BIOLOGICAL CONTROL - ONE OF THE FINE TRADITIONS OF ANCIENT CHINESE AGRICULTURAL TECHNIQUES

 

PENG, Shijiang, Laboratory of Agricultural History and Heritage, South China Agricultural University, Guangzhou, Guangdong Province, PR CHINA.

(Scientia Agricultura Sinica 1983(1):92-98. Transl. by Dr. Waei Tsao & Xiao Li; edited by B. Gordon)

 

ABSTRACT

Biological control has a long history in China. Our ancestors used it as an important method in controlling destructive insects and animals. As early as 304 A.D., there was an account of citrus pest control using Oecophylla Smaragdina, and many other biological controls were also widely adopted by farmers. It is evident biological control played an important role in plant protection since ancient times in China.

Knowledge of the Phenomena of Interaction Among Organisms

        Biological control stems from our understanding of natural control of prey by animals and plants; i.e., animals destructive to pests are used to protect plants. China thoroughly observed and understood this phenomena quite early, one record probably in Poetry Book - Xiao Ya "grain beetles give birth, but their larvae are carried by fruit flies". Others "welcome cats for their ability to catch field mice and tigers for their ability to catch wild boars", "spiders spin webs to catch prey, mantis catch cicada with strong arms", etc., proving ecosystem and food-chain knowledge existed since Spring-Autumn and Warring States periods.

        Ancient people not only observed carnivore behavior in biological control, but also knew much about parasitic insects; e.g.s, "Yan Zi Chun Qiu" records "a kind of East Sea insect feeding on mosquitoes, its presence not bothering them.". Ancient people relate the number of white-eyed wasps with the amount of leaves produced on mulberry trees for rearing silkworms. "Feng Ning Zhuan" records "mountains of white-eyed wasps in Feng and Ning cities in 713-714 A.D.. At the end of spring, their citizens predicted silk production accordingly". This is unrelated to superstition, but understanding relations between wasps and mulberry tree insect pests. Many ancient records occur on parasitic flies in silkworms; e.g.s, "flies injecting silkworms with eggs, ...of silkworms hatched from their own eggs in 2-3 groups, only the earliest being the strongest with no parasitic maggots". Other Ming Dynasty literature like "Jie Yi Xing Yu" by Huangpu Fang and "Tan Zi Diao Chong" by Tan Zenmo have similar descriptions, but more detailed in the latter: "eggs layed in silkworms by flies metamorphose to maggots in silkworm cocoons and are called "xiang zi". Ancient people also mention flying locusts dying of internal parasites; e.g., "in 1196, locusts dying on grass have brain parasites". None of these records mention effective methods to protect plants, but these observations are basic and the first process in developing it.

Protection and Utilization of Beneficial Animals

1. Pest control by insects

        The world’s earliest example of insect control of insects is when Chinese farmers used huang gan (huang = yellow, gan = citrus) ants (Oecophylla smaragdina) to prevent citrus fruit tree damage. Some foreign scholars also acknowledge Chinese origin of the very early idea of using a certain insect to control another (see "Biological Control" 1977:19), the earliest written record in "Nan Fang Cao Mu Zhuang" by Ji Han of Jin Dynasty: "Jiaozhi people sell ants and their nests attached to twigs looking like thin cotton envelopes, the reddish-yellow ant being larger than normal. Without such ants, southern citrus fruits will be severely insect-damaged". "Ling Biao Lu Yi" of late Tang Dynasty or Early Five Dynasties wrote similarly: "farmers buy ants to control insects in most southern citrus orchards to control harmful insects". The 17th century book "Guangdong Xing Yu" is even more detailed: "local people place big ants and their nests atop trunks, connecting trees with bamboo sticks in such a way that fruit, especially citrus, will be undamaged by insects". Similar records also occur in "Ji Le Pian" by Zhuang Jisu of Southern Song Dynasty, "Book of Tree Planting" by Yu Zhen Mu of Ming Dynasty, "Lingnan "Miscellanies" by Wu Zhen Fang of Qing Dynasty, "Nanyue Miscellanies" by Li Diao Yuan, etc., implying such a method has a long history and spread far. Recent research of Yang Shi of Zhongshan University said "Huang gan ants catch and devour certain insects, a method far better than chemicals, with fruit–dropping reduced >30%. With other methods, reduction of >60% also reduces yellow-dragon disease by one-half in citrus fruit trees". The Chinese farming society also uses red ants to control insects in sugarcane. After 1949, there were even reports of huge black ants controlling pine-damaging caterpillars (spruce bud worm) and rice paddy pests. It is worth more detailed research.

