The first underground pest we introduce to you today is the grub, which is called the silkworm or silkworm in many places (in some places the tiger is also called the silkworm), and the white and fat are indeed like silkworms. The adult insect of the grub is the golden turtle carapace, which is different from the adult insects of lepidoptera, and the adult insects of the golden turtle shell can also cause harm, especially in the forestry industry is an important pest.
Golden turtle shell is also a type of insect, the common golden turtle shell has gill golden turtle, li golden turtle, silk golden turtle three kinds, as follows:
Gill tortoises mainly harm wheat, corn, potatoes, peanuts and other field crops and vegetables, fruit trees, forest trees and so on.
The golden turtle mainly harms trees such as poplar, willow and apple, and vegetables and other crops such as legumes, solanaceae, cruciferous family. Heavy occurrence in areas with relatively humid climate and many fruit trees and trees is an important underground pest in the cotton area of the Huang-Huai-Hai Plain in China.
The silk turtle is a major forest pest in the north, especially harmful to seedlings.
Scarab hazards
Adults bite the leaves of the host plant, causing gaps, holes, and severely leaving only the base of the veins.
The larvae feed on the underground part of the plant, bite off the rhizome of the seedling, make the seedling yellow and die, and can also eat the plant seed, causing a serious lack of seedlings and ridges. The wound after the damage of the grub is obviously different from that of the golden needle worm, and the incision caused by the grub is relatively neat, while the plant damaged by the golden needle worm is untidy and filamentous.
Identification of one or three common scarab beetles
Scarab beetle is a common name for adult grubs, belonging to the family Coleoptera. Grub is a large group of underground pests with the largest species, the widest distribution, mixed diet and the most serious harm, and it is also one of the large taxa in Coleoptera, and there are more than 20,000 species recorded in the world, and there are more than 1,800 kinds currently recorded in China. Grubs feed on germinated seeds, young roots, and underground stems of a variety of crops, trees, pastures, medicinal herbs, and flowers and plants in the soil, and bite off seedlings and ring peel off the root bark of large seedlings and young trees. The larvae eat a large amount, light caused by lack of seedlings and ridges, heavy is the destruction of seedlings, after eating the seedlings neatly and flat, easy to identify; adult scarab beetles unearthed to feed on leaves, buds, young shoots and young fruits, often bite the leaves into missing and holes, residual leaf vein base, severe time will eat all the leaves. Among them, the North China large black gill golden turtle, dark gill golden turtle and patina golden turtle are the dominant species of underground pests that occur in China.
(1) North China great black gill golden turtle
Holotrichia oblita Faldermann of the insect order Coleoptera is a species of gill golden turtle in the family Coleoptera. One of the dominant species of underground pests. It is found in all provinces (regions) of China except Tibet.
Agricultural pests. Adult larvae can be pests. Miscellaneous eating habits. Adult insects feed on food crops, peanuts, vegetables and other crops and poplar, willow, elm, mulberry, walnut, apple, locust, oak and other tree leaves; larvae eat peanuts, soybeans, corn and other crops, a variety of seedlings and grass grass, grass and other plants underground parts.
Adults are oblong and oval, 21 to 23 mm long and 11 to 12 mm wide, and shiny black or black-brown. The shiny surface of the body is distinguished from its fellow dark gill golden turtle (H. parallela) salient features. The thorax and abdomen have long yellow hairs, the dorsal plate of the forebreast is twice as wide as the length, and the obtuse angle of the leading edge and the angle of the posterior edge are almost at right angles. 3 ridges per elytra. There are 3 teeth on the lateral side of the tibia segment of the forefoot, and 2 distances at the end of the tibia segment of the middle posterior foot. The ventral surface of the male terminal is concave and the female is raised.
The larvae are three instar, the mature larvae are 35 to 45 mm long, the foramen is 3 shots and cracked, and a group of flattened and hook-like bristles grow in front of them, and extend forward to 1/3 of the posterior part of the ventral patch.
(2) Dark gill golden turtle
Holotrichia parallela Motschulsky is a species of gill turtle in the family Coleopteraidae. It is found in China (middle and lower reaches of the Yangtze River and most of the area north of the Yangtze River), Japan, South Korea, North Korea, Russia (Far East) and other countries.
Agricultural and forestry pests, including adult and larval insects. Miscellaneous food, adult scarab beetles feed on elms, poplars, willows, locusts, mulberries, pears, apples and other tree leaves, is an important forestry pest; larvae grubs inhabit the soil, eat peanuts, soybeans, corn, potatoes, wheat and other crops underground parts, is one of the dominant species of underground pests.
Adults are ovate in length, 17 to 22 mm long and 9.0 to 11.5 mm wide, covered with black or black-brown villi, and dull. Gills of the antennae. The widest part of the dorsal plate of the anterior thorax is behind the middle of the lateral margin, and the small shield is in a broad arc-like triangle. The elytra are elongated, the lateral margins are almost parallel, slightly expanded at the back, and the 4 longitudinal ribs on each side are not visible.
