Mermithid Parasitism Research Articles

Widespread mermithid nematode parasitism of Cretaceous insects.

Mermithid nematodes are obligate invertebrate parasites dating back to the Early Cretaceous. Their fossil record is sparse, especially before the Cenozoic, thus little is known about their early host associations. This study reports 16 new mermithids associated with their insect hosts from mid-Cretaceous Kachin amber, 12 of which include previously unknown hosts. These fossils indicate that mermithid parasitism of invertebrates was already widespread and played an important role in the mid-Cretaceous terrestrial ecosystem. Remarkably, three hosts (bristletails, barklice, and perforissid planthoppers) were previously unknown to be parasitized by mermithids both past and present. Furthermore, our study shows that in contrast to their Cenozoic counterparts, Cretaceous nematodes including mermithids are more abundant in non-holometabolous insects. This result suggests that nematodes had not completely exploited the dominant Holometabola as their hosts until the Cenozoic. This study reveals what appears to be a vanished history of nematodes that parasitized Cretaceous insects.

Quatitative and Qualitative Estimation of Free Amino Acids in the Haemolymph of parasitized bugs (Leptocoris augur).

Leptocoris augur is a pest of Kusum plant, (Schleichera oleosa), which in turn is a host of Lac insect. This bug is a gregarious feeder and by its desapping habit loss the viability of seeds. In L. augur a total of 16 amino acids were identified in the control bug’s haemolymph (both sexes) by paper chromatogram. Thus, free amino acids level of haemolymph is greatly affected by the parasitization. In this way the Quantitative level of amino acid in parasitized bug haemolymph significantly altered by mermithid parasitism. Keywords: Leptocoris augur, Haemolymph, Free amino acids, Parasitized bug, Quantitative level.

First record of a mermithid nematode (Nematoda:Mermithidae) parasitizing winged females of gall‐forming aphids (Hemiptera:Aphididae:Eriosomatinae)

AbstractJuvenile mermithid nematodes were found to parasitize winged females (sexuparae) ofEriosoma auratumandTetraneura radicicola. The morphological characteristics of mermithid nematodes are briefly described. The 18S rDNA and 28S rDNA obtained from one nematode were sequenced and used to construct a Bayesian phylogenetic tree, on which the host ranges of mermithid nematodes were represented. Our study indicated that mermithid parasitism of sexuparae led to fewer and smaller sexual female embryos. This is the first record of a mermithid in relation to eriosomatine aphids and the fourth record with respect to Aphididae.

First record of a mermithid worm (Nematoda, Mermithidae) parasitizing a third instar nymph of Triatoma sordida (Stål, 1859) (Hemiptera, Reduviidae, Triatominae) from Mato Grosso, Brazil.

A juvenile specimen of a mermithid (Nematoda) was found parasitizing a third instar nymph of Triatoma sordida from Mato Grosso, Brazil. This is the first record of mermithid parasitism in a triatomine species. The Mermithidae represents a family of nematodes that are specialized insect parasites. Entomonematodes are one of the highly influential agents regulating the population dynamics of insects. This report introduces the opportunity to think about mermithids as a possible candidate for use as triatomine biological control.

Mermithid nematode (Nematoda: Mermithidae) parasites of a fossil black fly (Diptera: Simuliidae) in Baltic amber

Summary A new species of fossil mermithid, Heydenius simulphilus sp. n. (Nematoda: Mermithidae), is described from two parasitic juvenile specimens adjacent to a male black fly (Diptera: Simuliidae) in Baltic amber. It is proposed that the nematodes emerged from their developmental sites in the haemocoel of the black fly host through a wound in the abdomen of the latter, as indicated by the release of a droplet of haemolymph and damaged cuticle. Various internal structures of the nematodes are identified and related to those found on extant developing mermithids. This is the first fossil record of mermithid parasitism of a black fly.

Mermithid nematode parasites of eastern subterranean termites in North America

The subterranean termite Reticulitermes flavipes (Kollar, 1837) (Isoptera: Rhinotermitidae) occurs throughout the eastern USA and populations have been found as far west as Oregon. As with other termites, eastern subterranean termites live in colonies composed of workers, soldiers and reproductives. The blind, wingless workers, which are only between 3 and 4 mm long, feed on wood and can cause serious damage to wooden structures throughout their range (Edwards & Mill, 1986). Mermithid parasitism of termites is a rare occurrence and this report represents the first case of mermithid parasitism of termites in North and Central America.

