A species of egg parasitoid tentatively identified as Trichogramma papilionis Nag. was found attacking egg

masses of Ostrinia furnacalis Guenee. The life cycle of the parasitoid was completed within 9 days; the egg, larval

and pupal stages lastedfor 2,4 and 3 days, respectively. The female: male sex ratio was 3:1, higher than the usual

2:1 sex ratio for Trichogramma spp. Superparasitism was observed whereby 3 individuals were produced from one

. host egg. All eggs were parasitized in 4 days at 2:1 (host: parasitoid) ratio. The female parasitoid showed a high

degree of searching efficiency and normally parasitized all eggs in a batch before continuing her search for the next

egg batch. The female spent 40% of the time searching on the upper surface of a maize leaf, 30% on the lower

surface and 30% on the leaf edges. The female searching and parasitization behaviour followed the Type III

functional response curve. The female parasitoid showed positive response to the odour ofthe maize leaf, indicating a

possibility that a kairomone or contact communication chemical is involved. T. papilionis appeared to be a very

efficient egg parasitoid of O. furnacalis and a good candidate for a biological control programme of the pest

Hussein, Mohd Yusof

Schiltuzen, M.

Yahya, H. J.

Universiti Putra Malaysia Institutional Repository

Pertanika J. Trop. Agric. Sci. 19(2/3): 111-116 (1996)ISSN: 0126-6128© Penerbit Universiti Pertanian MalaysiaANew Egg Parasitoid for Possible Biological Control of theAsiatic Maize Borer in MalaysiaM.Y. HUSSEI ,H.J. YAHYA and M. SCHILTHUZENPlant Protection DepartmentFaculty of AgricultureUniversiti Pertanian Malaysia43400 Serdang, Selangor, MalaysiaKeywords: parasitoid, Asiatic m.aize borer, biological control, Trichogramma papilionis,Ostrinia furnacalisABSTRAKSatu spesis parasitoid teluryang telah dikenalpasti sebagai Trichogramma papilionis Nag. menyerang kelompoktelur Ostrinia furnacalis Guenee. Ianya merupakan parasitoid telur tunggalyang ditemui sepanjang masa kajian.Edaran hidup parasitoid ini disempurnakan dalam masa 9 hari dengan 2, 4 dan 3 hari diperingkat telur, larva danpupa. Nisbah seks (betina:jantan) ialah 3:1 yang mana didapati tinggi daripada nisbah 2:1 yang biasanyadiperolehi bagi Trichogramma spp. Superparasitisme telah dapat diperhatikan dimana 3 individu telah dihasilkandari sebiJi telur perumah. Semua telur boleh diserang dalam masa 4 hari pada nisbah 2:1 (hos:parasitoid).Parasitoid betina m..enunjukkan kecekapan memburu pada tahap yang tinggi dimana ianya akan menyerang kesemuatelur dalam sesuatu kelompok sebelum menyambung pemburuan. Parasitoid betina menggunakan 40% daripadakeseluruhan masa untuk memburu dipermukaan atas daun jagung, 30% dipermukaan bawah daun dan 30%dipinggir daun. Kelakuan parasitoid ketika memburu dan menyerang hos menuruti geraf respon 'Junctional" jenisIII. Parasitoid betina menunjukkan respon positif terhadap bauan daun jagung menandakan kemungkinan adanyapenglibatan stdenis kairomon atau kimia komunikasi kontak. T. papilionis adalah dianggap stdenis parasitoid teluro. furnacalis yang amat berkesan dan calon baik untuk program kawalan biologi perosak.ABSTRACTA species of egg parasitoid tentatively identified as Trichogramma papilionis Nag. was found attacking eggmasses ofOstrinia furnacalis Guenee. The life cycle of the parasitoid was completed within 9 days; the egg, larvaland pupal stages lastedfor 2,4 and 3 days, respectively. Thefemale: male sex ratio was 3:1, higher than the usual2:1 sex ratio for Trichogramma spp. Superparasitism was observed whereby 3 individuals were producedfrom one. host egg. All eggs were parasitized in 4 days at 2:1 (host: parasitoid) ratio. Thefemale parasitoid showed a highdegree of searching efficiency and normally parasitized all eggs in a batch before continuing her search for the nextegg batch. The female spent 40% of the time searching on the upper surface of a maize leaf, 30% on the lowersurface and 30% on the leaf edges. The female searching and parasitization behaviour followed the Type