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B-3772[1-6]

*Corresponding author’s e-mail: sumit87saini@gmail.com1MPRNL, LBS Building IARI, New Delhi.2CCS HAU, Hisar.

Indian J. Anim. Res.,Print ISSN:0367-6722 / Online ISSN:0976-0555

Efficient pollinators of threatened taxa, Sarpagandha (Rauvolfia serpentina)under North Indian conditionsVadde Anoosha1, Sumit Saini* and H.D. Kaushik2

Department of EntomologyCCS Haryana Agricultural University, Hisar-125 044, Haryana, India.Received: 22-12-2018 Accepted: 29-12-2018 DOI: 10.18805/ijar.B-3772

ABSTRACTAn experiment was carried out to investigate the diversity, abundance and pollination efficiency of different insect visitors/pollinators of Rauvolfia serpentina (Sarpagandha) during 2014 and 2015. This experiment was conducted at MedicinalSection, Department of G &PB, CCSHAU, Hisar. Sarpagandha flowers attracted wide varieties of insects belonging to 4orders, 10 families, 16 genera and 17 species. Among them nine belongs to order Lepidoptera, one Coleoptera, two Diptera,and two Hymenoptera. Lepidopterans came out to be the most abundant pollinators of this crop. Peak abundance of majorinsect pollinators was recorded at 1000h-1200h while minimum abundance was recorded at 0600h -0800h. Amegillazonata had the highest number of loose pollen grains, 23.50 (‘000), sticking to its body followed by Papilio demoleus andPieris sp. Papilio demoleus was reported as most efficient pollinator followed by Amegilla zonata and Pieris sp. based onthe pollination index. Long proboscis of lepidopterans i.e., Papilio demoleus and small sized hymenopterans i.e., Amegillazonata plays key role in pollination of Sarpagandha. Conservation of these pollinators in natural ecosystem is must forpollination of these threatened taxa.

Key words: Insect pollinators, Pollination efficiency, Pollen grains, Sarpagandha.

INTRODUCTIONPollination is one of the principal mechanisms in

the maintenance and conservation of biodiversity in generallife of earth. Pollinators provide an ecosystem service thatenables plants to produce fruits and seeds. Over 80 per centof total pollination activities are performed by insects andbees (Klein et al., 2007). Around 30 percent of human foodis derived from bee pollinated crops (O’ Toole, 1993).Pollinating insects are widely found in insect ordersColeoptera, Lepidoptera, Thysanoptera, Diptera andHymenoptera (Singh and Garg, 2003). The structure of theflowers, their degree of self-fertility and their arrangementon the plant determines the extent to which a plant isdependent on insects for pollen transfer (Free, 1993;Williams, 1994; Richards, 2001, Devi S et al., 2015).

Sarpagandha (Rauvolfia serpentina (Linn.) Benth.,ex Kurz.) is an evergreen shrub that belongs to the familyApocynaceae (Endress and Bruyns, 2000). Sarpagandha isa threatened species found in the sub-tropical regions. Itgrows wild in India, Bangladesh, Sri Lanka, Myanmar,Thailand, Indonesia and Malaysia. Within India, it is grownin almost all parts up to an altitude of about 1000 m abovesea level. Five species of sarpagandha (viz., R. hookeri, R.micrantha, R. serpentina, R. tetraphylla and R. Verticillata)have been recorded in India, of which R. Serpentina has

attained a great importance as medicinal plant (Pullaiah,2006). Roots and leaves of this plant contain several alkaloids(Verma et al., 2010) out of those resperine is pharma-cologically most important (Blackwell, 1990). It haslanceolate shaped pale green leaves in whorls of 3 to 5 leaves.It also has white and pink coloured flowers, having filiformstyle and stigma is bifid having bilocular ovary with twoovules in each locule. The flowers of Sarpagandha havenarrow and long tubular corolla. Such flowers make them aperfect representative of psychophilous pollination syndromenegating all other syndromes (Wadhwa and Sihag, 2012).Protogynous conditions of sarpagandha flowers need insectpollinators for cross-pollination. Fruit is drupe, ovoid andpurplish black in color when it reaches maturity. Lot ofresearch work done on commercial crops as bee forage butscanty information is available on underutilized medicinalplants. These plants also have important as medicinal cropand knowledge of their mode of pollination and pollinatorsis the need of the hour. They also serve as minor bee foragein the areas of scarcity. Keeping this idea in view, the presentstudy was undertaken to determine the efficient pollinatorsof sarpagandha.MATERIALS AND METHODS

Pollination studies in sarpagandha were carried outat Research Farm, Department of Genetics and Plant

2 INDIAN JOURNAL OF ANIMAL RESEARCH

breeding, CCS Haryana Agricultural University, Hisar, Indiaduring 2014 and 2015.

