How to get rid of weevils in rice. The rice weevil, a malicious pest of grain crops, was discovered by specialists from the Rostov branch. Is chemical treatment acceptable in the kitchen?

Rice weevil - Sitophilus oryzae

India is considered the homeland of the rice weevil, where it has been known almost as long as the granary weevil. In 1763, Linnaeus received this insect from Suriname (South America) and described it under the name “rice” for damage to stored rice. It is believed that it was brought to Europe long before Linnaeus learned about it.

The most common grain pest. Cosmopolitan. The damage is caused by beetles (they gnaw holes in the grain) and larvae (developing in the grain, they eat it from the inside).
Damages grains of rice, wheat, rye, oats, barley, corn, buckwheat, pearl barley; chestnuts, oilseeds and legumes, sorghum, millet, bran, crackers, cookies, pasta, dried apples; may develop in caked flour. The main habitat of the rice weevil is granaries, mills, cereal factories and other buildings with grain reserves stored in them.

The beetles are small in size (2.0-3.2mm), brown-brown in color, matte. At the base and towards the end of the elytra there are light reddish spots (two on each elytra). They can fly. They live in shaded places. At the slightest irritation they fall into a stupor, pretending to be dead.
Beetles are highly mobile and can travel considerable distances. With a sharp shock, they instantly become motionless and just as quickly come out of this state, trying to escape from danger.
The respiration process of rice weevil beetles is more energetic than that of barn weevil, therefore, when exposed to an atmosphere of poisonous gas, they die faster.

After fertilization by males, female rice weevils gnaw out a small depression in the grain and lay an egg in it, sealing it with a quickly hardening secretion on top.

The larva, which hatches after a few days, usually gnaws a hole towards the center of the grain, then gnaws holes along the groove. Therefore, two larvae can develop inside one grain, provided that their passages are on opposite sides of the groove. Larvae long. 2.5-3 mm, yellowish-white, legless. During its development, the larva eats about half of the grain. After molting four times, the larva turns into a pupa.

After a few days, a beetle emerges from the pupa, which, having grown stronger, gnaws through the grain shell and comes out. Molt skins and insect excrement remain inside the half-empty grain.
The entire development of the beetle from egg to adult takes 1-1.5 months at a favorable temperature. The lifespan of beetles is 3-6 months.
The optimal temperature for the life of the rice weevil ranges from 27 to 31? C, the optimal relative humidity is about 70%. Under such conditions, the female can lay up to 10 eggs per day. The average lifetime fecundity is about 380 eggs (maximum fecundity is 570 eggs per female).
Demanding on heat (optimal for development air temperature 27-29 °C, critical - O (C), air humidity (optimal - 80-90%, critical - 50%), grain moisture (optimal - St. 17%, critical - below 10%).
In warm rooms, the rice weevil can have from 3 to 8 generations per year.

Granary weevil or grain beetle, grain elephant - Sitophilus granarius

The grain beetle is the most common and dangerous pest of stored grain stocks. It was known to man several thousand years BC. Described by Linnaeus almost 200 years ago. It is called a “barn” weevil because it lives in barns (storages), and a “grain” weevil because it damages grains.
The countries adjacent to the Mediterranean Sea, South Asia and North Africa are considered to be the homeland of the granary weevil.

Cosmopolitan. In Russia it is found much less frequently than the rice weevil, but it is more cold-resistant. More often found in granaries and warehouses with poor ventilation. Usually the upper (up to 0.5 meters) layers of the grain mound are populated.

The damage is caused by beetles (they gnaw holes in the grain) and larvae (developing in the grain, they eat it from the inside).
Damages wheat, rye, barley, oats, buckwheat, rice, corn, sorghum, pasta, crackers, bagels, gingerbread and so on.

