Control Methods for the White Moth Wax Cicada and the Citrus Mealybug in Longan Orchards
How to control the white moth wax cicada and the citrus mealybug in longan orchards? Please provide control methods. The white moth wax cicada and the citrus mealybug both belong to the order Homoptera, the former to the family Flatidae and the latter to the family Pseudococcidae, and they mainly damage fruit trees such as citrus, longan, lychee and mango. In the past, the population of these pests was often naturally controlled by large numbers of natural enemies and rarely reached...
How to control the white moth wax cicada and the citrus mealybug in longan orchards? Please provide control methods.
The white moth wax cicada and the citrus mealybug both belong to the order Homoptera, the former to the family Flatidae and the latter to the family Pseudococcidae, and they mainly damage fruit trees such as citrus, longan, lychee and mango. In the past, the population of these pests was often naturally controlled by large numbers of natural enemies and rarely reached the level of economic loss. In recent years, because some longan orchards in our region have been managed extensively, with pesticides sprayed indiscriminately and killing natural enemies, and because the climate and environmental system has changed, the damage caused by these 2 pests has shown an increasing trend, seriously affecting the commercial quality of longan fruit and causing economic losses to fruit growers.
1. Damage characteristics. The symptoms of damage to longan by the white moth wax cicada and the citrus mealybug are similar. Their adults and nymphs feed by piercing and sucking the sap of young longan leaves, tender shoots, flower clusters and fruit with their piercing-sucking mouthparts. The bodies of both adults and nymphs of the 2 pests are covered with wax powder. Because wax is not hydrophilic, pesticides have difficulty reaching the insect body, and the pests have strong drug avoidance and drug resistance. When damaging the fruit stalk and fruit, both pests stick wax powder onto the fruit stalk or fruit, and it is difficult to remove even by rain washing. The insect bodies excrete honeydew, inducing sooty mold. Not only do the damaged fruit become smaller and the fruit appearance is damaged, but the flesh also carries a fishy odor and is unfit to eat; the damaged tender leaves, flower clusters and twigs wither or the young buds and new shoots become deformed and twisted, growth is hindered, and tree vigor is seriously affected.
2. Life habits. The white moth wax cicada has 2 generations a year. The first-generation nymphs are seen in March-April, and the second generation in July-August; it overwinters as adults in dense branches and leaves. The citrus mealybug has 5-6 generations a year. The peak period of first-generation nymphs is in early April, the second generation in mid-May, the third generation in mid-July, the fourth generation in early September, the fifth generation in early October, and the sixth generation in mid-November; it overwinters as adults and nymphs in tree trunks, branches, cracks, curled leaves or ant nests. Both pests begin activity in February-March of the following year when the weather turns warm, and both adults and nymphs are gregarious. The white moth wax cicada occurs more seriously under high temperature and high humidity in summer and autumn, while the citrus mealybug has the highest population density and causes the most serious damage in April-May and October-November. Both pests have strong natural reproductive capacity, especially the citrus mealybug. Under natural conditions, males rarely occur and it basically reproduces by parthenogenesis. Each egg sac contains 200-500 eggs, and the hatching rate is high. Both are prone to outbreaks, and both can parasitize many kinds of plants. The adult white moth wax cicada has extremely strong migration ability. Therefore, complete eradication is extremely difficult and the damage is very great.
3. Control measures
1. Agricultural control: Strengthen orchard cultivation management. In combination with spring flower and fruit thinning of longan and pruning after fruit harvest until before the sprouting of spring shoots, cut off overly dense branches and insect-infested branches and burn them in a centralized manner, so that the tree canopy is ventilated and light-transmitting, humidity is reduced, pest sources are reduced, and damage is alleviated. At the same time, control the sprouting of winter shoots of longan, which can not only prevent massive consumption of tree nutrients and affect flowering and fruiting the following year, but also interrupt the food source of the pests, thereby reducing the pest population base.
2. Biological control: Use orchards to raise pheasants. During the adult and nymph stages of the citrus mealybug, pests on longan trees can be manually brushed off to the ground for the chickens to eat; during the nymph stage of the white moth wax cicada, when disturbed it often jumps to the ground and becomes good feed for chickens, and during the peak emergence period of adults they can be caught with nets. At the same time, attention should be paid to protecting and utilizing predatory natural enemies and parasitic natural enemies, using pesticides rationally, and not using pesticides that are highly harmful to natural enemies.
3. Chemical control: Based on the characteristic that during the newly hatched nymph stage of the white moth wax cicada and the citrus mealybug, before feeding, the insect bodies have no wax powder or secretions and are relatively sensitive to pesticides, grasp the peak occurrence period of newly hatched nymphs and spray pesticides at the right time. For the citrus mealybug, the control focus should be during the spring shoot period. You can choose 80% dichlorvos 1000-fold solution or 90% trichlorfon crystal 1000-fold solution plus 0.2% washing powder, once every 5-7 days, for a total of 2 sprays; you can also choose 48% chlorpyrifos emulsifiable concentrate 1000-fold solution, 18% dimehypo aqueous solution 400-600-fold solution, or 50% monosultap wettable powder 600-fold solution for control.
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