Diversity of insect pollinators: Hand net with 30 cm ringdiameter was used to collect insects visiting the flowersthroughout blooming period (Anoosha et al., 2016, 2018a,2018b). Captured insects were preserved as dry specimensand were got identified from Division of Entomology, IARI,New Delhi and a record of the flower visitors was prepared.Abundance of insect pollinator: Abundance of mostfrequent insect visitors (number of visitors/m2 branch of atree/5minutes) was recorded from five randomly selectedbranches with the help of stop watch. The abundance wasrecorded at two hourly intervals, star ting fromcommencement to the cessation of insect activity andrepeated at weekly intervals on the experimental plant(Anoosha et al., 2016, 2018a, 2018b).Foraging Rate: Foraging rate of major pollinators wasrecorded in terms of number of flowers visited/minute. Tenobservations were taken for each pollinator species. For this,observations were recorded at 2 hours interval from 0600 hto 1800 h on a day and were repeated weekly interval duringblooming period.Loose pollen grains sticking on insect visitors: Insectswere collected gently by forceps from the flowers to avoidshaking of body, and the hind legs of those pollinators whichcollected the pollen were amputated. Insects were capturedat the time of their peak activity and were kept in 70% alcoholin vials. They were shaken vigorously to wash out pollengrains from its body. Ten samples were taken for eachpollinator species. The numbers of pollen grains werecounted with the help of a haemocytometer under themicroscope (15 x 10 magnifications). The identity ofsarpagandha pollen was confirmed by using standard pollenslides (Anoosha et al., 2017).Number of pollen grains = pollen grain count x dilution/number of squares (1mm2) countedPollination efficiency of major insect pollinators:Comparative pollination efficiency of different insectpollinators was calculated on the basis of their relativeabundance and foraging behaviour parameters such asabundance, foraging rate and the number of loose pollengrains sticking to their bodies by using the following formula:Pollination efficiency = Abundance X foraging Rate Xnumber of loose pollen grains sticking on the body of the bee

Abundance and Foraging Rate were analysed inrandomized block design and the results were compared.Loose pollen grains present on each species were calculatedand compared using Completely Randomized Design(Snedecor and Cochran, 1989). Three factorial statisticalanalyses was done using OPSTAT software (Sheoran et al.,1998).

RESULTS AND DISCUSSIONDiversity of insect visitors/ pollinators: Sarpagandhaflowers (Fig 1) attracted 17 species of insects. Out of these,Lepidopterans were the major floral visitors comprising fromthree families viz., Papilionidae (Papilio demoleus andPapilio polytes), (Fig 2) Pieridae (Eurema hecabe, Pierissp., Anaphaeis sp., Pieris canidia, Belenois aurota, Pierisbrassicae and Colotis etrida and Hesperiidae (Pelopidas sp.).They were followed in order of diversity by Dipterans fromtwo families viz., Sarcophagidae (Sarcophaga sp.) andSyrphidae (Eristalinus obscuritarsis) and two species fromtwo families of Hymenoptera viz., Vespidae (Polistesolivaceus) and Apidae (Amegilla zonata) (Fig 3) andColeopteran from family Coccinellidae (Coccinellaseptempunctata). Out of 17 insects all were top foragersexcept A. zontata which was side forager (Table 1). Thesefindings are in agreement with those of Wadhwa and Sihag(2012) who recorded 19 insect species visiting the blossomsof sarpagandha.Abundance of insect visitors/pollinators: Three insectspecies are major visitors of sarpangandha bloom. They werebelonging to Lepidoptera (2), and Hymenoptera (1). Among

Fig 1: Flowers of Sarpagandha.

Fig 2: Papilio demoleus.

Fig 3: Amegilla zonata.

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Table 1: Diversity of insect visitors/pollinators of R. serpentina (Sarpagandha).

