Insects

(1) Insect diversity in China

a. High species richness

The total number of insect species on earth varies according to different reports. No unanimous conclusion can be drawn. It used to be reported that there are totally 1.5 million species of insects. After studying canopy insects of the tropical rainforest in the Manas Valley, however, Erwin (1983) estimated that there may be 30 million insect species.

China is a large country with complicated geographical and ecological environments, and is rich in biodiversity. Due to insufficient study, nobody can place an exact number on the insect species in China. It has been roughly estimated that China has about 10% of the world total of insect species, i. e., 150 thousand species. However, an analysis of relatively well-studied insect groups indicates that the number of species in China should be far more than 10% of the world total. For example, there are 4,000 species of Aphidoidea and Adelgoidae in the world, but China has recorded 1,000 species, which is 25% of the world total. Similarly, for the Muscidae, Siphonaptera, Tachinidae and Galerucinae, the proportions of the world's total are 23.1%. 19.9%, 16.7% and 11.6%, respectively.

A rough estimation, based on the described species of more than 920,000 in the world and the 51,000 recorded from China is that 5.5% occur in this country. Since 1949, however, about 10,500 new species have been described from China with an average of 500 new species described each year recently. We are still, however, far away from determining what species stocks we have.

b. High abundance of endemic species

China is one of two countries with the highest biodiversity and endemism in Asia and the South-Pacific region. China's endemism is not, however, well understood. but there are many regions with a high degree of endemism, such as the Qinghai-Tibet Plateau, and the arid desert areas of Xinjiang Province. According to a survey of the Qinghai-Tibet Plateau, of the 200 species and subspecies of Acridodea, endemic ones make up 51% of the total; of the 62 described species of Hepialidae (Lepidoptera) in China. 41 are endemic and 90% of the species of Hepialus (40 species) are endemic to the plateau (Yang Darong). Of the world total of 93 species of Leptomias (Coleoptera), 55 (59%) are endemic to Tibet. Of the 3,080 described insect species from Hengduan Mountain Region, 1,229 (39. 9%) are endemic and the endemic species of several orders, such as the Diplura. Psocoptera, Phasmatodea, Neuropteran and Trichoptera, account for more than 50% (Wang Shuyong, 1992). Xinjiang is the most arid region in China, but where Palaearctic Central-Asia species are especially rich. For example, of the 11 genera of Pamphagidae (Orthoptera), 10 are restricted to northwestern China, and 5 are endemic to Xinjiang. The genus Sphinogonotus (Oedipodidae), is a typical group distributed in the Mongolian-Xinjiang region, with 75 species known in the world. Of these, however, 33 species are recorded from China and 14 are endemic to Xinjiang, i.e., 18.7% of the world total.

c. Beautiful and rare insects

The insects, which have an international trade value, are rich in China, butterflies being the most important. Only 14 insect species are listed as legally protected in China(two in Class Ⅰ, twelve in Class Ⅱ), although 24 species in 9 genera and most species of the genus Parnassius are tentatively listed as rare species in Table 1.

Table 1 List of rare Chinese butterflies (tentative)

Species	Distribution
Teinopalpus aureus	Fujian, Guangdong, Guangxi, Hainan
T. imperialis	Sichuan, Guangxi
Bhutanitis mansfieldi	Yunnan
B. thaidina	Shaanxi, Sichuan, Yunnan, Tibet
B. lidderdalii	Yunnan
B. pulchristata	Sichuan
B. yulongensis	Sichuan, Yunnan
B. nigrilima	Sichuan
Bhutanitis ludlowi	Yunnan
Luehdorfia longicaudata	Shaanxi
L.chinensis	Shaanxi, Henan, Jiangsu, Zhejiang, Hubei, Jiangxi, Sichuan
L.puziloi	Jiling
Agehana elwesi	Shaanxi, Jiangxi, Fujian, Zhejiang, Hunan, Hubei, Sichuan, Guangdong, Guangxi
A. maraho	Taiwan
Lamproptera curia	Guangdong, Guangxi, Hainan, Yunnan
L. meges	Guangxi, Hainan, Yunnan
Troides aeacus	Shaanxi, Jiangxi, Zhejiang, Fujian, Taiwan, Guangdong, Guangxi, Yunnan, Tibet
T. helena	Guangdong, Hainan, Yunnan
T. magellanus	Taiwan
Atrophaneura horishana	Taiwan
Parnassius spp. (all alpine species)	Gansu, Qinghai, Xingjiang, Sichuan, Yunnan, Tibet
Sasakia charonda	Hailongjiang, Jilin, Liaoning, Hebai, Shanxi, Henan, Shaanxi, Hunan, Zhejiang, Taiwan
S. funebris	Zhejiang, Fujian, Sichuan, Yunnan, Guizhou
S. pulcherrima	Sichuan
Euploea mulciber	Southern and Southwestern China, Taiwan, Southern Tibet

