mi(irnto to ami assiiiiMr in llu' dvidiuls and osiaiu' tl[i(in;;h tlif 

 gonititl aiH'itiiro. 



Both miilo ami foiiialf tliis an' iiarasiti/.i'd. liovicn t'uniul no 

 cvidoiico that male tlios arc romliTod sterile lint the ovaries 

 of iiifeeted females fail to develop and heeause of this the 

 nematode larvae ean seareely he transferred to onion )dants 

 with the OKKs of their host. However, Rovien noted that in 

 feeted female tlies "strelehed ont the ovipositor, as if thev 

 wanted to lav eRRS-" As in tlie life eyele of Ttilt iirliiiit ma ii.i 

 ciiiilhK. infeeted female Hies prol>;ilily .•leccnnpaiiy normal fe 

 males to the plaee where eRgs are laid Imt deposit there, not 

 ogRS, bat larval nematodes. Hovien fouiul no evidenee that the 

 genitalia of male tlies are invaded ami he eonelnded tlial larvae 

 ■liave no way of eseaping from male tlies. 



The free living stages of the nematode arc passed in elose 

 assoeiation with the larval insects, cither in the onion i)lant or 

 in nearby soil. The nematodes reach maturity, copulate and the 

 males die. Impregnated females (Fig. 171! M) enter larval 

 Hies presumably by penetrating the body wall though the act 

 of penetration was not observed. The adult male has a stylet 

 with basal swellings comparable to that of the female but 

 somewhat more slender. .\11 tlirei' esophageal glands are well 

 developed in the preparasitic female but inconspicuous or lack 

 ing in the male. After entering the host a female develops into 

 the large, parasitic individual of the gamogenetic generation. 



The life cycle of //. abirrans (Kig. I7(iK therefore, consi.sts 

 of a parthenogenetic generation, passed entirely within the host, 

 alternating with a gamogenetic generation that has both para 

 sitic and free-living stages. If the parthenogenetic generation 

 was omitted the life cycle would be es.sentially the same as 

 that of most other members of this family. 



Ferousobi.v cfRRlEl (Currie, IH.'fT) n. comb. [Synonyms: 

 Anguilhilina (Fcrflii.sobia) tiimifacii nx Carrie, 1937; Anguilhi' 

 Una (Fcrijiixobia) curriei (Currie, l!t37) Johnston, 103S; not 

 AnpuilluUna Uimtfacirns (Cobb, l!i.'!2) |. 



Fcrfjusobia curriri occurs in Australia where, in association 

 with flies of the genus Fergtisonhm, it produces galls on Eiica 

 lyptus trees. This association was discovered by Morgan (lii;^3) 

 and later investigated by Currie (1937), the following ae 

 count being based on the hitter's observations. There are many 

 species of Ffrgiisoiiiiia that attack Fiirnliiptiix trees in Aus- 

 tralia and, according to Currie, all are probabl.y associated 

 with a nematode. Several species of Eiirah/ptiif: are attacked 

 and galls may be formed on leaf buds, axil buds, stem tips, 

 and flower buds, depending on the species involved. The fol 

 lowing account of the life history of FcriivKnbia curriei is based 

 on a study of flower galls on Euciiliiptii.i tnacrorrhynchia and 

 of the associated fly, Frrffusoyiiiia iiirholxonia. Currie regards 

 the stages of the nematode found in the galls as true plant 

 para.sites but is inclined to regard the relationship with the gall 

 flies as symbiosis rather than parasitism. 



Each female fly harbors two gravid female nematodes (Fig. 

 172 S). These nematodes deposit eggs and the resulting larvae, 

 on reaching the proper stage, leave the body cavity and enter 

 the reproductive system of the "host." Adult flics emerge 

 during summer and females, after mating, lay eggs in young 

 flower buds, depositing with each egg from 1 to ."lO nematode 

 larvae. The same fly or different flics may lay numerous eggs 

 in a single bud as many as 74 eggs and 227 nematode larvae 

 having been found. The larval nematodes immediately start to 

 feed on the anther primordial cells that form a ring around 

 the inner wall of the bud cavity and under this stimulus the tis 

 sue proliferates rapidly forming masses of large, thin-walled 

 parenchymatous cells full of mucilagious cell sap. The fly eggs 

 hatch in about 6 weeks and by this time masses of gall tissue 

 are already i)resent in the bud. On hatching a fly larva moves 

 in between two of these cell masses and tears out a small crypt 

 in which to lie. The larval nematodes migrate into this crypt 

 and quickly develop into adults all of which are parthenogenetic 

 females (Fig. 172 R). Apparently the nematode passes through 

 several parthenogenetic generations feeding on surrounding 

 plant cells and in no way injuring the insect. During its first 

 two instars the fly larva feeds on the viscous cell sap which 

 oozes from surrounding cells that have been punctured by nem 

 atode stylets. During its last larval instar the fly larva tears 

 down the walls of the cavity and feeds on the ruptured cells. 

 In autumn both male (Fig. 172 Q) and female nematodes 

 appear that become the adults of the gamogenetic generation. 

 This "preparasitic" female does not differ materially from the 

 female of the preceding parthenogenetic generations (Fig. 172 

 R). Both the adult male and the adult "preparasitic" female 

 have a stylet and three well developed esophageal glands. As in 

 most other allantonematids, the male does not become parasitic. 

