Aphid damage and control methods that growers need to master
Aphids are a type of plant-eating insect, also known as nìchóng (greasy bugs), mìchóng (honey bugs) and so on. They include all members under the superfamily Aphidoidea and are distributed very widely around the world, but are mainly concentrated in temperate regions. So far, a total of about 4,400 species of aphids in 10 families have been discovered, of which about 250 species are pests causing serious damage to agriculture, forestry and horticulture. Let us take a look below at aphid damage and control!
Aphid damage
Most aphid species are oligophagous or monophagous, a few are polyphagous, and some species are important pests of economic plants such as grain, cotton, oil crops, hemp, tea, sugar crops, vegetables, tobacco, fruit, medicinal plants and trees. Because they repeatedly move about and taste-test plants while migrating and dispersing in search of host plants, they can transmit many kinds of plant viral diseases and cause even greater damage, including such important pests as the English grain aphid, the oat bird-cherry aphid, the cotton aphid, the green peach aphid and the turnip aphid.
Aphid habits
Aphids have a pair of cornicles, used to excrete a defensive fluid that hardens quickly, composed of triglycerides. The cornicles are usually tube-shaped, often longer than wide, and thick at the base. They suck plant sap and are major plant pests, not only hindering plant growth, forming galls and spreading viruses, but also causing deformation of flowers, leaves and buds. Their life cycle is complex: wingless females reproduce by parthenogenesis in summer, are ovoviviparous, and give birth to young aphids. When aphids on a plant become too crowded, some grow two pairs of large membranous wings and search for new hosts. In late summer, female aphids and male aphids appear; after mating, the female aphids lay eggs, which overwinter as eggs.
Aphid control
1. Protect natural enemies: Aphids have many natural enemies, including ladybugs, hoverflies, parasitic wasps, aphid midges, crab spiders, green lacewings and entomopathogenic fungi, and these natural enemies have a strong suppressive effect on aphids. Therefore, broad-spectrum pesticides can be applied as little as possible, and spraying should be avoided during the peak activity period of natural enemies. Where conditions permit, aphid natural enemies can be artificially reared and released.
2. Manual control: In autumn and winter, whitewash the base of tree trunks to prevent aphids from laying eggs. Prune out damaged branch tips and residual flowers and burn them in a concentrated way to reduce the overwintering insect population. In winter, scrape off or brush off the densely overwintering egg masses on the bark, and promptly clear away dead branches and fallen leaves to reduce overwintering eggs. In spring, when a small number of aphids are found on flowers, they can be brushed clean with a writing brush dipped in water.
3. Chemical control: When large numbers of aphids are found, spray pesticides promptly, using 50% malathion emulsifiable concentrate at 1000 times dilution, or 50% fenitrothion emulsifiable concentrate at 1000 times dilution, or 50% pirimicarb wettable powder at 3000 times dilution, or 2.5% deltamethrin emulsifiable concentrate at 3000 times dilution, or 2.5% fenpropathrin emulsifiable concentrate at 3000 times dilution, or 40% imidacloprid water-soluble concentrate at 1500-2000 times dilution, etc., spraying the plants 1-2 times.