Report of a mermithid nematode infecting Amyna axis, Chrysodeixis spp. and Spodopteraspp.from India

Amyna axis (Lepidoptera: Erebidae), Chrysodeixis spp. ( C. acuta and C. eriosoma ) and Spodoptera spp. ( S. exigua and S. litura ) (Lepidoptera: Noctuidae) are important polyphagous insect-pests of leguminous crops. A mermithid (Nematoda: Mermithidae) nematode was found parasitizing the larval stages of these insects in the western Indian state of Rajasthan. Morphological and molecular analysis suggests that the nematode might be a species of the genus Hexamermis . The average length of post-parasitic nematode juveniles was 15 cm, and the average greatest body width was 1.5 mm. The vulva was median (V% = 48) without vulval flap. Approximately 100-125 μm long caudal appendages were present on tail. The cross-section revealed the presence of six hypodermal chords at the mid body region, and stichosome was present. The 18S rDNA sequence showed 99% similarity to mermithid nematode. A phylogenetic analysis of 18S rDNA sequences of mermithids resulted in identification of a new clade “Lineage 3” which included representatives of Mermis sp., Isomermis sp., Limnomermis sp., and Pheromermis sp. This is the first report of natural mermithid parasitism of A. axis and Chrysodeixis spp. along with its molecular characterization.

Mermithid parasitism of shoot borer (Conogethes punctiferalis) infesting ginger and turmeric and its biocontrol potential

A mermithid nematode parasitic to larvae ofConogethes punctiferalis, a serious pest of ginger and turmeric was recorded under field conditions during 2015 at Peruvannamuzhi (Kerala, India). The infection reached epizootic levels during July to September 2015 exceeding 50% mortality in host insect populations and the parasitism ranged from 18.2 to 80.6% and 17.9 to 66.7% inC. punctiferaliscollected from ginger and turmeric, respectively. The level of host parasitism by the mermithid was positively correlated with rainfall and negatively influenced by maximum temperature. Molecular analysis of the partial 18S small ribosomal subunit gene region and phylogenetic analysis with other mermithid sequences available in the GenBank indicated that the present nematode clustered with other nematodes belonging to different genera and hence could not be attributed to a specific genus. The pairwise Kimura 2‐parameter (K2P) distance revealed that the closest taxon to the study nematode was an undescribed mermithid species reported to infect slugs with a K2P distance of 0.009. The epizootics caused by this mermithid nematode in the natural populations ofC. punctiferalissuggest its potential as a biocontrol agent against a polyphagous pest of international importance. The results of our studies provide a basis for using this nematode as a biocontrol agent for developing integrated pest management strategies againstC. punctiferalis.

Rarely reported, widely distributed, and unexpectedly diverse: molecular characterization of mermithid nematodes (Nematoda: Mermithidae) infecting bumble bees (Hymenoptera: Apidae: Bombus) in the USA.

Mermithid nematodes (Nematoda: Mermithida: Mermithidae) parasitize a wide range of both terrestrial and aquatic invertebrate hosts, yet are recorded in bumble bees (Insecta: Hymenoptera: Apidae: Bombus) only six times historically. Little is known about the specific identity of these parasites. In a single-season nationwide survey of internal parasites of 3646 bumble bees, we encountered six additional instances of mermithid parasitism in four bumble bee species and genetically characterized them using two regions of 18S to identify the specific host-parasite relationships. Three samples from the northeastern USA are morphologically and genetically identified as Mermis nigrescens, whereas three specimens collected from a single agricultural locality in the southeast USA fell into a clade with currently undescribed species. Nucleotide sequences of the V2-V6 region of 18S from the southeastern specimens were 2.6-3.0% divergent from one another, and 2.2-4.0% dissimilar to the nearest matches to available data. The dearth of available data prohibits positive identification of this parasite and its affinity for specific bumble bee hosts. By doubling the records of mermithid parasitism of bumble bee hosts and providing genetic data, this work will inform future investigations of this rare phenomenon.

Prevalence of parasitism and adult survival time of Aedes albifasciatus (Diptera: Culicidae) parasitized by Strelkovimermis spiculatus (Nematoda: Mermithidae).

