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

assuming a constant relationship when there is a risk of a difference, statistical outcomes of these tests are given
below even when these were not significant at the 0.05 level.
Table IV.B.1. Example of treatment of a data set (from a plywood MAT block on the third day of its deployment).
This data set after we ighting did not differ from the exponential decay model (Kolmogorov-Smirnov
D=0.0491ns), and the weighted observed data were less “elbowed” than the exponential model -
(O 1 E 1)-(O 2 E 2)+(O 3 E 3)=-11.8. Extension of the modelled catch to four metres from the killing point obtained a
total catch estimate of 122.17 flies; the actual central collector catch (115) was 98.2% of this estimated total
mortality.
Collector 1 2 3
Rim distance from killing point (m) 0.305 0.61 1.032
Horizontal distance from previous rim (m) 0.305 0.305 0.422
Vertical distance from previous rim (m) 0.06 0.8 0.8
Tangent of angle of declination (ratio) 0.1967 2.6230 1.8957
Original catch (No.) 115 4 1
Multiplied by tangent (No.) 22.623 10.492 1.896
Weighted to original sum (No.) 77.541 35.961 6.498
Exponential model (No.) 83.078 30.073 6.850
The descending tiers of collectors were sometimes damaged or dislodged, and useable data were not
obtained in all of the assessments described below. When these data were not obtained this is indicated and the
central collector data were analysed alone.
In comparisons of the catching effectiveness of different treatments, data are presented throughout as
the total catches over the period of killing point deployment. The evaluation of their crop protection usefulness
also requires estimation of how long killing points last before needing to be replaced. Catches were thus
compared with days elapsed from first deployment until the experiment ended. All decays of catches in time were
compared by least-squares regression to both linear and exponential fitted models and by visual inspection of
graphical plots. In no case was the fit of one regression model to the data significantly closer than the other, and
the exponential was chosen as the model for use, as considered likeliest to represent the decay in concentrated
effectiveness over time. With this model used to estimate the relationship, the value chosen for comparison of
treatments’ durability was the estimated time it would take for the daily catch per killing point to fall to one fly, a
point termed the killing point’s “persistence”. The use of a regression estimate also allowed data from analogous
experiments to be compared when, as often and inevitably happened, they were run for different lengths of time.
Research encountered operational difficulties, such as the vagaries of weather, crop development, field
access by bus or bicycle and the theft or destruction of collectors, and as a result comparisons unavoidably
varied in duration and level of replication. The analyses below are attempts to provide useful information in spite
of these shortcomings.
BAT
BAT studies were carried out (by QZ) in guava orchards between Rawalpindi (33 o 21'N, 73 o 6'E) and
Haripur (33 o 41'N, 73 o 6'E) in the growing seasons of 1998 and 1999. Trees were on experimental stations or farms,
and between 2 and 10Ha, interspersed with non-fruit arable crops and without fly controls. Space did not permit
the grouping of spot treatments into complete randomized blocks and these were evenly spaced throughout
orchards, at least 10m apart and 10m from orchard edges. Protein hydrolysate dosage was based on an
unpublished survey of the literature (Stonehouse, JM, Mumford, JD, 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 acid-hydrolysed protein hydrolysate (International
Pheromone Systems Ltd, Ellesmere Port, South Wirral, CH65 4TY, UK. ips_ltd@btconnect.com), and 3ml of
malathion 57%a.i. emulsifiable concentrate (“Fifinone” obtained locally), made up to one litre with water. Each
spot was of 12.5ml applied over approximately 0.125m 2 of fruit tree foliage with a hand-operated garden sprayer of
0.5l capacity.
The first experiment compared protein hydrolysate bait spots applied to different substrate surfaces.
Farm applications are generally to living leaves and branches of trees, but artificial substrates are quicker and
easier to use for both farm control and experimental assessment. Applications to living trees must be done by
moving the application equipment all through a field, but discrete artificial surfaces may be treated all together at
a convenient point and then carried into the field and hung up. For practical control and also for rapid
experimentation, therefore, the relative attractiveness of deposits on natural vegetation and on candidate artificial
surfaces must be known. Sprays were applied to living foliage of guava (Psidium guava) and to three artificial
54