“Key Informant Survey” of Production, Value, Losses and ... - DfID

tiers. It is proposed to replace this by deploying alongside the main collectors a few (2 per
experimental block) “calibration collectors”, flat sheets hanging below the killing points at the same
height at the treatment collectors, but allowing the precise location of each dead fly to be recorded
upon falling. The construction of these remains to be finalised, but the current plan is to use extrudedplastic
grille mesh used to support perspex sheets below fluorescent lights in suspended-panel ceilings.
This mesh comprises sheets of cells, about 3cm square in plan and with plastic walls about 2cm high. It
is already used to form individual-rearing cells for predatory insects by biological control researchers at
Gujarat Agricultural University, and may hopefully be put together by combining panels, both alongside
and on top of each other, to obtain sheets about 2mx2m square, composed of hundreds of cells, open at
the top (to allow flies to fall in) and floored with mesh (to trap flies while allowing rainwater to drain
out), 3cm square in plan and about 6cm high (to prevent dead flies from being plucked out by the
wind). The study of dead flies in such a grid, below a killing point, will allow the detailed analysis of
how dead flies fall, and thus the modelling of how catches in treatment collectors represent total
mortality by each killing point. The use of a rectangular grid will allow analysis by vector algebra
statistics (Batschelet, 1984).
Field SKP Evaluation: Requirements
- Treatments: - baits, lures, insecticide(s), ethanol solvent, lure blocks, bait applicators, traps
- 50 killing point collectors to be deployed by each research group, in various combinations of numbers
of treatments and levels of replication
- Access to field sites of adequate size and number for collectors with bait treatments to be 7.5m
apart, those with MAT treatments 15m apart.
2.3: On-Farm Trials
These will be required both for methods not amenable to single-killing-point analysis, such as
cover sprays, and for the final economic evaluation of attractant controls identified as promising by
smaller-scale studies - the attraction and killing of flies is not the same as obtaining actual control, and
should not automatically be taken as a proxy for it. There is often a suspicion that male lures merely
kill males without reducing female matedness, and that some recommendations for male trapping may
confuse in the farmer’s mind its usefulness for population monitoring as opposed to actual control.
Cover sprays, while considered by IPM practitioners the last resort, can and do control flies
when applied in a position to do so, and will not be assessable by single-killing-point technology but will
require full-field evaluation. The comparison of cover sprays of neem with BAT may be valuable.
Most recommendations to farmers combine at least two control techniques as an integrated
package. Full-field-level controls will be needed for assessment of combinations of cultural controls
(fruit destruction, ploughing), bait sprays, parapheromone lures, cover sprays etc. Only full-field trials
will show the fullintegrability of various control techniques.
Fruit samples will be of six fruit on each of five randomly-selected trees in each experimental
plot, with two or more experimental plots on each farm (depending on space). Initial results
(Stonehouse et al., in prep. B) indicate that six farms or sites will be required for each comparison.
Assessment will be by a standardised suite of records of fruit production, infestation and
harvest, initially developed elsewhere (Mahmood et al., 2001; Stonehouse et al., in prep. B),
comprising the following.
i - Harvested yield Harvests from all plots will be assessed and recorded by farmers and/or
assessors as weights of counts of fruit, at the farmer’s convenience. Prevailing price data will also be
gathered, along with relevant costs (particularly estimates of control costs) to allow the economic
returns to different practices to be compared.
ii - Fruit production Estimates will be made of the numbers of fruit on each of five trees sampled,
and the area of ground covered by each tree and its height. Numbers of fruit will be divided by an
estimate of tree volume, obtained by multiplying the height by area estimates, to obtain an estimated
density per cubic metre of tree canopy. Fruit on the ground will be counted in three randomly-thrown
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