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Written by: Lao Minyi
2021-05-30 00:00
Last update date: 2021-05-30 00:00
The expansion of the area of the vermillion moth has caused the banyan trees in many areas of the New Territories to "discolor".
The government tried "new tricks" to kill moths, putting bamboo, straw mats or burlap bags around tree trunks, causing some larvae to be trapped or accidentally "backflip" and fall to the bottom of the tree.
Some arborists believe that at this stage, we should focus on removing pupae from the ground and eliminating the sources of insects to reduce the potential crisis of a large outbreak in China. Do not continue "Buddhist management."
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Banyan moth plagues | Vermillion moths broke out again in the New Territories banyan trees were attacked and bald, affecting 23 ancient trees
Banyan moth plague: Four ancient trees suffering from "tree cancer" are trapped by insect pests
▼The government tries "new tricks" to catch moth larvae▼
Last year the vermillion moth pests were found in many areas in the New Territories. At the beginning of this year, some banyan trees were added with "new clothes". The trunks were wrapped in mats or burlap bags to catch larvae crawling on the trunks, reducing the "worm population" and slowing down eating Degree of foliage.
The reporter went to the Sheung Shui District to observe in the middle of this month and found that some larvae corpses had been stuck on the straw mats on some trees, and a large number of moth corpses had not been cleaned under some trees.
The seven banyan trees outside the Sheung Shui Bus Terminal are surrounded by straw mats, but the leaves of four of them have been gnawed away by moth larvae and become bald. The remaining three have also lost half to 80% of their leaves.
During the inspection, some larvae crawled slowly along the edge of the straw mat. Many pupae were also seen at the foot of the tree. After emergence, it will become the first generation of vermillion moth this year.
Xu Shujun, Conservation Manager of Changchun Society, said that moths crawled up and down on tree trunks during their growth period. After adding straw mats or burlap bags, they did successfully catch some of the larvae. I have also seen larvae "stamp" on them accidentally. The backflip fell to the tree foot, which is believed to help reduce the "insect population" to some extent, but it is believed that the authorities must also work harder to clean up the insect corpses on the tree foot.
One of the natural enemies of the vermillion moth is Diadema striata. After the moth hatches, it lays eggs on the moth, hatches and grows in the moth's body, and breaks out when the moth is approaching its final instar. , Find another place to pupate, and the moths will die by then.
Therefore, Xu Shujun believes that insecticides should not be used during larval outbreaks, so as not to kill the larvae of the bee bees.
She believes that the authorities must use the medicine during the incubation period of the eggs, and the larvae are poisoned to death when they start to eat the leaves.
At present, the scourge of Vermillion Moth is still concentrated in the New Territories. She hopes that while the authorities do a good job of prevention and control, "the boundary can be maintained, (a large number of Vermillion Moth) will not fly out of Kowloon."
▼The growth cycle of Vermillion Moth ▼
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Arborists criticize the government for insufficient prevention and control in winter
Yuan Dacheng, a retired arborist, believes that the vermillion moth cannot be completely removed. When its number is too large, it exceeds the tolerance level of the banyan tree, resulting in an ecological imbalance in the garden.
He said that at present, some of the final instar larvae have come to pupae under the tree, ready to form cocoons and emerge, and the number of females can be up to 100 each time. He believes that at this stage, we should focus on removing the pupae on the ground and eliminating the source of insects to reduce the number of first The potential risk of a large outbreak of adults.
However, according to his observation, the government's winter prevention and control work is insufficient, and it has not strengthened manpower to clean up the gaps that may contain pupae. Even if straw mats or burlap bags are used, it has not sent people to clean up frequently.
He suggested that the authorities adopt comprehensive control measures, including the use of insect nets and other methods to collect adult insects in the early stages of emergence peaks based on the characteristics of newly emerging adults, such as weak flying ability, often inhabiting low herbs or shrubs, and bright colors and easy to find. ; Appropriate chemical control measures can be adopted for larvae, that is, during the initial incubation period and 3 to 4 instars of the larvae, grasp the golden opportunity of dropping the medicine.
Xu Shujun believes that it is necessary to clean up the larvae at the foot of the tree.
(Photo by Ou Jiale)
Development Bureau said it has stepped up the removal of pupae to slow down the outbreak of pests in early spring
In view of the larvae gnawing on the leaves of banyan trees, the Development Bureau replied that the greening, landscape and tree management team has contacted the relevant tree management department since the middle of last year and consulted the expert opinions to continue to monitor the health of the affected banyan trees and take preventive measures. This includes spraying the affected tree canopy with soapy water and applying insecticide to the trunk to reduce the number of larvae.
Since then, during the cocooning and overwintering period of moths from November last year to February this year, the removal of pupae hidden in bark or tree roots, shallow soil layers and fallen leaves has been stepped up to reduce the potential risk of pest outbreaks in early spring.
The spokesman also pointed out that the department tried to use bamboo, straw mats or burlap bags to wrap part of the tree trunks as a pilot project, with a view to catching the larvae moving on the tree trunks in the next stage, and is closely monitoring its effectiveness.
Shenzhen also has pests
In addition, the management team contacted the expert consultants of Guangdong Province and learned that insect pests also occurred in Shenzhen, and sprayed moderate insecticides to control the number of larvae.
The management team will evaluate and monitor the effectiveness of the prevention and control work, adjust relevant measures when necessary, and consult expert consultants at appropriate times to prepare effective pest prevention and control strategies.
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Tree Conservation, Tree Management, Tree Management Office, Development Bureau