it tlic other reproductive organs as well as the modified intes- 

 tine or "fat body," and develops outside the body proper (Fig. 

 177 BD). This prolapsed uterus increases enormously in size 

 while the body proper remains a relatively minute, functionless 

 structure that may sometimes become detached (Fig. 11. "i A, p. 

 13G). 



Other Species. In addition to the species already discussed, 

 the number of allantonematids that have as yet been named 

 and described is not great and for most of these information 

 about life cycles, especially regarding free-living stages, is 

 meager or lacking. A few exceptions, however, may be noted 

 briefly. 



Bradynema rigldnm (v. Siebold, 1836) zur Strassen, LS92, is a 

 parasite of the dung beetle, Aphodiiis fimetarius (L.) and 

 Bradynema strasseni Wiilker, 1921, is a parasite of the wood- 

 boring beetle, Spondylis biiprcsloidcs (L.). These two nema 

 todes have been rather extensively investigated in Europe (zur 

 Strassen, 1892; Wulker, 1923) though the free-living stages of 

 B. rigldnm are still imperfectly known. Both have the typical 

 allentonematid life cycle, larvae passing out of the hosts by 

 way of the anus. 



Souardula benifftia Cobb, 1921, is a parasite of the cucumber 

 beetle, Diahrotica vittata (Fab.) and, less commonly, of the 

 related beetles, D. trivittata (Mann) and D. di(odcciinpuncta1a 

 (Fab.). This nematode has the typical allantoiiematid life cy- 

 cle, larvae passing out with the eggs of the host (Fig. 178). 

 Beetles of both sexes are infected and the fate of larvae that 

 find themselves in male beetles is not known. Cobb (1928) was 

 of the opinion that these larvae may be transferred to female 

 beetles during copulation. He found considerable numbers of 

 larvae in the proximal end of the male genitalia but was un- 

 able to demonstrate experimentally that such larvae are ac- 

 tually transferred to female beetles. 



In the genus Aphclenchuliis the adult, parasitic female is 

 usually characterized by being curved dorsad with the vulva 

 on the outside of the curve. A. diplogaster (Linstow, 1890), 

 Filipjev, 1934 (Fig. 172 P) is a parasite of the bark beetle, 

 Ips typographus (L.) and A. tomici Bovien, 1937, is a parasite 

 of the bark beetle, Pityogenes bidenlalus (Hbst.) (Syn. Tomi- 

 ciis bidens (F.)). These two nematodes are very closely related 

 and both have the typical allantonematid life cycle, larvae pass- 

 ing out of the host by way of the anus (Fuchs, 1915; Bovien, 

 1937) to undergo free-living development in the frass of the 

 beetle galleries. 



■' Tylenchus" aptini Sharga, 1932, was found in Scotland, 

 where it is a parasite of the thrips, Aptinothrips rufiis (Gme- 

 lin). Eggs of this parasite are deposited in the body cavity 

 of the host and larvae leave by way of the anus. Males remain 

 in the host until bursa, spicules and gubernaculum arc formed 

 and Sharga (1932), finding no evidence that males enter the 

 gut or pass out through the anus, suggests that copulation 

 takes place before the parasites leave the host. Furtliermore, 

 Sharga states that "after several ecdyses the mature female 

 stage is reached" and his discussion and drawings seem to in- 

 dicate that one or more of these ecdyses take place after the 

 female has passed through the free-living stage and entered a 

 new host. If copulation takes place before this parasite leaves 

 the first host and the female molts after entering the second 

 host, the life cycle is, indeed, a departure from that known for 

 any other allantonematid. 



Parasitylenchtis dif:par (Fuchs, 191:1) Mieoletzky, 1922, sub- 

 species, typographi (Fuchs, 1915) is a parasite "of the bark 

 beetle, Ips 1 ypographiis (L.). In general this nematode has the 

 typical allantonematid life cycle. The adult, parasitic female 

 gives birth to larvae, large numbers of which accumulate in 

 the body cavity of the host to eventually enter the gut and 

 pass out through the anus. In one respect, however, the life 

 cycle differs from that of most allantonematids. After com 

 pleting free-living development young adults of both sexes enter 

 the new host. One finds in the body cavity of infected beetles 

 200 to 300 adult parasitic females (Fig. i72 U) and an even 

 greater number of adult jiarasitic males (Fig. 172 T). 



Fuchs (1915) did not observe copulation or determine 

 whether it takes place before or after entering the new host. 