Order Family Insect Species IP/IV Working BehaviourLepidoptera Papilionidae Papilio demoleus Linnaeus IP T

Papilio polytes Linnaeus IP TPieridae Pieris sp. IP T

Anaphaeis sp. IP TPieris canidia Linnaeus IP TBelenois aurota Fabricius IV TPieris brassicae Linnaeus IP TColotis etrida (Boisduval) IV T

Hesperiidae Pelopidas sp. IV TColeoptera Coccinellidae Coccinella septempunctata Linnaeus IV THymenoptera Apidae Amegilla zonata (Linnaeus) IP T and S

Vespidae Polistes olivaceus De Geer IV TFormicidae Monomorium sp. IV S

Diptera Sarcophagidae Sarcophaga sp. IP TSyrphidae Eristalinus obscuritarsis (de Meijere) IV S

Eristalis sp. IV SHemiptera Scutellaridae Chrysocoris stolli Wolff IV T

*IP –Insect Pollinator and IV – Insect Visitor, T – Top and S - Side

Lepidopterans, maximum mean population was of P.demoleus (3.70 insects/m2 branch/5min) followed by that ofPieris sp. (1.23 insects/m2 branch/5min (Table 2). InHymenoptera, mean population of A. zonata was (1.83 bees/m2 branch/5 min).

Time and week wise, the highest population of P.demoleus (6.40 insects/m2 branch/5min) was recorded at1000h -1200h during 2nd week of flowering which wassignificantly different with 1st week (4.60 insects/m2 branch/5min) and 3rd week (5.00 insects/m2 branch/5min). In caseof Pieris sp. maximum population (2.60 insects/m2 branch/5min) was recorded at 1000h -12000h during both 2nd and3rd week which was significantly different with 1st week (1.80insects/m2 branch/5min) (Table 2). In case of Hymenoptera,highest population of A. zonata (4.40 bees/m2 branch/5min)was recorded at 1000h-1200h during 2nd week of floweringwhich was significantly different with 1st week (3.60 bees/m2 branch/5min) and 3rd week (3.80 bees/m2 branch/5min).

Highest pooled mean abundance (3.70 insects/m2

branch/5min) was recorded in p. demoleus followed by A.zonata (1.83 bees/m2 branch/5min). Lowest pooled meanabundance was recorded in Pieris sp. (1.23 insects/m2

branch/5min).During 2015, similar trend followed as of previous

year. Minimum activity of both lepidopterans (P. demoleusand Pieris sp.) was recorded between 0600h - 0800h andpeak activity was recorded at 1000h – 1200h irrespective ofweeks (Table 3). Highest pooled mean abundance (3.47insects/m2 branch/5min) was recorded in P. demoleusfollowed by A. zonata (1.85 bees/m2 branch/5min). Lowestpooled mean abundance was recorded in Pieris sp. (1.53insects/m2 branch/5min).

From the present pollination study, it is evident thathighest pooled mean abundance of P. demoleus, Pieris sp.and A. zonata were reported during 2nd week of floweringon Sarpagandha flowers. Irrespective of different day hours,significantly maximum number of P demoleus was recordedfrom sarpagandha flowers followed by A. zonata and Pierissp. Peak abundance of P. demoleus, A.zonata and Pieris sp.was recorded at 1000h-1200h irrespective of weeks.Minimum abundance was recorded at 0600h -0800h (Table2 and 3).

Similarly, Wadhwa and Sihag (2012) observed thatP. demoleus was most abundant pollinator and also foundabundance of insect visitors of sarpagandha were low at thetime of commencement and cessation of the flowering andhigh during peak flowering period. These reports were inline with present findings as highest population of all majorinsect pollinators were recorded during 2nd week of floweringwhich was significantly different with 1st week and 3rd week.Charnov, (1976) and Pyke et al. (1977) stated that duringpeak flowering more pollen and nectar were available whichsimultaneously attract more pollinators similar findings wererecorded in the present study.

