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Very few nematode species are honey bee parasites.16 There are no records of nematodes that live freely in bee colonies and attack the honey bees therein.17 Those that have been found in forager bees are usually nematodes of the Mermithidae family.15

Spodoptera frugiperda invaded in India at the end of 2018 and has caused severe damage to maize including other crops. Several S. frugiperda naturally parasitized by nematodes were observed in Nauni, Himachal Pradesh, India. The morphological features based on the results of scanning electron microscopy indicated that the nematode belongs to the family Mermithidae. Furthermore, characters discovered that the nematode belongs to Ovomermis sinensis, a known entomoparasitic nematode. Our finding was the first record that S. frugiperda, was naturally parasitized by O. sinensis. The results of this study are of great importance for potential biological control of S. frugiperda by indigenous natural beneficial organisms, i.e., O. sinensis within an integrated pest management system.

Pesticide susceptibility tests against preparasitic (infective stage) Romanomermis culicivorax Ross and Smith (= Reesimermis nielseni Tsai and Grundmann, auct., partim.) indicated that 24-h exposure to abate (0.001 ppm), malathion (0.100 ppm), baytex (0.003 ppm), dursban (0.001 ppm), Dimilin® (0.005 ppm), and Altosid® (0.005 ppm) produced no apparent detrimental effects to the viability and infectivity of R. culicivorax preparasites, or to the viability of the resulting postparasites. However, concn of 0.0035 and 0.004 ppm baytex, and 0.004 ppm dursban resulted in significantly lower preparasite infectivity when compared to controls, even though acute mortality of preparasites was not evident at these concentrations.

EARLY reports of virus infections of nematodes remain unconfirmed1,2, although more recently virus-like particles were reported occurring in the intestinal cells of a plant-parasitic nematode3. The only confirmed reports of viruses found inside nematodes are plant viruses which occur in the digestive tracts of their nematode vectors4. We report here the presence of virus-like particles in cells of the infective stages of the mosquito parasitic nematode, Romanomermis culicivorax.

A gravid female Mermis nigrescens Dujardin (Mermithidae: Nematoda) was recovered from the mouth of a 1-month-old infant in Mehama, Oregon. This nematode is a parasite of grasshoppers and deposits its eggs on vegetation. The parasite was probably carried on the hair of the household dog or cat to the vicinity of the patient and was attracted to the moisture in the region of the mouth.

Black flies are commonly infected by pathogenic species or Microsporidia, Mermithidae, and the fungal parasite Coelomycidium simulii . One of the first significant reports on nematode parasites of Simuliidae in the U. S. was by Anderson & DeFoliart (1962, Ann. Ent. Soc. Amer. 55 : 542–46). These workers investigated the nematodes attacking various species of Simuliidae in Wisconsin. Phelps & DeFoliart (1964, Univ. Wis. Res. Bull. 245 : 78 p.) later reported the life cycle, pathology, and effects of nematodes on simuliid populations in Wisconsin, primarily Simulium vittatum Zetterstedt. These workers reported that nematode parasites were a major limiting factor to S. vittatum populations in Wisconsin. Fredeen & Shemanchuk (1960, Can. J. Zool. 38 : 723–35) reported that 95% to 100% of the larvae at 1 collection site in Canada were infected with nematodes and few pupae were noted to occur as a result.

Puttler and Thewke (1971) reported Hexamermis arvalis Poinar & Gyrisco as a parasite of several species of noctuid cutworms in Missouri. In a continuing effort to obtain information on the biology and ecology of mermithid nematodes, observations were made in the summer of 1966 on a Hexamermis sp. reared from the red admiral butterfly, Vanessa atalanta (L.); Polygonia comma Harris; P. interrogationis F. (Nymphalidae); and the banded woollybear, Isia Isabella (J. E. Smith) (Arctiidae). They were all collected from wood nettle, Laporta canadensis (L.), and slender nettle, Urtica procera Muhl., growing in creek bottom habitat with an overstory of silver maple, box elder, and elm in the vicinity of Columbia, Mo. Larval collections were initiated earlier in the year in 1967 and 1968 and carried out periodically in those years. V. atalanta was the most prevalent host and it is from this species that most of the observations are reported. An undetermined mermithid from V. atalanta is cited by Van Zwaluwenburg (1928) as occurring in Europe, the United States, and the Hawaiian Islands.

