Deladenus Bonabensis n. Sp. (Tylenchomorpha: Neotylenchidae) from East Azarbaijan Province, Northwestern Iran: A Morphological and Molecular Phylogenetic Study.

A population of Deladenus, representing a new species, was recovered from Bonab's Ghara-Gheshlagh lagoon. It is mainly characterized by having a long body (1051-1185 µm), long distance of anterior end to pharyngeal glands end (270-312 µm), six lines in lateral fields, and a short mucro-like differentiation on the tail tip. Furthermore, it has a small-sized stylet (8.5-11.0 µm) with three knobs, no postvulval uterine sac, and males with 24- to 28-µm-long tylenchoid spicules and penial tube. With six lateral lines, the new species is comparable with seven species of the genus: D. apopkaetus, D. brevis, D. cocophilus, D. durus, D. obtusicaudatus, D. processus, and D. ulani. It was furthermore compared with D. oryzae with an unknown number of lateral lines and D. aridus, D. obesus, and D. parvus having a different number of lateral lines but similar morphology. In the molecular phylogenic analyses using small and large subunit ribosomal DNA (SSU and LSU D2-D3 rDNA) sequences, the relationships of the new species with other species and genera were not resolved in SSU phylogeny. However, it formed a clade with Deladenus sp. and D. brevis in LSU phylogeny.

The Draft Genome of Deladenus siricidicola.

The nematode Deladenus siricidicola is used as biological control agent against the invasive woodwasp Sirex noctilio, a serious invasive pest of Pinus plantations globally. The draft genome of this ecologically and economically important entomoparasitic nematode was determined.

Population biology of the European woodwasp, Sirex noctilio, in Galicia, Spain.

Sirex noctilio Fabricius (Hymenoptera, Siricidae) is rare and rarely studied where it is native in Eurasia, but is a widespread pest of pines in the Southern Hemisphere. Here we report on the abundance, basic biology, host use patterns and natural enemies of native S. noctilio in Galicia, Spain. Most trees attacked by S. noctilio failed to produce any adult progeny: >90% of emergences came from <20% of the attacked trees. The highest reproduction was in Pinus pinaster, followed by Pinus sylvestris and Pinus radiata. The proportions of S. noctilio requiring 1, 2 or 3 years for development were 0.72: 0.24: 0.04. Delayed development could be an adaptation to avoid parasitic nematodes, which sterilized 41.5% adults with one year generation time but only 19% of adults with 2 years generation time. Hymenoptera parasitoids accounted for 20% mortality. Sex ratios were male biased at 1: 2.9. Body size and fecundity were highly variable and lower than previously reported from the Southern Hemisphere. On attacked trees, there were 5-20 attacks per standard log (18 dm2), with usually 1-3 drills per attack. Attack densities and drills per attack were higher in trees that subsequently died. The production of S. noctilio per log was positively related to total attacks, and negatively related to: (1) attack density, (2) incidence of blue stain from Ophiostoma fungi and (3) frequency of lesions in plant tissue around points of attack. A preliminary life table for S. noctilio in Galicia estimated effects on potential population growth rate from (in decreasing order of importance) host suitability, unequal sex ratio, parasitic nematodes and Hymenoptera parasitoids.

Descriptions of Deladenus albizicus n. sp. and D. processus n. sp. (Nematoda: Hexatylina) from Haryana, India.

