Fund Project: Biological characteristics and control measures of the grape-winged curl moth
Fund Project: National Key R&D Program (2018YFD0201303) Ministry of Finance and Ministry of Agriculture and Rural Affairs: National Modern Agricultural Industry Technology System Funding (CARS-29-bc-4)
Ma Gang and others
Lobesia botrana belongs to the lepidoptera, mainly harmful to grapes, but also harmful to blackberries, gooseberries, olives, cherries, European plums, persimmons, kiwis, pomegranates, etc. and a variety of caryophyllus plants, is an important imported plant quarantine harmful insect in China and many countries in the world. Native to Italy, the flower-winged curl moth has spread throughout Europe and is found in northern and western Africa, the Middle and Far East in Asia, and parts of the United States. Although the flower wing curl moth has not yet been found in China as a pest, the main grape producing areas in China are suitable for the flower wing small curl moth, so it is more important to do a good job in the quarantine of imported plants to strictly prevent the insect from invading China. The biological characteristics and management methods of this insect are summarized below.
1 Biological characteristics
1.1 Morphological characteristics
The grape-winged moth has four types of insects, including eggs, larvae, pupae, and adults. Adult forewings are tan with grayish-blue, brown, and black spots; the hindwings are grey with stripes on the edges; the dorsal back has two distinct clusters of brown scales; when the wings are combined, they resemble inverted bells; and the females are slightly larger than the males. The larvae are 5 years old, the hatching larvae are pale yellow, and the old mature larvae are green, brown and so on. Egg yield, flattened ellipsoidal. Pupae are creamy, light brown, light green, or light blue at first, but turn brown or dark brown after a few hours. The reproductive structure is located in the 8th segment of the web as a female pupa, and the web at the 9th segment is a male pupa, and the female pupa is larger than the male pupae.
1.2 Harmful characteristics
The grape-winged curl moth is mainly infested with larvae, which have a spitting habit and connect the affected part with adjacent parts to prevent falling. The first generation of larvae harmed the ear of grapes and suffered little economic loss. The second generation of larvae begin to infest the young fruit, and the newborn larvae can penetrate the skin and moth within a few hours after hatching, and finally hollow out the flesh to leave the peel and seed. The third generation of larvae is the most harmful, starting to eat mature fruits, and each larvae can harm 1 to 6 fruits. Grapes that are infested with larvae are more susceptible to infestation by fungi such as gray mold, resulting in outbreaks of grape gray mold, which reduces grape yield and quality, and serious economic losses.
1.3 Life history and occurrence
The grape-winged curl moth is a typical facultative diapause species that occurs in multiple generations depending on local latitude and climatic factors. Two generations occur each year in Germany, Switzerland, Austria and northern France, while three (and sometimes four) generations occur in southern France, Spain, Portugal, Greece and Italy. In Israel, Egypt and Crete, some populations are not diapause, spending the winter with larvae. In vineyards, the flower-winged curl moth overwinters mainly in pupae in flaking bark, cracks and gaps in trunks. When the temperature reaches about 10 °C in the next year, the overwintering pupae feathers into adults and lay eggs after mating for 1 to 2 days. The general egg stage is 3 to 5 days, the larval stage is about 20 to 30 days, after the old mature pupal, the next generation of adult worms will appear 6 to 14 days after pupal pupalization.
2 Quarantine
Post-harvest irradiation treatment is an effective quarantine measure for imported berries, generally 250 Gy irradiation dose can kill the eggs and larvae of the flower wing curl moth, and the irradiation dose of 325 Gy can kill pupae. Passengers should be prohibited from bringing fruits into the country during travel inspections, and once found, they should be destroyed. For fruits and fruits from the epidemic area, strict inspection should be carried out, especially whether the fruit has eggs or damaged fruit grains, and the rotten fruit should be cut open to check for larvae. Once larvae and eggs are found, measures such as quarantine or destruction should be taken. When transporting seedlings from the epidemic area, we must also pay attention to the procedures for eliminating pests.
3 Prevention and control measures
3.1 Chemical control
Chemical agents are still an indispensable means of control of the flower-winged curl moth, but in the context of integrated pest management, the insecticides used in the past have gradually been replaced by more selective materials that are less harmful to human health. Such as new neurotoxic insecticides (polyficides and oxadiazines), chitin synthesis inhibitors, microbial insecticides, avermectin and so on. Most of the above agents can be used when the pest is at its most susceptible stage to achieve the best results.
