How to control lawn beetles? Detailed explanation of control techniques

Maoming City is located in the southwest of Guangdong Province, with a warm and humid climate. The green spaces in the city have large areas of lawn, with the main varieties being Taiwan grass and large-leaf carpetgrass, etc. These special geographical and plant conditions cause beetles to occur frequently in our city, and sometimes in very large numbers, which causes great harm to the growth of plants and the landscape of the city's public green spaces. After many years of practice, the occurrence and control techniques of lawn beetles in our city are introduced as follows:

I. Beetle species and morphological characteristics: After many years of observation, the beetle species that cause relatively serious damage on lawns in this city are:

1. Adoretus tenuimaculatus: The adult body length is 10-11.5 mm and the width is 4.5-5.2 mm, oblong-oval, body color tea-brown, the whole body densely covered with yellow-brown scales, compound eyes relatively large, antennae with 10 segments, scutellum triangular, elytra with 4 longitudinal lines and interspaces, with relatively obvious gray-white hair spots, and 1 large and 1 small white spot each composed of scales at the apical protuberance and the lower side.

2. Proagopertha lucidula: The adult body length is about 10 mm and the width is about 5 mm; except for the smooth and hairless elytra and scutellum, the whole body is densely covered with yellowish-white fine pubescence. The head and thorax dorsum are purple-copper colored and glossy; the elytra are tea-brown, semi-transparent, and glossy, and through the elytra the folded wings can be seen forming a "v" shape. The elytra have longitudinal rows of fine punctures, the sides of the abdomen have yellowish-white hair tufts, and the end of the abdomen is exposed beyond the elytra.

3. Popillia quadriguttata: The adult body length is 7.5-12 mm and the width is 4.5-6.5 mm, and the body color is mostly dark copper-green; the elytra are light brown to straw yellow, with the surroundings dark brown to ink-green; the legs are black-brown; the base of the pygidium has 2 white hair spots, and the sides of the lower 5 abdominal sternites each have 1 white hair spot composed of dense fine hairs.

4. Maladera orientalis; The adult body length is 6-9 mm and the width is 3.5-5.5 mm, the body is small, oval, black-brown to brown, densely covered with gray-black pubescence, the top of the head and the back of the head are smooth, and the antennae have 9 segments, a few with 10 segments. The elytra have 9 longitudinal puncture striae, and the thoracic sternites are densely covered with brown long hairs. The abdomen is smooth, and each sternite has 1 row of hairs.

5. Anomala corpulenta: The adult body length is 18-21 mm, and the body color is copper-green and glossy; the elytra are grass-green, and each elytron has 3 longitudinal ridge lines; the pronotum and the elytral margins are yellow-green; the antennae and legs are yellow-brown; the abdomen is dark brown and densely covered with fine hairs.

II. Damage caused by beetles: Beetles have a miscellaneous diet, a large food intake, and strong outbreak potential. The larvae (white grubs) mainly damage the underground root and stem parts of plants, such as the root and stem parts of Taiwan grass and large-leaf carpetgrass. After the root and stem parts of the lawn are damaged, the lawn turns yellow; if not controlled in time, large areas of lawn will die. The adults mainly feed on the tender leaves and flowers of plants, causing irregular notches or holes, and in severe cases only the leaf veins remain. For example, the leaves of small holly, large-leaf crape myrtle, small-leaf crape myrtle, and Boston ivy on the lawn, and the flowers of canna (mainly damaged by Popillia quadriguttata) are also targets of damage.

III. Living habits of beetles; Beetles generally have one generation a year from adult, egg, larva, and pupa. The larvae move within 30 cm underground, and when overwintering they go dormant within 30-50 cm below the soil. In early to mid-March to April of the next year, as the temperature rises and the soil becomes moist, the overwintering larvae climb from the deep soil layer to the shallow soil layer to pupate, and then emerge as adults. On stuffy evenings, especially on days when it clears up after rain, adults emerge from the soil in large numbers, and April to July is the peak period of adult activity. From August to September, adults lay eggs in loose, humus-rich soil or in piled manure, rotten weeds, or fallen leaves.

The larvae of beetles (white grubs) prefer neutral or slightly acidic soil, with a humidity of 15%-20%. Beetles have a strong attraction to undecomposed organic fertilizer, and the damage period is mostly concentrated in spring and autumn. Adults usually hide by day and come out at night, and generally have phototaxis, death-feigning behavior, and gregariousness.

The adult occurrence periods of the above 5 beetle species are mainly from April to August, so the key time for chemical control of adults can be set in late March, June, and mid-August. In this way, effective control can be achieved before the peak adult occurrence period.

IV. Specific control measures;

1. Agricultural control: (1) Turn over and sun-dry the soil in green spaces where white grubs occur seriously. (2) Avoid using undecomposed organic fertilizer. Because beetles have a strong attraction to undecomposed organic fertilizer. (3) Selectively apply chemical fertilizers. Chemical fertilizers such as ammonium bicarbonate, ammonium humate, ammonia water, and ammoniated superphosphate release ammonia gas, which has a repellent effect on underground pests such as white grubs. (4) Control soil humidity. The most suitable soil humidity for white grub development is 15%-20%. Soil that is too wet or too dry will cause white grubs to move to deeper soil layers; if it is too dry or too wet for a long time, beetle eggs cannot hatch and the larvae will die.

2. Chemical control: (1) During the larval stage, 1000-fold 50% phoxim emulsifiable concentrate or 1000-fold 50% methamidophos emulsion can be used to drench the roots, applying 15-25 kg per square meter. Alternatively, spread phoxim poisoned soil on the lawn; use 400-500 mL of phoxim emulsifiable concentrate per mu, add 3 kg of fine soil and mix well, combine with fertilization, spread the mixture evenly on the surface soil, and then water to kill the larvae. Carry out a second chemical control after 7 days. Note that 2 days before applying the chemicals, the lawn must not be watered, and the soil should be kept dry rather than moist for a better effect. (2) Spray chemicals to control adults. Late March, June, and mid-August are the peak occurrence periods of adult beetles; using 1000-fold 50% phoxim emulsifiable concentrate, 1500-fold 25% deltamethrin, 1000-fold 40% dimethoate emulsifiable concentrate, 1000-fold 50% methamidophos emulsion, etc. all have a very good effect.

3. Biological control: Biological control mainly involves introducing natural enemies of underground pests and providing them with a good living environment; planting more nectar plants, using more biological agents (such as BT emulsion), and using agents that are safe for humans, plants, and natural enemies and do not pollute the environment (such as diflubenzuron). Natural enemies that prey on beetles include birds, chickens, cats, hedgehogs, and bombardier beetles, and natural enemies that prey on white grubs include robber fly larvae. Natural enemies that parasitize white grubs include parasitic wasps, parasitic mites, and parasitic flies. At present, the pathogenic microorganisms effective for white grub control mainly include Metarhizium anisopliae, with a control effect reaching 90%. The application of Milky Disease bacteria can cause some species of white grubs to be infected with milky disease and die; in countries such as the United States, Milky Disease bacteria and their variants have already been used to control white grubs, and in the United States the Milky Disease bacteria preparations Doom and Japidemic have been made into commercial products for sale. The control dosage is 0.05 kg of Milky Disease bacteria powder per 23 square meters. This bacterial powder contains 1×10×E9 viable spores per gram, and the control effect is generally 60%-80%. This environmentally friendly biological preparation should be actively promoted and applied in our country.