IIIfunctional response curve. The female parasitoid showed positive response to the odour of the maize leaf, indicating apossibility that a kairomone or contact communication chemical is involved. T. papilionis appeared to be a veryefficient egg parasitoid of O. furnacalis and a good candidate for a biological control programme of the pest.INTRODUCTIONThe Asiatic maize stem borer, Ostriniafurnacalis Guenee (Lepidoptera: Pyralidae)generally can be controlled by the applica-tion of insecticides (Hussein and Kameldeer1988). With the growing interest in theimportant role of biological agents (pre-dators, para~itoids and p':lthogens) inintegrated pest management PPM) pro-grammes, in 1988 U niversiti PertanianMalaysia (UPM) started research on thenatural enemies of O. furnacalis to evaluatethe possibility of using parasitoids as amajor component in its management.M.Y. HUSSEIN, H.J. YAHYA AND M. SCHILTHUZENAmong its parasitoids are a larval-pupalparasitoid, Brachymeria lasus Walker (Hy-menoptera: Chalcididae) and a larvalparasitoid, Xanthopimpla stemmator Thun-berg (Hymenoptera: Ichneumonidae)(Hussein et al. 1983). An egg parasitoid,identified as Trichogramma papilionis Nag.(Hymenoptera: Trichogrammatidae), wasrecently found parasitizing eggs of O.furna-calis in the maize field at Serdang, Selangor(H ussein and Ibrahim 1992). It wasconsidered that the parasitoid might be asuccessful control agent. This paper reportsvarious biological studies carried out on theparasitoid.MATERIALS AND METHODSLife HistoryA study was carried out to determine thedevelopmental period of the egg, larval andpupal stage of the parasitoid. Twenty-fourhours after oviposition, eggs of O. furnacaliswere individually reared and exposed to theparasitoid. Four days after oviposition, 100eggs of the parasi toid were observedthrough the larval and pupal period ofdevelopment in the laboratory at 25 ± 3°Cand 60 ± 10% R.H.LongevityLongevity and mortality rates of theparasitoids were determined, comparingadults fed with (1) sucrose and water, and(2) water only. Fifty adult parasitoids wereincluded in the test. The numbers of liveand dead parasitoids were recorded daily.Sex RatioThe sex ratio of the parasi toid wasdetermined by rearing' individuals on eggsof O. furnacalis until the adults emerged. Atotal of 700 eggs were parasitized and keptfor observation. The adults emerging fromthe host were immediately sexed, based onantennal morphology (Pak and Oatman1982) .SuperparasitismA total of 100 24-h-01d eggs of the host wereexposed to allow maximum parasitism byT. papilionis inside a large closed petri dish(15 cm diameter) for a period of 4-5 days.The eggs were left in the laboratory untilpupation of the parasitoid occurred. Eachhost egg was then dissected and the numberof parasitoids present was counted.Maximum Parasitization .Twenty different sized batches of host eggswere each exposed to a single newly matedfemale parasitoid in a closed plastic petridish. The number of eggs parasitized wasrecorded daily for 5 days until all the eggshad been parasitized. The sequence ofparasitizing individual eggs was recorded.Host: Parasitoid Ratio and Parasitization RateThe relationship of host:parasitoid ratio tothe rate of parasitization was determinedusing a factitious host egg of Corcyracephalonica under laboratory conditions.The number of host eggs was 5, 10, 14,20and 25. Regression analysis was performedon the data.Functional ResponseEggs of the factitious host, C. cephalonica,were glued on pieces of 3 x 3 cm paper cardin a regular pattern. Seven different hostdensities were tested: 1, 5, 9, 22, 36, 72 and108 eggs per 9 cm2 with 10 replications.The eggs were then placed in a closedplastic petri dish (5 cm diam). A singlenewly mated T. papilionis was released intoeach dish for 5 h. The parasitoid was thenremoved and the dish left for another 4days, after which the number of parasitizedeggs was counted. The data were fitted toHolling's Type III model of functionalresponse (Holling 1965).Searching BehaviourThe preference of the parasitoid to search112 PERTANlKA