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population dynamics of the target pest. Population monitoring is an important
component of any 1PM strategy and various trapping methods have been used
for this purpose. Pheromone traps have been particularly useful for monitoring
and reducing the activity of Lepidopteran adults (Roelofs 1981); however,
Leucinodes pheromone has not yet been isolated.
Methods
The research was carried out in Calamba, Laguna, from February to June 1990
as part of an ongoing project on 1PM in rice and vegetable crops, funded by
the International Development Research Centre (IDRC). The fields are owned
by a farmer, who managed all nonresearch activities. The fields were also used
to demonstrate research results to local vegetable farmers.
The study was designed to facilitate adoption of procedures by farmers. All
research was carried out in a farmer's fields with the farm family fully
informed of all activities and participating in most. Neighbouring farmers
often inquired about the experimental results and they were invited to two
demonstration meetings at the fields. During monthly meetings at a local
school, researchers also explained 1PM and its use to farmers. Because women
play a large role in vegetable production, fieldwork, decision-making, and
marketing (UPLB 1990), most of the staff were female, and extension activities
were directed toward both women and men.
Plots (4 x 5 m) were laid out in the experimental field on which six pest-control
strategies were tested: two biological agents (Trichogramma and Euborellia); two
culture methods (manual sanitation and trapping); chemical spraying; and no
treatment. Each treatment was replicated three times with an average of 25
plants in each plot (Fig. 1). This layout permitted minimal interference
between treatments. Because of the strong prevailing winds, the experimental
field had to be east of the farmer's field to avoid pesticide drift, and different
treatments were separated by 12 m in a north-south direction.
The methods used for the various treatments were:
a Trichogramma chilonis were released at a rate of 300 per 20-rn2 plot
(150 000/ha). The population of insects in the field was monitored
beginning in February to time Trichogramma releases to occur I day after
peak adult flights of Leucinodes. Releases began on 23 April.
Euborellia annulata were released at a rate of 17-35 per 20-m2 plot
(8500-17500/ha). Releases began on 1 June and were timed to coincide
with increases in the larval population of Leucinodes.
Manual control involved handpicking and destroying all damaged
fruits and shoots from the plots and from a 2-m border around the plots
after each harvest.
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