seasonal incidence and biology of sapota seed borer, trymalitis ...

Pak. Entomol. Vol. 31, No.2, 2009SEASONAL INCIDENCE AND BIOLOGY OF SAPOTA SEED BORER,TRYMALITIS MARGARIAS MEYRICKAbhishek ShuklaFruit Research Station, Navsari agricultural University, Gandevi-396 360, Gujarat, IndiaABSTRACTThe seasonal incidence and life cycle of Sapota seed borer, Trymalitis margarias Meyrick was determined in thepresent study in field and laboratory, respectively. The seasonal in sapota seed borer, Trymalitis margariasMeyrick revealed that the larval population fluctuated throughout the year with two peak period of infestationi.e., October in 2007-08 and November in 2008-09, respectively. The biology of T. margarias indicated that thefemale moth laid 161.8±77.236 eggs. The average pre-oviposition, oviposition and post-oviposition periodlasted for 1.83±0.185, 1.44±0.373 and 1.61±0.443 days, respectively. The duration of egg, larval and pupalstages lasted for an average of 11.16±0.715, 12.33±0.832 and 13.15±1.663 days, respectively. The adult maleand female survived for a period of 4.125±0.690 and 4.865±0.971 days, respectively. The total life cycle fromegg laying to adult emergence complete in 38.50±3.117 days.Key words: sapota seed borer, T. margarias, seasonal incidence, biology.INTRODUCITONSapota or Sapodilla (Manilkara achras (Mill)Forsberg) commonly known as “chiku” belongs tofamily Sapotaceae. Sapota is a native of Mexico andspread to other countries. The fruit was introducedduring 1888 in a village Gholwad of Thane district ofMaharashtra in India (Cheema et al., 1954). Atpresent, Sapota cultivation is confined mostly to thecoastal areas of Gujarat, Maharashtra and TamilNadu(Bose, 1985). In Gujarat, this fruit crop plays asignificant role in socio-economic upliftment of bothmarginal and big farmers. Moreover, its orchards canbe developed comparatively with fewer efforts aswell as the marketing facilities are also welldeveloped by co-operative societies of farmersespecially in South Gujarat. Presently, 14885 ha isunder Sapota cultivation with 138592 MTproduction. In South Gujarat especially Valsad,Navsari and Surat Districts, the area under this cropis 7169 ha which comprises 48 per cent of the totalarea of the state (Anonymous, 2000). Sapota tree isattacked by about 16 insect pests (Marin-Acosta,1975), which includes bud borer, chiku moth, leafminer and fruit flies (Deshmukh, 2001). A new pest,sapota seed borer, Trymalitis margarias Meyrick(Lepidoptera: Tortricidae) has appeared in the areaand causing very serious damage. This pestexclusively feeds on endosperm of the seed. Fullgrown larvae prepare a tunnel to come out from thefruit for pupation. Through this exit hole the fungusas well as ants enters inside the fruits and the fruitbecomes unfit for consumption. As high as 40 to 80per cent damage to the mature fruits have beennoticed. Due to the infestation of this pest, quality ofthe fruit deterorates and hence the market price goesdown and farmers also lose their goodwill in themarket. Keeping in view growing importance ofpests, seasonal incidence and biology of T. margariason sapota cv Kalipatti, was studied.MATERIALS AND METHODSSeasonal incidence: To study the seasonal incidenceof Sapota seed borer, ten medium sized trees ofSapota were selected randomly at Sapota orchard ofFruit Research Station, Navsari AgriculturalUniversity, Gandevi, Gujarat, India and permanentlymarked with white paint for recording theobservations. No insecticidal measures were taken inthe field selected for present studies during the entireperiod of study i.e., April 2007 to March 2009. Everymonth the fruits harvested from each marked treewere examined for infestation of Sapota seed borer.The damaged and healthy fruits were counted at eachharvest to work out the per cent fruit damage.Biology of Sapota seed borer: The biology of T.margarias was studied in the laboratory at roomtemperature and relative humidity at Fruit Research107