J. TRap. AGRIC. SCI. VOL. 19 NO. 2/3, 1996A NEW EGG PARASITOID FOR POSSIBLE BIOLOGICAL CONTROL OF THE ASIATIC MAIZE BORERfor its host on either the upper or lowersurface of the maize leaf was measured. Afreshly picked maize leaf blade wasstretched horizontally between two verti-cal wooden sticks and illuminated fromabove with strong fluorescent light. Onefemale parasitoid was released at the centreof the leaf. Several aspects of behaviour andpositioning were recorded and timed usinga stopwatch.KairomonesFour extracts were assessed for attractive-ness to adult parasitoids. Two wereprepared by soaking eggs of O. furnacalisin hexane and methanol respectively for atleast 6 hours. The other two from scales ofthe moth, similarly soaked in hexane andmethanol, were then filtered. Bioassay testsusing a petri dish were run following themethod described by Jones et al. (1973).Olfactometery tests were also carried outusing a glass Y-tube (Schilthuizen 1989).RESULTS AND DISCUSSIONThe developmental period of T. papilionisfrom egg stage to adult emergence was 9days. The egg, larval and pupal stageslasted for 2, 4 and 3 days, respectively.These periods are quite close to those ofT. australicum (8 days) but differ from thoseof T. minutum (6 days) and T. fasciatum (6days) (Metcalf and Breniere 1969). Thedevelopment period of Trichogramma speciesin general is very similar (Metcalf andBreniere 1969).In this study, the sex ratio variedaround 3:1 (female:male). The females arealways predominant. Usually, the sex ratiofor Trichogramma species is 2: 1. T. papilionis,in this study, follows the biparental andarrhenotokous mode of reproduction. Thelongevity of unmated female T. papilioniswas 9-10 days when fed on sucrose andwater. Females lived for only 3 days whenfed on water alone.Superparasitization was observed inT. papilionis parasitizing eggs of O. furna-calis; as many as three individuals wereproduced from one host egg. The phenom-enon is common to all Trichogramma species.In general, the number of both hostsparasitized and the number of progenyincrease initially with increasing hostdensity but level off after reaching athreshold (Pak and Oatman 1982).In the laboratory the parasitoid wasable to parasitize all the maize stem borereggs presented in a batch as it often does inthe field. In this study, the maximumparasitization rate was achieved in 4 daysregardless of the size of egg batch as long asthe ratio was kept at 2: 1 (host:parasitoid).The rate of parasitization rapidly increasedat lower host ratios (Fig. 1). No parasitiza-tion was observed at 5: 1 ratio if only 5 eggs/batch were presented. At 10 eggs/batch ormore and at 3:1 ratio only 10-20%parasitization occurred. Pak and Oatman(1982) found the rate to be lower if older(> 36-h-old) host eggs are used. In thisstudy, the host eggs used were < 36-h-old.Not all egg parasitoids are adapted toparasitizing host eggs that are laid inbatches. T. papilionis, as shown in thisstudy, is very efficient in parasitizingbatches of O. furnacalis eggs in the labora-tory as well as in the maize field. When theoviposition behaviour was traced egg byegg in different batch sizes, a regularpattern was discerned (Fig. 2). Uponencountering an egg batch, the femaleparasitoid first parasitizes all the eggsbefore continuing her search for anotherbatch. Burbutis et al. (1983) also observedthe same behaviour when T. nubilaleparasitized eggs of the European cornborer, Ostrinia nubilais.The female parasitoid spent 40% of hersearching time on the upper surface of themaize leaf, 30% on the lower surface and300/0 on the edges of the leaf. MostPERTANIKA J. TROP. AGRIC. SCI. VOL. 19 NO. 2/3, 1996 113M.Y. HUSSEIN, H.J. YAHYA AND M. SCHILTHUZEN•••1.81.61.4r2 = 0.6101.20.8••0.6•••0.40.2oo120100c: 800:;~'iii60~asa..