The new star of flowers and trees "Erythrina japonica" creates gall like tumor on trees

Paulownia wasp

The leaves of the sick paulownia tree have many small bumps, which are actually galls, which are wrapped with paulownia wasp larvae.

It is a tiny bee that is too small for the human eye to see; it is a cruel intruder who is good at destroying flowers with "disfiguration"; it is a new face of the animal kingdom, and its origin is still an unsolved mystery. It is the "new star" Chitongji wasp that invades the world of biology. It is spreading in many countries and regions at the speed of wildfire, and has been included in the third batch of "Chinese invasive species list" published by the Ministry of Environmental Protection.

Identify new faces of bees

Human beings can map the whole picture of the earth, but so far we have not been able to fully count how many species there are on the earth. There are news and reports about the discovery of new species of animals and plants all over the world every year. In the list of new species officially released and confirmed as new species in 2004, there is a small bee named Erythrina gall wasp (EGW for short), which is called "paulownia wasp" in China. Dr. John Russell of the Australian Biological Atlas Institute (ALA) described the new species in specimens taken from Singapore, Mauritius and Reunion, France.

The bug appeared in China the year after it was named, and Shenzhen was the first place it was found in China. In July 2005, when the Shenzhen entry-exit Inspection and Quarantine Bureau investigated the pastoral scenic spots at sea, it was found that several paulownia trees introduced and planted were sick and two had died. The leaves of the sick paulownia tree have many small bumps (scientific name galls), which are wrapped with unknown insects, which are initially confirmed as paulownia wasps after monitoring. After that, the Quarantine Bureau sent the samples to Zhejiang University and the Chinese Academy of Sciences for review, and contacted Dr. John Russell of Australia to obtain the specimen data, which was finally identified as the paulownia wasp.

At the end of August 2005, the Ministry of Agriculture, the State Forestry Administration and the General Administration of quality Supervision, Inspection and Quarantine jointly issued a public announcement, listing the pest as an imported plant quarantine and forestry quarantine pest in China, and suspending the introduction of paulownia plants. Emergency quarantine, control and extermination measures are required. What means does this little bug have to make the relevant departments react quickly as if they were facing an archenemy?

Make galls like tumors on trees

The inconspicuous nature of paulownia wasps is that they do no direct harm to human beings and are much smaller than mosquitoes and flies. It is only 1.45 to 1.6mm as big as a female and 1.0mm to 1.15mm as small as a male. Under the microscope, it looks like a bee. The larger, dark brown and macular ones are females, and the small ones with light yellow colors are males. It has four forms: egg, larva, pupa and adult, and it lasts only one month in a generation (from the egg leaves the mother to the adult sexual maturation and begins to lay eggs).

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The flower and tree Xinshaxing "Qitong Ji wasp" makes galls like tumors on the trees.

Paulownia wasp

The morphology of eggs, larvae, pupae and adults of paulownia wasp. Source: University of Hawaii, USA

The leaves of the sick paulownia tree have many small bumps, which are actually galls, which are wrapped with paulownia wasp larvae.

China Garden Network, Oct. 9: it is a tiny bee that is too small for the human eye to see; it is a cruel intruder who is good at destroying flowers with "disfiguration"; it is a new face of the animal kingdom, and its origin is still an unsolved mystery. It is the "new star" Chitongji wasp that invades the world of biology. It is spreading in many countries and regions at the speed of wildfire, and has been included in the third batch of "Chinese invasive species list" published by the Ministry of Environmental Protection.

Identify new faces of bees

Human beings can map the whole picture of the earth, but so far we have not been able to fully count how many species there are on the earth. There are news and reports about the discovery of new species of animals and plants all over the world every year. In the list of new species officially released and confirmed as new species in 2004, there is a small bee named Erythrina gall wasp (EGW for short), which is called "paulownia wasp" in China. Dr. John Russell of the Australian Biological Atlas Institute (ALA) described the new species in specimens taken from Singapore, Mauritius and Reunion, France.

The bug appeared in China the year after it was named, and Shenzhen was the first place it was found in China. In July 2005, when the Shenzhen entry-exit Inspection and Quarantine Bureau investigated the pastoral scenic spots at sea, it was found that several paulownia trees introduced and planted were sick and two had died. The leaves of the sick paulownia tree have many small bumps (scientific name galls), which are wrapped with unknown insects, which are initially confirmed as paulownia wasps after monitoring. After that, the Quarantine Bureau sent the samples to Zhejiang University and the Chinese Academy of Sciences for review, and contacted Dr. John Russell of Australia to obtain the specimen data, which was finally identified as the paulownia wasp.

At the end of August 2005, the Ministry of Agriculture, the State Forestry Administration and the General Administration of quality Supervision, Inspection and Quarantine jointly issued a public announcement, listing the pest as an imported plant quarantine and forestry quarantine pest in China, and suspending the introduction of paulownia plants. Emergency quarantine, control and extermination measures are required. What means does this little bug have to make the relevant departments react quickly as if they were facing an archenemy?

Make galls like tumors on trees

The inconspicuous nature of paulownia wasps is that they do no direct harm to human beings and are much smaller than mosquitoes and flies. It is only 1.45 to 1.6mm as big as a female and 1.0mm to 1.15mm as small as a male. Under the microscope, it looks like a bee. The larger, dark brown and macular ones are females, and the small ones with light yellow colors are males. It has four forms: egg, larva, pupa and adult, and it lasts only one month in a generation (from the egg leaves the mother to the adult sexual maturation and begins to lay eggs).