Two different nematodes were isolated from the bark of Albizia lebbeck trees; one from insect infested and another from noninfested, healthy tree. Based on the biological, morphological, and molecular evidences, the nematodes are described as Deladenus albizicus n. sp. and D. processus n. sp. (Nematoda: Hexatylina). Deladenus albizicus n. sp., isolated from insect-infested tree, multiplied on the fungus Nigrospora oryzae. Myceliophagous females of this nematode reproduced by parthenogenesis and spermathecae were indistinct. Infective females, readily produced in the cultures, are dorsally curved. Only one type of males containing small-sized sperms in their genital tracts were produced in the culture. Myceliophagous females: L = 0.75 to 1.71 mm, a = 32.3 to 50.8, b = 9.3 to 11.2, b' = 5.2 to 7.3, c = 27.2 to 35.6, V = 91.0 to 93.3, c' = 2.0 to 2.9, stylet = 11 to 12 µm, excretory pore in the region of median pharyngeal bulb, 43 to 47 µm anterior to hemizonid. Deladenus processus n. sp., isolated from bark of healthy A. lebbeck tree, was cultured on Alternaria alternata. Myceliophagous females reproduced by amphimixis and their spermathecae contained rounded sperms. Infective females were never produced, even in old cultures. Myceliophagous females: L = 0.76 to 0.99 mm, a = 34 to 49, b = 13.3 to 17.7, b' = 3.8 to 5.8, c = 19.6 to 22.8, V = 92.2 to 93.5, c' = 2.7 to 3.5, stylet = 6 to 7 µm, excretory pore in the proximity of hemizonid, tail conoid, tapering from both sides to a long pointed central process. It is proposed to classify Deladenus species in three groups: durus, siricidicola, and laricis groups based on female and spermatogonia dimorphism, mode of reproduction, and insect parasitism.

Deladenus valveus n. sp. (Nematoda: Neotylenchidae) in Dunnage Wood from South Korea Intercepted in Ningbo, China.

Deladenus valveus n. sp., isolated from packaging wood originated from South Korea and intercepted in Ningbo, P.R. China, is described and illustrated. Both mycetophagous and infective forms were recovered and are described. The new species D. valveus n. sp. resembles other Deladenus species in which the excretory pore is situated anterior to the hemizonid: in mycetophagous females, the excretory pore is 59 to 74 µm from the anterior end and 37 to 54 µm anterior to the hemizonid. The new species is characterized by the presence of a distinct valve at the esophago-intestinal junction in mycetophagous females and by a degenerate esophagus in mycetophagous males, both of which characters are reported for the first time in a species of Deladenus.

Deladenus cocophilus n. sp. (Nematoda: Hexatylina): A Mycetophagous and Entomoparasitic Nematode in Infested Coconut Fruits from Balochistan, Pakistan.

Deladenus cocophilus n. sp. was isolated from infested coconut fruits in Winder, Balochistan, Pakistan. Descriptions are given of the entomophagous (insect-parasitic females) and mycetophagous (fungus-feeding) free-living females, males, and juveniles. The new species D. cocophilus resembles those species in which the excretory pore is situated anterior to the hemizonid, namely, D. apopkaetusChitambar, 1991; D. leptosomaGagarin, 2001; D. ipiniMassey, 1974; D. laricis (Blinova and Korentchenko, 1986) Ebsarry, 1991; D. (siricidicola) caniiBedding, 1974; D. (s) imperialisBedding, 1974; D. nevexiiBedding, 1974; D. (wilsoni) proximusBedding, 1974; D. (s) rudyiBedding, 1974; D. (s) siricidicolaBedding, 1968; D. (wilsoni) wilsoniBedding, 1968 and D. minimus Chizhov and Sturhan, 1998. The new species differs from D. ipini in the absence of a post uterine sac vs. present; a = 17 to 30 vs. 35 to 40; stylet = 8 to 10 vs. 11 to 12 µm and vulva-anus = 21 to 28 vs. 35 to 48 µm. From D. apopkaetus it differs in tail length in female 22 to 28 vs. 31 to 43 µm and in the male it is 24 to 32 vs. 30 to 46 µm. It differs from D. leptosoma in the c ratio in females, c = 21 to 37 vs. 16 to 22, presence of 6 lines in lateral field vs. 10 lines and slightly longer spicules 16 to 18 vs. 15 to 16 µm. From D. laricis it differs in a shorter stylet length 8 to 10 vs. 11 to 12 µm; in the c ratio in males 16 to 22 vs. 22 to 35 and hemizonid from anterior end 76 to 90 vs. 90 to 119 µm. It also differs from the following species: D. (siricidicola) canii; D. (s) imperialis; D. nevexii; D. (wilsoni) proximus; D. (s) rudyi; D. (s) siricidicola; D. (wilsoni) wilsoni and D. minimus in having shorter tail length, lower values of a,b,c ratios and a slightly anteriorly located vulva in females.

