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Floral host plants for Tachinid flies (Diptera: Tachinidae) from
Kolhapur and Satara districts, India
T .V. Sathe, * P. M. Bhoje and A. S. Desai
Department of Zoology, Shivaji University, Kolhapur- 416 004, India.
*Department of Zoology, Y. C. Warana College, Warananagar, India.
ABSTRACT
Tachinid flies have been studied at Kolhapur and Satara district, India with respect
to floral host plant associations and their sex ratio. Overall, 82 species were collected from
13 floral plants of different ecosystems from Kolhapur and Satara districts. Majority of
flora belong to family Asteraceae. Out of which Tecoma castanifolia and Eupatorium
odoratum plants showed maximum number of tachinid flies. In Kolhapur district the
occurrence of tachinids was more in number than Satara district. Out of total 82 flies, 52
were collected from Kolhapur district.
Thelaira nigripes
and
Exorista larvarum
were
reported maximum in numbers from both districts. The tachinids were also good
pollinating agents for increasing yield of the crops in Kolhapur and Satara regions of
Maharashtra, India.
Key words: Tachinids, biocontrol agents, pest management, floral host plants, pollinators.
INTRODUCTION:
Tachinid flies are good biocontrol agents of many harmful insect pests from different
agroecosystems which belong to Tachinidae, one of the largest families of Diptera with 10,000
described species worldwide (Irwin et al., 2003 and Stireman et al., 2006).Tachinid flies are
endoparasitic forms of insect pest larvae which feed on internal tissues of pest insects and cause
mortalities in them. However, adults feed upon flowering bodies of plant species.
The adults
commonly visit flowers and use the nectar for energy and also pollen for proteins, lipids and
vitamins (Faegri and van der Pijl 1979). These floral resources enhance the longevity, fecundity
and searching ability of adult flies (Shahjahan 1968, Topham and Beardsley1975, Sathe and
Margaj, 2001).
In many plant species tachinids act as a good pollinating agents. Nutritional dependency
of tachinid flies on flowering plants simultaneously helps for regulation of pests of herbivorous
plants.
Effective control of pest species by conservation of such biocontrol agents therefore, may
depend on knowledge of floral host associations (Jervis et al. 1993, Colley and Luna 2000,
Tooker and Hanks 2000b).The floral sugars from agricultural environments helps directly to pest
suppression (Lee and Heimpel, 2005; Lavandero et al., 2006) and flowering plants do benefit the
biological pest control (Heimpel and Jervis, 2005).
Keeping
in view above facts, present work
was carried out.
MATERIALS AND METHODS
Adult Tachinid flies have been collected from different agroecosystems of Kolhapur and
Satara districts during the years 2011-2013, especially from some important flowering plants at
15 days interval with the help of swift insect net. The host plant twigs of one feet length with
tachinid flies were brought to the laboratory for identification. The host plants and tachinids have
been identified by using appropriate literature (Irwin et al, 2003., O’Hara, 2008, O’Hara et al.,
2009., Wood, 1987, Yadav and Sardesai., 2002).Observations were also made on plant flowering
and occurrence of tachinids upon flora by one man one hour search method throughout the year
from morning hours 7.00 am to 9.00 am and from evening hours 5.00 pm to 7.00 pm. Increase in
the yield of crops specially cereals and pulses have been reported with the help of questionnaire
asked to the farmers of the region.
RESULTS AND DISCUSSION
The results indicated that 52 Tachinid flies were associated with 13 floral host plants
from Kolhapur region and 30 plants from Satara region (Table- 1, 2 and fig. 1). The flies were
abundant during morning hours (7.00am to 9.00am) and evening hours (5.00pm to 7.00pm) than
noon and afternoon. The observations were made from June to July. The population of tachinids
was in peak in the months October-November. The best floral plant for optimum catches of
Tachinid flies was Tecoma castanifolia in both districts i.e. Kolhapur and Satara. The floral
plants Aster amellus, Clematis gouriana, Fragaria nubicola, Helianthus elastic and Nepeta
indica were not observed in the district Satara and hence the occurrence of tachinids. The non
occurrence of tachinid species was probably due to the high altitude of the region from sea level,
less floral density and short height of the plants. The sex ratio was in favour of females on most
of the plants in both the districts. The reason of sex ratio favoring the females might be the
nutritive quality of the floral components. During the study period the yield of the crops
particularly horticultural and cereals was found increased in the area where tachinid floral host
plants were abundant (Table- 2).
Table- 1: Floral host plants for tachinid flies and their occurrence in Kolhapur and Satara districts
Sr.
no
Floral host
plants
Family
Tachinid species
No. of fly
species
collected
Occurrence (District) and
Sex ratio
(Male: Female)
Kolhapur Satara
1.
Aster amellus
Asteraceae Gonia picea 2 2 (0 : 2) 0 (0 : 0)
2.
