In a survey in India in 1980-81, parasitism of Melanagromyza obtusa (Mall.) on pigeon pea [Cajanus cajan] (by Euderus spp., Ormyrus sp., Eurytoma sp. (less common than the 2 preceding) and Antistrophoplex sp. (least common)) averaged 0-20.6% at different places in different month

Rao, V R

Reed, W

Sithanantham, S

ICRISAT Open Access Repository

The wasps were seen to drink water and then regurgitate onto the soil to make a small mud ball. The mud ball was then carried between the fore legs and mouthparts to a solid sur­face and used for the construction of the cells making up a "nest." In the cage the nests were built on the metal cage supports while in the fields they were found on rocks, trees, and buildings. A single drink of water appeared to be sufficient for the preparation of two or three mud balls and five or six balls were generally required to construct each ce ll. In the cage the nests consisted of five to eight cells but in the fie ld  there were up to 16 cells in a nest. Most nests found in the fie ld  were constructed with red s o il.After each cell was constructed, the wasp collected larvae and placing four to seven of them in each ce ll. The larvae were paralyzed by stinging, pressed between the mandibles and then carried to the nest. A single egg is laid inside each ce ll, before or after the f irs t  larva is entered. After f il l in g , each cell is then sealed. Only the female wasps built cells and collected larvae, the males appeared to have no role except in mating.The field-collected adult wasps were fed with honey solution in our cage and they lived for up to 67 days after capture. In the fie ld  we have observed them apparently feeding upon the nectar of flowering plants, includingVernon-ici sp. Each female construc­ted and f ille d  more than one mud nest. The time taken from cell closure to emergence of the young adult from the cell varied from 34 to 48 days for D. pyriforme and 30 to 40 days for D. oonoideisn.The D. aampanifome esuviens wasps in our cage were not successful in reproduction, because ants fed on the cell contents before the adult wasps could emerge. We also re- corded predation by ants in nests in the fie ld . In addition we found that the para­sites, Chxysis fuscipem-ia Brulle, Chrysis quaepita Nurse, and StiThum oyani&um (Fors­ter) emerged from the cells of D. concideum and D. pyrifoms having fed upon either the lepidopteran larvae and/or the wasp larvae.The adults of these parasites were seen to follow the female wasps while they were con­structing their nests. These elements ob­viously lim it populations of wasps and hence the level of predation on Heliothis  larvae.I t  is also probable that the activity of wasps is limited by the nonavailability of water.Possible means of increasing the activityof these predatory wasps in pigeonpea fields would be to provide sources of water, and nesting sites protected from ants. However, the long generation time and the high level of parasitism would appear to impose s tr ic t limitations on the natural increase of popu­lations and consequently the value of these wasps in H&liothis control.We are grateful to Dr. V.S. Bhatnagar for laying the foundations for this stuc(y and to the Commonwealth Institute of Entomology for identifying the insects.ReferenceBHATNAGAR, V.S. 1981. Cropping Systems (Entomology) Progress Report-8. Interna­tional Crops Research Institute for the Semi-Arid Tropics, Patancheru, A.P.,India, pp.7-21.-  C .S . Pawar and D .R .  Jadhav (ICRISAT)Survey of Pigeonpea Podfly Parasites in IndiaJhe podflyj-i-Me&aft&g#emy-za dbtuaa* i s—an~Tmpor- tant pest of pigeonpeas in India. . This pest is d ifficu lt to study in the fie ld  since most of Its  l ife  stages (egg, larva/and pupa) are concealed inside the pod. At ICRISAT. we are. searching for varietal resistance to this pest and investigating other means of control.In order to assess the potential for biolo­gical control of this pest we initiated a survey to determine the natural incidence of parasitism that occurs across India. Earlier reports listed two species of Eudsrus occur­ring as parasites of the podfly (Ahmad 1940; Gangrade 1960). Our collections of podfly larvae and pupae at ICRISAT Center from 1977 to 1980 revealed three more parasites, Omy- i*ub sp, Euxytoma sp, and Antistxophoplex sp. The f irs t  two of these were also reported from this podfly in Sri Lanka (Fellowes and Amarasena 1978). However, taxonomists of the Commonwealth Institute of Entomology (C IE ), London, and the Indian Agricultural Research Institute (-IARI), Delhi, warned us that Ovmy- rus spp are generally involved in forming plant galls and some iSuryboma spp feed on seeds, so they' suggested we should check that these insects were in fact parasitic.. We therefore conducted further observations dur­56ing the 1980-81 season at ICRISAT Center and confirmed that both the Ormyrus sp and Enry- tom  sp eme_rged from the puparia of the podfly and so are clearly parasitic or hyperparasitic.We also conducted a preliminary survey dur­ing 