Pak. Entomol. Vol. 31, No.2, 2009Station, Navsari Agricultural University, Gandevi,Gujarat, India during 2008-09. The initial culture wasobtained by collecting larval stages from the infestedfruits of Sapota from orchards in the vicinity andreared in the laboratory in the glass jars. Fresh seedkernels were provided to the larvae as food till thelarvae become full grown and ready to undergopupation. The freshly emerged female and two maleswere sexed and released for mating and ovipositionon a fresh shoot of Sapota with a fruit whose stemwas kept dipped in 100 ml conical flask filled withwater and covered with a polythene cage of 40 x60 x100 cm.The top of the cage was covered with muslin clothand secured firmly with rubber band. Cotton swabsoaked in 5 per cent honey solution was keptsuspended as adult food. The Sapota fruits werechanged daily. Twenty such sets were kept underobservation for egg laying. The freshly laid eggs onSapota fruits were collected by wet camel hair brushand placed in petriplates (9 cm diameter) with apiece of wet blotting paper at its bottom. Thirtyindividuals of larvae were transferred on tender seedsof Sapota cv kalipatti. The larval food was changed atan alternate day till the feeding cease. The larvaewere observed carefully for moulting, pre pupationand pupation. Accordingly larval and pupal periodsand their measurements were recorded. The periodfrom emergence of adult to its death was worked outto note adult longevity. The sex ratio was alsodetermined by counting the number of male andfemale adults emerged from 50 pupae reared onSapota seed kernel.RESULTS AND DISCUSSIONSeasonal incidence The per cent fruit infestation(Table 1) revealed that the infestation fluctuatedthroughout the year, but intensity varied duringdifferent months. During 2007-08 the incidence ofthis pest was at it peak in October with 10.50 per centfruit infestation, while in year 2008-09 the highestfruit infestation was recorded in the month ofNovember which was 7.00 per cent fruit infestation.Thereafter it declined and reached only 1.5 per centin January 2007-08 and 0.5 per cent in February2008-09, respectively. The data revealed that the pesthas one peak in a year i.e., in October or Novemberof certain years (2007-08, 2008-09). The peakcorresponds to the crop harvesting periods.Table 1. Seasonal incidence of sapota seedborer, T. margariasMonth &weekPer centinfested fruitMonth &weekPer centinfested fruitApril-07 I 0.00 April-08 I 0.00II 0.00 II 0.00May-07 I 4.00 May-08 I 0.00II 5.50 II 1.50June-07 I 4.00 June-08 I 2.00II 0.00 II 1.00July-07 I 0.00 July-08 I 0.00II 0.00 II 0.00Aug.-07 I 0.00 Aug.-08 I 0.00II 0.00 II 0.00Sept.-07 I 5.50 Sept.-08 I 2.50II 6.00 II 3.00Oct.-07 I 10.50 Oct.-08 I 4.50II 9.00 II 5.00Nov.-07 I 9.00 Nov.-08 I 7.00II 6.00 II 3.50Dec.-07 I 10.00 Dec.-08 I 3.50II 6.00 II 4.00Jan.-08 I 4.00 Jan.-09 I 2.00II 1.50 II 2.00Feb.-08 I 0.00 Feb.-09 I 0.50II 0.00 II 0.00Mar.-08 I 0.00 Mar.