Abstract:

【Objective】 The beetle (Monochamus alternatus) is an important wood borer in pine forests and it is also the most important vector of pine wood nematodes in Asia. The effects of temperature, sex and weight on the feeding ability and the bark thickness, trunk diameter, and weight on oviposition ability were analyzed regarding M. alternatus to provide a scientific guidance for controlling the beetles.【Method】 The beetles were collected from an insect cage with a weight in the range of 0.3 g≤M<0.6 g that was placed in the insect incubator to compare the feeding ability under four temperature conditions (25, 30, 35 and 40℃). Five female and five male adult beetles of the similar weight were selected and placed in an insect incubator to compare feeding between adult males and females. Beetles with different weights (M<0.3 g, 0.3 g≤M<0.6 g and M≥0.6 g) were placed in the insect incubator at the same temperature to compare feeding abilities with different weights. In order to study the effect of trunk diameter and bark thickness on the oviposition of beetles, pine trunks with different diameters (2.0 cm<D< 3.0 cm, 4.0 cm≤D<5.0 cm, and D≥6.0 cm) and trunks with different bark thicknesses (d=1, 4 and 9 mm) with beetles were placed separately into the insect barrel. The number of oviposition scars was counted. To compare the relationship between the oviposition ability and weight, the number of oviposition scars made by the beetles with different weights (M<0.3 g, 0.3 g≤M<0.6 g and M≥0.6 g) on the trunk was counted, and the abdomens were dissected to count the number of eggs inside.【Result】 The feeding ability of beetles at different temperatures order was as follows: 35, 40, 30, 25 ℃; however, there was no significant difference in feeding between male and female adults. The feeding ability of beetles with M≥0.6 g was the strongest, and that of beetles with M<0.3 g was the weakest. Among trunks with different diameters, beetles preferred to lay eggs on trunks with diameters of D≥6.0 cm, and the number of eggs laid on trunks with diameters of 2 cm<d<3 cm was the lowest. Among trunks with different bark thickness, beetles laid the most eggs on trunks with bark of d=1 mm and the least eggs on trunks with bark of d=9 mm. The oviposition ability of beetles with M≥0.6 g was significantly better than that of beetles with M<0.3 g and 0.3 g≤M<0.6 g. the number of eggs in the abdomen of beetles with M≥0.6 g was significantly more than that of those with other weights.【Conclusion】 The feeding ability of M. alternatus had no significant relationship with sex but was related to weight and temperature. Feeding capacity increased with beetle weight; the feeding ability of M. alternatus at 35 ℃ was higher than that at other temperatures. The oviposition of M. alternatus was related to the size, bark thickness, and trunk diameter. The oviposition ability of the beetles increased with weight, and they preferred to lay eggs on thinner barks and trunks with larger diameters.

Key words: beetle (Monochamus alternatus), feeding, oviposition, temperature, weight, trunk diameter, bark thickness