        Other beneficial insects stayed at natural control levels, with artificial use rare, but their knowledge was widespread and thorough; e.g., Zhuang Xing asks Chu Xiang King in "Zhan Guo Ce": "Did the King see the dragonflies? - six legs and four wings, flying between ground and sky, catching mosquitoes as it flies and eating them". In Ancient and Modern Observations, Cui Bao of Jin Dynasty observed "Flying Tigers appearing like a spider but gray and white and capable of catching flies". Records of insects devouring locusts is also recorded; e.g.s, in 1074 AD, "locusts in Song Territory’s Guiyi and Laishui counties were all eaten by wasps; and in summer of 1530 AD, "black wasps were everywhere, and locusts began to die...Suddenly, when locusts swarmed, little red or black insects arrived, chewing and devouring them, people were happy, and in only 2-3 days, the place became locust-free". Ancient people also observed natural slug enemies "in 1078-1085 AD, (when) slugs destructive to autumn fields appeared at Qingzhoujie. Fortunately for farmers, a scorpion-like insect moved into the field and halved slugs with their pincers until all were gone in about 10 days". Cheng Daihe of Qing Dynasty wrote, "If several mantis nests are placed around chrysanthemums in the 5th lunar month, young mantises hatching in early autumn will not eat their leaves but will disperse butterflies and other insects"...a fully intentional act.

2. Pest control by frogs

        History also records much pest control by frogs; e.g.s, Chen Zang Qi of Tang Dynasty described frogs as "small creatures from swampy areas with black spots on the back, capable of leaping and catching various insects"; and "Ling Biao Lu Yi" by Liu Xun of Tang Dynasty records that "young Gaozhou children of the Xi Zong (874-888 AD) period heard frogs croaking while herding buffalo and tried to catch them. After a frog disappeared into a hole in the ground, the hole was enlarged, but the frog disappeared and the children found a drum…, thinking the croaking frog was the drum fairy". There is obviously no drum fairy, but the drum may resemble a "Chi You" tomb copper drum displaying an ancient southern frog shape. The many Guangdong Museums copper drums are mostly engraved with frogs because Ling Nan region farmers saw them as a harvest symbol. As the frog’s ability to control pests was discovered long ago, many officials used government power to add protection. In an ancient book, Shen Wen Tong (1025-1062) ordered Zhejiang people not to eat frogs because they eat pests. Wang Feng of Qing Dynasty also suggested in his book to use frogs to control locusts.

3. Pest control by flying birds

        Many records exist on this subject; e.g.s, in 502-549 AD, Fan Hong Wen In Southern History records autumn-arriving locusts in fields...with "birds suddenly covering the sun, and in a few seconds chasing them all away, but didn’t identify the bird"; "in 743 A.D., the Purple pest came to eat the young crops at Ping Hu, with a flock of bald-headed birds coming from the northeast to eat them; in 735 A.D. slugs in Yuguan entered Pinngzhoujie, the crops only being saved by birds; in 713-714 A.D., when Beizhou locusts devoured crops, thousands of huge white birds and hundreds of thousands of small white birds ate the locusts"; plus similar records in the Tang Book. Bird control records also appear in 982, 1074, 1088, 1299, 1327, 1337 & 1858 A.D..

        Protection of beneficial birds began long ago when people had knowledge of pest control. Records forbidding their hunting began before 547-490 B.C., with birds unidentifed, but modern observations show most birds are beneficial, rendering undisputed benefits of bird protection.

        Other records delineating protection of beneficial birds exist; e.g., Huang Yi Zhong of the Jin Dynasty said "As there is a bird that kills weeds, the county magistrate forbade citizens to shoot it, anyone disregarding this rule will never be pardoned." Some later emperors also protected birds.

        All the above prove the importance of birds was realized long ago.