-09 I 0.00II 0.00 II 0.00Biology of Sapota seed borer The mating of maleand female moths was observed during evening hoursbetween 7.00 to 11.00 p.m. and the period of coituslasted for 8 to 13 minutes. The pre-oviposition,oviposition and post-oviposition period lasted for1.50 to 2.1, 1.0 to 2.0 and 1.0 to 2.2 days,respectively. The fecundity was ranged from 29 to255 with an average 161.8±77.236 eggs per female.The incubation period varied from 10.35 to 12.25days with an average of 11.16 ± 0.715 (Table-2). Theaverage percentage of eggs hatched was found to be92. The total period required for completion of larvaldevelopment ranged from 10.75 to 13.75 days withan average of 12.33 ± 0.832 days. The first instarlarvae were very minute, white in colour with pinkishtinge, without distinctly segmented and hairless body.The average length and breadth of first instar larvawas 1.761 ± 0.038 and 0.692 ± 0.012 mm,respectively. Fully developed larvae was pinkish incolour and it measured about 12.467 ±0.022 mm in108

Pak. Entomol. Vol. 31, No.2, 2009length and 2.673 ± 0.013 mm in breadth. The fullgrown larva stopped feeding come out of the seedand started folding the leaf with the help of series ofsilken threads to form a cocoon. The pre-pupal periodvaried from 17 to 33 minutes. The pupa was small,dark brown in colour and obtect. The pupal periodranged from 10.0 to 15.0 days with an average of13.15 ± 1.663 days. The pupa measured from 7.61 to10.10 mm in length and 2.6 to 3.6 mm in breadth.The adult moths were small in size, having whitishforewings with grayish spots on it and fringed withhairs at the margins of the wings. The hind wingswere cream coloured with thick hairs at the margins.The adult measured 7.1 to 12.0 mm in length, 2.1 to2.6 mm in breadth. The adult male lived for 3.25 to6.0 days, while female moths lived for 4.0 to 7.0days. Total life cycle from egg laying to emergenceof adults varied from 34.10 to 45.0 days with anaverage of 38.5 ± 3.117 days.Table 2. Life cycle of sapota seed borer, T.margariasDuration in daysParticulars Maximum Minimum MeanEgg period 10.35 12.25 11.16±0.715Larval period 10.75 13.75 12.33±0.832Pupal period 10.00 15.00 13.15±1.663Pre-ovipositionperiod1.50 2.10 1.83±0.185Ovipositionperiod1.00 2.00 1.44±0.373Post-ovipositionperiod1.0 2.2 1.61±0.443Adult longevityMale3.25 6.0 4.12±0.690Adult longevityFemale4.0 7.0 4.86±0.971Total life cycle 34.10 45.0 38.50±0.311Sex ratio -- -- 1:1.20Fecundity (No.of eggs laid perfemale)29 255 161.80±77.24Table 3. Morphometric measurements ofsapota seed borer, T. margariasMeasurement in mmParticulars Maximum Minimum MeanI instar larvaelength1.70 1.79 1.761±0.038I instar larvaebreadth0.69 0.71 0.692±0.012Full maturelarvae length12.44 12.50 12.47±0.022Full maturelarvae breadth2.65 2.69 2.673±0.013Pupal length 7.61 10.10 9.143±0.920Pupal breadth 2.6 3.6 3.090±0.458Adult length 7.1 12.0 9.940±1.860Adult breadth 2.1 2.6 2.280±0.248PLATE-1. Fully grown larvae109

Pak. Entomol. Vol. 31, No.2, 2009PLATE-1. Pupation of sapota seed borerPLATE:5 Damaged sapota fruitREFERENCESPLATE: 3 Adult moth of sapota seed borerAnonymous, 2000. District wise estimated data inarea and production of fruit crop in Gujarat Stateduring 1998-99, Directorate of Horticulture,Gujarat State, Ahmedabad, 221 p.Bose, T. K., 1985. Fruits of India, Tropical and Subtropical.Naya Prakash, Culcutta, India, pp.87-94.Cheema, G. S., S. S. Bhatt and K. C. Naik, 1954.Commercial fruits of India. Macmillan and Co.,422 p.Deshmukh, D. V., 2001. Varietal screening of sapotaagainst pest complex, comparative biology ofAnarsia achrasella Bradley and bio-efficacy ofchemical insecticides against bud boring insectsof sapota. M. Sc. (Ag) Thesis. Gujarat Agric.Univ., S. K. Nagar, India.Marin-Acosta, J., 1975. Preliminary list of pests ofAnnonaceae and Sapodilla and Guava inVenezela. Agron. Trop., 23(2): 205-216.PLATE:4 Damaged seed kernel of sapota110