Larger than the rice weevil (2.3-4.1mm), body color from dark brown to black, shiny. There are no light spots on the elytra. The antennae and legs remain a deep brown color throughout the life of the beetles. The head is small and significantly narrower than the body, extended forward into a long and slightly downwardly curved outgrowth, the rostrum, incorrectly called the proboscis. In the male, the rostrum is somewhat thickened and flattened, up to 1.25 mm long, while in the female it is more slender and curved, about 2 mm long. There are small dotted grooves on the elytra. Beetles don't fly.
Compared to the rice weevil, the beetles cannot climb up vertical glass or other smooth surfaces as quickly or as high and penetrate less deeply into the grain mound.
On average, a female granary weevil lays about 150 eggs in her lifetime, with a maximum of 300 eggs.

The laying of eggs by female granary weevils and the lifestyle of larvae are the same as that of the rice weevil. The only difference is that the granary weevil larva gnaws through the groove of the grain and occupies its middle. Therefore, more than one individual weevil rarely develops in one grain.
The larva is up to 3 mm long, yellowish-white, with a brown head, legless.
Adult beetles feed by randomly gnawing on the outside of grains.
The optimal temperature for development is 25-27°C.
Optimal conditions for the development of the weevil: air temperature 25-27 °C, air humidity 93%, grain moisture 15-17.5%. When exposed to low (below 0 °C) temperatures, beetles contained in dry grain die faster.
The granary weevil cannot develop in grain whose moisture content is below 11%, but can remain without food for a long time.
From 2 to 5 generations of granary weevil develop per year.

Morphology

Development

The rice weevil is more prolific than the granary weevil, laying up to 500 eggs. The laying method and all further development proceed in the same way as in the granary weevil.

The optimal temperature for development is 28 - 30 °C, and grain moisture is 18%. Under these conditions, the development cycle lasts 23-25 ​​days. The development of one generation at 21 - 25 °C lasts about 40 days, and at 14 -18 °C it lasts up to 3.5 - 7 months.

When the ambient temperature is below +13 °C and the grain (wheat) moisture content is below 10%, the development of the rice weevil does not occur.

Geographical distribution

Distributed on all continents.

In Russia and the CIS countries it is found mainly in the southern regions.

It is often brought to more northern areas from the south, but, as a rule, it develops only in warm rooms. However, in recent years, this pest is more often found than other weevils in grain storage facilities in the middle zone, where it is imported from the south with seed, food and feed grain, and where it successfully overwinters.

Maliciousness

The rice weevil damages grains of rice, wheat, rye, corn, barley, flour, beans, hemp seeds, pearl barley and dry flour products, millet seeds, oilseeds and legumes.

There are known cases of grain contamination in the field at a distance of up to 1.5 km from warehouses with contaminated grain.

Control measures

Preventive control measures

Destructive control measures in grain, products and raw materials

Physico-mechanical methods of controlling pests of grain stocks.

similar to barn weevil, but differs from it in that it has wings. Distributed in the Ukrainian SSR in the North. Caucasus, Crimea, Kazakhstan (southern part). Damages rice, wheat, rye, maize, barley, hulled oats, peas, sorghum, crackers, pasta, sugar, beans, chestnuts, etc.

Rice weevil: 1 larva in rice grain; 2nd thing, doll; 3-beetle; at the bottom is the exit hole.

Control measures: the same as for the granary weevil.

Agricultural dictionary-reference book. - Moscow - Leningrad: State publishing house of collective farm and state farm literature "Selkhozgiz". Editor-in-Chief: A. I. Gaister. 1934 .

See what "RICE WEEPLE" is in other dictionaries:

A beetle of the weevil family, a pest of grain (mainly rice) and grain products. Brown, length 2.1 3.5 mm. Widely distributed... Big Encyclopedic Dictionary

A beetle of the weevil family, a pest of grain (mainly rice) and grain products. Brown, length 2.1 3.5 mm. Widespread. * * * RICE WEevil RICE weevil, beetle of the weevil family, grain pest (mainly... ... encyclopedic Dictionary

See Barn and Rice Weevils...

rice weevil- rice weevil, see Granary and rice weevils ...

