This paper provides additional information on the morphology of Steinernema scapterisci. For females, the amphids are shown for the first time, and clearer scanning electron microscope (SEM) photographs of the six labial and four cephalic papillae are presented. For males, six labial and four cephalic papillae, one or two pairs of additional genital papillae, and the death shape are shown. For infective juveniles, six labial and four cephalic papillae and an elevated oral disc are shown.
amphid; cephalic papilla; epiptygma; labial papilla; genital papilla; morphology; nematode; SEM; Steinernema scapterisci
This paper is the second in a series studying procedures for estimating and calibrating features of nematodes from digital images. Two kinds of features were analyzed for recognition: those with a directional component and those with a textural component. Features that have a directional component (lateral field and annules) were preprocessed with classic algorithms and modified by directional filters. Features having texture (esophagus and intestine) were analyzed with vectors of measures to define them and the statistical technique CART (classification and regression trees) to explain the role that each measure plays in the identification and discrimination process.
automatic identification; classification; digital image; Doylaimus sp,; line detection; Mesocriconema sp.; nematode; Rotylenchus cazorlaensis; Rotylenchus magnus; texture; Tylenchorhynchus sp.
A 3-year field trial near Kunia, Oahu, Hawaii, was conducted to evaluate four nematicide treatments for efficacy against Rotylenchulus reniformis in drip-irrigated pineapple (Ananas comosus L. (Merr.)). The treatments were (A) preplant fumigation with 1,3-dichloropropene (1,3-D) (336 liter/ ha) and postplant drip application of fenamiphos (3.4 kg/ha) with restricted irrigation, (B) preplant 1,3-D only, weekly irrigation, (C) 1,3-D fenamiphos, weekly irrigation, and (D) postplant fenamiphos only, weekly irrigation. Fenamiphos was applied at 3-month intervals for 1 year after planting in three treatments. Although nematode populations increased in all treatments 1 year after planting, no differences in fruit yield were detected among treatments in the first (plant crop) harvest 19 months after planting. In the second (ratoon) crop (33 months after planting) significant yield differences, larger fruit size, and greater root biomass were obtained in the dual nematicide treatments. Root biomass increased continuously throughout the crop cycle, was greatest near the drip line, and showed a shallow depth distribution (30-40 cm). Rotylenchulus reniformis populations and fenamiphos concentrations were negatively correlated in soil profiles taken 13 months after planting. In the absence of postplant fenamiphos applications, nematode numbers were positively correlated with root biomass.
Ananas comosus; 1,3-dichloropropene; drip irrigation; fenamiphos; nematicide; nematode; pineapple; reniform nematode; root development; Rotylenchulus reniformis
Pinewood nematode, Bursaphelenchus xylophilus (Steiner &Buhrer) Nickle, spatial dispersion was determined in Scots pine, Pinus sylvestris L., bolts infested with the pine sawyer beetle, Monochamus carolinensis (Olivier) and in bolts without M. carolinensis. According to Taylor's power law and Green's index of dispersion, nematode dispersion was aggregated in both sets of bolts. The degree of aggregation did not differ significantly between beetle-infested and noninfested bolts, suggesting that the presence of M. carolinensis does not affect nematode dispersion within a bolt. Nematode population densities differed radially in bolts not infested with pine sawyers, but in a nonregular pattern. Moisture content of the bolts was correlated with population density of B. xylophilus, suggesting that nematode aggregates occur in areas of high moisture content.
Aphelenchoididae; Coleoptera; M. carolinensis; nematode; pine sawyer; pinewood nematode
Nematode population densities and yield of sweet corn and sweet potato as affected by the nematicide fenamiphos, in a sweet corn-sweet potato-vetch cropping system, were determined in a 5-year test (1981-85). Sweet potato was the best host of Meloidogyne incognita of these three crops. Fenamiphos 15G (6.7 kg a.i./ha) incorporated broadcast in the top 15 cm of the soil layer before planting of each crop increased (P ≤ 0.05) yields of sweet corn in 1981 and 1982 and sweet potato number 1 grade in 1982 and 1983. Yield of sweet corn and numbers of M. incognita second-stage juveniles (J2) in the soil each month were negatively correlated from planting (r = - 0.47) to harvest (r = -0.61) in 1982. Yield of number 1 sweet potato was inversely related to numbers of J2 in the soil in July-October 1982 and July-September 1983. Yield of cracked storage roots was positively related to the numbers of J2 in the soil on one or more sampling dates in all years except 1985. Some factor(s), such as microbial degradation, resistant M. incognita development, or environment, reduced the effect of fenamiphos.