Clematis
gouriana
Ranunculaceae Prosena siberita
1 1 (0 : 1) 0 (0 : 0)
3.
Eupatorium
adenophorum
Asteraceae Sturmia bella 4
3 (2 : 1) 1 (1 : 0)
Estheria cristata
1 1 (1 : 0) 0 (0 : 0)
4.
Eupatorium
odoratum
Asteraceae Blepharipa schineri 8 5 (3 : 2) 3 (1 : 2)
Exorista larvarum
12 6 (1 : 5) 6 (3 : 3)
5.
Fragaria
nubicola
Rosaceae Macquartia tessellum 3 3 (1 : 2) 0 (0 : 0)
6.
Gnaphalium
indica
Asteraceae Sturmia bella
2 0 (0 : 0) 2 (0 : 2)
Prosena siberita
5 4 (2 : 2) 1 (1 : 0)
7.
Helianthus
elastic
Asteraceae Macquartia macularis 1 1 (1 : 0) 0 (0 : 0)
8.
Justicia
betonica
Acanthaceae Thelaira solivaga 3 2 (0 : 2) 1 (0 : 1)
9.
Nepeta indica
Lamiaceae Redtenbacheria insignis 1 1 (1 : 0) 0 (0 : 0)
10.
Rorippa
indica
Brassicaceae Thelaira solivaga 1 1 (1 : 0) 0 (0 : 0)
Siphona boreata
2 1 (0 : 1) 1 (0 : 1)
11.
Ruellia
brittoniana
Acanthaceae Voria ruralis
9
5 (3 : 2) 4 (2 : 2)
Gonia picea
1 1 (0 : 1) 0 (0 : 0)
12.
Solidago
canadensis
Asteraceae Dexiosoma caninum 3
2 (0 : 2) 1 (0 : 1)
Thelaira solivaga
2 2 (1 : 1) 0 (0 : 0)
13.
Tecoma
castanifolia
Bignoniaceae Xylotachina diluta 3 1 (0 : 1) 2 (1 : 1)
Estheria cristata
2
1 (0 : 1) 1 (0 : 1)
Prosena siberita
4
3 (1 : 2) 1 (0 : 1)
Thelaira nigripes
8
5 (3 : 2) 3 (1 : 2)
Macquartia macularis
3 1 (1 : 0) 2 (0 : 2)
Gonia picea
1 1 (0 : 1) 0 (0 : 0)
TOTAL
82 52 30
Table 2: Pollinating effect of tachinids on agricultural crops
No. of farmers consulted Crops Yield increase in times
Kolhapur Satara
10 Cereals 2 2
15 Pulses 2 1.5
Fig.1: Tachinid flies on floral host plants.
In overall, 82 specimens were collected from floral plants of different ecosystems from
Kolhapur and Satara districts. Tachinid flies were found on different 13 floral plants. Majority of
flora belong to family Asteraceae. Out of which Tecoma castanifolia and Eupatorium odoratum
plants showed maximum number of tachinid flies which conclude that these plant are good
attractants for tachinid flies and important habitat for them. In Kolhapur district the occurrence
of tachinids was more in number than Satara district. Out of total 82 flies, 52 were collected from
Kolhapur district.
The tachinids,
Thelaira nigripes
and
Exorista larvarum
were reported
maximum in number in both districts, providing good information on natural habitat for their
possible conservation strategies and utility in biological pest control programs. The tachinids
were also good pollinating agents for increasing yield of the crops in Kolhapur and Satara
regions of Maharashtra,India.
Al-Dubai et al (2012) captured tachinids and identified to genus and species level. Their
sex was determined and the lengths of their mouthparts were estimated and compared with the
numbers, sexes and tongue lengths of flies collected in flower baited and control traps. The
controls were either associated with plants without flowers or pots without plants or both. The
ratios of flies captured in the flower baited to control traps were subsequently related to flower
density, width, depth and plant height in order to test the hypothesis that flower and plant
morphology influenced their attractiveness and/or accessibility to Tachinidae (Fiedler and
Landis, 2007a, b; Sivinski et al., 2011).More or less, the present results are in agreement with
Sivinski et al., (2011).
According
to
Stireman et al., (2006), 909 tachinids were feeding on
flowering plants with 28% of individuals from Phasiinae.
Al Dobai et al., (2012)
also studied the sex ratio of flies captured in the various types of
traps and recorded the nature of responses to plants. If host searching was the motivation for
entering flower baited traps, greater absolute and relative abundances of females were expected
in the flower and no flower traps compared with the no plant traps. In contrast, sexually
independent motives (perhaps such as floral feeding?) have showed sex ratios the same in all
traps. Overall, sex ratios were female biased but there were no differences in the proportions of
males and females taken in the flower-baited and control traps, in either significantly attractive
or unattractive plants.
Certain plants, in flower or not, were more frequented than others. Two
plants deserve special consideration because they exceeded or failed to meet expectations. In the
present study, sex ratio was favoring the females on most of the floral host plants and might be
related to quality floral components.