A beetle of the weevil family (See Weevils); dangerous pest of grain, mainly rice and grain products. Body length 2 3.5 mm, brown color. Homeland India, from where it spread with rice throughout... ... Great Soviet Encyclopedia

Beetle family weevils, a pest of grain (mainly rice) and grain products. Brown, long 2.1 3.5 mm. Widely distributed... Natural science. encyclopedic Dictionary

rice- oh, oh. riz m. 1. Rel. to the rice. Rice husk. BAS 1. || Planted with rice. As we approached, we found ourselves in a swampy rice field. Garin From the day. around the world trips. 2. Made from rice; made from rice. Rice starch. BAS 1. There is porridge on the table... Historical Dictionary of Gallicisms of the Russian Language

granary and rice weevils- Granary and rice weevils: 1 granary weevil; 2 rice weevil; 3 grains of wheat, barley and corn damaged by the rice weevil; 4 egg of the rice weevil, laid in the endosperm of the grain;… … Agriculture. Large encyclopedic dictionary

GRAIN AND RICE WEEELS- beetles fam. weevils, dangerous pests of grain and grain products. Distributed everywhere (in the northern regions they constantly live only in heated rooms). The damage is caused by beetles (they gnaw holes in the grain) and larvae (developing in the grain, they eat it up... ... Agricultural Encyclopedic Dictionary

SITOPHILUS ORYZAE L. (CALANDRA ORYZAE) - RICE WEevil- see Sitophilus oryzae L. (Calandra oryzae) Rice granary weevil. Pronotum with dense round punctures. The top is matte or slightly shiny. Elytra with 2 vague, round, reddish spots (behind the shoulder and in front of the apex). Hind wings... ... Insects - agricultural pests of the Far East

Despite their pretty name, they cause serious damage to grain crops. In total, there are about 50,000 species, and it is sometimes difficult for an inexperienced layman to identify each of them. The rice weevil occupies a special place in the family. Its historical homeland is India, from where it spread throughout the world. In some countries, the pest is a quarantine object.

Description of the rice weevil

The name of the pest is not entirely justified. When describing specimens, naturalist Carl Linnaeus discovered a weevil in rice, which predetermined the species identity of the insect. In fact, the beetle's diet is not limited to rice - it does not disdain buckwheat, wheat, barley and other cereals and can easily be found in the listed products.

Characteristic features of the beetle:

1. The rice weevil in the photo is distinguished by its elegant rostrum and distinct red spots on the elytra.
2. The size of adult individuals does not exceed 2.5-3 mm.
3. Body color is variable and can range from dark brown to brown. The entire back is densely covered with dots, which create a peculiar pattern.
4. The rice weevil has well-developed wings, so it exhibits extraordinary flight abilities.
5. The rostrum is equipped with a powerful mouthparts that allow it to gnaw through the grain shell.

The beetle is heat-loving, as a result of which its greatest distribution is observed in the southern regions. The optimal development temperature is 26-30 °C and grain humidity is from 15%.

Interesting!

The rice weevil has a lot in common with. They can be distinguished only by the pattern on the back. The rice pest is also characterized by higher fertility and harmfulness.

In field conditions, insects overwinter in underground tunnels, rodent burrows, and under a mound of grain. If there is a constant supply of food, they lead a sedentary lifestyle. When food supplies run out, rice weevils migrate and fly to the fields with a new crop.

Features of insect reproduction

Representatives of the rice weevil species are characterized by complete transformation. The female gnaws a hole in the grain and lays eggs in it. The fertility of one female is estimated at 300-500 embryos. After laying eggs, the beetle covers the hole with its secretions. Embryo development lasts from 6 to 12 days.

Newborn larvae are white in color without any pattern. The size of the young is 2.5-3 mm and their development continues in the grain. The larvae eat up all the nutrients and after 20-30 days, when they have gained the necessary mass, they enter the pupation stage. Initially, the pupae are white, but at the end of the phase they become yellow.