Der Bohrapparat der vorparasitischen Larven von Hydromermis contorta besteht aus dem Bohrstachel und einem tutenformigen Widerlager. Beide Strukturen befinden sich in einer ventralen Erweiterung des vorderen Abschnitts des Pharynx, sie entspringen aus der Pharynxwand. Der vordere Abschnitt des Bohrstachels hat etwa die Gestalt eines Rohres, das sich nach distal zuspitzt und durch einen ventralen Langsspalt zum Pharynxlumen hin offen ist. Die Basis des Bohrstachels hat die Form eines massiven Zylinders, der in 2 proximale Zipfel ausgezogen ist. Diese Zipfel ragen in den Hohlraum des tutenformigen Widerlagers hinein. Eine spaltformige Mundoffnung fuhrt in die vor der ventralen Pharynxerweiterung gelegene Mundhohle. Letztere ist wie ein mit Langsfalten versehenes Sackchen gebaut, dessen Cuticulaauskleidung in die Korperwandcuticula ubergeht.

The parasitic juveniles of mermithid nematodes attack a variety of hosts from 15 insect orders (Welch 1963, 1965). Little is known of the extent to which they are parasites of Miridae. Menzel (1922) and Cobb et al. (1927) recorded parasitism of the bug Helopeltis theivora Waterh. by Mermis sp. and by Agamermis paradecauta Steiner, respectively. A related mirid, H. antonii Sign., was reported parasitized by Mermis sp. (Menzel 1922), and by A. paradecauta and Hexamermis microamphidis Steiner (Steiner 1925). Recently King (1969) found that the mirids Sahlbergella singularis (Hagl.) and Distantiella theobroma (Dist.) were hosts of the genus Mermis Dujardin.

Nine nematode taxa were collected during a study of the effects of sewage effluent on benthic macroinvertebrates in Bulimba Creek, Brisbane. The nematode, T. diversipapillatus, previously unknown from Australia, comprised 80% of the collection, and was most abundant at polluted sites with high biological oxygen demand and high levels of total organic carbon. Free-living adult and juvenile Mermithidae made up 15.6% of the collection and were most abundant at sites with low biological oxygen demand. The potential of T. diversipapillatus and Mermithidae to serve as biological indicators of organic enrichment and toxic pollution is discussed in terms of these preliminary findings and literature data.

Pheromermis pachysoma (von Linstow) n. gen., n. comb., a parasite of the yellowjacket, Vespula pensylvanica (Saussure), is described from California. The genus, Pheromermis, is characterized by the presence of four submedian cephalic papillae; large anteriorly placed cup-shaped amphids; an S-shaped vagina not bent in a transverse plane to the body; six hypodermal cords; paired, short, separate spicules; cuticle with cross fibers; and eggs lacking processes. The development of P. pachysoma is unique because a paratenic or transport host is required for completion of the life cycle. The adult nematodes occur in water or saturated soil and the eggs are fully embryonated at oviposition. The eggs hatch in the gut of various insects and infective stage juveniles penetrate the gut wall and enter a quiescent state in the tissues of these paratenic hosts. Wasp larvae are probably infected when they are fed paratenic hosts captured by worker yellowjackets. Postparasitic juveniles of P. pachysoma emerge from adult wasps when the latter visit wet sites after their fall emergence from the nest. The ant parasite, Mermis myrmecophila Baylis, is transferred to the genus Pheromermis.