Apiaceae in general were less frequently represented than were Asteraceae and Rosaceae
in the long term field surveys of tachinid flower associations analyzed by Tooker et al. (2006).
Perhaps there is an unrevealed variance in attractants/nectar within the genus. Over a multiyear
survey of Illinois Tachinidae flower associations, Solidago canadensis L. was fed upon by a high
diversity of flies while Solidago gigantean Aiton was not (Tooker et al., 2006).
Sivinski et al.,
(2011) also studied, flower/ plant morphological patterns in captured tachinid were largely
absent; this is in contrast to the parasitic Hymenoptera. Among wasps, larger floral areas were
more attractive and this was a characteristic similar to one positively associated with predator
and parasitoid abundance on a variety of native and introduced plants in Michigan (Fielder and
Landis, 2007a, b).
Floral area could increase flowering plant conspicuousness and advertise the presence of
denser and more abundant resources. A tachinid, Protohystricia huttoni (Malloch) made more
visits per hour to individual Myosotis colensoi (Kirk) (Boraginaceae) plants with larger floral
displays in New Zealand (Robertson and MacNair, 1995).
Although flies collected in flower
baited traps overall had longer mouthparts than those taken in controls, the absence of such
tongue flower patterns argues that tachinids were not seeking flowers to which their mouths were
particularly adapted; i.e., longer tongued flies did not predominate at deeper flowers. Long
tongues need not preclude feeding on shallow flowers (Allen1929), but the inclusion of more
species of plants with deep flowers in the study have produced a stronger association with long
tongued tachinids.
There is a substantial body of evidence that increasing the floral diversity of
agroecosystems enhances natural enemy diversity and abundance and ultimately the biological
control of pest insects. However, some of the abundantly collected tachinids in have contributed
to pest suppression. (Al Dubai et al., 2012). Genus Archytas attacked a wide variety of
Lepidopteran larvae (Arnaud, 1978) and out of unknown some use agriculturally more economic
important and mass reared for augmentative release (Mannion et al., 1995). The hosts of C.
townsendi, 32% of the capture of Tachinidae, identified, species of Campylocheta have been
recovered from larvae of the pest containing families Geometridae, Notodontidae, Noctuidae and
Tortricidae (Arnaud, 1978).
The most preferred plant species by tachinids were the asteraceous Aster pilosus
Willdenow, Heracleum maximum Bartram and the umbellifer Pastinaca sativa L. (Tooker et al,
2006).The most frequently recorded fly species were three syrphids: the aphidophagous
Toxomerus marginatus (Say) and Sphaerophoria contiqua Macquart and the detritivorous Syritta
pipiens (L.).Most fly species evidently visited only a few plant species. Out the 186 fly species
recorded, most were visiting species of the Asteraceae and Apiaceae. Such findings have
important implications for research in pollination ecology and insect behavior and for use of fly
species as agents of conservation biological control.
Robertson (1929) recorded syrphids and tachinids on 257 species of flowering plants in
57 families. Of these plant species, 64 (25%) were in the Asteraceae, 18 (7%) in the Rosaceae,
17 (7%) in the Apiaceae, and 15 (6%) in the Lamiaceae; the remaining plant families were
represented by nine or fewer species (4%).These plants were visited by 186 fly species, including
100 tachinid species and 86 syrphids species, of which 26 syrphid species were predaceous The
number of fly species that Robertson recorded from plant species could have been influenced by
plant abundance. Syrphids and tachinids did not differ significantly in the proportion of their
species that visited the 15most preferred plant species. The introduced syrphid, Syritta pipiens
(L.) (Thompson et al. 1990) was apparently the only visitor to flowers of the exotic plant
Polygonum persicaria L., but it was relatively abundant on S. pipiensis native to the Palearctic
region where it is broadly distributed (Lambeck and Kiauta 1973, Thompson et al. 1990, Torp
1993).
The odours both of host food plant and of the host insects (Sawfly larvae) were attractive
to the females of tachinid, D. bihemica (Monteith, 1964).Some species detected their hosts by
perception of sound or vibrations produced by host larvae. However, workers disproved the
hypothesis that host produced sound but, vibrations/sound produced by the parasitoid or odour
were obligatory host finding stimuli (Richerson and Borden, 1972).Hafez (1961) reported that
the olfactory response of D .rapae females to mustard oils was in aid to habitat selection. Read
et.al., (1970) reported that the parasitoids attacked a variety of Aphids which they encountered
by chance, through the response to the mustard oil probably accounted for the limitation of
parasitism to Brevicoryne brassicae, M. persicae and other Aphids feeding on Crucifers plants.
Vinson (1976) says that parasitoids respond to both short range and long range volatile chemicals
by certain cues during host location.
However, regional field surveys, such as this, can offer empirically based guidance for
plant selection, food, shelter and mate for natural enemies like tachinid flies.
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