When it comes to the most "eye-catching" insects in China in the past two years, the grassland nightcrawler should be regarded as a more representative, it is considered to be one of the most destructive pests in the world, and its huge destructiveness mainly stems from its "greedy" nature - gluttony, greed, greed, wide adaptability, and drug resistance.
The grassland nightcrawler has single-handedly invaded more than 100 countries around the world, and has spread to thousands of counties in 26 provinces and counties in China since its introduction to China in early 2019. Wherever the "demon moth" went, crops such as corn were eroded and farmers suffered heavy losses, and even the State Council realized its harm and "specially" named it.
So, why is the grassland moth so harmful, and how to prevent and control it? Let's take a look at the latest research reports!
What is the Meadow Moth?
Image credit: Forestry Images
Spodoptera frugiperda, commonly known as fall armyworm, belongs to the genus Nocturnidae of the family Lepidoptera, is an omnivorous pest native to tropical and subtropical regions of the Americas, widely distributed in the American continent, harmful to a variety of crops, in the 2017 State of the World's Plant Status Report was rated as one of the world's top ten plant pests by the International Center for Agricultural and Biological Sciences (CABI).
Image credit: Andermatt Biocontrol
The body color is yellow-green, the head is bluish black, only 1.7 mm long, like a big-headed doll.
Image source: entnemdept.ifas.ufl.edu
The body color is variable, and the larvae have a rough epidermis, wrinkled and granular structure.
How to distinguish the meadow moth?
The grass moth is very easy to collide with the relatives of the destruction king - twill moth, armyworm, etc., how do we distinguish it?
The iconic features of the grass moth larvae are:
Image source: www.fao.org
In line with these two characteristics is the grass moth:
Otherwise, you can exclude:
The ability of the grass moth to fly
The grassland night moth is an adult insect, although its appearance is gray and inconspicuous, but it has a remarkable and headache super flight ability. Adults can use wind to carry out long-distance directional migration at altitudes of several hundred meters, flying 100 km per night, and 500 km before spawning.
Meadow nocturnal moth male
Meadow nocturnal moth Female
The voraciousness of the grass moth
The grassland moth is a multi-food pest that can feed on almost any plant group, including 353 species of plants in 76 families, including herbs, vines, and woody. A single grass moth can destroy an entire plant of corn because it can feed on various organs of the plant and has a destructive effect at all growth stages of the crop. Young larvae usually hide behind the leaves to feed, forming translucent membrane "window holes" after feeding. The old mature larvae are more harmful to the corn, and after eating the leaves, they form irregular long holes, which can feed the leaves of the whole corn plant, and also eat the male ears and fruit ears of the corn.
Image source: fao.org
The maize that is infested with the grass moth is simply unbearable, resulting in a loss of 15% to 73% of the yield.
The fervorability of the meadow moth
The meadow moth is a completely metamorphosed insect that can complete a generation in about 30 days under the conditions of 28 °C in summer. Adults mostly migrate, mate and lay eggs at night, and female moths can mate and lay eggs multiple times, each time laying 100 to 300 eggs, and the total number of eggs in a lifetime can reach 1500 to 2000. Its ovoid dome is of the dome type, about 0.4 mm in diameter, and the eggs are usually covered with light gray villi, i.e. female moth scales. It is light green or white at first birth and gradually turns brown before hatching. The newly hatched larvae begin to cluster into harmful young leaves and start a foodie life, and the larvae are generally divided into 6 ages, and can grow into mature larvae in 14 to 30 days. The old larvae pupate underground and build an earthen pupa for themselves, waiting for feathering. It will feather into adult insects in 8 to 9 days in summer and 20 to 30 days in winter.
Eggs of the meadow moth
Larvae of the meadow moth
The pupae of the meadow moth
Adult of the meadow moth
The greediness of the meadow moth
Like a greedy invader, the grass moth is never satisfied with its current place of life, and the invasion migration has evolved into an important part of the life history of the grass moth. The grassland moth, first found in the Americas, has been harming there for more than 200 years and is now rapidly invading and spreading:
First discovered in Africa in January 2016;
In 2017, the invasion spread rapidly to the Indian Ocean islands and many asian countries;
After being discovered to invade China in early 2019, it quickly spread to most provinces and regions...
As of June 2020, the meadow moth has been found in 32 countries in North America, 13 in South America, 47 in Africa, 18 in Asia, 4 in Europe and Australia.
Broad adaptability of the grass moth
The grassland moth not only has a strong ability to migrate and spread, but also has a strong adaptability, and is comfortable in the face of various environmental and climatic conditions:
Whether it's farmland, greenhouses, orchards, meadows, riversides, wetlands, bushes, suburbs...
Whether it is a tropical rainforest climate, a tropical monsoon climate, a grassland climate, a desert climate...
Whether it is the absolute minimum temperature of 8.2 ° C, or the continuous dry season of 3 to 7 months, as long as it is given a land, it can live its own world!
Resistance of the grass moth
The most headache of the grassland moth is drug resistance, the previous chemical pesticides were considered to be the magic weapon to fight the spread of the grassland moth, but the ideal is very plump reality is very bone, chemical pesticides not only did not prevent its further spread, development and spread, but also promoted the evolution of the grassland moth, making it more and more powerful. Whether it is more than a dozen insecticides such as carbamates, organophosphates and pyrethroids, or Cry1F insect-resistant gene corn, the grassland moth has slowly developed serious resistance to it!
How to control the grassland night moth
Although the grassland moth has super abilities such as good flight, wide adaptability and drug resistance, it is difficult to control, but it is not incurable and preventable.
Biocontrol
The parasitic natural enemy insects of the grassland nightcrawler include 51 species, and the parasitic rate of its larvae can reach 20% to 70%, such as the famous natural enemy insect Cotesia Marginiventris:
Coiled cocoon bee Cotesia marginiventris
Predatory predators include 19 species, such as: Chrysopa pallens, East Asian small-flowered bug Orius sauteri, large red rhinoceros hunting bug Sycanus falleni, etc., but there are still few examples of large-scale applications.
Chrysopa pallens
There are 19 pathogenic pathogens that have a pathogenic effect on the grassland moth, of which 4 are widely used, including: Bulbophyllum beauveria bassiana, Green Zombie Mebarhizium lepidiotae, Nomuraea rileyi and Phytophthora erynia sp.
2. Medicinal plants
At present, more than 80 species of medicinal plants with application prospects in the prevention and control of the grassland nightcrawler have been reported around the world, with the most abundant plant resources in the Asteraceae family, such as: Lychnophora of the genus Lamprod, as well as plants such as the labial family and legumes, such as Lupinus of the genus Lupinus.
Lupinus montanus
The extracts of these plants contain active components that have a controlling effect on the grassland moth, and have obvious control effects on the grassland moth.
In addition, prevention and control strategies such as cultivation control, ecological regulation, new pesticides, pheromones, and integrated control are being vigorously exerted to accurately snipe the grassland night moth.
(Source: Journal of Plant Protection)