Hmt. Hokkanen, OVERWINTERING SURVIVAL AND SPRING EMERGENCE IN MELIGETHES-AENEUS - EFFECTS OF BODY-WEIGHT, CROWDING, AND SOIL TREATMENT WITH BEAUVERIA-BASSIANA, Entomologia experimentalis et applicata, 67(3), 1993, pp. 241-246
High overwintering mortality was recorded for Meligethes aeneus in the
field in Finland, ranging from 85 to 98% depending on the source of t
he overwintering population. The main factor explaining variation in s
urvival was the body weight of the beetles in the autumn: only the hea
viest beetles survived. Body weight, on the other hand, was influenced
by treatment of the rape field soil with Beauveria bassiana, resultin
g in a 50% decrease in winter survival compared with the reference. Th
e soil treatment did not appear to have direct mortality effects (path
ogenesis) on the beetle neither in the summer nor in the winter, and t
here was no apparent effect on survival of crowding of the insects at
the overwintering site. Density dependence in overwintering survival o
f M. aeneus may function through the availability of pollen food in th
e autumn, and intraspecific competition for it. Treatment of the rape
field soil with B. bassiana may be a feasible way to increase the wint
er mortality and to lower the pollen beetle populations, but requires
further research.