fenamiphos; Ipomoea batatas; Meloidogyne incognita; nematicide; nematode; root-knot nematode; sweet corn; sweet potato; vetch; Vicia sativa; Zea mays
Afenestrata koreana n. sp. collected from roots of bamboo (Phyllostachys pubescens) in Gyeongnam Province in the southern part of the Korean peninsula is described and illustrated. Its primary differentiating characteristics are a globose to subspherical body in adults with a prominent neck and terminal cone, thick cuticle, terminal vulva, and deep vagina. Fenestra, bullae, and underbridge are absent. The anus is on the immediate posterior side of the cone. Superficial small tubercules cover all the terminal cone area. The new species differs markedly from the other two known species in the genus, specifically in having three incisures in the lateral field of juveniles and a shorter stylet length in juveniles and adults. The male is unknown.
Afenestrata koreana n. sp.; bamboo; cyst nematode; Heteroderidae; morphology; nematode; new species; Phyllostachys pubescens; scanning electron microscopy; taxonomy
The cuticle of Ceramonema carinatum (Chromadorida: Ceramonematidae) is described and illustrated from scanning and transmission electron microscopy. Each of ca. 200 annules is composed of a single ring with eight external flat faces (plates), which are divided by longitudinal ridges formed by pairs of parallel upstanding vanes. Vanes and plates overlap those of the adjacent annules. Longitudinal ridges extend from the cephalic capsule to the tail spike. On the cephalic capsule a simple ridge extends each of the eight ridges to a position just anterior to the amphid. Cuticular plates are formed from the electron-dense cortical layer and contain lacunae filled with fine fibrils. The vanes are denser, with laminations on a central core. In the annular grooves between the plates there is an electron-lucent layer, which it is suggested, by comparison with other nematodes, is the basal layer. An epicuticle overlies the cortical plates, the vanes, and the interannular lucent layer. Cuficular structure is compared with that of other Ceramonematidae and related nematodes.
annulation; Ceramonema carinatum; cuticle; marine nematode; nematode; scanning electron microscopy; transmission electron microscopy; ultrastructure
Steinernema neocurtillis n. sp. isolated from the mole cricket Neocurtilla hexadactyla Perty can be distinguished from other members of the genus by characteristics of the first-generation male and the third-stage infective juvenile (IJ). In the male, the distance from the anterior end to the excretory pore (DAE) is less than the body width at the excretory pore; D% (DAE divided by length of esophagus x 100) is low at 19. The gubernaculum legth is greater than three-fourths the spicule length. Range of the ratio gubernaculum length divided by spicule length is 0.82-0.93 in the first-generation male and 0.92-1.00 in the second-generation male. In the IJ, the distance from the anterior end to the excretory pore is extremely short (18 μm), causing the D% and E% (DAE divided by tail length x 100) to be low (D% = 23 and E% = 12). Average body length of the IJ is 885 μm.
entomopathogenic nematode; mole cricket parasite; morphology; nematode; new species; Neocurtilla hexadactyla; Steinernema neocurtillis n. sp.; taxonomy
Greenhouse and microplot experiments were conducted to evaluate the damage potential of Ditylenchus destructor on four South African commercial peanut cultivars as influenced by harvest date. The cultivars Sellie and Harts should be harvested by 150 and 120 days after planting, respectively. Losses were 12-13% with early harvest, but a 15-day delay resulted in losses of 45-49%. Harvest of Natal Common and Norden at 125 and 145 days after planting, respectively, resulted in the highest seed grade. By normal harvest time (140 and 160 days, respectively) these two cultivars were downgraded to crushing seed quality. Even though seed weight increases with time, a net loss occurs if harvest is delayed.
Arachis hypogaea; Ditylenchus destructor; economic loss; nematode; peanut
Migration of exsheathed infective juveniles of Steinernema carpocapsae to plasma of the host insect Spodoptera litura was not affected by treatments with the lectins concanavalin A, soybean agglutinin, or wheat germ agglutinin; with the enzymes neuraminidase, α-mannosidase, lipase, pronase, or phospholipase C; or with cetyl trimethylammonium bromide or spermidine. Treatment with sodium metaperiodate or sodium hypochlorite inhibited nematode attraction towards insect plasma; numbers of randomly wandering nematodes increased. Nematode migration towards the source of attraction was unaffected by temperatures below 33 C but was impaired at 35 and 37 C. The adverse effect of 5 mM and 10 mM NaIO₄ on migratory behavior was reversed 24 hours after rinsing with buffered saline. The effect of NaOCl on nematode behavior was slightly reversible at concentrations of 0.2 and 0.4% (v/v) but apparently irreversible at 0.6 and 1.0%. The effect of heat treatment at 35 and 37 C was reversible.
