields have been rotated, these beetles are able to fly up to several miles to find new host habitat. Overwintered adults live for one to two months after colonizing host plants in the spring.
A single Colorado potato beetle female is capable of producing roughly 600 eggs. Eggs laid by the overwintered beetles begin to hatch within one week. Newly emerged larvae disperse over short distances and almost immediately start feeding on potato foliage. The larvae spend most of their time on plants. They undergo three molts over the course of 10 to 20 days and then burrow into the soil to pupate. The pupal stage lasts for 10 to 15 days. Then the first summer generation of adults digs out of the soil and climbs back onto potato plants to feed. It takes them about 7 to 9 days to develop reproductive systems and flight muscles. After development has been completed, the beetles mate and start laying eggs.
The reproduction continues until diapause (dormancy) is induced by decreasing day length in early to mid-August. Then the beetles either walk to the overwintering sites or burrow into the soil directly in the field. In Maine, usually, a single generation is completed during the growing season, although two generations may be possible in southern parts of the state during especially warm years. Later generations are usually less of a concern for potato growers because of their smaller size, as well as the fact that mature plants can better withstand defoliation without yield reduction.
Figure 1. Colorado potato beetle life stages.
For more detailed information on Colorado potato beetle biology, as well as on the monitoring and control of its populations, please refer to “Colorado Potato Beetle,” Bulletin #5012 (Potato Fact Sheets) from University of Maine Cooperative Extension Publications Catalog.
The Phenomenon of Insecticide Resistance
Pesticide resistance in arthropods costs farmers millions, if not billions, of dollars each year. Currently, more than 500 different species of arthropods are resistant to a wide variety of chemicals.
Insects may decrease their susceptibility to toxins in a variety of ways. In some cases, they become capable of digesting insecticides before their vital organs and tissues are affected. In other cases, their bodies change on the molecular level so that toxins no longer affect them. In still other cases, resistant individuals quickly excrete the poisons before the damage is done. Also, some resistant insects may become less exposed to insecticides, either because they become capable of detecting and avoiding toxins, or because toxin penetration through the body wall is reduced.
Insecticide resistance is a matter of the frequency of resistant individuals in the population. The simple presence of resistant genes does not mean that a particular insecticide is doomed. As long as resistant individuals are few and far between, they are not capable of doing enough damage to decrease the yield. Thus, effective control is still being achieved.
Development of insecticide resistance in insect populations is a typical evolutionary process driven by survival of the fittest individuals. Initially, resistant insects result from random mutations caused by internal factors, such as various molecules bumping against DNA in their chromosomes, or external factors, such as solar radiation. Under normal conditions, survivorship and reproductive success of resistant mutants is usually lower than that of susceptible insects of the same species. Therefore, relatively few resistant mutants persist in a population that is not exposed to a particular insecticide to which they have developed resistance.
Figure 2. Generalized process of insecticide resistance development. (Schematic by Andrei Alyokhin)
Full description for Figure 2, below. Figure 3. A cumulative number of insecticides to which resistance in the Colorado potato beetles has been reported. (Arthropod Pesticide Resistance Database, 2007)
The situation changes dramatically when such an insecticide is applied. The chemical kills off susceptible genotypes, while resistant mutants survive and thrive in the absence of competition. Pretty soon, their numbers increase to the densities sufficient to cause significant economic damage.
Most commonly, insects become resistant to a single chemical to which they were exposed. However, in some cases, resistance to one pesticide results in resistance to multiple pesticides. Usually—but not always—these pesticides have similar chemistry and modes of action (ways they kill their target pests). This phenomenon is known as cross-resistance. In other cases, simultaneous and/or successive selection by several different pesticides may result in resistance to all of them. This phenomenon is known as multiple resistance.
Insecticide resistance in the Colorado potato beetle
The Colorado potato beetle has a remarkable ability to develop resistance to a wide range of pesticides. Plants in the family Solanaceae, which are natural food sources for this insect, have high concentrations of rather toxic glycoalkaloids in their foliage. These toxins protect them from a wide range of herbivores. However, Colorado potato beetles have evolved an ability to overcome the toxic defenses of its hosts. Apparently, this ability also helps them to adapt to a wide range of human-made poisons. Also, high beetle fecundity increases the probability that one of the numerous offspring mutates, as well as ensures that the resistant population builds up rapidly once such a mutation has occurred.
