The Colorado potato beetle (Leptinotarsa decemlineata) is an insect belonging to the Coleoptera order and the Leaf beetle family, belongs to the genus Leptinotarsa and is its only representative.
As it turned out, the homeland of this insect is the north-east of Mexico, from where it gradually penetrated into neighboring territories, including the United States, where adaptation to climatic conditions took place faster. For a century and a half, the Colorado potato beetle has spread literally all over the world and has become the scourge of all potato growers.
Origin of the species and description
For the first time, the Colorado potato beetle was discovered and described in detail by an entomologist from America, Thomas Sayem. It was back in 1824. A scientist collected several specimens of a hitherto unknown beetle in the southwestern United States.
Name «Colorado potato beetle» appeared later than — in 1859, when the invasion of these insects destroyed entire fields of potatoes in the state of Colorado (USA). A couple of decades later, there were so many beetles in this state that most local farmers were forced to give up growing potatoes, despite the fact that the price of them has risen dramatically.
Video: Colorado beetle
Gradually, year after year, in the holds of ships that were loaded with potato tubers, the beetle crossed the Atlantic Ocean and got to Europe. In 1876, it was discovered in Leipzig, and after another 30 years, the Colorado potato beetle could be found throughout Western Europe, except for Great Britain.
Until 1918, the breeding grounds of the Colorado potato beetle could be successfully destroyed, until he managed to settle in France (Bordeaux region). Apparently, the climate of Bordeaux was ideal for the pest, as it began to multiply rapidly there and literally spread throughout Western Europe and beyond.
Interesting fact: Due to the peculiarities of its structure, the Colorado potato beetle can drown in water, so even large bodies of water are not a serious obstacle for him in search of food.
The beetle supposedly entered the territory of the USSR in 1940, and after another 15 years it was already found everywhere in the territory of the western part of the Ukrainian SSR (Ukraine) and the BSSR (Belarus). In 1975, the Colorado potato beetle reached the Urals. The reason for this was a long-term abnormal drought, due to which livestock feed (hay, straw) was brought to the Urals from Ukraine. Apparently, along with the straw, the pest beetle also came here.
It turns out that in the USSR and other countries of the socialist bloc, the mass distribution of the beetle coincided with the beginning of the so-called “cold war”, so accusations of an unexpected disaster were addressed to the American special service CIA. Polish and German newspapers even at that time wrote that the beetle was deliberately thrown by American aircraft into the territory of the GDR and Poland.
Appearance and features
Colorado beetle A beetle is a rather large insect. Adults can grow up to 8 — 12mm and about 7mm wide. The shape of the body of beetles is somewhat reminiscent of a water drop: oblong, flat from below and convex from above. An adult beetle can weigh 140-160 mg.
The body surface of the beetle is hard and slightly shiny. At the same time, the back has a yellowish-black color with black longitudinal stripes, and the abdomen is light orange. The black oblong eyes of the beetle are located on the sides of a rounded and wide head. On the head of the beetle there is a black spot similar to a triangle, as well as movable jointed antennae, consisting of 11 parts.
The hard and rather strong elytra of the potato beetle lie close to the body and are usually yellowish-orange, rarely yellow, with longitudinal stripes. The wings of the Colorado are membranous, well developed, very strong, which allows the beetle to travel long distances in search of food sources. Female beetles are usually slightly smaller than males and look no different from them.
Interesting fact: Colorado potato beetles can fly pretty fast — at a speed of about 8 km per hour, and also climb to great heights.
Where does the Colorado potato beetle live?
Entomologists believe that the average lifespan of the Colorado potato beetle is approximately one year. At the same time, some more hardy individuals can easily endure the winter and even more than one. How do they do it? Very simple – they fall into diapause (hibernation), therefore, for such specimens, the age of even three years is not the limit.
In the warm season, insects live on the surface of the earth or on plants that they feed on. Colorado beetles wait out autumn and winter, burrowing into the soil up to half a meter, and calmly endure freezing down to minus 10 degrees there. When spring comes, and the soil warms up well – above plus 13 degrees, the beetles crawl out of the ground and immediately begin to look for food and a mate for procreation. This process is not too massive and usually it stretches for 2-2.5 months, which greatly complicates the fight against the pest.
Despite the fact that the habitat of the Colorado potato beetle has increased by almost several thousand over a century and a half Once again, there are several countries in the world in which this pest has not yet been seen in the eye and does not represent how dangerous it is. There are no Colorados in Sweden and Denmark, Ireland and Norway, Morocco, Tunisia, Israel, Algeria, Japan.
Now you know where the Colorado potato beetle came from. Let's see what it eats.
What does the Colorado potato beetle eat?
The main food of Colorado potato beetles, as well as their larvae, are young shoots and leaves of plants of the nightshade family. Beetles will find their food wherever potatoes, tomatoes, tobacco, eggplants, petunias, sweet peppers, physalis grow. They do not disdain wild plants of this family.
At the same time, beetles like to eat potatoes and eggplants most of all. Insects can eat these plants almost completely: leaves, stems, tubers, fruits. In search of food, they are able to fly very far, even tens of kilometers. Despite the fact that insects are very voracious, they can easily endure forced hunger for up to 1.5-2 months, simply falling into short-term hibernation.
Due to the fact that the Colorado potato beetle feeds on the green mass of plants of the nightshade family , in his body constantly accumulates a toxic substance – solanine. Because of this, the beetle has very few natural enemies, since the beetle is corny inedible and even poisonous.
An interesting fact: It is curious, but not adult Colorado beetles, but their larvae (stages 3 and 4), do the most harm to plants, since they are the most voracious and capable of destroying entire fields in a few days under favorable weather conditions.