Two species of Teinopalpus occur in the world and both are also distributed in China. The famous T. aureus is endemic and listed in the lst grade of protected species in China. There are seven species of Bhutanitis in the world and these also occur in China. Of these, five are endemic. B. mansfieldi and B. thaidina are 2nd grade protected species. Of the four species of Luehorfia, three occur in China, i. e., L. chinensis and L. longicaudata are endemic and L. chinensis is a 2nd grade-protected species. Two species of Aegehana occur only in China, so that they are all endemic. A. maraho, with a restricted distribution in Taiwan is facing extinction. Two species of Lamproplera occur only in the Oriental Region, including China. Three species of Triodes occur in China. T. aeacus is the largest butterfly in China and the subspecies T. aeacus kaguya is an important protected species. T. magellanus is endemic to Taiwan, but is now facing extinction. Atrophaneura is distributed in the Oriental Region with many species. An endemic species in Taiwan, A. horishana, is an important protected species. There are 38 species of Parnassius in the world, of which 35 occur in China and 10 are endemic. Most Parnassius species are distributed on high mountains. The well-known P. apollo is extinct in some European countries but is relatively common in China. Of the three species of Sasakia (Palaearctic species) which occur in China and Japan, S. funebris and S. pulcherrima are endemic in China and S. charonda is now facing extinction in Taiwan and Japan. The genus Euploea includes many species, of which E. mulciber is rare in China.

d. The importance of insects

There are nearly one thousand species of insect pests. They are harmful to agriculture, forestry, husbandry, and the health of mankind, and have to be either controlled or managed.

Of the beneficial insects, the most important are natural enemies and pollinators. Several hundred species of parasites and predators of pests play important roles in integrated pest management and the protection of ecosystems. Pests in about 10 million hectares of crops are controlled effectively by natural enemies, so that the pollution of the environment by chemical pesticides has been reduced. There are thousands of species of insect pollinators, including the domestic honeybees (Apis mellifera and A. cerana), wild bees, flies, butterflies and moths, but bees are more important than others. They are economically significant in the pollination of various flowering plants and the maintenance of ecosystems. The yield of many crops can be increased by about 20% by insect pollinators.

Chinese sericulture production occupies an important place in international trade. The cocoon yield accounts for 65% of the world total, and silk and silk fabric exports rank the first in the world. Silk fabric exports account for more than 90% of the total international trade volume. China is also famous for apiculture. There are 6.5 million colonies of honeybees. The exports of both the honey and the royal jelly are first in the world. The production and international trade volume of Chinese gall nut, white wax, Chinese caterpillar fungus and insect-tea are also first.

There are about 300 species of insects used in traditional medicine in China. The products of bee-venom and ants are developing rapidly. Edible insects are nutritious and are being paid more and more attention to.

(2) Threatened status of insect diversity

There is no detailed scientific information about endangered insect diversity in China, since not enough attention has been given to its study and the protection of insects. The deterioration of the natural environmental is the main factor that threatens insect diversity. Over-exploitation has led to rapid decreases in some insect resources, such as the caterpillar fungus. Because of habitat loss, environmental pollution and deforestation, the numbers of species and individual butterflies in the famous "Butterfly Well" in Dali have decreased. Due to excessive digging of host plants and over collection of Bhutanitis thaidina in Sichuan, populations of this species have decreased. Some resources have been exported blindly and illegally smuggled, further causing the decrease in wild insects. Improper uses of chemicals have made many natural insect predators and pollinators endangered.

(3) Conservation and sustainable exploitation of beneficial insects

In recent years, China has paid more attention to the protection of its insect resources. For example, a protection area for the Japanese silk moth (Antheraca yamamai) has been established in Ningan, Heilongjiang Province, and is the first example of insect protection. A patch of forestland has been identified in the suburb of Nanjing for The protection of the butterfly Luehdorfia chinensis. The production and research of the traditional Chinese insect industry, for sericulture and apiculture, is good. The protection and introduction of natural enemies and mass-breeding with artificial food is increasing rapidly. Artificially bred butterflies, foraging insects (the fly larvae and yellow mealworm), cockroaches and ants are also on sale. Artificial nests of several bee-pollinators have been set up. All of these lay a foundation for the sustainable utilization of insect resources.

It is urgent to increase public awareness of the importance of insect diversity and to strengthen the implementation of the laws protecting insect resources in natural reserves and to speed up the establishment of protection areas for rare species.