Africa may be its birthplace in a brief map of the distribution of paulownia wasps produced by the University of Florida.

After the administration of medicine, the damage caused by paulownia wasp was obviously weakened.

Like many invasive creatures, the parasitoid has a strong ability to reproduce. Soon after the adults grow wings, they mate. Before spawning, the female uses an ovipositor to pierce the epidermis of the host (paulownia plants) and lays eggs in the epidermis of new leaves, petioles, twigs or buds. After the small white larvae hatch, they reveal a ferocious side and feed on the mesophyll tissue of flowers and trees. Some people will say that if such a small bug opens its belly to eat, how much can it eat?

The answer lies in that the larvae not only eat plant mesophyll, but also use chemical weapons to secrete special substances to stimulate plant tissue, causing abnormal growth of mesophyll tissue and forming galls. Just as the fast-growing tumors of the human body absorb a large amount of nutrients from the body, galls also provide nutrients for the growth and development of larvae. Galls contain thin-walled and nutrient-rich tissues and a large number of vascular tissues, which directly affect the production and transport of plant nutrients. Scientists have found that there are often one or two larvae in a gall, whether alone or "shared". The closed environment provided by galls can be called eating and drinking, safe and comfortable. It is the plants that suffer, the flowers are destroyed, the branches grow and languish because of lack of nutrition, and the serious ones wither and die.

The larva develops into a pupa in the gall, and then the adult crawls out of the gall. Although the life cycle of paulownia wasp is short, the number of eggs laid at a time is about 320 and the number of generations within a year is endless, which makes its family "worm" Ding prosperous and brings great difficulty to management.

High recurrence rate and slow progress in scientific research

It is easy to escape from customs quarantine because of the characteristics of small individual, hidden living place, rapid change of generations, large population and fast spread. Also because of its late discovery, it is an upstart in the list of invasive creatures, and there are very few studies and reports on it. After the serious damage of Tongji wasp occurred in Taiwan in 2004, the scientific research department of Taiwan only used the words "small wasp has backside and phototaxis, does not like the smell of camphor, and has no obvious response to the odor of citronella oil (with mosquito repellent effect)" in some scientific research literature. to describe the conclusion of observing its behavior, which makes targeted control more difficult.

In the emergency notice of extinguishing the epidemic situation of paulownia wasp and carrying out monitoring and census work, the State Forestry Administration first asked all localities to cut off the introduction channels from the source, suspend the introduction and approval of seeds, seedlings and other reproductive materials of paulownia plants from affected countries and regions (Mauritius, Reunion Island of France, Hawaii, Singapore, Taiwan Province of China). And temporarily suspend the processing of the Plant Quarantine Certificate for the transportation of paulownia plants.

In 2005, Guangdong and other provinces and regions took measures to remove all the 1-2-year-old branches of paulownia plants that had occurred, and destroy all the branches and leaves, and immediately cut down and destroy all the seriously harmful trees or carry out quarantine and pest control treatment. Despite such extraordinary efforts, in June 2006, the relevant departments in Shenzhen organized a review and found that the recurrence rate of about 8000 paulownia trees damaged by wasps the previous year was as high as 60 per cent, which was very tricky.

In August 2014, the Ministry of Environmental Protection and the Chinese Academy of Sciences jointly released the "China Alien invasive species list (the third batch)" list, which listed the paulownia wasp as one of the 18 invasive species. The Ministry of Environmental Protection proposes to cut off the leaves and twigs of the trees found with paulownia wasps, clean up the galls and branches that fall on the ground, burn the leaves and twigs centrally or dig holes to bury them, so as to prevent spread. The newly isolated epidemic spots and plants were cut and destroyed on the spot, and the paulownia plants around the occurrence area were sprayed to prevent them. However, from the 10-year management experience, the control of paulownia wasp is not optimistic. Africa may be its birthplace in a brief map of the distribution of paulownia wasps produced by the University of Florida.

The origin of life is still a mystery.

Over the past 10 years, the scientific research community has traced back to the origin of Tongji wasp, but it is still not clear where its hometown is. Some scientific research literature believes that it "almost certainly comes from East Africa." The expert Group on Alien invasive species (ISSG) analyzed the data and situation of paulownia wasp in various parts of the world, and concluded that the wasp showed invasiveness in Chinese mainland, Hong Kong and Taiwan, India, Japan, the United States, Singapore, Mauritius, American Samoa and other places. In Viet Nam, the Philippines, Malaysia, South Africa, Thailand, Tonga, Maldives, Fiji, Guam, New Caledonia, Micronesia (Federated States of), Samoa, Reunion and Vanuatu, its invasiveness is "not yet clear". This also shows that the definition of invasive species needs time to observe, and also needs corresponding technical means to identify.

In 2005, the paulownia wasp was first discovered on the island of Oahu in Hawaii. Researchers have found that the bug is very harmful to the local unique Hawaiian paulownia, killing 95% of the local paulownia trees within two years. In 2008, Hawaii spent $1 million on pest control, mainly by removing leaves and pesticides from affected branches, and setting up 15 monitoring sites for long-term observation. The data from the University of Hawaii show that there are two kinds of natural enemies in Africa, but little progress has been made in the biological management of the wasp, which shows how difficult it is to introduce natural enemies of invasive species.