346 NATURE July 23, 1960 VOL. 187

Immunity of to Parasites relatively thick capsules described by Salt'-6 in a A STUDY has beenbccn madmadee of the susceptibility to, or variety of different insect spspeciesecies as a result of arti• immunity from, parasitism which certain aphis fificialcial injection of eggs anda.nd larvre of the parasite exexhibithibit towards the ininsectsect M onoctonus paludum NemeritisN emeritis (Hym. Ichneumonidae) but resembles more Marshall (Hymenopt(Hymenoptera,era, BraBraconidac).conidac). Stary"Staryl, in a the thin, brown capsules ddescribedescribed by SchneiderSchneider'7 in recent revision of the European species of Monoctonus,Monoctonus, the syrphid Epistrophe balteata as a defence againsta.gainst identifies M. paludum with M. crepidiscrepidis Haliday, which the ichneumon Diplazon. The appearance of the has been recorded from various hosts on plants capsule in A. circumfleoircumflexumxum during its process of relatedrelated to lettuce. TheThe present accountaccOunt is conccrnedconcerned formation is shown in Fig. 1. only with the association between the parasitparallitee and D. C. GRIFFITHS aphids which occur on letettutuce,ce, and it has been foundfounel that although the pparasitearasite will readily oviposit into DDepartmentepartment of Zoology, thethe five species of lettucelettuce aphids which have been University of Durham, studied, successful development of the parasite can King's College, only occur in one of theseese species.species. Newcastle upon Tyne. During oviposition ththee female parasite lays a single 1 SStar~\tar~\ PP., .• AclaAela Soc. Ent. Cecko., 5666 (3), 237 (1959). egg, with precision, into the fused thoracic ganglia of • Griffiths, D. C., Bull. Ent. nes.Res. (in the press). 2 eeachach aphid, and it has bbeeneen shown that the parasite 3 FlFlanders,anders, S. E., J. Econ.Eeon. Ent., 27 (4)(4),, 861 (1934). will readily attack the following species of aphids 'Salt, G.,G., Proc. ROll.Roy. Soc., B, 144, 380380 (1955).(1 955). occurring on lettuce: NasonoviaNasonovia ribis·nigri (Mosley), •, Salt,Salt, G.,G" Proc. ROll.Roy. Soc., B, 146, 9933 (1956)(1 956) . MacrosiphumMacrosiphum euphorbiae (Thos.), Myzus persicaepersicae • Salt,Salt, G ., Proc. Roll.Roy. Soc., B, 147, 167 (1957).(1 957). (Sulz.), Aulacorthum 80lani (Kalt.), Aulacorthum 'Schneider'Schneider,, F. von, Vj8ckr. natur!.naturf. Gos.a es. Zurich, 95, 22 (1950). circucircumjlemfiexumxum (Buckton). However, of thethesese five speciesspecies of aphids only N. 1ri·ibis.nigribis.nigri supports succesuccessfulssful development of the Function of the Corpus Allatum in parasite's eggs and, in order to ddetermineetermine the reasons 'Dauer-''Dauer-pupa" of the Silkworm, for failure of parasite development in the other Bom&yx mor; species, sections and dissections of these aphids have been carried out at various time·intervals after RECENTLY it was reportedl than whenwhen the corpora attack. allata in the Eri silkworm pupre wwereere transplanted A full report of this work will be given in a sub• into artificially diapausing pupropUpl1l which were obtained sequentsequent paper. The intinterestingeresting facts which emerge by rremovingemoving their brains at ecarlyarly pupal time, the at the present time are that segmentation of the diapausing pUpal were induced to emerge in 25 days parasite egg begins normally in all the aphids studistudieded aftafterer the implantation. On ththee contrary, contrary, when the but that, in the species MacrosiphumMacrosiphum euphorbiae, corpora allata derived from the fourth, the fifth MyZU8Myzus persicae and AulacorthumAulacorthum solani, degenerative instar larlarValVal or moths of ththee same insect were trans• changes then occur which rresultesult in the shrinkage of plantplanteded into the artificiartificiallyally diapausing puppUpalre of the the parasite tissues and their subsequent disappear•disappear- Eri silkworm, most operated entered the ance at a later stagstage.e. . second pupal instar several wweekseeks after transplanta• In the species AtdacorthumAulacorthum circumjfexum,circumjfexum, however, tion. The same results were obtained in an experi• a different form of immunity reaction occurs. This ment on the Cecropia silkwormsilkworm'. 2. When the corpora 3 l'eactionreaction is contrary to the contention of Flanders , aallatallata from the Cecropia moths wwereere transplanted into who stated that cellular or phagocytic immunity doesdoes ththee diapausing puprepUpal of HyalophoraHyalophora cecropia,cecropia, the R.ot occur in aphids bbecauseecause the number of blood cells operated became ththee secondsecond pupm.pllpm. is relatively few, for, in this species of aphid, the My co-worker and I have showns3 that in Bombyx developmentdevelopment of the parasite is arrested by the secre• mori eacheaoh corpus allatum removed from the fourth, tion, around it, of a capsule formed by certain of the the fifth instarinstal' larvre,larVal, pupro and moths respectively host's blood cells. 'IhisThis capRulecapsule differs from thethe had a function which brought about imaginal development probably throuthroughgh the prothoracic gland in ''Dauer-pupre'.Dauer-pupre'. It is not known, however, whether the corpus allatum in 'Dauer-pupa'Da.uer-pupa'' of ththee silkworm, Bombyx mmori,ori , has the same functionfunct.ion in relation to imaginal diffdifferentiationerentiation as corpus allatum in normal ,larva, pupa and moth. In this communication a function of the corpus allatum in thethc 'Dauer-pupa' of ththee silkworm, Bombyx mori, is revealed. So-called 'Dauer-pupal'Dauer-puPal'' of an F, hybrid between two va.rieties, J.122 and 0.115,C.Il5, which had been obtained by extirpating the brain immediately after pupation and did not show ananyy sign of imaginal differentiation for 45 days at 25 0 C. after pupation, were usedused as as recipientsreoipients of the corpora,corpora, allata which were rememovoveded from 'Daucr-pupDaucr-pupm'm' of 45 days old as grafts.grafts. As shown in Table 1, of 20 'Dauer-pupre' grafted Fig. 1. Section through pa.rtpart of ththee thoracic nerve ganglia of Au/acortkumAulacortkum circumjtexucircumjtexum,m, 24 hrhr.. aftafterer attack by MmoctorlusM&noc/Qnus with 3 pairs of corpora aUataallato. derivodderived from the paZudum. The capsule ((C)C) is be~illllinl!beginning to form aroundarounrl ththee 'Dauer-pupro', 11II recipients became moths 17-24 parasite embryo :(E), which lilieses inIn aII space In the nervous tissuetissue of the host daydayss after operation, but the othotherllr 4 animals survived

© 1960 Nature Publishing Group