attraction; insect plasma; nematode surface coat; Spodoptera litura; Steinernema carpocapsae; temperature dependency
To determine the effect of soil environment on the life stages and total numbers of Bursaphelenchus xylophilus, nematode-infested wood chips alone and mixed with soil were incubated at 12 and 20 C. Nematodes were extracted at 2-week intervals for 12 weeks. Numbers of nematodes and percentage of third-stage dispersal larvae were greater at 12 C and in chips without soil. Percentage of juveniles of the propagative cycle was greater at 20 C and in chips with soil. Although B. xylophilus survived in chips with soil for 12 weeks, nematode numbers and life stage percentages changed little over time. To determine if B. xylophilus was capable of infecting wounded roots, infested and uninfested chips were mixed with soil in pots with white and Scots pine seedlings. Trees were maintained at 20 and 30 C and harvested at mortality or after 12 weeks. Only seedlings treated with infested chips contained nematodes. In field experiments, planted seedlings were mulched with infested chips to determine if nematodes would invade basal stem wounds. Among these trees, Scots pine was more susceptible than white or red pines to infection and mortality.
Bursaphelenchus xylophilus; nematode; pine; pinewood nematode; Pinus strobus; P. sylvestris; root; soil; temperature; wood chip
The effect of temperature (10, 20, 25, 30, and 35 C) on attachment and development of Pasteuria penetrans on Meloidogyne arenaria race 1 was elevated in growth chambers. The greatest attachment rate of endospores of P. penetrans occurred on second-stage juveniles at 30 C. The bacterium developed more quickly within its host at 30 and 35 C than at 25 C or below. The development of the bacterium within the nematode female was divided into nine recognizable life stages, which ranged from early vegetative thalli to mature sporangia. Mature sporangium was the predominant life stage observed after 35, 40, 81, and 116 days at 35, 30, 25, and 20 C, respectively. The body width and length of M. arenaria females infected with P. penetrans were smaller initially than the same dimensions in uninfected females, but became considerably larger over time at 25, 30, and 35 C. This isolate of P. penetrans also parasitized and completed its life cycle in males of M. arenaria.
Arachis hypogaea; bacterium; biological control; development; life cycle; Lycopersicon esculentum; male; Meloidogyne arenaria; nematode; parasitism; Pasteuria penetrans; sex reversal; scanning electron microscopy; peanut root-knot nematode
In a petri-dish study, development of the nematode Pratylenchus neglectus was observed every 4 days, and stage-specific development times were estimated, using a parameter estimation algorithm for a distributed-delay population model. The lower threshold temperature for development of a population of P. neglectus was 7.75 C. Temperatures above 25 C were unfavorable for this population on barley. Total numbers of P. neglectus in barley roots and associated soil in pots were greatest at 25 C and lower at temperatures above and below that level. There was no change in nematode numbers per gram of root as temperature increased between 24 C and 32 C because root weights decreased at higher temperatures. Restricted root mass may contribute to the lower total nematode population levels at higher temperature. Maximum number of nematodes moved through a 2-cm layer of sand on a Baermann funnel at about 20 C; lowest number of nematodes moved at 10 C and 30 C.
barley; development; lesion nematode; lower temperature threshold; movement; nematode; population; Pratylenchus neglectus; temperature
The role of microbes associated with chicken litter in the suppression of Meloidogyne arenaria in amended soil was investigated. Amended soil treatments were prepared, including combinations of sterile and nonsterile chicken litter and soil. Microbial biomass in different treatments was compared by measuring carbon dioxide evolution. There was less CO₂ evolved in sterile litter than in nonsterile litter treatments. Tomato seedlings cv. Rutgers were transplanted into soil mixtures and inoculated with 2,000 M. arenaria eggs. After 10 days, fewer second-stage juveniles (J2) had penetrated the roots in soils amended with nonsterile litter than sterile litter. The effects of sterile and nonsterile litter-amended soil solutions on M. arenaria eggs and J2 were observed over a period of 6 days. A lower percentage of eggs remained apparently healthy in nonsterile than in sterile-amended soil solutions over 6 days. Microbial degradation of the egg shells was apparent. Fewer J2 survived in sterile- and nonsterile-amended-soil solutions as compared to water controls.
