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

choice chambers, so allowing extraneous differences, such as time of day, fly age, nutrition and the order of
testing, to be discounted.
Comparisons were made in a series of two-way choices, between two potted young melon plants treated
with different bait formulations and placed at opposite ends of a long cage arena. On the cage centre line,
equidistant between the two treated plants, freshly-emerged adult flies were released, and subsequent fall of
dead flies recorded on either side of the centre line, to give a relative estimate of the power of each deposit to
attract and kill flies. Each cage was 2m long, 0.5m wide and 0.5m high, with painted wood frame, floor and ceiling,
walled with glass on one side and with wire gauze at the other and at either end. Doors in the glass side allowed
flies in jars to be placed on the centre line and then released. Each cage contained a dish with a sugar-water wick
placed on the centre line. Between the two treated plants at the cage extremities, the arenas were filled with
untreated potted young melon plants, to mimic a melon field in which only a fraction of plants have been treated,
and to evaluate realistically the powers of the deposits to attract and kill flies at a distance through a stand of
untreated plants. Plants were about 15cm high, and were selected and positioned to maximise the symmetry of the
stand about the centre line. The arenas were positioned to be symmetrical to light and warmth, and their facing
directions adjusted until daily catches by two identical preparations were evenly divided. Six arenas were used as
replicates, in three pairs built one on top of the other and standing on legs in dishes of water to prevent ant raids.
In each cage pair the two treatments were placed at opposite ends in a Latin square design. The cages are
illustrated in a preliminary graphical report elsewhere (Zia et al., 2001).
Insects were from a laboratory culture of melon flies, Bactrocera cucurbitae Coquillet, from a stock
taken near Karachi. Emerged adults from pupae taken from the culture were fed sugar water only until
experimental release. Ten males and ten females were released in each run.
Each comparison lasted until no live flies were observed, typically five to ten days. Not all of the 20 flies
released in each experiment were always recovered; the missing ones were inferred to have expired in the soil in
the melon pots. Records were taken of the maximum and minimum temperatures and of the time elapsed before
each experiment ended. Treated melon plants were destroyed; untreated plants were reused, but rotated through
the greenhouse to refresh them. The cages were washed with soap and water at the end of each experiment.
The protein dosage was based on an unpublished survey of the literature (Stonehouse, J.M., Mumford,
J.D., 1998, Protein Bait Spray Control of Fruit Flies: A Survey of Recommended Doses and Application Rates,
Imperial College, London, 5pp, available from j.stonehouse@ic.ac.uk). It comprised 30ml of commercial protein
hydrolysate (International Pheromone Systems Ltd, Ellesmere Port, South Wirral, CH65 4TY, UK.
ips_ltd@btconnect.com) and 3ml of malathion 57% active ingredient emulsifiable concentrate (“Fifinone”
obtained locally) made up to 1l with water. The preparation of animal protein was based on that recommended by
the FAO Afghanistan Rural Development Programme. It comprised 0.75l of broth made from 300g cheap beef
meat, boiled for two hours, stood overnight and skimmed of fat, 0.125l boiled and mashed cucumber filtrate liquid,
mixed with 50g of urea and stood to ferment for two days, with 3ml of malathion (Fifinone), made up to 1l with
water. In order to ensure homogeneity of non-experimental variables, the preparations of commercial hydrolysate
bait, meat preparation bait, cucumber extract, urea and insecticide were made initially in a single batch, and all
frozen in compartmented ice cube trays, and then thawed out and mixed with other ingredients when needed. The
literature survey found a typical application rate of protein hydrolysate bait to be 7.5lha -1 (0.75mlm -2 ), repeated
every 10 days. Each half of a cage arena was approximately 0.5m 2 and so each treated plant was treated with 0.5ml
of mixture, applied to the leaves with a pipette in droplets of approximately 1mm diameter.
Six comparisons were performed, between March and July 1999. First were two to test the validity of the
method; subsequently, baits were compared to test four questions of crop protection importance.
i - Two identical bait preparations (method check).
Protein hydrolysate with malathion was compared with itself to see if flies confronted with two theoretically
equally attractive options fell dead evenly about the centre line.
ii - Bait preparation compared with nothing (method check).
Protein hydrolysate with malathion was compared with an untreated plant to see if larger numbers of dead flies
fell on the side of the centre line facing the putatively more effective mixture.
iii - Bait preparation compared with insecticide without bait.
Protein hydrolysate with malathion was compared with a preparation of the same strength of malathion with no
bait, to confirm whether bait significantly attracted flies to the deposit.
iv - Commercial and home-made bait preparations.
Protein hydrolysate formulation was compared with standard animal protein formulation, to evaluate the ability of
home-made animal protein baits to attract and kill flies as efficiently as commercial preparations.
v - Value of urea component.
Standard meat preparation mix was compared with an identical preparation without urea, to see if the urea may be
omitted to simplify and economise the preparation with no severe loss of efficacy.
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