Studies On Conditions And Mechanism Of Melanophila Acuminata Outbreak And The Preventive Measures

Since 2001, Melanophila acuminata has been a disaster in Beijing areas, which mainly attacked unfired Chinese pine (Pinus tabulaeformis). So far, there is no research data about Melanophila acuminata in China. Therefore, it was necessary for us to study the biological characteristics of Melanophila acuminata, the conditions and the mechanism of Melanophila acuminata outbreak. Finally, we also put forward the preventive measures. The main research results are as follows.Melanophila acuminata had one generation each year in Beijing region, overwintering as larva under the bark of trees. The overwintering larvae started to move in early March of the following year. The mature larvae pupated from early April to late August. The adults emerged from late April to early September, the peak times were late May and early August.The larvae lived and pupated in the area between bark and xylem where they were well concealed. The adults emerged and were active in daytime. The number of emergence on sunny day was obviously more than that on cloudy day.Melanophila acuminata was weak parasitic and was not a quarantine object in Beijing and even China. Under ordinary conditions, Melanophila acuminata inhabited and multiplied on the weak or dead branches of the growing well pine trees, without causing the death of trees and the disaster, so it was hard to be discovered. A large number of weak pine trees were the elementary condition of Melanophila acuminata outbreak. Photosynthetic rate and water content of weak trees were decreased. The content of high-calorie substances which were easily digested and absorbed by Melanophila acuminata such as sugar and fat increased. And the content of Fe, Cu, Mg, Na, P and Zn increased. All these above provided favorable growth and development conditions for Melanophila acuminata. The increase of body temperature and their differences accelerated the growth and development of Melanophila acuminata. Thus, Melanophila acuminata outbroke due to these combined reasons.The body temperature of pine trees increased with the decrease of the amount of growth. The body temperatures of dead and weak trees were higher than that of strong ones. The body temperature of pine trees was influenced by air temperature, while the body temperature of weak trees was more closely associated with air temperature. And the water content in pine trees had the function of adjusting body temperature.Clearing off the dead and weak branches regularly, watering the trees in time to cool down the temperature, root rejuvenation and utilizing predators are all effective measures for preventing Melanophila acuminata outbreak.