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

Table II.8. Inferred table (the "absent;absent" cell was in fact untried so its "0" value is
assumed) of catch of B. cucurbitae by cuelure, methyl eugenol and both together (all with
Naled) in Bangladesh (Nasir Uddin et al., 2000a).
Cue-lure
Absent Present
Methyl eugenol Absent (0) 171.7
Present 17.5 268.5
The record of lure/bait mixtures is patchy - in terms of the evolution of a pattern of responses
to food and reproduction stimuli, there seems no prima facie reason why food and sex stimuli should
benefit from each others’ presence. Table II.9 shows how methyl eugenol mixed with protein
hydrolysate was less attractive than with mango pulp and sugar, to both species, but also that the two
species significantly differed in their attractions.
Table II.9. Average numbers of Bactrocera fruit flies caught per trap (N=3) by four traps
with methyl eugenol between May and August 1997. B. dorsalis data from Kumar and
Agarwal (1998); B. zonata data from Agarwal and Kumar (1999). There were significant
differences between species caught (F=1426[1,16]***) and treatments (F=21[3,16]***) and
for interactions between them (F=7[3,16]**).
Methyl eugenol (2ml) + malathion 50EC (1ml) +:- dorsalis zonata
Protein hydrolysate (20g) 821 2580
Fermented palm juice (20ml) 1082 2394
Sugar (20g) 970 2648
Ripe mango pulp (20g) 1430 2797
Another study of a mixture of bait with lure, over the months of a year, found its average
catch of male B. zonata to be higher than that of the two components separately; however this was
largely because of the much higher catch in the single heaviest month - in all other months of the year,
and when the monthly catches were converted to logarithms, the catch of the two combined was less
than that of its components (Agarwal et al., 1995). A study of attraction of C. capitata to trimedlure
with and without protein found that the attraction of a mixture was less than that of lure alone for
males, and less than that of bait alone for females, so that the total catch by the mixture was less than
that by its two components separately (Stravens et al., 2001).
Cultural Controls Cultural controls most effectively used are the ploughing and/or harrowing of soil
to destroy pupae and the collection and destruction of fallen fruit. In general, in other areas, the
difficulty with fruit collection is its destruction - burial must be to at least 15cm to prevent adult
emergence (Patel, 1994). Burial to shallower depths may actually increase survival: Makhmoor and
Singh (1999) found survival of Bactrocera cucurbitae pupae was 87% at 10cm depth, but only 7% on
the surface. Gathered fruit will not immediately burn and cannot be easily composted. The practice
needs precise tailoring to farmer resources and views - in Réunion fruit is sun-baked in plastic bags,
whereafter it will burn (Jeffrault, 2001). It may be fed to animals, probably the most beneficial use if it
may be made practical to farmers. An additional area of study may be the extent to which larval and
pupal and controls depend on scale-economies - whether the complete extermination of larvae and
pupae over an area of, say, 1/4 acre will offer economic protection if the area is prone to reinvasion
from neighbouring fields, and thus whether coordination between farms significantly enhances the
usefulness of the method.
Other cultural controls may make small but useful differences. Host plant resistance is known
for fruit flies, but is generally weak. Some resistance traits have been reported in jujube (Makhmoor
and Singh, 1998; Sharma et al., 1998) and peach (Nijar et al., 1998) but overall strengths are only
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