The larvae are three in age, the mature larvae are 35 to 45 mm long, the head width is 5.6 to 6.1 mm, and the skull is dull. The anterior parietal bristles of the head are one on each side, located on the side of the crown slit. The ventral surface of the gluteal segment is spiny, with only hook-like bristles and three lobes in the foramen. The glossiness of the adult body surface and larval head shell is one of the main features that distinguish it from the Holotrichia oblita of the same genus.
(3) The patina golden turtle
Anomala corpulenta Motschulsky is a species of loggerhead in the insect order Coleoptera. It is named after the copper-green metallic luster on the back of the adult body. It is found in China (all provinces except Xinjiang and Tibet), North Korea, South Korea, Japan, Russia, Mongolia and other countries.
Agricultural pests, with adult and larvae as pests. Adult insects feed on the leaves of dozens of trees and plants, such as elms, willows, pines, chestnuts, walnuts, pears, apples, privets, beans, etc., while the larvae are harmful to the roots of plants and seedlings.
Adults are oblong-ovate, 15 to 21 mm long and 8 to 11.3 mm wide, with a metallic luster in copper-green on the dorsal surface, and yellowish brown or brown on the dorsal plate of the forebrea and lateral margins of the elytra. The elytra brass green and longitudinal ridge are slightly visible, and the joint ridge is more prominent. The foot is yellowish brown, the tibia and tarsal segments are dark brown, and the forefoot tibial segment has 2 teeth on the outside and 1 spine on the medial side.
The larvae are three in age, with mature larvae 29 to 33 mm long and a head width of about 4.8 mm. The head is dark yellow and nearly round, with 8 hairs in the front of the head, 10 to 14 hairs in the posterior top, and 2 to 4 hairs on the middle of the forehead. The breech mask burr column is composed of 13 to 14 long tapered spines, the two columns of spine tips intersect or meet, the posterior end is slightly forked outward, and the hook-like hairs are distributed around the quill. The foramen is transversely lobed. The opening of the no-spiny burr column and foramen at the end of the abdomen is the main hallmark that distinguishes the larvae of the patina golden turtle from the Holotrichia parallela and the holotrichia oblita.
Second, grub integrated control technology
China's grubs have the basic characteristics of wide distribution, many types of harmful crops, long feeding time and strong concealment. And there are many types, the occurrence rules are complex, and the distribution is also very extensive. Most species of grubs live on the ground during the adult stage, and the larval stage is mostly hidden in the soil to inhabit and harm. The control of grubs must first understand the local species, determine their dominant species and other species according to their degree of harm, and more importantly, grasp the living habits and occurrence laws of the dominant species, so as to determine the control strategy, under the guidance of the control strategy, select the single control technology suitable for local insect species, and assemble the best control technology system.
Years of practice have proved that the control of grubs should be based on the overall perspective of the farmland ecosystem, using the combination of agricultural control and chemical control, the combination of crop sowing control and growth period control, the combination of adult pest control and the control of larvae, the rational and comprehensive use of agricultural, chemical, biological, physical and other methods and the use of means to transform environmental conditions, the grubs are controlled below the permissible level of harm, so as to achieve the purpose of protecting plants and increasing yields.
(1) Agricultural prevention and control
Agricultural control is an indispensable key link in grub control, mainly from the following aspects.
1． Clean up the farmland And concentrate on the treatment of weeds at the edge of the field; level the land, deeply turn the soil, eliminate ditches and barren slopes, plant trees and grasses, in order to eliminate underground pest breeding areas and create environmental conditions that are not conducive to the occurrence of underground pests. At the same time, pay attention to cleaning up the stubble residue of the straw.
2． Reasonable rotation of stubble Grubs are prone to wheat and corn, leguminous peanuts, soybeans and potatoes and other root and tubers, and it is not easy to eat crops such as cotton, sesame seeds and rapeseed in the straight root system. Therefore, reasonable crop rotation, especially water and drought crop rotation, can significantly reduce the infestation of underground pests.
3． In this way, the grubs living on the surface of the soil can be turned to the depths, and the deep ones can be turned to the ground, and some grubs can generally be eliminated through exposure, birds and finches pecking, etc. Technical measures such as ploughing the soil, picking up insects to kill, and freezing and drying should be used in combination. At the same time, combined with autumn sowing, it can also destroy the insect path under the grub, so that it cannot overwinter safely, reducing the insect population base in the coming year.
4． Reasonable fertilization Must apply organic farm fertilizers such as decomposed pig manure manure, otherwise it is easy to attract scarab beetles, moths and other spawns.