3.2 Biological control
In lepidoptera insects such as the grape-winged curl moth, the search for a mate is usually mediated by female sex pheromones, moth females release small amounts of sexual pheromones, males rely on highly sensitive neurosensory structures to detect these pheromones, these pheromones mediate competition between male insects for female insects, and pheromone-mediated mating interference techniques are also born. After mating interference with the flower-winged curl moth using a dispenser that releases synthetic pheromones, the populations of the first, second and third generations of the flower-winged curl moth were significantly reduced, and the number of inflorescences and fruits affected was also significantly reduced. But when the pest population density is too large, mating interference does not take effect .
Bacillus thuringiensis, abbreviated as Bt, a crystalline protein encoded by the Cry gene produced during its spore-forming stage, is the main substance that causes Bt to cause susceptibility in certain Coleoptera, Diptera, and Lepidoptera insects. In most cases, the optimal time for Bt treatment is 5 to 7 days after the start of adult flight, and treatment must be repeated after 7 to 10 days. During the spraying process, the grapes should be covered as fully as possible, because the larvae must be ingested to be effective, and to increase spray coverage, some of the leaves can be removed. Bt has a good effect on the second and third generation of pests of the flower-winged curl moth, and Bt has a high degree of specificity for the flower-winged curl moth, which can reduce the risk of death of beneficial insects, reduce toxic residues in grapes and wine, and shorten the harvest interval (3 d), and the flower-winged curl moth is not easy to develop resistance.
3.3 Cultivation management
The leaf removal method around the grape ear is used to properly remove the leaves above the berries, so that the surface temperature of the berries exposed to direct sunlight is increased by at least 9 °C, and the high temperature reduces the survival rate of the eggs and larvae of the flower wing moth, thereby affecting the infestation of the flower wing moth. Studies have found that if the leaf removal method around the fruit spike is applied during the second flower wing curl moth flight, the infestation of the second and third generations of the flower wing curl moth can be reduced by up to 70%. The use of leaf removal around the panicle to control eggs and larvae also reduced the incidence of grape gray mold. However, care needs to be taken to avoid the occurrence of grape burning when applying this method in warmer wine-growing areas and hotter years.
3.4 Physical control
Radiation sterility technology is an alternative, environmentally friendly pest control method. In Lepidoptera, low doses of gamma rays can lead to hereditary infertility, leaving males partially sterile while females are completely sterile. The number of females of the irradiated flower-winged curl moth, whose offspring enter the pupal stage, is significantly reduced, and as a result, the number of F2 generations is significantly reduced. After males are irradiated, the number of F1 offspring decreases, and the number of F2 offspring is extremely low.
Kaolin on plants may prevent pests from identifying hosts, while kaolin particles attached to the pest's body can also impair their activity. This may be due to changes in the color of the berries coated with kaolin, which affects the visual signals of adults, and the physical barrier formed by kaolin also changes the insect's tactile and chemical perception of the host. As a result, kaolin can make the smooth surface of the berries dusty and irregular, which in turn hinders the laying of eggs by the flower-winged curl moth. Kaolin powder can also adhere to the chemical and mechanoreceptors of the pest tarsus and spawners, interfering with the female's ability to identify suitable spawning sites. Therefore, kaolin cover can effectively reduce the field spawning of flower-winged curl moths and reduce the number of larvae.
Kaolin has a high resistance to rain erosion and is not degraded by ultraviolet radiation, and when combined with the defoliation method around the grape panicle, kaolin compensates for the possible shortcomings of this cultivation method by reducing sunburn damage and vine moisture stress from exposed berries without negatively affecting grape yield and grape quality. Moreover, the effect of kaolin cover combined with the leaf removal method around the fruit spike did not differ significantly from that of Bacillus thuringiensis in the control of the flower-winged curl moth.
4 Summary
Flower wing small curl moth harm is serious and spread rapidly, China's grape growing areas as the flower wing small curl moth suitable for the growth area should strengthen the inspection and quarantine measures on the import and export shore, to prevent its introduction into China. At the same time, grape and other fruit tree growers should also improve their awareness of prevention, strengthen the daily cultivation management of orchards, and pay attention to monitoring the occurrence of flower wing moths. In addition, methods such as leaf removal around the ear and kaolin cover can also interfere with the spawning of pests such as fruit flies, so these methods can also be used to control other grape diseases and insect pests.