Surveys of Chironomous plumosus larvae in Lake Itasca, Minnesota, in the summers of 1959 and 1961 document the existence of a cystic larval stage of Octomyomermis itascensis. The cysts are concentrated in the thoracic hemocoel and vary in number from 1 to 5 per insect. Each cyst contains a single juvenile nematode. Apparently the nematode reaches a given stage of development in the cyst and must excyst to continue development. Evidence is presented for the parasite origin of the cyst wall. Humoral factors of the host may play a role in excystation of the nematode. Couturier (1951) reported the presence of a capsule investing a mermithid juvenile in the development of Tunicamermis melolonthae in grubs of Melolontha melolontha in France. Couturier (1963) indicated that the preparasitic juvenile penetrates the grub and induces proliferation of host tissue around the parasite. The capsule enlarges as the nematode grows in size. The final capsule is large, irregular, and attached to the host by a stalk. This is the only record of encapsulation of mermithids as a normal developmental event. In July of 1959 an examination of 1,844 fourth-stage larvae of Chironomus plumosus from the benthos of Lake Itasca, Minnesota, revealed the presence of a small encysted nematode in 34.4% of the insects. Johnson (1963) described the adult of this form, Octomyomermis itascensis. Three other undescribed species of mermithids are known by the investigator to be present in the same host in the same habitat. One of these nematodes is imagocidal and the other two larvicidal. Early stages of the two larvicidal forms are known and do not have a cyst enclosing them. The small, round, flattened cysts of O. itascensis contain a single juvenile reaching a maximum size of 1.7 mm in length. The cysts are contiguous with muscles, fat bodies, imaginal discs, salivary glands, and other structures of the host. The cyst wall is not connected to host tissues or the juvenile. The red, transparent larvae of C. plumosus possess a head capsule, prothoracic prolegs, 12 body segments (3 thoracic, 9 abdominal), Received for publication 12 July 1973. posterior prolegs, and posterior "gills." A sample of 172 infected host larvae was documented as to the number of cysts per host; 121 or 70% had one cyst, 34 or 20% had 2, 8 or 5% had 3, 7 or 4% had 4, and 2 or 1% had 5. Despite the presence of more adequate hemocoelic space posteriorly the cystic nematodes were more abundant in anterior segments. Two hundred twenty-six cysts were di tributed as follows: thoracic segment I, 51; II, 65; III, 45; abdominal segment I, 30; II, 8; III, 5; IV, 2; V, 1; VI, 1; VII, 0; VIII, 1; IX, 5; and posterior prolegs, 12. As many as three cysts have been found in one segment. No mechanical problems were observed in the insects. The acellular membrane composing the cyst wall is transparent, homogeneous, without pigmentation, and about twice the thickness of the cuticle of the nematode. The entire cyst can be readily dissected out of the host. The staining properties of the membrane resemble those of the nematode cuticle very closely. The size and structure of the cystic nematode was uniform. Measurements of six cystic juveniles indicate the following ranges: Length 1.4 to 1.7 mm, greatest diameter 87 to 97 It, stichosome length 600 to 900 u and gonad length 87 to 230 j/. The prominent structures in the cystic juvenile (Fig. 1) are the two large granular cells with oval nuclei anterior to the stichosome, the 16 linearly arranged irregular nuclei of the stichocytes, a rudimentary gonad posterior and ventral, and a trophosome occupying most of the posterior pseudocoel. The cuticular esophagus was present but could not be traced posterior to the granular cells.

and MERMITHIDAE. Gmelin (1788) divided the genus Gordius into Gordius and Filaria. Dujardin (1842) named the genus Mermis and considered it belonged among the nematodes. Creplin (1847) separated the genus Chordodes from Gordius. Villot in his monograph (1874) referred all 34 of the then known species of GORDIACEA to Gordius, but Chordodes was accepted and clearly defined by Janda (1893). Camerano (1897) added the genera Paragordius and Parachordodes. Camerano's (1915) revision listed 113 species which he considered valid. Most of the taxonomic studies of GORDIACEA in America have been made by Montgomery (1898-1907). May (1919) described the families GORDIIDAE and CHORDODIDAE and studied the life cycles of Gordius robustus Leidy and Paragordius varius (Leidy). G. W. Muller (1927) split the genus Parachordodes into Parachordodes and Gordionus. Heinze (1933-1937) erected the genera Beatogordius (1934), Paragordionus (1935), Chordodiolus (1935) and Euchordodes (1937), and four subfamilies (1935) of CHORDODIDAE. Heinze (1937) also developed new techniques in preparing specimens (especially the cuticula) for study. Dorier (1930) showed that larvae of GORDIACEA may encyst on vegetation and infect their host by mouth. Many species of GORDIACEA have been named without sufficient description to distinguish them. Identification must be based on details of the extremities and especially on the minute structure of the cuticula: its areolae, pore canals, furrows, tubercles, bristles.

Numerous species of fungi, bacteria, and worms have been recorded as parasitizing mosquitoes. Some have been shown to be definitely destructive of these insects (for a bibliography of the relevant literature up to 1927 see Speer, 1927). Among the worms, there are nematode parasites of adult mosquitoes, such as those described from Aedes sollicitans by Stiles (1903), by Smith (1904), and those from A. vexans females by Hearle (1926). These latter, collected first in 1920 and 1921 by Hearle, were called Paramermis canadensis by Steiner (1924), and were said to interfere with ovarian development. Stiles (1903), who was the first to describe a mermithid worm from a mosquito in North America, proposed the name Agamomermis culicis for his form. Other similar worms are described as parasitizing the larvae of land and fresh water arthropods, including mosquitoes, and are placed in the superfamily MERMITHOIDEA, family MERMITHIDAE (Chitwood, 1950). For a discussion of this group of parasites see Christie (1941), and Steinhaus (1949). Mermithid parasites of the larvae of mosquitoes were first noted from this hemisphere by the author (1945a and 1945b). They were observed in fourth instar larvae of Aedes vexans and Culex salinarius from Delaware Co., Penna., and were seen to be invariably fatal to their hosts. Jenkins, in a paper before the Amer. Assoc. Econ. Ent. at Denver in December, 1950, reported a similar worm from the larvae of arctic and subarctic mosquitoes (northern Canada and Alaska). Drs. Jenkins and West kindly allowed me to see their manuscript on these worms. They present a thorough review of the literature, and plan extensive field and laboratory studies.