biological control; chicken litter; chitinase; Lycopersicon esculentum; Meloidogyne arenaria; microbe; nematode; organic amendment; tomato
On a few occasions, soybeans with broken root tips were included in tests to evaluate resistance to Heterodera glycines. Although females developed on these plants, the numbers tended to be lower than on similarly treated intact roots. To test the possibility that removal of the root meristem affected nematode development, a culture system using pruned soybeans was devised that permitted access to the roots without disturbing the plants. Treatments included removal of 2 mm of root tip at various times ranging from 24 hours before to 10 days after inoculation, or roots left intact. In each experiment, all roots were inoculated at the same time with equal numbers of freshly hatched second-stage juveniles of Heterodera glycines. No differences in nematode development were detected in plants with root tips removed after inoculation compared to the control. When tips were removed at or before inoculation, fewer juveniles entered roots and relatively fewer nematodes developed. Penetration levels and development correlated with root tip removal such that progressively fewer nematodes entered roots and relatively greater numbers of nematodes remained undeveloped as the time interval between root tip removal and inoculation was increased.
cyst nematode; Glycine max; Heterodera glycines; nematode; penetration; soybean
The host status of 50 commercial maize hybrids for a Mississippi population of Rotylenchulus reniformis was determined in greenhouse experiments. Reproduction was measured by determining RF values ([final egg number + juveniles and vermiform adults in soil] ÷ initial egg number) and number of eggs per gram of fresh root. All hybrids maintained R. reniformis below the initial population level, indicating that they are relatively poor hosts for this species. RF values for R. reniformis among hybrids were different (P ≤ 0.05) and ranged from 0.03 for 'Pioneer 3147' and 'Pioneer 3136' to 0.60 for 'Hy Performer HS60'. No R. reniformis eggs were recovered from the roots of 15 of the maize hybrids.
corn; host suitability; maize; nematode; reniform nematode; resistance; Rotylenchulus reniformis; Zea mays
Field trials were conducted at the Delhi Research Station, Ontario, Canada, on a Fox loamy sand soil during 1987 and 1988 to evaluate the effects of row application of the fumigants Telone II, Telone C-17, Vorlex Plus, and Vorlex Plus CP on the yield and quality of paste tomato (Lycopersicon esculentum Mill. cv. Ferry Morse 6203). The four fumigants were equally effective in controlling the natural field populations of root lesion nematodes (Pratylenchus penetrans Cobb). A significant reduction in marketable red fruit yield due to different nematode densities at time of transplanting was observed in 1988. Fumigation did not significantly affect the yield of nonmarketable fruit, the relative maturation rate, or the processing quality in either year.
chloropicrin; 1,3-dichloropropene; fumigation; Lycopersicon esculentum; methyl isothiocyanate; nematode; paste tomato; Pratylenchus penetrans; tomato
Tank mixes of a fungicide (metalaxyl) and a nematicide (fenamiphos) with herbicides (isopropalin or pendimethalin) and an insecticide (chlorpyrifos) were applied by soil incorporation or irrigation to control the black shank-root knot complex and weeds on four tobacco cultivars. The disease complex was more severe on cultivars McNair 944, NC-2326, and K-326 than on Speight G-70. The disease complex was reduced (P ≤ 0.05) on all cultivars with the pesticide combinations containing metalaxyl + fenamiphos. On most cultivars, percentage disease, disease index, root-gall index, yield, and weed control did not differ (P ≤ 0.05) between the tank mixes containing isopropalin or pendimethalin or among methods of application. Generally, the most effective method of treatment application for control of the disease complex and weeds was preplant incorporated followed by postplant irrigation and preplant irrigation.
black shank; chemigation; Meloidogyne spp.; nematode; Nicotiana tabacum; Phytophthora parasitica; root-knot nematode
Field trials were conducted with a chitin-urea soil amendment and several other nematicides on four crop-nematode combinations: tomato-Meloidogyne incognita; potato-Meloidogyne chitwoodi; walnut-Pratylenchus vulnus; and brussels sprouts-Heterodera schachtii. Significant (P ≤ 0.10) nematode population reductions were obtained with the chitin-urea soil amendment in the trims on potato and walnut. In the trials on brussels sprouts and on tomato, phytotoxicity occurred at rates of 1,868 and 1,093 kg/ha, respectively. Significant (P ≤ 0.10) nematode reductions were also obtained with metham sodium on potato; with 1,3-D on tomato and brussels sprouts; and with sodium tetrathiocarbonate, XRM 5053, fenamiphos, ethoprop, LX1075-05, LX1075-07, and SN 109106 on tomato. The following materials did not provide significant nematode control under the conditions of the particular experiments: metham sodium, oxamyl, and Yucca extract on tomato; and dazomet granules on brussels sprouts.