5． Reasonable and timely irrigation During spring and summer crop growth, timely irrigation can reduce the harm by forcing grubs living on the surface of the soil to dive or die.
(2) Physical prevention and control
The blooming period of adult insects in the field (the period can be determined according to different types of scarab beetles), using the tendency of some scarab beetles to light, booby-traps are carried out by rationally arranging frequency vibration insecticidal lamps or black light lamps, and the control area of a single lamp can reach about 4hm². It is also possible to use the suspended death of adult insects in the evening to carry out artificial hunting, and eliminate adult insects before laying eggs to reduce the number of insect populations. Adult insects can also be used to feed on the leaves of trees such as poplar, willow, elm, etc., and set up branch handles in the field to lure the insects and kill them intensively.
(3) Chemical prevention and control
When using chemical control, it is necessary to pay attention to the information on diseases and insects released by the local plant protection department, and carefully and timely select effective agents for prevention and control of fields that meet the control indicators. Different crops may have different control indicators in different areas, such as the control index of grubs in Anhui Province is set at 4 heads/m², and in some areas it is limited to 2 to 4 heads/m².
1. Seed treatment The simple treatment method of medicinal seeds is an effective way to protect seeds and seedlings from grubs, which has the lowest dosage and therefore the least impact on the environment. At present, China mainly selects liquid agent seed mixing (wet mixing), and advocates microencapsule suspension seed mixing. Microcapsule suspension seeding saves time and labor, which is very much in line with the current situation of rural labor shortage, coupled with its long residual period, it can last until most of the time of crop growth, so it can better control the harm of grubs. At present, the microcyst seed coating agents with good effect include octylthion, chlorpyrifos, fipronil • chlorpyrifos, avermectin and so on. Seeds are mixed with 18% octylthion microcaprine suspension 2000 times liquid at 1:10 when used, or the octyl thion agent can be evenly sprayed to the ground before sowing, and then ploughed or mixed with the soil with the agent; or the agent is mixed with the seed when sowing. The recommended dose of 20% chlorpyrifos microcapsular seed coating agent in the field is 1500~2100mL/hm², and the effect can be more than 90%. Use 15% chlorpyrifos granules 9 to 10.5kg or 48% chlorpyrifos emulsion 3000mL per hectare, spread along the ridge between peanut rows, and then apply the poisonous soil to the soil with the cultivation hoe grass, and can also be sprinkled after combined with watering, and the prevention effect is obvious. 15% chlorpyrifos granules are applied at the peanut flower needle stage, with an active ingredient of 1.8 to 3.6 kg per hectare, and the prevention effect can reach 80%. It can also be mixed with 40.7% chlorpyrifos emulsion. Germination tests should be done before seed mixing to determine the appropriate dosage.
2． Soil treatment There are many kinds of general soil treatment methods: first, the agent is evenly spread on the soil surface (actually surface treatment), and then ploughed into the soil, it can also be applied in a strip, and then the seeds are sown along the drug belt, that is, the so-called strip application; second, the application of granules; third, the chemical agent and fertilizer are mixed, that is, fertilizer and pesticide compound agent; fourth, ditch application or hole application. In order to reduce pollution and the killing of natural enemies, topical application, especially granules, can be applied as a selective soil treatment has its advantages. Although the application of granules is more expensive than ordinary seed treatment, it has a long shelf life and can be used during the growing period in addition to the sowing period, and can also reduce the damage of the agent to the seed (drug damage). If you use a particle spreader to apply, you can also save time and effort, saving labor.
(4) Biological control
While attaching importance to chemical control, the combination of biological control and physical control is also an indispensable and increasingly important technical link in grub control. At present, the biological agents promoted are mainly Bacillus thuringiensis
While attaching importance to chemical control, the combination of biological control and physical control is also an indispensable and increasingly important technical link in grub control. At present, the biological agents promoted are mainly Bacillus thuringiensis (Bt) and Aerantosbacterium for the control of grub larvae, and the sexual hormones of scarab beetles can also be used to induce plant extracts to achieve the effect of controlling adult insects.
1. Insect pathogenic bacteria: In the field application, Bt fungus powder (10 billion spores/g) can be applied during the sowing period according to the ratio of 1:10 of the drug seed to have a good control effect on grubs. During the crop growing season, Bt powder (10 billion spores/g) of 0.5 kg per 666.7 m² was used for root irrigation to control grubs.
2. Insect pathogenic fungi: During the sowing period, it is possible to mix seeds with white zombie powder (4 billion spores/g) and green zombie powder (2 billion spores/g), and the seed mixing according to the ratio of 1:10 to the seedling ratio has a better control effect on the grubs that are harmful at the seedling stage. In the crop growing season, every 666.7 m2 can be irrigated with 1.5 kg of white zombie powder (4 billion spores/g) and 1.5 kg of green zombie powder (2 billion spores/g) with water 100 to 150 kg.