Character and lifestyle features
The Colorado beetle is very prolific, voracious and can quickly adapt to different environmental factors, whether either hot or cold. The pest usually survives adverse conditions by briefly hibernating, and can do this at any time of the year.
The young Colorado potato beetle (not a larva) is bright orange in color and has a very soft outer coat. Within 3-4 hours after birth from the pupa, the beetles acquire a familiar look to everyone. The insect immediately begins to feed intensively, eating leaves and shoots, and after 3-4 weeks reaches sexual maturity. Colorado beetles that are born in August and later usually hibernate without offspring, but most will make up for this the following summer.
One of the features that is unique to this species of beetles is the ability to go into prolonged hibernation (diapause), which can last 3 years or even longer. Although the pest flies beautifully, which is facilitated by strong, well-developed wings, for some reason it does not do this in moments of danger, but pretends to be dead, pressing its paws to its abdomen and falling to the ground. Therefore, the enemy has no choice but to simply leave. Meanwhile, the beetle «comes to life» and then goes about his business.
Social Structure and Reproduction
As such, Colorado beetles do not have a social structure, unlike other insect species (ants, bees, termites), because they are solitary insects, that is, each individual lives and survives on its own, and not in groups. When it becomes warm enough in the spring, the beetles that have successfully wintered crawl out of the ground and, having barely gained strength, the males begin to look for females and immediately start mating. After the so-called «marriage games» fertilized females lay their eggs on the underside of the leaves of the plants they feed on.
One adult female, depending on the weather and climate of the area, is able to lay approximately 500-1000 eggs during the summer season. Colorado eggs are usually orange, 1.8 mm in size, oblong-oval, arranged in groups of 20-50 pieces. On days 17-18, larvae hatch from eggs, which are known for their voracity.
Stages of development of Colorado potato beetle larvae:
- in the first stage of development, the larva of the Colorado beetle is dark gray with body up to 2.5 mm long and fine fine hairs on it. It feeds on exceptionally tender young leaves, eating their pulp from below;
- at the second stage, the larvae are already red in color and can reach sizes of 4-4.5 mm. They can eat the whole leaf, leaving only one of its central veins;
- in the third stage, the larvae change color to red-yellow and increase in length to 7-9 mm. There are no longer any hairs on the surface of the body of individuals of the third stage;
- at the fourth stage of development, the beetle larva changes color again – now to yellowish-orange and grows up to 16 mm. Starting from the third stage, the larvae are able to crawl from plant to plant, eating not only the pulp of the leaves, but also young shoots, which cause great harm to plants, slowing down their development and depriving farmers of the expected harvest.
All four stages of development of the Colorado potato beetle larva last about 3 weeks, after which it turns into a pupa. «Adults» the larvae crawl into the soil to a depth of 10 cm, where they pupate. The pupa is usually colored pink or orange-yellow. The duration of the pupal phase depends on the weather. If it is warm outside, then after 15-20 days, it turns into an adult insect that crawls to the surface. If it is cool, then this process can slow down by 2-3 times.
Natural enemies of the Colorado beetles
The main enemies of the Colorado potato beetle are the bugs Perillus bioculatus and Podisus maculiventris. Bed bug adults and their larvae feed on Colorado beetle eggs. Dorifophagous flies also make a significant contribution to the fight against the pest, which have adapted to lay their larvae in the body of the Colorado.
To our great regret, these flies prefer a very warm and mild climate, therefore they do not live in the harsh conditions of Europe and Asia. Also, familiar local insects feed on eggs and young larvae of the Colorado potato beetle: ground beetles, ladybugs, lacewing beetles.
It is worth noting that many scientists believe that the future in the fight against pests of cultivated plants, including the Colorado potato beetles, is not for chemicals, but for their natural enemies, since this method is natural and does not cause severe harm to the environment.
In some farms specializing in the cultivation of organic products, turkeys and guinea fowl are used to combat the Colorado potato beetle. These poultry are very fond of eating both adults and their larvae, since this is a feature of the species, and they are accustomed to such food almost from the first days of life.
Photo: Colorado potato beetle in Russia Russia
For a century and a half after the discovery and description, the habitat of the Colorado potato beetle has expanded by more than two thousand times. As you know, the potato beetle is the main pest of potato plantations not only in large agricultural firms, but also in smaller farms, as well as in private farms. For this reason, even for any summer resident, the question of how to permanently get rid of the Colorado potato beetle is always relevant. The fight against Colorado requires a lot of effort.
To date, two types of pest control are most actively used:
- folk remedies.
Large areas of potato plantings in large farms are usually treated with special systemic insecticides that are not addictive for beetles. They are expensive and highly toxic. It is important to remember that the last treatment should be carried out no later than 3 weeks before harvesting, since harmful toxins accumulate in potato tubers. In the last few years, there have been biologically active agents for the control of the Colorado potato beetle. Such drugs do not accumulate in shoots and tubers. The biggest disadvantage of this method of struggle is the need for strict adherence to the number and interval of treatments. To achieve the desired effect, it is necessary to do at least three treatments with an interval of exactly one week.
Chemical preparations (insecticides, biological action) should be used strictly following the instructions that are always printed on the package, following certain rules and always using personal protective equipment. So that gardeners, farmers and agricultural firms do not suffer from pest control, breeders have been working for many years to develop potato and other nightshade varieties that are resistant to the Colorado potato beetle. Moreover, this parameter may depend on a number of factors – the rules of care, the taste of leaves, etc. Scientists have already made certain conclusions about this during this time. not yet succeeded, but it is already possible to talk about some individual sustainability factors. Not the last role in this is played by gene modification technologies, when the genome of another organism is introduced into the genome of one organism, which completely changes its susceptibility to diseases, pests, and adverse weather effects. However, GMO opponents have been actively campaigning in the media lately, and developments in this area, if any, are not advertised much.