Brassica oleracea gemmifera; brussels sprouts; chemical control; Heterodera schachtii; Juglans hindsii; Meloidogyne chitwoodi; M. incognita; nematode; potato; Pratylenchus vulnus; Solanum tuberosum; tomato; walnut
Placement of a 3-m-wide, black, polyethylene film mulch down rows of peach (Prunus persica 'Red Haven' on 'Lovell' rootstock) and almond (Prunus dulcis 'Nonpareil' on 'Lovell') trees in the San Joaquin Valley of California resulted in irrigation water conservation of 75%, higher soil temperature in the surface 30 cm, a tendency toward greater root mass, elimination of weeds, and a greater abundance of Meloidogyne incognita second-stage juveniles in soil but reduced root galling when compared to the nonmulched control. Population levels of Pratylenchus hexincisus, a nematode found within tree roots, were reduced by mulching, as were those of Tylenchulus semipenetrans, which survived on old grape roots remaining from a previously planted vineyard, and Paratrichodorus minor, which probably fed on roots of various weed species growing in the nonmulched soil. Populations of Pythium ultimum were not significantly changed, probably also due to the biological refuge of the old grape roots and moderate soil heating level. Trunk diameters of peach trees were increased by mulching, but those of almond trees were reduced by the treatment. Leaf petiole analysis indicated that concentrations of mineral nutrients were inconsistent, except for a significant increase in Ca in both tree species.
almond; irrigation management; Meloidogyne incognita; mulching; nematode; peach; Paratrichodorus minor; Paratylenchus hamatus; Pratylenchus hexincisus; Prunus dulcis; Prunus persica; Pythium ultimum; soil heating; solarization; Tylenchulus semipenetrans
Application method had an appreciable effect on the efficacy of Heterorhabditis sp. (isolate T390) in reducing the numbers of Otiorhynchus sulcatus infesting field-grown strawberries. Results were related to nematode placement. In Trial 1, the mean weevil mortality was 36% for trickle-irrigated Steinernema sp. (isolate NC513) at a dose of 100,000 nematodes per plant, whereas the same dose of Heterorhabditis sp. (isolate T390) resulted in mortality of 65% and 86% for trickle-irrigated and surface-sprayed nematodes, respectively. Mortality rate (y) was inversely related to initial weevil population size (x) by y = 4.96x-0.957 and y = 4.71x-0.558 for trickle-irrigated Steinernema sp. (isolate NC513) and Heterorhabditis sp. (isolate T390), respectively. In Trial 2, using 100,000 Heterorhabditis sp. (isolate T390) per plant, mean weevil mortalities were 61%, 63%, and 79% for single-injection, irrigation, and multiple-injection techniques, respectively.
application method; biological control; Fragaria; Heterorhabditis; nematode; Otiorhynchus sulcatus; pest density; Steinernema; strawberry
During 1986 and 1988, selected farms in all of the major carrot-growing counties of Michigan were surveyed to determine the extent of infestation by Heterodera carotae and Meloidogyne hapla. Both species were found in all eight counties surveyed, but not on all farms. Heterodera carotae was recovered from 67.4% of the fields surveyed. Meloidogyne hapla was detected in 24.8% of the samples and from 69.8% of the fields. In most cases, H. carotae and M. hapla occurred in the same field.
carrot; carrot cyst nematode; Daucus carota; Heterodera carotae; Meloidogyne hapla; nematode; northern root-knot nematode
Resistance to Meloidogyne arenaria race 1 is not currently available in commercial peanut cultivars. Moderate levels of resistance have been identified in Arachis hypogaea plant introductions (PI) in previous greenhouse studies. The purpose of this work was to evaluate the effects of resistance in peanut PI on populations dynamics of M. arenaria in field plots. The PI designated as resistant in greenhouse studies had fewer M. arenaria in roots than the most susceptible PI. At midseason and at the end of the season, resistant PI had fewer M. arenaria in rhizosphere soil than the most susceptible PI. Seven resistant PI had lower numbers of M. arenaria than 'Florunner' at the end of the growing season. Gall index, egg mass index, number of eggs/plant, and number of eggs/g root from greenhouse screening were highly correlated with population levels of M. arenaria in the field, especially at midseason. These greenhouse indices should provide reliable estimates of host suitability in future studies.
Arachis hypogaea; Meloidogyne arenaria; nematode; peanut; resistance; root-knot nematode
A record of 84 plant species in 32 families that are hosts to the root-knot nematode species found in Argentina is presented. The genus Meloidogyne appears to be widely distributed in the country, with Meloidogyne incognita and M. javanica the most frequently detected species. Other species found in Argentina include M. arenaria, M. cruciani, M. decalineata, M. hapla, and M. ottersoni. The present survey is supplemented with existing published information.
Argentina; geographical distribution; host record; Meloidogyne spp.; nematode; root-knot nematode; survey