Indian Journal of Experi mental Biology Vol. 41 , ove mber 2003 . pp. 1346- 1348

Occurrence and cross infectivity of granulovirus of field bean pod borer atkinsoni Moore

K ara yan an*

Projec t Direc torate of Biological Control. Hebbal. Banga lore. 560024 . Rece i l'ed 7 February 2003: rel'ised 27 May 2003

A granulovirus (G V) was isolated fro m th e fi eld- bean poel borcr. Adisllm {/tkil1.wJll i. Electron microscopi c obse rva ti on showed capsult: or granu lar shaped occlu sion bodies. The virus was hi ghl y virulcnt aga inst seco nd instar larvae II hcn les ted al I x 10" occ lusions/larva throu gh food , urface (pod/secd) contaminati on lec hniquc. The incubati on peri()(1 ranged from 6- 10 days in Ihc casc of sec ond in stal' larvac. In contrast 10 gree n co lou red healthy larvae. GV in fecled A. mkillsolli became bro wni sh/ pal e Ilhite in co lour mos tl y due to accumul ation of large number of occ lu sion bodi es . Study on the crllSS infectiv­ ity of A. mkillsolli GV to gram ca terpillar. Helic(}\ 'I' I"/ }(1 arllligera reveal ed the hi gh susce pti bility of !-I. arllligera to A. mkill­ sOlli G V. Ihereby widening thc sc ope of cont ro lling both lhe specics on lhe sam e cropping sys tem . This is the fi rst record of GV fnlm A. mkillsolli from India.

Keywords : Adi.wrt/ atkillsolli. Granulovirus. Gross-infec ti vity

Fi eld bean LaNab pll rpurells (Linn .) Sweet is an im­ supernatant was then decanted and further centrifuged portant pul se - cum vegetab le crop. A lthou gh about at 12,000 rpm for 30 min. The differen tial cen tri fuga­ 5S in sect spec ies and mites have been recorded on tion process was repeated twice and the resultant pel­ field beans, onl y a few of th em are considered to be let was re suspended in sterile distilled wa ter. The important and known to appea r re gul arl y cau sing eco­ number of capsules/ml of th e stock suspension was nomi c loss while oth ers arc casual fee d e r~. Of th e 8 determined us ing a Petrauff- Hausser counting cham­ spec ies of pod borers reported to cause damage to the ber. A test wa s conducted to determine its pat hogeni c­ crop, Adi.l'lIm alkillsolli Moore: pl ume , ity against second instal' larvae of A.alkinsoni. Second Sl'hoello relies all isor/au\' /II.1' Wa I ker and J-I e/i col'e ' pa in stal' larvae (30) were inoculated with a dose of anlligero Hubner are th e more import ant on es, cau s­ I x lor' occ lusionliarva by food surface contamination ing hea vy damage hy wa y of feed ing th e devc loping tec hnique. T he larvae were reared individually on th e pods and reducing the marke tabl e yield I. A granulovi­ virus-contaminated diet till th eir death. Similar nu m­ rus (GV) was i.-;o lated from a few dead cate rpillars of ber of same instal' larvae, treated without virus serve d i\. Olkil1sulli collected from the fi eld in and around as co ntrol. The dead larvae were diag nosed by micro­ Ba nga lore. The present communica ti on de al s with sco pic ex aminati on of th e squ as hed preparations for ()bse r va ti o n~ made on th e sy mpt omotology and gross th e prese nce of ca psules. In ord er to tes t its cross in­ pat hology or A. Ctlkill.l'oni larvae, when th ey were ad ­ fec tivity, a preli minary study was conducted with GV mi ni stered with known quantity of G V thro ugh food of A. alkinsol1i against 8 lepidopteran pests l Table I ) su rface (pod and seed) contamination technique along at a concentration of I x 106 occ lusions/ml either with ce rt ain preliminary cross infec ti vit y stu dies. through diet su rface or lea f surface co nt aminat ion Granular occlusio:l bodies of GV we re pu ri fi ed technique depending on th e av ailabi lity of artificial from th e diseased larvae of !\, olkinsoni by differential diet for the respec tive insec ts . ce ntrifuga ti on fo llowing the meth od of Narayan an"­ The pathogenicity of A. alkinsoni GV re vealed Diseased larvae were homogeni zed with distilled wa­ 100% mortal ity of th e second instal' larvae when ad ­ ter for 3 min and th e hOll1ogenate was th en filtered ministered through diet surface contamination tech­ twice through severa l layers of muslin cloth and th e nique. The incubation peri od ran ged from 6-10 days. filt ra te was ce ntri fu ged at 1000 rpm for 10 min. The The sy mptoms of the GV infected A. alkinsoni were

* Correspondent author: E-mail : KnJJdbc(l) rcd i lTmai l.colll genera lly comparable with th ose of most of th e granu ­ Fax: (080) 34 11 96 1 losis viruses reported in other . Li vi ng diseased NOTES 1347

Tablc 1- Cross infccti \'ity of A. iilkillSolli c.;V to othc-r lepidopt cran pcs ts

amc or thc inscct No. or in.'e.:ts lI scd M ortality (%) Pupation ("Ir )