 However, he was able to rear to maturity larvae taken from 

 the rectum of a beetle, the adult stage being reached in 7 to 

 10 days. The experimentally reared females did not lay eggs 

 and it seems probable that eggs are not laid until after en- 

 trance into a new host. If this is true we have, not a free- 

 living generation, as Fuehs called it, but a free-living stage. 



Ostensibly, Tripiii.\ gibbositf: and Sphaenilaria hombi are the 

 only members of the Sphaerulariinae that have as yet been re- 

 ported. It may be noted, however, that Fuchs (1929) has de- 

 scribed two very unusual nematodes from bark beetles, viz., 

 "Tylenchus sulplnirriis picear" and "Tylenchus siilphiireiis 

 pini." Fuchs maintained that in the case of these two nema- 

 todes the gravid female is not a prolapsed uterus basing his 



contention, in part, on a failure to find any vestige of the body 

 proper or transitional stages showing the uterus in the process 

 of prolapsus. But in (he case of Sphaenilaria bombi, as Leuck- 

 art points out, the body proper is sometimes detached and one 

 wonders if Fuehs' material included a sufficiently complete 

 series of developmental stages. If the gravid female of ' ' Ty- 

 lenchus siiiphnreiis picear" (Fig. 177 J) is not a prolapsed 

 uterus its resemblance to the gravid female of Sphaerularia 

 hiinibi is, to say the least, very renuirkable. 



Fig. 178. EOWARDVLA BESHI.\S 



Showing relative size of beetle. Diabrotvja vittattt, and of its par.i- 

 ?'ites (line XY indicates actual length of beetle) : also egg of beetle and 

 larval nematodes deposited with it. After Cobb, 1921. 



Bibliography 



AOKERT, J. E. and W.\dley, F. M. 1921. — Observations on the 

 distribution and life history of Ccphalobium microbivorum 

 Cobb and of its host, Gryllus assimilis f^abriciiis. Tr. Am. 

 Micr. Soc, V. 40(3) :97-il5, l.j figs. 



Alicata, J. E. 1934. — Observations on the period required for 

 Ascaris eggs to reach infectivity. Proc. Helm. Soc, Wash., 

 v. 1(1) :12. 



Barthelemt, a. 1858. — Etudes sur le developpement et les 

 migrations d'un nematoide parasite de 1 'oeuf de la limace 

 grise. Ann. Sc. Nat., Zool., 4. s., v. 10(1) :41-48, pi. 5, figs. 

 8-15. 



Bovien, Prosper. 1932. — On a new nematode, Scatonema 

 wiillccri gen. et sp. n. parasitic in the body cavity of Sca- 

 topse fiiscipes Meig. (Diptera nematocera). Vidensk. Medd. 

 Dansk. Naturh. Foren, Kj0benhavn, v. 94:13-32, figs. 1-7. 

 1937. — Some types of association between nematodes 

 and insects. Ibid., v. 101:1-114, figs. 1-31. 



Claus, C. 1868. — Beobachtungen iiber die Organisation nnd 

 Fortpflanzung von Leptodera appeiidiciilata. Schrift. Ge- 

 sellsch. Befbrd Ges. Naturw. zu Marburg, Suppl. Heft 3, 

 24 pp., 3 pis., 31 figs. 



Caullert, M. and Comas, M. 1928. — Le determinise du sexe 

 chez un nematode {Paramermis contorta), parasite des 

 larves de chironomes. Compt. Rend. Acad. Sc, Paris, v. 

 186:646-648. 



Chitwood, B. G. and Chitwood, M. B. 1937. — Snails as hosts 

 and carriers of nematodes and Nematomorpha. Nautilus, 

 Quart. J. Devoted to Interests of Conchologists, v. 50(4): 

 130-135. 



Christie, J. E. 1929. — Some observations on sex in the mer- 

 mithidae. J. Exper. Zool., v. 53(1) :59-7fi, figs. 1-5. 



1936. — Life history of Agamerniis decaiidata, a nema- 

 tode parasite of grasshoppers and other insects. J. Agric. 

 Res., V. 52(3):161-198, figs. 1-20. 



1937. — Mermis snbnigrcscens, a nematode parasite of 

 grasshoppers. Ibid., v. 55(5) :353-364, figs. 1-6. 



Christie, J. R. and Chitwood, B. G. 1931. — Chnndronema pas- 

 salt (Leidy, 1852) n. g. (Nematoda), with notes on its life 

 history, j. Wash. Acad. Sc, v. 21(15) :356 36^, figs. 1-17. 



264 



