Large-Scale Augmentative Biological Control of Asian Corn Borer Using Trichogramma Second International Symposium on Biological Control of Arthropods

Asian corn borer, Ostrinia furnacalis (Guenée), is the most destructive pest of corn in China. It causes 6 to 9 million ton yield loss in an average year. Biological control using releases of Trichogramma has increased greatly since T. dendrolimi Matsumura can be successfully mass reared on eggs of the Chinese oak silkworm, Antheraea pernyi Guérin-Méneville. The process and technique for mass production and releasing of Trichogramma has been greatly improved in recent years. A series of machines and devices for mass rearing the Trichogramma with the eggs of oak silkworm has been developed, which promote Trichogramma production and make application for control of the Asian corn borer more practical and efficient. Asian corn borer control by release of T. dendrolimi on a large scale has been the key pest management technique in North China. In T. dendrolimi release areas parasitism of corn borer eggs ranged from 73.4% to 87.8%, with a 92.5% decrease of stalk-boring. Overall, augmentative releases have been made on 4.1 million ha of corn from 1990 to 2002 in Jilin Province with good pest control effects. T. dendrolimi and T. chilonis have been successfully produced by means of artificial host eggs and releases of these have had similar effects to the same species reared from factitious host eggs. Field application techniques also have been greatly improved. Large ecological and economic benefits have been achieved in the area where Trichogramma have been released continuously for many years. In Miyun County of Beijing, where Trichogramma have been released for more than 20 years, populations of natural enemies in cornfields have increased, which allow natural control of other insect pests without application of pesticides. Parasitism due to natural Trichogramma increased from 1% and 79.3% in 1980 to 33% and 92% in 1991 for first and third generation of Asian corn borer eggs, respectively. In Gongzhuling City, Jilin Province, the mean borer holes and number of larvae per hundred stalks decreased by 73.66% and 75.93%, respectively, where the Trichogramma were released from 1990 to 1996. In recent years Trichogramma releases for control of Asian corn borer cover 1 to 1.3 million ha annually, and have become one of the key techniques for IPM of corn pests in China.