The first instance of Colorado potato beetle resistance to synthetic organic pesticides was noted for DDT in 1952. Resistance to dieldrin was reported in 1958, followed by resistance to other chlorinated hydrocarbons. In subsequent years, the beetle has developed resistance to numerous organophosphates and carbamates. In some cases, a new insecticide failed after one year — or even during the first year — of use.
Presently, resistance has been reported to nearly every chemical that has ever been used to control Colorado potato beetle. Obviously, not every single population is resistant to all insecticides. However, both cross-resistance and multiple resistance are rather common. The major problem area is the northeastern United States; however, resistance has also been detected in other areas of the U.S., as well as in Canada, Europe, and Asia.
Physiology and genetics of resistant beetles
Although many details still need to be figured out, a significant amount of information on insecticide resistance in the Colorado potato beetle is already available.
First, we know that in the absence of insecticides, the fitness of insecticide-resistant individuals is usually low compared to insecticide-susceptible individuals. They have lower reproductive success, higher mortality, and are incapable of successful competition with their susceptible brethren.
Secondly, insecticide-resistant versions of genes are usually incompletely dominant, meaning that the level of resistance in hybrid crosses between resistant and susceptible beetles are somewhere in between that of their parents.
Third, when such semi-resistant hybrids mate with each other, some of their offspring will be highly resistant.
Preventing Insecticide Resistance
Preventing resistance is as essential a part of good insecticide stewardship as minimizing drift or wearing personal protective equipment. Similar to most other problems, resistance is more easily avoided than mitigated. Don’t wait until insecticide failure becomes noticeable in the field, as you may find yourself with few control options. A better strategy is to incorporate these preventive practices into your management system:
- Identify fields where Colorado potato beetles are at high risk of developing resistance. In theory, any field that has been treated with insecticides is at risk. However, in some fields, the risk is higher than on the others. Generally speaking, the more extensively a given chemical—or class of related chemicals—is used, the higher the probability becomes that it will fail due to resistance development (Figure 4). Conversely, integrating various chemical and non-chemical techniques will keep beetle populations under damaging levels for greater periods of time.
- Rotate among different insecticide mode-of-action groups. Relying on a single insecticide as a sole method of keeping the beetle populations in check will eventually result in failure. Relying on a single class of chemically related insecticides will have the same effect: similar chemicals are likely to poison their target insects in a similar way. If an insect becomes capable of overcoming one of them, it is fairly likely that it will also overcome another one that has a similar chemical structure and mode of action. This phenomenon is known as cross-resistance. The Insecticide Resistance Action Committee, a specialist technical group supported by the agrochemical industry, has arranged all insecticides in groups based on the similarities in their chemical structures and modes of action. Insecticides belonging to different mode-of-action groups (Table 1) should be rotated throughout the growing season.
- Use the full label rate of insecticides. Otherwise, you might not kill the hybrid crosses between resistant and susceptible beetles (“Physiology and genetics of resistant beetles”).
- Do not rely on insecticides alone. Every grower should practice crop rotation, which has been repeatedly shown to suppress Colorado potato beetle populations. Rotated fields should be located as far from the previous year’s crop as possible so that the beetles have difficulty finding them. This allows growers to reduce the number of insecticide applications necessary to control the beetles, thus reducing selection pressure towards resistance development. For example, an average of 4.78 insecticide applications was required to control Colorado potato beetles on non-rotated commercial potato fields during the 2005 growing season in southern Maine, compared to only 2.73 applications on rotated fields.
- Figure 4. Risk of insecticide resistance depends on management practices. (Schematic by Andrei Alyokhin)
Use economic thresholds when making decisions about spraying. Not only does chasing every single beetle with a sprayer result in wasted time and money; it also contributes to rapid resistance development. Trying to kill all the beetles with insecticides usually results in killing all susceptible beetles. Only resistant beetles survive—which is why they are called resistant in the first place. When resistant beetles mate with each other, all their progeny are resistant. When resistant beetles mate with susceptible beetles, their progeny are less resistant, and usually can be killed by the full label rate of insecticide.