We described the carryover of Strelkovimermis spiculatus (Poinar and Camino) (Nematoda: Mermithidae) from mosquito larvae, the primary site of maturation, to adults. We analyzed the survival time of male and female Aedes albifasciatus (Macquart) (Diptera: Culicidae) parasitized by S. spiculatus, the time of emergence of nematodes from adult mosquitoes, and the state of parasitism in the same mosquito cohorts during the immature stages. Mosquito larvae with single and multiple parasitism (up to 11 parasites) were observed. The mortality of mosquito larvae and adults was produced in all cases where at least one mermithid emerged. The mortality of S. spiculatus showed an increasing trend in mosquito larvae with larger numbers of nematodes and was higher in larvae parasitized by eight or more nematodes. Maximum survival of parasitized adult females of Ae. albifasciatus was 38 days, while non-parasitized adult males and females survived 39 and 41 days, respectively. Strelkovimermis spiculatus mortality was observed in Ae. albifasciatus larvae with single or multiple parasitisms. The spread of mermithid parasitism in adult mosquito populations is discussed.

First extant records of mermithid nematode parasitism of Auchenorrhyncha in Europe

Parasitic nematodes of the family Mermithidae were found within four specimens of Auchenorrhyncha from two families (Cicadellidae and Delphacidae). This appears to be the the first extant example of mermithid parasitism of Auchenorrhyncha in Europe. The insect hosts were collected from agricultural grassland field margins at three locations in Ireland during a farmland biodiversity study in 2007.

Mermithid parasitism of Hawaiian Tetragnatha spiders in a fragmented landscape

Hawaiian Tetragnatha spiders inhabiting small forest fragments on the Big Island of Hawaii are parasitized by mermithid nematodes. This is the first report of mermithid nematodes infecting spiders in Hawaii, and an initial attempt to characterize this host–parasite interaction. Because immature mermithids were not morphologically identifiable, a molecular identification was performed. A phylogenetic analysis based on 18S small ribosomal subunit nuclear gene sequences suggested that Hawaiian spider mermithids are more closely related to a mainland presumptive Aranimemis species that infects spiders, than to an insect-infecting mermithid collected on Oahu, HI, or to Mermis nigrescens, also a parasite of insects. Measured infection prevalence was low (ranging from 0 to 4%) but differed significantly among forest fragments. Infection prevalence was associated significantly with fragment area, but not with spider density nor spider species richness. Results suggest that mermithid populations are sensitive to habitat fragmentation, but that changes in infection prevalence do not appear to affect spider community structure.

Heydenius brownii sp. n. (Nematoda: Mermithidae) parasitising a planthopper (Homoptera: Achilidae) in Baltic amber

AbstractA fossil mermithid nematode, Heydenius brownii sp. n. (Nematoda: Mermithidae) emerging from a planthopper (Hemiptera: Fulgoroidea: Achilidae) in Baltic amber, is described. This is the first parasite of a fossil member of the order Hemiptera. There are no reports of mermithid parasitism of extant achilids; however, other families of planthoppers are attacked by mermithids in North America, Asia and Australia today. This find shows that parasitism of achilid fulgorids by mermithid nematodes was well established some 40 million years ago.

Heydenius araneus n.sp. (Nematoda: Mermithidae), a parasite of a fossil spider, with an examination of helminths from extant spiders (Arachnida: Araneae)

Abstract. A mermithid, a parasite of a spider (Araneae: Thomisidae) in Baltic amber (40 mya), is described as Heydenius araneus n.sp. (Nematoda: Mermithidae) and represents the first fossil record of a nematode parasite of an arachnid. After a critical examination of reports of naturally occurring helminths of extant spiders, I conclude that although mermithid parasitism is well established in this host group, previous reports of hairworm parasites of spiders are “nomina dubia,” putative records, or refer to mermithid nematodes.

Mermithid Nematode Parasitism of Solenopsis Ants (Hymenoptera: Formicidae) of Northern Florida

Sexuals collected from nests of the fire ant, Solenopsis geminata (F.), the red imported fire ant, S. invicta Buren, and S. pergandei Forel in the Apalachicola National Forest were parasitized occasionally by a large mermithid nematode. Summer infection rates (1991–1993) varied by species and sex: 0% for S. invicta gynes, between 1 and 7% for S. pergandei gynes and males of all 3 species, and 16% for S. geminata gynes. The seasonality of infection coincided with the summer reproductive period of S. geminata and suggests the mermithid has an annual life cycle. The parasites, up to 15.5 cm in length, distend the abdomen of the host, but have little anatomical effect other than detracting from sex organ development. Mermithisized ants do not participate in mating flights and die when the parasites emerge. The mermithids emerge as sexually immature larvae, precluding their identification or taxonomic description. A mermithid this large has not been reported previously in Solenopsis . Currently, there is no record of mermithid parasitism in S. invicta and S. pergandei nor have mermithisized sexuals been reported in the genus.

Further Report on Nematode-pseudoscorpion Associations.

