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

killing points”, and these techniques will be used for the rapid evaluation of large numbers of candidate
attractants.
Although the assessment of cover sprays requires full-field trial analysis, single-killing-point
evaluation can evaluate both attractants and lethal ingredients. As ingredients in attractant controls,
there are many lethal elements used against fruit flies, including synthetic chemicals, neem, other
botanicals and pathogens. Neem may be suitable for cover application but not for combination with
attractants, which depends on the attraction of flies to baits and lures, and a question is whether neem,
which has a slight repellent as well as insecticidal effect, may work as the killing ingredient in these, or
may repel flies and thus undermine attraction and mortality. Other botanicals such as Ipomyia and
Pongamia may be worth assessment for use alongside neem. Active-ingredient comparisons may also
include entomopathogens. In general, farmers distrust sprays of these because of the destruction the
pests may cause in the incubation interval between being infected and overcome. If it is the case,
however, as generally assumed, that many protein meals are taken by females who need the protein to
develop eggs, fungal bait applications may be effective, as the fungus may develop pathogenicity in the
interval needed for egg development. Several Indian research institutes have cultures and expertise of
Metarhizium, Beauvaria and faster-acting crystalline Bt proteins.
This study will include a systematic evaluation of the real cost-effectiveness of different baits,
with kills distinguished by sex, and with the evaluation of pH (Heath et al., 1994) and possibly salinity
and amino acid content effects. It will allow for the rapid mass-scale processing of evaluations, with
reference to commercial protein hydrolysate as a standard. “Home-made” preparations will at least
initially be from commercial preserved preparations, with the same batch number, to allow reliable
comparability of baits in different sites - for example tinned cat food for fish.
Preliminary assessments of the autolysis of brewer’s yeast cells may be carried out with use
of a medical haemocytometer to record cell rupture - this may provide a quick way to assess the
relative performance of proteolytic enzymes to find a cheap alternative to papain (several fruits contain
proteolytic enzymes).
Methyl eugenol, the best-known parapheromone lure, is available and used over much of India
to attract males of Bactrocera dorsalis and zonata. Lures may be used in a variety of formulations
such as plastic traps, with and without insecticide, and soaked-wood killer blocks; which of these are
most cost-effective for farmers with different resource availabilities in terms of chemicals, traps and
labour, will be studied.
The study will also compare the performance of mixtures of baits and lures relative to one
alone, by a series of fully factorialised comparison of possible combinations, as the following
treatments: current unconfirmed impressions are that bait and lure may negatively affect each other,
but that mixes of multiple baits or of multiple lures may offer advantages, hinted at by some results
reported in Appendix II.
Assessment will be by a tier of control assessments for bait and other on-farm controls,
progressing in increasing cost, complexity and realism. This process of “industrialising” bait and lure
assessment allows the rapid, replicated and systematic evaluation of baits, hopefully permitting “fine
tuning” of sensitive variables known to affect effectiveness. It economises by the initial assessment of
attractant controls by counting flies which are attracted to, and killed by, a single “killing point”. This
produces direct information about the effectiveness of individual killing points, and reduces demands
for space, as only one point is assessed instead of an entire plot, and time, as the number of killed flies
itself comprises the data, instead of the assessment of fruit damage and yield. This method includes
insecticide in the full field bait formulation, allowing comparison of not only attractants but also
insecticides and deployment methods - comparing, for example bait spots applied to foliage and wood
and traps as are used made of coconut shells or ceramics. This research will proceed in a hierarchy of
levels of increasing realism with increasing cost and time-consumption, in three stages from laboratory
single-killing-point studies to field single-killing-point studies to farm-level studies (with economic and
social evaluation forming in a sense a fourth tier). These research strategies have been evaluated by
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