Effects of temperature on the transmission of Bursaphelenchus xylophilus by Monochamus alternatus

Monochamus alternatus is the main vector of Bursaphelenchus xylophilus. The transmission of Bursaphelenchus xylophilus is closely related to ambient temperature. It is of great significance to study the effect of temperature on the transmission of Bursaphelenchus xylophilus by Monochamus alternatus.

150 Monochamus alternatus were divided into 3 groups by setting 3 constant temperatures (15, 20, and 25°C). The life span of Monochamus alternatus and the survival rates of Bursaphelenchus xylophilus under different temperatures were measured to explore the effect of temperature on the transmission of Bursaphelenchus xylophilus by Monochamus alternatus.

The average life span of Monochamus alternatus decreased with the decrease in temperature. The three temperature treatments had significantly different effects on the average life span of Monochamus alternatus, which had no effect on the number of initial Bursaphelenchus xylophilus. The life span of Monochamus alternatus was related to temperature, but not to body weight. The number of Bursaphelenchus xylophilus carried by Monochamus alternatus was basically unchanged in the first 5 days, which then decreased with the increase of the age of Monochamus alternatus. When the initial load of Bursaphelenchus xylophilus was between 100 and 999, the average transmission efficiency decreased with the decrease in ambient temperature. There were significant differences in the effect of temperature treatment on the average transmission efficiency of Bursaphelenchus xylophilus when the initial load was from 1 to 9 or from 10 to 99. With the decrease in temperature, the time required for Bursaphelenchus xylophilus to leave Monochamus alternatus increased. The time required for Bursaphelenchus xylophilus to leave Monochamus alternatus was the shortest at 25℃ and the longest at 15℃. Under the 3 temperature treatments, the transmission efficiency of Bursaphelenchus xylophilus showed a single peak transmission curve, and the maximum carrying capacity of Bursaphelenchus xylophilus decreased with the decrease in temperature.

With the decrease in ambient temperature, the life span of Monochamus alternatus is shortened, the transmission efficiency of Bursaphelenchus xylophilus is reduced, and the transmission peak of Bursaphelenchus xylophilus is delayed, which value is reduced with the decrease of ambient temperature. These results indicate that the transmission efficiency of Bursaphelenchus xylophilus can be controlled by low temperatures.