Factors Affecting the Flight Capacity of Two Woodwasp Species, Sirex noctilio F. (Hymenoptera: Siricidae) and Sirex nitobei M. (Hymenoptera: Siricidae).

Sirex noctilio F. is an invasive woodwasp that causes pine mortality in plantations in China. Sirex nitobei M. is a native woodwasp in large areas of China. In this study, the flight capacity of the two woodwasps was studied and compared using a tethered-flight mill system to find individual factors affecting the flight capacity. After flight bioassays, woodwasps were dissected to determine nematode infestation. Post-eclosion-day (PED) age significantly influenced the flight capacity of S. noctilio females and males; as woodwasps become older, their flight capacity decreased. For S. nitobei, PED age did not significantly affect their flight capacity. In general, the flight capacity of S. noctilio was greater than that of S. nitobei. Females flew further and for longer than males for both Sirex species. The Deladenus spp. parasitism status of the two Sirex species did not significantly affect their flight performance parameters. PED age and body mass were key individual factors significantly affecting the flight capacity of the two Sirex species. In this study, detailed and accurate tethered-flight parameters of S. noctilio and S. nitobei were obtained. Although this is different from natural flight, it also provides us substantial laboratory data on their flight capacity, and facilitates risk analysis of the two woodwasp species.

New Records of Wood- and Bark-Inhabiting Nematodes from Woody Plants with a Description of Bursaphelenchus zvyagintsevi sp. n. (Aphelenchoididae: Parasitaphelenchinae) from Russia.

Wood- and bark-inhabiting parasitic nematodes are of great economic importance. Nematodes can cause wilt diseases in conifers and deciduous trees. In 2014-2022, during nematology surveys conducted in different regions of Russia and Belarus, adults and dauer juveniles of nematodes were collected from wood, bark and beetle vectors. Using traditional morphological taxonomic characters integrated with molecular criteria, we identified in the studied samples the following nematode species: Aphelenchoides heidelbergi, Bursaphelenchus eremus, B. fraudulentus, B. michalskii, B. mucronatus, B. willibaldi, Deladenus posteroporus, Diplogasteroides nix and Laimaphelenchus hyrcanus, several unidentified species: Aphelenchoides sp.1 and sp.2, Cryptaphelenchus sp.1, sp.2 and sp.3, Laimaphelenchus sp.1, Micoletzkya sp.1, Parasitaphelenchus sp.1, Parasitorhabditis sp.1, three unidentified tylenchid nematodes and a new species, Bursaphelenchus zvyagintsevi sp.n. Morphological descriptions and molecular characterization are provided for B. zvyagintsevi sp. n. belonging to the Abietinus group and B. michalskii belonging to the Eggersi group. Findings of Aphelenchoides heidelbergi, Bursaphelenchus eremus, B. michalskii, Deladenus posteroporus, Diplogasteroides nix and Laimaphelenchus hyrcanus are new records for Russia. Phylogenetic positions of studied species were reconstructed using D2-D3 expansion segments of 28S rRNA gene sequence analysis. The data obtained in this study may help to detect the refugia of opportunistic plant pests and find possible native biocontrol nematode agents of insect vectors causing diseases.

Interactions Among Latitude, Nematode Parasitization, and Female Sirex nigricornis (Hymenoptera: Siricidae) Fitness.