~04020Host: Parasitoid RatioFig 1. Effect of host-parasitoid ratio on percentage parasitization of Ostrinia furnacalisby Trichogramma papilionis13Eggs27Eggs16Eggs33EggsFig 2. Sequence of egg parasitization by Trichogramma papilionis on the different sized clusters ofOstrinia furnacalis eggs114 PERTANIKA J. TRap. AGRIC. SCI. VOL. 19 NO. 2/3, 1996A NEW EGG PARASITOID FOR POSSIBLE BIOLOGICAL CONTROL OF THE ASIATIC MAIZE BORER3530'g 25.JiC(J~<20II)ClClWco 15o::I:'0i 10.0E~ 510 20 30 40 50 60 70 80 90 100 110Number of Host Eggs PresentFig 3. Functional response of Trichogramma papilionisTrichogramma species generally prefer tosearch the more exposed parts of the plant(Metalf and Breniere 1969; Vinson 1976).Parasitoid searching behaviour was furtherelucidated by the Type III functionalresponse curve (Fig. 3). The sigmoidresponse curve confirmed the observationmentioned earlier that at low host densitysome female parasitoids may find it difficultto encounter any eggs after a certain periodof time and react by stopping their search.Several egg parasitoids use kairomonesto guide them while searching for host eggsin the field. In this study, attempts todemonstrate the presence of semiochemicalson the egg surface or moth scales did notproduce a positive result from adultT. papilionis that could be detected usingthe petri dish method. However, using theY-tube olfactometer, the female parasitoidshowed some response to the odour of maizeleaf. Whether a kairomone or a contactchemical was involved remains to beinvestigated.CONCLUSIONTrichogramma papillionis can be rearedsuccessfully on eggs of C. cephalonica, in theabsence of eggs of O.furnacalis. In Serdang,it parasitizes high numbers of egg masses,and almost no egg escaped parasitization.The parasitoid is well adapted to a hostthat produces egg masses instead of singleeggs. A type III functional responseindicates that relatively more hosts areattacked at high host densities. Thechemical communication aspect of theparasitoid searching behaviour needsfurther investigation and is crucial indeveloping techniques to increase thesuccess of parasitization in the field.ACKNO~EDGEMrnNTSThe authors wish to thank the Ministry ofScience, Technology and Environment forproviding the research grant under IRPAProgramme Project No. 1-07-05-052.PERTANIKA J. TROP. AGRIC. SCI. VOL. 19 NO. 2/3, 1996 115M.Y. HUSSEIN, H.J. YAHYA AND M. SCHILTHUZENREFERENCESBURBUTIS, P.P., B.W. MOORE, D. MORRIS andG. BENZON. 1983. Trichogramma nubilaleprogeny distribution and superparasitism inEuropean corn borer. Environmental Entomology12: 1587-1589.HOLLI G, C.S. 1965. The functional response ofinvertebrate predators to prey density. Mem-oirs Entomological Society of Canada 48: 20-26.HUSSEIN, M.Y. and M.B. IBRAHIM. 1992. A lifetable of the Asiatic maize borer Ostriniafurnacalis Guenee. Pertanika 15: 27-30.HUSSEIN, M.Y. and A.K. KAMELDEER. 1988. Afield study on the oviposition of Ostriniafurnacalis Guenee (Lepidoptera: Pyra1idae)on maize in Selangor, Malaysia. Tropical PestManagement 34(1): 44-47.HUSSEI , M.Y., A.K. KAMELDEER and N.M.AHMAD. 1983. Some aspects of the ecology ofOstrinia furnacalis Guenee on corn. MAPPSNewsletter 7(2): 11-12.JONES, R.L., W.J. LEWIS, M. BEROZA, B.A.BIERL and A. . SPARKS. 1973. Host seekingstimulants (kairomones) for the egg parasite,Trichogramma evanescens. Environmental Entomo-logy 2: 593-596.METCALF, J.R. and J. BRE IERE. 1969. Eggparasites (Trichogramma spp.) for control ofsugar cane moth borers. In Pests of Sugarcanep. 81-115. Amsterdam: Elsevier.PAK, G.A. and E.R. OATMAN. 1982. Biology ofTrichogramma brevicapillum. Entomologia Experi-mentalis et Applicata 32: 61-67.SCHILTHUIZEN, M. 1989. Searching behaviourand searching efficiency of Trichogrammapapilionis Nag. (Hymenoptera: Trichogram-matidae). Unpublished research report. Fa-culty of Agriculture, U niversiti PertanianMalaysia.VINSON, S.B. 1976. Host selection by insect para-sitoids. Annual Review of Entomology 21: 109-133.(Received 17 December 1994)(Accepted 1 October 1996)116 PERTANIKA J. TRap. AGRIC. SCI. VOL. 19 NO. 2/3, 1996

A new egg parasitoid for possible biological control of the asiatic maize borer in Malaysia

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A new egg parasitoid for possible biological control of the asiatic maize borer in Malaysia

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