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8 th International Symposium on Fruit Flies of Economic Importance. Valencia 2010.
OVIPOSITION CHOICE OF BACTROCERA PAPAYAE DREW & HANCOCK (DIPTERA:
TEPHRITIDAE): FULLY-RIPE FRUIT OR UNRIPE FRUIT WITH WOUND ON FRUIT
SURFACE.
Rattanapun, Wigunda* 1 & Amornsak, Weerawan 2
1 Department of Agricultural Technology, Faculty of Technology and Community Development, Thaksin
University, Phatthalung, 93110 Thailand. Email: rwigunda@tsu.ac.th; 2 Department of Entomology, Faculty of
Agriculture, Kasetsart University, Bangkhen Campus, Chatuchak, Bangkok, 10900 Thailand.
Background: The oviposition preference of many species of tephritid fruit fly relies on fruit
firmness. To minimise aculeus wear, female tephritid flies are thought to prefer to oviposit in
fruit wounds or softer exopericarp of ripe and fully-ripe fruits over harder exopericarp of
unripe fruit. The fully-ripe fruit was suitable for larval growth and preferred for oviposition by
female fly of Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) more than unripe fruit, soft
exocarp of fully-ripe fruit appeared to be the limiting factor of oviposition, with few successful
ovipositions recorded in all studies, and very few in unripe fruit. In this study, we asked
whether female flies that were exposed to both fully-ripe fruit without wound and unripe fruit
with wound on fruit surface, would choose fully-ripe fruit for oviposition or not. The result of
this study can enhance our understanding of host utilization by female fly.
Methods: A choice experiment was conducted to determine the behavior of individual female
Bactrocera papayae Drew & Hancock (Diptera: Tephritidae). Both fully-ripe mango without
wound and unripe mango with wound on fruit surface of mango, Mangifera indica,
Namdorkmai varity (Anacardiaceae) were offered simultaneously in a 30×30×30 cm
observation cage. An individual, 21–22-day-old, mated female fly was released in an
observation cage. Fruit fly behaviors observed and recorded were: (i) duration of fly visits to a
fruit, (ii) number of attempted ovipositions (unsuccessful penetration), and (iii) duration of
successful oviposition events. Observations were done from 09:00–15:00 hours. Twenty
single-fly replicates were conducted. At the end of the day, female flies were dissected to
check whether eggs were presented in their ovaries. All fruits that female flies had laid eggs
into were dissected for number of egg count.
Results: The total duration of visits differed significantly between the stages of ripening (t-test:
t = 15.010, d.f. = 38, P < 0.0001), with unripe fruits being visited in longer and fully-ripe fruit
significantly less. There were also significant differences in the number of attempted
ovipositions between the various fruit ripening stages, with fewer attempted ovipositions into
fully-ripe fruit and higher penetration into unripe fruit (t-test: t = 6.696, d.f. = 38, P < 0.0001).
All female flies could not oviposit into full-ripe fruits. The average time of successfully
oviposition duration into wound on unripe fruit of female flies is 35.05 ± 1.52 minutes.
Conclusions: The results of this study indicated that fruit wound play an important role in the
oviposition determination of female fly B. papayae. Female B. papayae chose unsuitable host
that she could easier oviposit than nutritious host which was hard to oviposit. Thus, it is
difficult to assume that oviposition preference of female flies relates solely to the performance
of their larvae.
Keywords: Bactrocera papayae, oviposition preference, mango, ripening.