P. demoleus was reported as most abundantpollinator followed by A. zonata and Pieris sp. these findingsgot support from Wadhwa and Sihag (2012) wherelepidopterous insect, P. demoleus was most abundantfollowed by P. brassicae. Similar findings were also reportedby Patil et al., (2008) in pollination studies of brinjal.Loose pollen grains on the body of insect visitors/pollinators during 2014 and 2015: Significant differenceswere found among the number of loose pollen grains (‘000)sticking to the body of different foragers of three insect

4 INDIAN JOURNAL OF ANIMAL RESEARCH

Tabl

e 2:

Abu

ndan

ce o

f in

sect

visi

tors

/pol

linat

ors

on S

arpa

gand

ha f

low

ers

durin

g 20

14.

Each

val

ue r

epre

sent

s m

ean

of 5

obs

erva

tions

. *Fi

gure

s in

par

enth

eses

are

squ

are

root

tran

sfor

med

val

ues.

Tabl

e 3:

Abu

ndan

ce o

f in

sect

visi

tors

/pol

linat

ors

on S

arpa

gand

ha f

low

ers

durin

g 20

15.

Each

val

ue r

epre

sent

s m

ean

of 5

obs

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. *Fi

gure

s in

par

enth

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are

squ

are

root

tran

sfor

med

val

ues.

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Table 4: Loose pollen grains (‘000) sticking on insect visitors/ pollinators during 2014 and 2015.

Insect species 2014 2015 Pooled meanPapilio demoleus 12.50 15.50 14.00Amegilla zonata 21.50 23.50 22.50Pieris sp. 12.50 10.50 11.50Mean 15.50 16.50 —Factor Insect Year Insect X YearSEm (±) 1.12 0.92 1.59C.D. 3.20 NS NS

Each value represents mean of 10 observations.

Table 5: Pollination efficiency of major insect pollinators.

Insect Species Abundance Foraging Loose pollen grains Pollination index PollinationRate sticking on the body (abundance x foraging efficiency (Rank)

of insect species(‘000) rate x loose pollen grains)Papilio demoleus 3.58 23.24 14.00 1164.78 1st

Amegilla zonata 1.84 8.05 22.50 333.27 2nd

Pieris sp. 1.38 6.34 11.50 100.61 3rd

species during 2014 (Table 4). A. zonata (21.50) had thehighest loose pollen grains on their body followed by P.demoleus and Pieris sp. (12.50). In the year 2015,significantly the highest mean number of loose pollen grains(‘000) carried by A. zonata (23.50) followed by P. demoleus(15.50) and Pieris sp. (10.50) (Table 4).

The pooled mean over two years revealed thatsignificantly highest number of loose pollen grains (‘000)entrapped by the A. zonata (22.50) followed by P. demoleus(14.00) and Pieris sp. (11.50). Present findings are inagreement with Wadhwa and Sihag (2012) who reported thatpollen grains carried by the body of P. demoleus weremaximum followed by P. brassicae in sarpagandha.Pollination efficiency of major insect visitors/ pollinators:Pollination efficiency of major visitors/pollinators foragingon Sarpagandha flowers revealed that A. zonata (22.50)

entrapped the maximum number of pollen grains (‘000)followed by P. demoleus (14.00) and Pieris sp. (11.50)(Table 5). Abundance of P. demoleus (3.58) was highestfollowed by A. zonata (1.84), while the abundance of Pierissp. was least (1.38) and the foraging rate of P. demoleus(23.24) was highest followed by A. zonata (8.05), whileforaging rate of Pieris sp. was least (6.34).

Pollination index of P. demoleus (1164.78) washighest followed by A. zonata (333.27) and Pieris sp.(100.61). Hence, it was observed that P. demoleus came outto be most efficient pollinator of Sarpagandha. Otherpollinators with relatively lower ranking in pollinationefficiency were A. zonata and Pieris sp. in descending order.These findings are in agreement with those of Wadhwa andSihag (2012) who reported that P. demoleus was the mostefficient pollinator based on the pollination index.

It is concluded that Psychophilous mode ofpollination is prevalent due to the tubular flower structureof Sarpagandha. Tubular flowers easily located bylepidopteran pollinators of having long proboscis to drawthe nectar from flowers. Small body sized hymenopteranshave advantage over large ones due to the tubular structure.In this present study it was reported that long proboscislepidopterans i.e., P. demoleus and small sizedhymenopterans i.e., A. zonata plays key role in pollinationof sarpagandha. Conservation of these pollinators innatural ecosystem is must for pollination of thesethreatened taxa.

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