L. FURLAN, V. GIROLAMI
Department of Agronomy, Entomology, University
of Padova, Agripolis, via Romea 16, Legnaro PD
A. PAVAN, M. BIANCHI
Freelance
In Northeastern Italy Ostrinia nubilalis (ECB) is usually present at high levels and regarded as a main problem by most farmers. Therefore ECB population levels and behaviour have been studied for many years. A summary of data collected from 1982 to 2001 is given.
MATERIALS AND METHODS
The swarming period of ECB has been studied
by using light traps and Hartstack traps baited with Isagro E/Z caps placed
in large maize field. The numbers of moths caught have been compared with
the presence of egg clusters that was estimated by observing 1000 plants
twice per week. At harvest time the number of larvae and tunnels per plant
were recorded. In addition in 2000 the effect on ECB populations of insecticides
treatments was evaluated; three theses were compared: insecticide (Decis
1 Kg/ha) treatment every 8 – 10 days, insecticide treatment at the peak
of egg hatching, untreated.
RESULTS
First generation damage was usually low
while all the plants after the second generation were injured by the larvae.
The highest eggs parasitization rate (by Thricogramma spp.) was
observed in 1982: 33% while in other years ranged between 11 to 24%. The
number of larvae and tunnel per plant ranged from 0.5 (2000) to 2-3 in
most of the other years. At the highest one Lydella thompsoni pupae
out of 5 plants was observed. The peak of eggs presence usually occurred
in the second ten days of August, about 15 days later from the peak of
moth presence and several days after the period when most of treatments
in normal farms had been done. Light traps only recorded conspicuous captures
while the sex pheromone traps gave no reliable data (no more than 10 moths
per season).
Many treatments only slightly improved
crop protection in comparison with one treatment in the appropriate period.
Light traps and observation of the eggs
only gave reliable information about ECB population development.
The research was partly funded by HGD S.r.L.