Preventing resistance development requires additional effort on the grower’s part. However, the era of cheap and readily obtainable insecticides is coming to an end. Therefore, few control options may be on hand if currently available chemicals fail as a result of resistance. Good stewardship of existing products is essential for ensuring long-term success in chemical pest control.
Table 1. Insecticides registered for Colorado potato beetle control, arranged by mode of action groups, (developed by the Insecticide Resistance Action Committee). Products belonging to the same group should never be used after each other.
Please visit this publication’s companion website, “Insecticide Resistance in the Colorado Potato Beetle,” at PotatoBeetle.org’s Insecticide Resistance page. You will find detailed information on Colorado potato beetle (CPB) life history, resistance development, the timeline of CPB resistance, management principles, and links to other resources, including a CPB bibliography.
This publication is based upon work supported in part by the U.S. Environmental Protection Agency’s Pesticide Environmental Stewardship Program (PESP) Region 1 Assistance Award No: PE-97145501.
- CPB biology and management
- Insecticide resistance
Full Descriptions for Figures
Figure 2: Schematic depicts four green rectangles arranged in a square, linked by clockwise arrows. Beginning from the top left, the first rectangle is filled with beetle silhouettes (4 rows of 8 each for a total of 32), all of them white. Over the arrow joining the first rectangle with the second is a stylized image of the DNA double helix. Under the arrow is this caption: “The first individuals with reduced susceptibility to a given insecticide appear as a result of a random mutation.” The second rectangle shows the same 32 beetle silhouettes, except that two of them are colored red and yellow. The arrow down from the second to the third rectangle has a spray nozzle on one side of it and this caption on the other: “All susceptible individuals are killed by the insecticide, leaving only resistant insects in the population.” The third rectangle contains only the two red and yellow beetles; no white beetles. The arrow pointing left from the third rectangle to the fourth has a photo of two beetles mating above it, and this caption below it: “Resistant individuals multiply, eventually becoming numerous enough to cause economically significant damage.” The fourth rectangle shows 32 beetles, but they are all colored red and yellow.
Figure 3: The rectangular chart contains data points connected by a line that trends upward at about a 45-degree angle The X-axis values at the bottom of the chart are labeled “Year of Reported Resistance,” and run from 1950 on the left to 2010 on the right, in ten-year increments. The Y-axis values up the left side are labeled “Cumulative Number of Chemicals” and run from 0 a the bottom to 60 at the top, in increments of 10. The data points are as follows:
|Year||Cumulative Number of Cases|
Figure 4. The figure depicts trapezoid with top and bottom lines parallel, the top line being longer and thus the top of the trapezoid being wider. The label below trapezoid reads “Low Risk” and label above trapezoid reads “High Risk.” Four phrases appear along the inside bottom of the trapezoid, above “Low Risk.” Each is topped by an arrow pointing up at a slight outward angle to a corresponding phrase at the inside top of the trapezoid, under “High Risk.” The following table conveys the pairing of the phrases:
|Low Risk||High Risk|
|Alternating applications of different insecticides||Repeated applications of the same insecticide|
|Spraying based on an economic threshold||Regular calendar-based spraying|
|Annual crop rotation||Continuous potato crop|
|Spot and perimeter treatment||Treatment of the whole field|
Information in this publication is provided purely for educational purposes. No responsibility is assumed for any problems associated with the use of products or services mentioned. No endorsement of products or companies is intended, nor is criticism of unnamed products or companies implied.
Call 800.287.0274 (in Maine), or 207.581.3188, for information on publications and program offerings from University of Maine Cooperative Extension, or visit extension.umaine.edu.
The University of Maine is an EEO/AA employer, and does not discriminate on the grounds of race, color, religion, sex, sexual orientation, transgender status, gender expression, national origin, citizenship status, age, disability, genetic information or veteran’s status in employment, education, and all other programs and activities. The following person has been designated to handle inquiries regarding non-discrimination policies: Sarah E. Harebo, Director of Equal Opportunity, 101 North Stevens Hall, University of Maine, Orono, ME 04469-5754, 207.581.1226, TTY 711 (Maine Relay System).