1980-81 to record the occurrence of these parasites in other areas of India. We collec­ted pods from some areas and received pods from other areas through cooperation of the entomologists in the All India Coordinated Pulses Improvement Project (AICPIP). We re­corded the numbers of larvae and puparia inthese pods and the emergence of parasites from these in our laboratory. The results of this survey (Table 1) indicated that Ormyrus sp might be as widespread and common as Eudsrus spp; Euxytoma sp was less commons and Anti- stvopholex sp was rare.More extensive surveys in collaboration with AICPIP entomologists are in progress in 1981-82 to study the regional and seasonal incidence of these natural enemies of podfly. We are grateful to the taxonomists, Drs. SubbaTable 1. Summary of the pigeonpea podfly parasitism survey in India, 1980-81.STATE/1ocation (Cooperator) MonthPodfly larvae-puparia Observed ParasitisedParasi- 'v tfsm ($)Parasitesobserved3HARYANAHissar NovemberJanuaryMarch255354077~5~422.7"14.310.3A,B ,CB,C B,CbKARNATAKABangalore(M. Vishakantaiah)December 218 45 20.6 A,B,CbMAMYA.PRADESHGtoalior DecemberMarch44247613702.9 --- >4.7A#B.CbB»CbPUNJABLudhiana(K. S . Chhabra).December 25 2 8.0 B,CTAMIL NADUVamban(C. Ramakrishnan)February 258 4 1.6 BUTTAR' PRADESHNainital (V.K. Sehgal)April 685 11 1.6 B,CbKanpur (S.S. Lai)DecemberApril3464221273.51.7CB,CVaranasi (A.R. Reddy)February 49 0 0.0a. A = Euvytoma sp (Eurytomidae: Hym)B = OrmyruB ? Orientalis (Ormyridae: Hym) C * Spp {Eulophidae: Hym)b. Dominant parasite.67Rao, Gauld, and Boucek of CIE and Dr. S1 dd1 qui of IA R I, and a ll other cooperators in India for their advice and assistance in th is stucly.ReferencesAHMAD, T, 1940. On the biology o f Euderus lividaa (Ashm), a parasite of Agromyza obtusa Mall. Indian Journal of Entomology 2: 59-63.FELLOWES, R.D., and AMARASENA, I .  1978. National Parasites of some major grain legume pests in the dry zone. Tropical Agriculturist 133(2).GANGRADE, 6.A. 1960. Description of a new species of the genus, Euderus Hall day, 1884, (Eulophidae: chalcidoidea). Indian Journal of Entomology 22: 80-82.The podwalls of more susceptible cultivars had a s ign ifican tly  lower concentration of total soluble sugars than the less suscepti­ble cu ltivars and a narrower ratio of sugars to nitrogen, but there were no sign ificant differences in total nitrogen and total poly­phenol contents between the two groups (Table 1). These results suggest that a detailed analysis of the various sugars in the podwall of more and less susceptible cultivars may be useful. Pods from ‘washed1 terminals had s ign ifican tly  lower concentrations of a ll three constituents in the ir w alls, than the 'unwashed' ones. The re lative role of the individual constituents inhibiting oviposition in the 'unwashed' pods w ill have to be asses­sed through bioassay tests.tWe also analyzed the chemical contents of the podwalls of pods at different stages of- S .  Sithanantham , V. Ramashwar Rao, and W. Raed (ICRISAT)Differences of Some Chemical Constituents of Pigeonpea Podwalls in Relation to Podfly SusceptibilityThe differences, in susceptib ility of pigeon­pea cultivars to podfly, Melanagrortvjza obtusa, are being studied at ICRISAT. Some morpholo­gical and anatomical characters of the podwall are probably associated with differences in susceptib ility to this pest and water sprays on the fru iting  terminals have been found to Induce greater ov1position in several c u lt i­vars (Sithanantham et a l . 1980). Here we present our preliminary observations on some :hemical constituents o f the podwall 1n re- ation to po_dfly suscep tib ility , based on oint work done by the pulse entomology and iochemistry units at ICRISAT during 1979-81.Me sampled the pods in several cu ltivars, at were known to d iffe r in the ir suscepti- l i t y  to podfly infestation, from the rainy ison plantings in pesticide-free fie lds of tISAT during 1979-81. These samples inclu- those from water-sprayed ("washed'1) and trol ( “unwashed") terminals. The pods ? opened, seeds removed and the podwalls 1 then dried in an oven at about 65°C, nd into fine powder and analyzed for r content of total nitrogen, total solu- ;ugars and total polyphenols.Table 1. Summary of biochemical comparison "o f pigeonpea podwall composition 1n relation to podfly susceptibi­l i t y ,  ICRISAT Center, 1979-81.Constituents on dry weight basis— --- -------------  *  -------------- --®♦I-** c  o  o>C  » i/i 0  4) CL £CO a> w*i“-  i—  S- O  O  i—(B ttf fO ^  <T5 t/l+J 4:  9  4-> -M 4-> 1—.O  0  3  <5 -r -  ©  Ot— CO K  C. H  CPodfly susceptib ility (36 reps/treatment)Less susceptible 2.64 4.16 1.58 73.7More susceptible 2.64 3.43 1.32 75.2CD (5%) NS 0.67 0.26 NSEffect of pod 'washing'Mashed pods 2.62 3.50 1.35 66.7Unwashed pods 2.66 4.08 1.55 82.1CD (5%) 0.03 0.17 0.06 7.2

Survey of pigeonpea podfly parasites in India

http://oar.icrisat.org/7426/1/IPN_2_66-68_1983.pdf

Survey of pigeonpea podfly parasites in India

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