Field Guide of Discovery-based Exercises for - Aseanipm ...

Section 4 • Integrated Insect and Rodent Pests Management
Exercise No. 4.09 146
‘PULLING THE GUTS’ TECHNIQUE: MEASURING
DEGREE OF PARASITISM BY DIADEGMA ON
DIAMONDBACk MOTH OF ORGANICALLY-GROWN
CRUCIFERS
BaCKGroUND aND raTIoNalE
The standard approach in managing diamondback moth
(DBM) population is the use of biological control with
parasitoid Diadegma. Augmentation release of parasitoid
early at onset of dry season is usually practiced so that future
DBM populations are effectively held in check. In some
areas, augmentation releases may not be necessary where parasitoid is already well established.
The establishment of Diadegma can be determined by knowing the degree of DBM parasitism in
a field. Insect parasitism is a process of how an insect parasitoid kills a host as it completes its life
cycle. An effective method of monitoring DBM larval parasitism by Diadegma in farmers’ field is
by pulling the guts technique 147 . ‘Pulling the guts’ will also show farmers how a DBM larva is killed
by Diadegma parasitoid present inside it. Simply hold a DBM larva on both ends between thumb
and index finger and slowly pull until gut or bituka breaks to show a developing larva of Diadegma
inside.
In FFSs, this practical tool will improve farmers’ decision-making skills and will help them analyze
and find out if there is a need to release or augment Diadegma in organic vegetable fields.
How long will this exercise take?
• Thirty minutes field walks, observations, hands-on, and interaction with farmers; and
• Thirty minutes brainstorming session in processing area.
146 Adapted from Callo, Jr., D.P., L.B. Teofilo, and H.A. Tauli (eds). 2002. Field Guide of Discovery-based Exercises for Vegetable IPM, Volume II. SEAMEO
Regional Center for Graduate Study and Research in Agriculture (SEARCA), Los Baños, Laguna, Philippines. pp174-176.
147 IIBC. 1996. Integrated Pest Management for Highland Vegetables, Volume 4: Training Guide for Participatory Action Towards discovery Learning.
International Institute for Biological Control, BPI Compound, Baguio City, Philippines. pp63-64.
209
when is this exercise most
appropriate?
ɶ In FFS, TOT, and VST
sessions, when there are
early infestation of DBM
in learning and adjoining
crucifer fields; and
ɶ When farmers want to
learn a practical tool of
determining degree of
DBM larval parasitism by
Diadegma in their field.