 Jnst before pupating, if the fly larva is a female two adult, for 

 tilized female nematodes enter its body cavity, presumably by 

 penetrating the body wall. Male flies are never infected, female 

 flies invariably so. Once in the body cavity of the "host" the 



feniah' ui'malodes iiruceed in their di'VelopmeMl and, li\ tlie 

 time the fly has emerged as an adult, they :ire dipositing eggs. 

 The life cycle of Fcrriusohia curriri, therefore, consists of 

 several i);irthenogi'nelic gener.ations passed entirely outsid<' the 

 "host" alternating with a gamog<Mietic geru'ration that has 

 lioth a "freeliving" and a "parasitic" stage. If the parthe 

 migenetic generations were omitted the life I'ycle would be es- 

 sentially the sanu' as that of uu)st allantonematids. 



In the case of Frriiiixoliia curriri associated with FerfjusoiiiiKi 

 iiicliDl.ioiiia in galls of Fiicnlnptiis macrorrlninchia, only two 

 gr.ivid "parasites" are normally found in each female fly but 

 in souu' other species of Frrnu.soiiiua, usually those of larger 

 size, a female fly may harbor a gre.-iter number. As Currie sug 

 gests, further work may demonstrate that the nematodes asso 

 ciated with difTcrent species of flies are themselves specifically 

 distinct. 



Tripius (Jinnosus (Lcuckart, 1886) Chitwood, 1!135 |Syno 

 iium, Atr<icl<i)\<ma (jibhoxum (Leuckart, ]8S())1 is a parasite of 

 the dipterous insect Cccidomjiia pini (Degeer). Since the in- 

 vestigations by l-enckart (18S7'), following its original discov 

 cry in (jermauy, this nematode has not been reported else 

 where or received further study. Each infected larva of C. 

 pini usually harbors a dozen or more, sometimes as many as 

 .'lO, adult female parasites showing diffi'rent degrees of de 

 velopment. 



Eggs are laid in the body cavity of the host where they 

 hatch and where larvae (Fig. 177 E) accumulate in great num 

 bers. Leuckart could never find larvae in the alimentary tract 

 or secure other evidence that they pass out through the anus 

 and he was inclined to believe that they are liberated by the 

 death and decomposition of the insect. The extrusion of larvae 

 along with the eggs of the host when adult flies are ovipositing 

 seems to be an uninvestigated possibility. 



The free living period, passed in the soil, is of short duration 

 and in a few days after leaving the host the larval nematodes 

 have developed to adult males and females (Fig. 177 F & G). 

 Ijcuckart mentions one molt, apparently the last, but noted 

 that sometimes the cuticle shed by the male is double. After 

 copulation males die and females enter new hosts. Leuckart 

 did not determine how the young females reach the body cav 

 ity of larval flies but suggests entrance through the mouth or 

 anus as a possibility. In the light of our present knowledge of 

 this group, penetration directly through the body wall seems 

 more proliable. Fly larvae are su.sceptible to infection from 

 the time they hatch until they go into the pupal stage. 



During parasitic development of the female the uterus is 

 gradually everted through the vulva (Fig. 177 H) and develops 

 on the outside eventually forming an oval structure, somewhat 

 exceeding in size, but always firmly attached to, the body 

 proper that, in the meantime, has become greatly foreshortened. 

 The remainder of the reproductive system and part of the 

 modified intestine occupy this prolapsed uterus (Fig. 177 I). 



The effect on the host is not pronounced and when the nem- 

 atodes are present in moderate numbers fly larvae are able to 

 pupate and become adults. However. Leuckart concluded that 

 this parasite is not harmless and that heavily infected flies 

 frequently die in the pupal stage. 



Spn.*.ERUL.VRl.\ BOMBi Dufour, 1S37. This remarkable nema- 

 tode is a parasite of queen bumble bees. It has been reported 

 from several species of Bomhiis, each host usually harboring on(> 

 or, at the most, only a few adult female parasites though 

 Leuckart (1887) found 32 in one bee. Vespa rufa and V. viil- 

 f/arix have also been reported as hosts. This parasite has been 

 found in several localities in Europe and North America and is 

 apparently widesjiread. 



S. bombi, in so far as information is available, has the typi- 

 cal allantonematid life cycle. Eggs are laid and hatch in the 

 body cavity of the host and larvae, after a period of parasitic 

 development, pass out by way of the anus and enter the soil. 

 Here the nematodes reach maturity and cojiulate whereupon the 

 males die and the impregnated females enter their new hosts. 

 The free-living period, according to Leuckart, is of several 

 months' duration. 



Queen bees hibernate in the soil and Leuckart found that 

 under coniferous trees where the soil is moist and covered with 

 humus and moss is a favored place. Leuckart concluded that 

 the bees become infected in autumn when they are penetrating 

 the soil preparatory to hibernation and that this explains why 

 only queens are parasitized. Infected queens, due to retarded 

 development of the ovaries, are either unable to produce eggs 

 or produce only a few and both Schneider (188.")) and Leuckart 

 were convinced that such queens never found colonies. 



The interesting and unusual feature about this nematode is 

 not its life cycle but the morphological development of the 

 parasitic female. After entrance into the new host the body 

 of the young female undergoes little or no increase in size. 

 Instead "the uterus is everted through the vulva, carries within 



263 



