Dispersal of adult grasshoppers,Mecostethus magister, under the field condition |
| |
Authors: | Kazuo Nakamura Yosiaki It? Kazuyoshi Miyashita and Akira Takai |
| |
Institution: | (1) Division of Entomology, National Institute of Agricultural Sciences, Tokyo;(2) Ryugasaki Experimental Farm, Ibaraki Prefectural Agricultural Experiment Station, Ryugasaki, Ibaraki Prefecture |
| |
Abstract: | Summary Estimation of the number of adult grasshoppers,Mecostethus magister, was made by means of the mark-and-recapture method. The birth and death rates are possible to be estimated at the same time,
but the immigration and the emigration rate are inevitably involved in these respectively. The immigration and emigration
rates must be made clear to know the true birth and death rates. For this purpose the movement of the marked males in 1963
was analyzed.
The grasshoppers dominantly moved in the directions of N, NW and W, and the difference in frequency among the movement directions
was not so large. The distribution of the dispersal-distance relationship of each quadrate on each released day was fitted
approximately to normal distribution. It could be concluded that almost all of the grasshoppers moved within the range of
about 31–35m. The emigration rate from the quadrate (12×12m2) was about 0.73–0.77 and the difference in the rate among the released days was small. From these values the emigration rate
from the station (84×60m2) was estimated as 0.21–0.23.
Subtracting the emigration rate from the death-and-emigration rate, the true death rate was calculated. The death rate was
very low until the number of males reached to the peak, then increased gradually. Supposing that immigration rate was equal
to the emigration rate, the true birth rate was also estimated. But the presumption might not be pertinent, for the value
of birth rates became negative. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|