Potato moth has always been a natural neighbor of the famous Colorado beetle. It was in South and Central America that it harmed tobacco and potatoes ever since ancient Indian civilizations and only began to spread around the world at the beginning of the last century.
First, the countries of southern Europe, followed by the south of Russia and Africa, submitted to it, and today it is the potato moth that is considered the main pest in New Zealand and Australia. It can be considered a true cosmopolitan, which has already spread throughout all the continents of the planet.
Such an increase in the range may seem particularly surprising given that the potato moth is an insect highly thermophilic. It is believed that its populations can sustainably multiply only in places where the average annual temperature does not drop below 10 ° C. In such areas, this butterfly can become a real scourge of farmers.
Appearance and distinctive features of the species
Looks like a potato moth is quite unsightly. The general background of her wings is dirty gray with numerous black spots, which, when the wings fold, form two distinct dark bands. The photo below shows a potato moth with folded and straightened wings:
Butterfly potato moth has a characteristic long antennae and a reduced oral apparatus. She can not eat, and does not live long - usually several days, very rarely - several weeks.
The length of the butterfly with folded wings is 6-7 mm, and the protective coloring allows it to remain invisible even with a direct view from a short distance.
Larvae of potato moths are small - about 13 mm has a body length of the last caterpillar. Such a larva is weaving a cheholchik in which it pupates and turns into an adult butterfly. The length of the pupa is about 10-12 mm.
Caterpillars have a white-salad or white-pink color with a pale stripe along the entire back.
Eggs of potato moths are difficult to see even at close range. Having a length of about half a millimeter, they are placed by the female from the underside of the leaves in small groups and develop very quickly.
Immediately after laying, such eggs are pure white, and later darkens a little.
Nutrition, reproduction and pest lifestyle
Under optimum conditions, the whole life cycle of potato moth from egg to laying new eggs of an adult specimen lasts only for a short time - about 33-35 days. In winter, this period stretches to several months.
In mid-latitude butterflies do not extend far to the north, because they do not know how to winter, and at temperatures below minus 4 ° C perish. As a rule, their distribution is limited by a line beyond which in winter the soil freezes below this temperature. With a slight frostbite of potato tubers, the caterpillars in them can remain alive. It is believed that often they move from the harvested fields to the vaults, they multiply in winter, and in spring with seed potatoes they are again buried in the ground.
Sometimes butterflies and pupae can winter under a layer of leaves in the open ground.
Caterpillars of potato moth feed on various plants of the Solanaceae family. It can be potatoes, tomatoes, nightshade, eggplant, pepper, and even belladonna and numerous wild nightshade nightshades.
In this case, the larvae gnaw the leaf blades, and also bite the legs of the leaves themselves and feed on the tubers. It is because of this versatility that a potato moth has the ability to spread very widely and rapidly.
Butterflies of potato moths are active at night and have a huge number of enemies. They are fed by everyone who is not lazy - and other insects, and bats, and birds. At the same time the life expectancy of an adult butterfly is from the strength of several weeks, for which she manages to mate and lay eggs. During one summer season in the south of Ukraine the mole has time to give 3-4 generations.
Potato moth equally successfully multiplies in closed warehouses, on agricultural lands and in the wild. However, it is in the first two places that its reproduction is practically not controlled by natural enemies, and the butterfly can reproduce at ultrafast rates. And already her caterpillars will cause the main harm.
Danger and harm of potato moths
The main danger of potato moth is as follows:
- weakening of bushes of agricultural plants due to the destruction and mining of leaves
- damage to potato tubers and decreased yield quality
- a decrease in the quality and volume of the potato inoculum
- weakening and death of young tomato and pepper bushes.
A potato tuber, infected with 9-10 caterpillars at a time, will look like a sponge, in which the larvae almost completely eat out the core.
In the presence of a large number of insects and breeding conditions favorable for them, the moth reproduces faster than the fodder crop itself develops. In early spring, a small number of larvae diligently destroy young and tender seedlings, later they harm adult plants, and the maximum number of caterpillars is excreted when tubers and fruits develop on the bushes.
In places with a strong infestation of a potato moth, up to 80% of the crop is not suitable for export because of the loss of ability to be stored and to be recycled.
Fighting the Potato Moth: Measures and Means
One hundred percent methods of combating potato moths are not developed today. The fight against it must be comprehensive and consist of both liquidation and preventive measures.
To destroy the butterflies and caterpillars themselves, the following means are used:
- Preparations based on bacteria Bacillus thuringiensis - Bitoksibatsillin, Dendrobacillin, Entobakterin, Lepidotsid. They process bushes at any stage of development until the appearance of ovaries, and such measures ensure the death of a part of the larvae, a decrease in the fecundity of females, and a delay in the development of moths at each stage;
- Methyl bromide - gas, which allows to fight potato moth after harvesting potatoes (fumigated with methyl bromide, the tubers stored for storage are processed);
- Special traps for butterflies and larvae.
Measures to combat potato moth also include literate crop rotation, hilling of potato and tomato bushes, laying only healthy tubers for the maximum depth for the variety.
A good preventive way to get rid of potato moth is to grow only the early varieties of potatoes, which the pest is practically not scary.
The tubers themselves must be carefully examined and screened out before sowing those with signs of damage. This will help if not to get rid of the potato moth completely, then at least significantly reduce the scale of the defeat of the site by it. It is even better to heat the tubers for several hours at a temperature of 40 ° C - this will not decrease their germination, but will kill a significant portion of the moth larvae.
It is also very important to control the growth of weed plants on the borders of the cultivated territory.
All wild Solanaceae near the site are natural reservoirs of the pest, from which the moth easily moves to garden crops.
On a note
Many farmers in South Africa attract a special kind of wasps to their farms, which are parasites of potato moth larvae. In the northern hemisphere, these wasps do not live.
Today many countries observe quarantine measures from potato moths. For example, the importation of potato tubers by private individuals to Ukraine is prohibited, and potatoes imported to Australia are necessarily subjected to heating and treatment with insecticides. But even despite such measures, the potato moth successfully continues to conquer the world.