STUDIES ON COMPARATIVE BIOLOGY, POPULATION DYNAMICS AND MANAGEMENT OF ORCHARD FLIES (Bactrocera spp.)
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Date
2009-06
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Navsari Agricultural University, Navsari
Abstract
Investigations on the comparative biology, population
dynamics and management of orchard flies (Bactrocera spp.) were
carried out during 2004-2005 and 2005-06 at Navsari Agricultural
University, Navsari.
Studies on comparative biology of B. dorsalis on various
hosts revealed that the female laid eggs in small clusters just
underneath the rind of fruit, 2-4 mm. deep in the epidermis. Freshly
laid eggs were shiny, translucent and whitish coloured. The shape
of egg was cylindrical, slightly curved on one side and narrow at
both ends. The length and breadth of eggs was varied from 0.8 to
1.07 and 0.14 to 0.25 mm on different hos ts. During the studies,
lower incubation period of B. dorsal is was recorded in mango (2.68
± 0.60 days) followed by that sapota (2.76 ± 0.83 days), guava (3.00
± 0.71 days) and banana (3.12 ± 0.67 days). The difference in
hatching percentage of eggs laid in various fruits was not observed
markedly during the investigation. The larva completed its larval
period earlier when fed on mango (7.44 ± 1.66 days) compared to
guava (7.84 ± 1.03 days), banana (8.52 ± 0.71 days) and sapota
(9.40 ± 1.47 days).
The pre-pupal period did not differed (0.5 to 1 day) when
B. dorsalis was reared on different hosts. The pupation of B.
dorsalis took place at depth of 0.5 to 5.0 cm in soil. The longer
pupal period was recorded on sapota (7.80 ± 0.82 days) compared
to guava (7.20 ± 0.76 days), banana (7.20 ± 0.82 days) and mango
(7.00 ± 0.71 days). The average pre-oviposition period was recorded
as 9.20 ± 1.41 days on sapota, 8.80 ± 1.08 days on banana, 8.32 ±
1.11 days on guava and 8.16 ± 1.18 days on mango. The average
oviposition period was recorded as 6.12 ± 1.44 days on mango, 5.96
± 1.65 days on guava, 5.52 ± 1.50 days on banana and 5.48 ± 1.45
days on sapota. Similarly, the post-oviposition period was recorded
as 3.40 ± 0.82 days on sapota, 3.04 ± 0.84 days on banana, 3.00 ±
0.76 days on guava and 2.88 ± 0.78 days on mango. The
measurements of each stage of B. dorsalis on different hosts were
also discussed. The maximum numbers (180.00 ± 35.76) of eggs
were laid on mango fruits compared to rest of the fruits.
Studies on longevity of adults indicated that the female
fly lived longer (13 to 24 days) than male fly (7 to 14 days). The
total life cycle of male was shorter (24.50 to 36.50 days) than the
female (30.00 to 46.00 days) irrespective of host f ruit. The total life
cycle was completed in 24.50 to 46.50 days on different hosts,
however, i t was shorter on mango than rest of the frui ts. Thus, the
studies on comparative biology indicated that mango was the most
suitable fruit for faster development of B. dorsalis.
Studies on population dynamics of fruit fly indicated that
the f ruit fly population prevailed throughout the year in mango,
guava and sapota orchard. However, its maximum activity was
found during March to August on sapota, April to July on mango,
August to September on banana and June to November on guava.
The correlation and multiple regression studies between frui t fly
population and weather parameters were also worked out and
discussed.
Studies on population dynamics of f ruit fly based on per
cent infestation indicated that the maximum fruit fly infestation
was observed from April to August on sapota, May to July on
mango, in August on banana and August to October on guava. The
infestation also coincided with harvesting period of respective fruit.
The studies on species composition revealed the
prevalence of three species of fruit flies in south Gujarat. Among
them, B. zonata was found as most dominant (62.05 per cent)
species of fruit fly followed by B. dorsalis (37.27 per cent) and B.
correcta (< 1 per cent).
Studies on effect of different traps indicated that the
D.F.I.D (Department for International Development) water bottle
trap caught significantly higher male flies than the modified (Patel)
and conventional fruit fly trap. Further studies on efficacy of D.F.I.D
water bottle trap indicated that the D.F. I. D water bottle trap
(5x5x1.2cm.) remained more effective up to three months after
installation.
During the studies on effect of trap height and
placement it was found that the traps placed at border at 1.5 m
height caught more number of f ruit flies.
Studies on marking and recapturing of fruit flies,
revealed that the effective range of attraction of frui t flies toward
methyl eugenol was from 1 to 3 Km.
Installation of traps at many sites is rather impossible
during monsoon, which was overcome by designing trap of five
times bigger in size than the D.F.I.D block trap during present
investigation.
Studies on varietal response against fruit fly indicated
that the overall infestation in different varieties ranged from 3.33
to 46.47 per cent. Moreover, the late maturing varieties were
heavily infested by fruit flies compared to early and mid late
varieties.
Studies on effect of chemical cons tituents of four mango
varieties against fruit fly infestation revealed that the fruit fly
infestation had positive correlation with total soluble solids and
total sugar; whereas, it had negative correlation wi th phenol.
During studies on hot water treatment, it was found that
the treatment of 52 oC temperature for 60 min gave higher number
of dead and lower number of live maggots than the other
treatments.
During the studies on area wide control of f ruit flies by
male annihilation technique, significantly lowes t fruit infestation
was recorded in villages under area wide control treatment than
the villages under untreated control . Further studies indicated that
the f ruit fly infestation was reduced to 8.33 per cent from 40.33 per
cent by adopting area wide control, which tuned to 80 per cent
reduction in fruit fly infestation.
Studies on awareness about frui t fly among farming
community of south Gujarat indicated that the majori ty of farmers
of study area had medium level of awareness about fruit fly.
Description
Keywords
fruits, mangoes, animal developmental stages, biological interaction, guavas, sapota, bananas, eggs, orchards, irrigation