Nematode-pseudoscorpion associations were studied in Neobisium bernardi VACHON, N. carpaticum BEIER, N. simoni (L. KOCH), N. sylvaticum (C. L. KOCH), and Roncus jarilo CURCIC, all from Yugoslavia. Mermithid parasitism of pseudoscorpions was re-established for N. carpaticum and R. pannonius CURCIC, DIMITRIJEVIC, et KARAMATA (Neobisiidae). Phoretic associations of rhabditid nematodes and false scorpions were found in R. jarilo and re-established in N. carpaticum. The possible origin of such associations, their characteristics, frequency, and significance are briefly discussed. The total number of pseudoscorpion species associated with nematodes, is at present 15; of these, the majority belong to the family Neobisiidae (11 species), while 3 species belong to the Chthoniidae, and one to the Sternophoridae.

Mermithid Parasitism of Adult Mosquitoes in Sweden

-Parasitism of adult Aedes communis (Diptera: Culicidae) by an undetermined mermithid nematode was investigated near Uppsala, Sweden, during 1989 and 1990. Parasites resided in the head capsules of infected larvae and were found predominantly in the abdominal cavities of adult hosts. Migration between these body regions coincided with host pupation. Nematode postparasites emerged 10-21 days after eclosion of adult hosts. Neither parasite prevalence nor parasite load differed with host gender. Nematodes emerged from both male and female mosquitoes collected as larvae. Postparasites also emerged from adult males collected from swarms and from adult females netted near the larval pool. None emerged from females that took blood meals. Immune responses were observed in both sexes but a significantly higher proportion of female hosts encapsulated parasites. Aedes cantans and Culiseta morsitans from the same site also were infected but higher infection rates and parasite loads suggest that Aedes communis is the principal host.

The effect of nematode parasitism on the osmolality and major cation concentration in the haemolymph of three larval mosquito species

Parasitism by a mermithid nematode, Romanomermis culicivorax, causes severe depletion of haemolymph carbohydrates and proteins in mosquito larvae. We undertook a study to determine if haemolymph osmolality and cation concentrations were affected also by mermithid parasitism. The haemolymph osmolality of R. culicivorax-infected and control Aedes taeniorhynchus and Culex pipiens fourth-instar larvae was not significantly different. However, the haemolymph osmolality decreased significantly in infected Anopheles quadrimaculatus. Each mosquito species demonstrated significant alterations in the haemolymph concentration of at least one cation when infected although the cation concentrations affected differed for each species. The changes observed were statistically significant but the magnitude of change was not great. Overall, despite the severe nutritional burden of the mermithid nematode, these species of mosquito larvae can continue to maintain osmoregulation.

Effects of mermithid parasitism on the haemolymph composition of the larval blackflies Prosimulium mixtum/fuscum and Simulium venustum

SummaryHaemolymph of larval blackflies Prosimulium mixtum/fuscum and Simulium venustum parasitized by the mermithid nematode Neomesomermis flumenalis was compared with that of non-parasitized hosts with respect to protein, amino acid and carbohydrate composition. The mermithid depleted most protein fractions in a non-selective manner in both host species. In P. mixtum/fuscum, the levels of most amino compounds were reduced by mermithid parasitism, but these metabolites were approximately evenly divided into three categories (decreased, increased, unaffected by parasitism) in S. venustum. The mermithid caused a significant decrease of haemolymph glucose levels in both host species but did not affect blood trehalose concentrations. These effects of parasitism are discussed in relation to the nematode's nutritional requirements.

Notes on mermithid parasitism of Newfoundland blackflies, with the first record of Neomesomermis flumenalis from adult hosts.

Field-collected pupae of Simulium venustum and Prosimulium mixtum were allowed to eclose in the laboratory and the adults were dissected to reveal the presence or absence of mermithid parasites. Twenty-six (11.7%) of 221 female P. mixtum were found parasitized; all 187 males examined were unparasitized. Nematodes emerged from 10 (14.3%) of 70 female P. mixtum when placed in water-filled dishes. The nematodes recovered from P. mixtum were Neomesomermis flumenalis (66.6%), Isomermis sp. (26.7%), and Gastromermis viridis (6.7%). Forty-three (22.2%) of 194 female S. venustum were parasitized; all 134 males examined were unparasitized. Three (5%) of 60 male pupae of S. venustum were parasitized; 7 (8%) of 86 females were found to harbour mermithids. The nematodes recovered from S. venustum were Hydromermis sp. (75%), G. viridis (12.5%), and N. flumenalis (12.5%).