Chilo par/el/II.I (S\\ illhoc) 30 I O() TrichoJlllIsio IIi (1Iuhncr) 10 100 Opisill(/ (/rl'lI (1s( 'I/(I (Walkcr) 20 I O() Cailm ('wlll'l/a (Wall,cr) 10 100 Core."m ('(pfw!rJll iclI (Stainton) 30 100 CuI/crill 1II1'1/01lCI/(I (Linllacus) 3D 100 SJlodul',erfl filllm (Fahricius) J() IUO ffl'lic()\'erf)a arllligel"O (H uhncr) 10 100

larvae of A.Olkillsoni showed typical sluggishn ess in their moveillellt and we re :l lso less respnllsive to ex­ tcrn~ 1I tactile stimuli . Further. in contr:lst to green col­ ou red healthy larvae,the GV infected!\. al/':illsoni be­ came light whit e in co lour (Fig. I ), ancl it was well pronoun ced on the ve ntral side 1ll0sLl y due to the ac­ cumul at ion uf large number of occlusion bodies. Unlike tha t of NPV of A. a//':illsolli. th e sk in of GV in fec ted A.OIkins()ni H'as Ilot liquefied. A fter death, a characterist ic w hi te liqui d oozed out through the ski ll aft er piercing. This flu id was of the consistency or t thin cream, and contai ned large numbers or capsu les . Upon diss 'ction or a diseased larva. ex treme ly en larged and thickened fat body was noticed w hich appeared <.jui te whitc whe n compared tll the less mas­ : i ve and practically co lourless adipose tissue of the hea lthy larva . Afrer death, the illleguIllent remained rather tough and leat hery in CO lltr:lst to larvae inl"ccted with nuclear po lyhedrosi: vi rus. in which case th e integ uillent ruptured qu it e ea: ily . Exaillination (1f the tissue in wa ter mounts w ith either th e pilase-contrast or da rk rieid miclw;copc. revca led Il Ulllerous capsules emanating from thc ruptured cell~. Samples oj" occlu­ Fig. 1- Gr

susceptibility of H onlligem to hetero logous GV of II. ol /.:illSOlli evcn after passage through H (I rill igel"O . A . ot/':insf)lI i. rec ording cc nt per ce',ll mortality of th ereby co nrirll1ing th e cross inrecti vity or A. OI/':ill ­ second instal' laryae w hen admi niste rcc\ at I x I d' sOlli C\I against II. o m ligera. occ lusion/ larva through food surface contamination Generally. vi ru ses are considered to be rela­ tech nique. In contrast to hea lthy H orlllige ro larvae, ti ve ly spec ies-spec ific or at leas t havc a limited h\.) st the GV ini"ccted H wmigera be 'al11 e pu ffy and pale range.l . However. cro:..s infec tion of insect v ir u ~es be­ \vhite in co lour (Fig. 3). In order to confirlll. th e iden­ twee n close ly related as we ll as unrelated lepidopter­ tity or th e progeny of th e virus obtained rrom H ar­ an~ has bee n reported-l -(,. In this case , th e GV of lII igem larvae challenged w ith /1. atkillson; GV, 10 /1. ol/':illsolli was ro und to be cross-infecti vc to 1348 INDIAN J EXP BIOL, NOVEMBER 2003

Though the occurrence and field efficacy of A.atkinsoni NPY has been reported7.8 , this is the first report on the natural occurrence of GV on A. atkin­ soni from India. The author is grateful to the Project Director, Pro­ ject Directorate of Biological Control, Bangalore for providing the faci lities.

References I Govindan R, In sects of the field bean Lab-lab niger var lignosus Medikus with special reference to biology and ecology of the pod borer, Adislira lltkinsoni Moore (: ). M. Sc. Th es i ~ . University of Agricultural Sciences, Hebbal, Bangalore, 1974. 2 Narayanan K, Isolation, purification and inocul ation of viral pathogens. in Microbial cOlltrol alld I,est management. edited Fi g. 2 - Electron micrograph of granules of A. atkinsoni by S. Jayaraj (Tamil Nadu Agricultural University. Arul Jothi GV(x7000) Pri nters, Coimbatore) 1985. 76. 3 Ignoffo C M, Specificity of insect viruses. BIIII £ 11/0 Soc Am. H. (lrl11i gera. This can be advantageously utilized fo r 14 ( 1968) 265. the large-scale multiplication of GY in H. armigera in 4 Vail P V, Jay D L & Hunter D K, Infecti vity of a nuclear the laboratory in view of its short larval period of polyhedrosis virus fro m the alfa lfa looper. Awographn 12-14 days and large biomass (407 mg) without californica, after passage through alternate hosts. J invertt'br Pathol, 2 1 (1973) 16. undergoing any dormancy, when compared to 5 Harper J D, Cross in fectivity of six Pl usiinc nuclear A. atkinsoni which has a very long larval period of polyhedrosis virus isolates to Plusiine hosts, J inverlebr Pathol, 20-22 days with average weight of 350 mg and 27 (1976) 275. 6 6 Narayanan K, St udies on the cross-infectivity of nuclear undergoing pupal di apause . Further, since H. armigera polyhedro. is virus of Adi.l'ura atkillSoni Moore (Nocluiddc: is also found to occur and cause damage on fie ld Lepidoptera) Curr Sci, 7 (1986) 372. bean, along with A. atkinsoni the sllsceptibil ity of 7 Godse D B, Studies on in sect polyhedral viruses, Ph . D. Ih esis. H. armigera to A. atkinsoni GY ,widens the scope of Universit y of Agricultural Sciences, Hebbal, Bangalore, 1976. controlling both species vi z A. otkinsoni and 8 Narayanan K, Use of nuclear po!yhedrosis in the integrated H. armigera, occulTing on the same cropping system, control of ildiSllrll atkillsoni Moore on field bean, in Microbial control and l'esT mallugel1l elli, edi ted by S Jayaraj (Tamil Nadu by the application of A. atkinsoni GV which can be Agric ultural Un iversit y, AmI JOlhi Printers. Coimbatore) easily multiplied in H. annigera host in future. 1985,>l7.