Sirex nigricornis F. (Hymenoptera: Siricidae) is an innocuous pine-inhabiting woodwasp native to eastern North America, utilizing dead or dying pine trees as hosts. Although S. nigricornis F. does not cause economic damage, a closely related species, Sirex noctilio, was discovered in New York in 2004 and has continually spread throughout the northeastern United States and southern Canada, threatening the multi-billion-dollar pine timber industry of the southeastern United States and raising interest about potential interactions with native woodwasps and associated mortality agents. A non-sterilizing strain of the biological control agent, Deladenus siricidicola Bedding (Tylenchida: Neotylenchidae), was introduced along with S. noctilio but is not inhibiting the spread or establishment of S. noctilio A North American congener, Deladenus proximus Bedding, has been recently isolated from S. noctilio and shows promise as a biological control agent. To better understand the potential of D. proximus as a control agent for S. noctilio, we measured and dissected nearly 1,200 S. nigricornis females from Arkansas and Mississippi and evaluated differences among collection location with regard to nematode virulence, woodwasp body size, and egg load. Body size and egg load were related to collection location, and nematode infestation resulted in significantly smaller females who produced significantly fewer eggs. Female woodwasps, especially those collected in Arkansas, were often fully sterilized by nematodes, and a higher percent sterilization was inversely related to body size and fewer eggs. We propose field studies to test the nematode's ability to sterilize S. noctilio in the northeastern United States.

Nonlethal Effects of Nematode Infection on Sirex noctilio and Sirex nigricornis (Hymenoptera: Siricidae).

A nonnative woodwasp, Sirex noctilio F., has established in pine forests in eastern North America. To facilitate prediction of the full range of impacts S. noctilio could have as it continues to spread in North American forest ecosystems, we studied the effects of infection by a nonsterilizing parasitic nematode on S. noctilio size, fecundity, and flight capacity and on the native woodwasp, S. nigricornis, size and fecundity. We also developed predictive models relating size to fecundity for both species. On average, S. noctilio (3.18 ± 0.05 mm) were larger than S. nigricornis (2.19 ± 0.04 mm). For wasps of similar size, S. nigricornis was more fecund. Nematode infection negatively affected potential fecundity by a mean difference of 36 and 49 eggs in S. noctilio and S. nigricornis, respectively. Nematode-infected males of S. noctilio, however, were larger than uninfected individuals. Nematode infection showed inconsistent results on mean speed and total distance flown by S. noctilio males and females. Nematode infection did not affect total distance flown by females, and so is unlikley to have a direct, or strong influence on S. noctilio flight capacity. Models developed to predict fecundity of Sirex spp. from body size, based on the close relationship between pronotum width and potential fecundity for both species (R(2) ≥ 0.69), had low measures of error when compared with true values of fecundity (± 25-26 eggs).

Biocontrol: the potential of entomophilic nematodes in insect management.

A review of the development of entomophilic nematology and a commentary on the potential of entomophilic nematodes in controlling insect pests. The paper considers some of the major contributions to our knowledge of entomophilic nematology; factors involved in insect pest management and how they are applicable to the use of nematodes; nematodes which are most promising as biological control agents; and problems to be solved to facilitate the use of entomophilic nematodes in insect management.

Drip irrigation as a delivery system for infestation of field plots with nematodes.

A drip irrigation delivery system was used to infest field sites with the plant-parasitic root-knot nematodes, Meloidogyne incognita. Juvenile or egg inocula passed through the system without blockage of emitters or harm to the nematodes. Field sites so infested were available for experimentation. Delivery of approximately 5 x 10 to 10 juveniles or 10 to 3 x 10 eggs per emitter through the drip system resulted in heavy root galling of tomatoes planted next to the drip emitters. Nematodes feeding on bacteria (Acrobeloides sp.) and on fungi (Deladenus durus) also were successfully applied through the drip system. This method has potential for uniformly infesting experimental sites with plant-parasitic or entomogenous nematodes and for manipulation of nematode community structure for soil ecological studies.