4. Pest control by poultry

        Pest control by poultry is a Chinese invention. Shi Kuang’s Book of Poultry says "when white ants hear the zhu ji (shu = bamboo, ji = chicken) crow, they turn into water...the white rooster melting the white ants." Similarly, Jia Ming of Yuan Dynasty says "the bamboo rooster’s crow turns white ants into soil", and "roosters also keep flees away". Even more records exist about household ducks as pest control: "A small red crab pest (Grapsussp) that eats rice plant buds is common in Xiangshan, Shunde, Fanyu, Nanhai, Xinhui and Dongwan, but as they are eaten by ducks, the latter is a widespread household bird in southern Guangdong province". This is the earliest record of using household ducks as a Grapsussps control. Chen Jing Lun of Ming Dynasty first revealed how household ducks eliminated young locusts. His 1597 journal shows that in his journey spreading sweet potato, north China locusts were very severe, but that a kind of bird that eats fish eggs also eats locusts. As they fly everywhere, they are undomesticated, but their habits suggested he use ducks to eliminate young locusts, with very good results in the Wuhu region. Lu Shi Yi’s Locust Elimination (1611-1672) also describes successful killing of young locusts by ducks: "As young locusts are unable to fly, ducks eat them. With many ducks landing in a paddy field, bugs were eliminated in seconds...a method used to catch pests in south China." Then, Wang Zhiyi, Gu Yan and others cited passages from this famous book, Gu Yan saying, "in April of 1857, Wyyijunzhang Mountain locusts were hastily eliminated with 7-800 ducks," proving the method useful. In 1892, Xu Baoshu stated "as young locusts in a dry rice field cannot fly or jump far for 2 weeks after hatching, one should use ducks to eliminate them." As ducks not only eliminate locusts but all types of pests, it is especially worth attention to eliminate weeds in the Zhu Jiang Triangle sandfields.

5. Weeding by animals

        Weeds and pests are the two biggest enemies to agriculture, the Chinese having gained experience and knowledge through a long history of fighting weeds and pests. Zhang Hua’s ancient book records, "Hailing County is close to the sea, and it has many groups of mi animal devouring weed roots and turn them into good soil, called mi jun. If farmers plant their crops in mi jun soil, good harvest comes without effort". The "Record of Thirteen States" mentions the county magistrate especially protecting wild geese because it "helps farmers by killing weeds in spring and autumn"...a record of intentionally protecting beneficial birds. Liu Xun of Tang Dynasty records that farmers "in the Xin Long mountains spread a variety of carp fish eggs in wet fields. After 1-2 years, they hatch and mature to devour weeds, increasing both harvest and fishing"...a method still used. Farmers in Canton Province’s Gaoyao and Sihui counties use black carp to eat only weeds not rice, harvesting both rice and fish. The Tong nationality on the border of Qian, Gui and Xiang regions keep the tradition of breeding fish near wet fields, the fish devouring weeds day and night. Many countries have now spread this kind of fish to eliminate canal weeds, not only profitting from it, but also eliminating the cost of mowing. Thus, this fish is also called a "biological mowing machine".

Weeding and Insect-Killing Plants

        Ancient books also record insect-killing plants; e.g.s, "Wang Shunqiu said Guo Kingdom ‘wo cai’ (celttuce, a celery and lettuce hybrid – note by WT) is very offensive to insects. Even snakes are blinded if they circle and touch it by mistake", a comment reiterated in Abstract Description of Things: "if a snake touches wo ju (= wo cai), it is blinded", plus "there are no spiders in a garden full of creeping leeks". Research and experiments must be conducted before we are certain these plants really prevent pests. There are also many historic records of weeding plants; e.g.s, Left Memoir says "unwanted plants do not grow under coniferous trees", while a Jin Dynasty record says, "nothing other than the same species grows under conifers." Some believe this is due to sun blocking by trees, but others challenge this because other trees block the sun. Recent studies confirm conifers have a special substance inhibiting weeds. It is worth knowing if the theory of pine needles killing grain beetles is true? Ge Hong of Jin Dynasty also mentions "the absence of other plants near poison ivy", while Agriculture Encyclopedia states "the mi variety of red beans best kills weeds." These records indicate ancient people knew biological controls, warranting further study of the use of plants and animals.