Interesting!

If weevils infest rice, the grain loses 30 to 70% of its original weight.

The adult lives no more than 6 months. The full development cycle ranges from 25 to 210 days. The determining factors for generation are humidity and temperature. If the temperature is below 12°C, the development of rice weevil embryos and larvae stops. From 2 to 4 generations develop per year.

How to get rid of pests at home

Infection of grain crops occurs in the fields. Improper storage of cereals in warehouses aggravates the problem and insects get into the apartment with the food. Most often, weevils are found in rice, buckwheat, wheat groats, pasta, baked goods, legumes, flour, and dried fruits. Rice weevils easily chew holes in plastic bags and penetrate all accessible products.

The algorithm of actions boils down to the following:

1. Detection of sources and foci of infection. To do this, you should carefully examine all cereals, flour, and pasta to identify larvae and adults. Contaminated products should be disposed of immediately.
2. If you suspect that there are pests in the cereal, but a visual inspection failed to identify them, treat the products with heat or cool them in the refrigerator. Low and high temperatures are detrimental to weevils at all stages of development.

For preventive purposes, a number of measures are taken:

• processing of products before storage;
• storing cereals and pasta in containers equipped with airtight lids;
• regular inspection of products;
• reduction of strategic food reserves;
• timely disinfection of kitchen utensils.

Among folk remedies, plants with a repellent aroma are most often mentioned. It is suggested to place lavender branches in cabinets and unpeeled garlic cloves in storage containers.

– Sitophilus oryzae L.

Class: Insects - Insecta

Squad: Hardwings - Coleoptera

Family: Weevils - Curculionidae

The harmfulness of the rice weevil

The species is found mainly in warm southern regions. It got its name because it was first discovered in rice grains. In addition to rice, adult insects and larvae also damage corn, wheat, flour, bread, cookies, pasta and many other products.

Morphology of the rice weevil

The adult reaches a size of 2.4-3.5 mm, dark brown or black-brown color, matte, elytra with two reddish spots behind the shoulder and in front of the apex; the pronotum is covered with punctures very close to each other, and the elytra also have coarse speckled grooves. The insect has hind wings and therefore flies excellently.

The egg is about 0.6-0.7 mm in size, oval or pear-shaped, painted in grayish-white tones. The larva of the rice weevil is 2.5-3.0 mm long, yellow-white, legless. The pupa is 3.6-5.0 mm, yellowish or white and covered with transparent delicate skin.

Developmental biology of the rice weevil

The development cycle of the rice weevil is in many ways similar to the development cycle, but is more sensitive to low temperatures and at the same time much more resistant to dry food. It can withstand an ambient temperature of minus 5 o C for four days, plus 5 o C for 20 days. Insects are able to feed on grain at a humidity of 8%.

The lifespan of the weevil is 240 days, and on average 90-180 days. Females are very fertile and lay an average of 580 eggs. Embryonic development lasts 6-9 days. The larvae complete their development in approximately 11-16 days, but this depends on the ambient temperature: at 10 o C - 17 days, at 22 o C - 15 days, 36 o C - in 5-12 days. The pupa develops in 7-10 days.

In temperate latitudes, the rice weevil develops in two generations. In warmer conditions, it can produce seven to eight generations per year. If it feeds together with the granary weevil or beetles, it displaces them due to its high reproduction rate.

Protective measures against rice weevil

To prevent contamination of grain and other food products, certain storage rules should be followed, namely, the room where the grain is stored should be dry, clean and well ventilated. It is necessary to thoroughly clean granaries, carry out wet and gas disinfestation, and whitewash the premises with lime before placing grain for storage. In winter, in frosty weather, clean grain using grain cleaning machines. Warm up the grain to 50-60 o C in granaries.

For the purpose of disinsection, the following insecticidal preparations can be used: Actellik 500 k.e., - 0.5-0.8 ml/m2 when treating walls, ceilings, floors and 0.16 ml/t when processing grain.