Egg dispersal in the acanthocephalan Acanthocephalus dirus: field data

Among acanthocephalans, eggs are typically dispersed in the feces of definitive hosts. A recent laboratory-based study provided support for the hypothesis that some female acanthocephalans (Acanthocephalus dirus) carry eggs into the environment prior to dispersal. Here, we examined the potential occurrence of this relationship under natural conditions. Using 6 field surveys, we searched the sediment of a local stream to determine whether the bodies of A. dirus females could be located. We recovered the bodies of 24 intact A. dirus individuals from the stream sediment, of which 5 were mature females. All 5 of the mature females contained mature eggs, with 1 female carrying approximately 10,000. These results are consistent with the interpretation that eggs can be dispersed from the bodies of female A. dirus in nature. We also found that there was significant variation in the number of mature eggs present in the females, with 4 of the 5 females carrying fewer than 400 mature eggs. In addition, we recovered approximately 20,000 mature eggs from a fecal pellet that had been expelled from a fish. We propose that eggs may be dispersed both in the feces of definitive hosts and from the bodies of expelled female A. dirus under natural conditions.     

Studies of the genus Enchodelus Thorne, 1939 (Nematoda, Nordiidae) from Arctic polar deserts. 1. Species with long odontostyle: E. makarovae sp. n. and E. groenlandicus (Ditlevsen, 1927) Thorne, 1939, with an identification key to the species of the E. macrodorus group

Two nematode species of the genus Enchodelus Thorne, 1939, one new and one known from Arctic polar deserts were studied. Enchodelus makarovaesp. n. is an amphimictic species, characterised by females with body length of 1.57-2.00 mm, lip region 15-17.5 μm wide, amphid duplex, odontostyle 38-43 μm long or 2.3-2.8 times lip region diam. Odontophore with flanges, 1.2-1.4 times as long as odontostyle; pharynx length 320-377 μm, pharyngeal expansion 113-130 μm long or 32-37% of total pharynx length; female genital system amphidelphic, uterus tripartite, pars refringens vaginae with two trapezoid sclerotisations, vulva a transverse slit (V=45-51%); tail bluntly conoid (25-35 μm, c=45.8-70.3, c'=0.6-0.9 in females, and 29-33 μm, c=46.4-58.9, c'=0.7-0.8 in males). Males with 65-74 μm long spicules and 10-12 spaced ventromedian supplements. Additional information for Enchodelus groenlandicus is provided, this being a new geographic record for the Putorana Plateau, Russian Arctic.     

Sarcocystis dubeyi (Huong and Uggla, 1999) infection in water buffaloes (Bubalus bubalis) from Egypt

Water buffaloes (Bubalus bubalis) are intermediate hosts for 4 species of Sarcocystis , i.e., Sarcocystis fusiformis and Sarcocystis buffalonis with cats as definitive hosts; Sarcocystis levinei with dogs as definitive hosts; and Sarcocystis dubeyi with an unknown definitive host but thought to be zoonotic. Currently, the latter species has been identified with certainty only from Vietnam. In the present study, sarcocysts of S. dubeyi are reported in 11 (30%) of 35 Egyptian water buffaloes from which the esophageal muscles were examined histologically. Sarcocysts were microscopic, measuring 180-250 × 70-110 μm in size. Ultrastructurally, the sarcocyst wall was 3.5-6.5 μm thick and had palisade-like villar protrusions which give it a striated appearance. The villar protrusions contained microtubules that were distributed along the whole villus. This is the first report of S. dubeyi from water buffaloes in Egypt.     

Oviposition of potato tuber moth,Phthorimaea operculella zell. (Lepidoptera: Gelechiidae); fecundity in relation to mated state,age, and pupal weight

The fecundity of individually held potato tuber moths ranged from 0 to 236 eggs deposited over the total life span. The number of eggs laid was not correlated with pupal weight, but pupal weight and the number of mature eggs in the ovaries shortly after emergence from the pupa were positively correlated. This initial egg complement accounted for slightly more than half of the total number of eggs laid. Among moths held in groups at 25°c in the absence of host‐plant material, multiple‐mated females did not lay significantly more eggs (mean 98.4) than those mated only once (mean 91.0), but their life span was shorter (8.5 days cf. 14.4). Virgin females laid a small number of non‐viable eggs (mean 7.7), and lived about as long as single‐mated females. Males were significantly longer‐lived (23.6 days) than all groups of females. Peak oviposition of mated females occurred 2–5 days after emergence, and declined to low levels by age 7 days.     

Host selection by virgin and inseminated females of the parasitic wasp, Dinarmus basalis (Pteromalidae, Hymenoptera)

1. Fitness is related to reproduction and survival. There apparently exists a negative correlation between the numbers of male and female offspring. There also exists a trade-off between survival and reproduction. This paper investigates optimal decisions with the reproduction and survival trade-off in host selection by wasps.
2. Whereas inseminated female wasps could manipulate the sex of their offspring, virgin females produced only male offspring. I surveyed behavioural differences and the consequences of oviposition by inseminated and virgin females of a solitary parasitic wasp in host choice situations.
3. Two host types were available at the same time to both inseminated and virgin female wasps: one (a 17-day-old host in one bean) presenting difficulties for the laying of eggs, but more benefits for the offspring and the other (five 12- or 13-day-old hosts in one bean) easier for the female wasp for laying of eggs but less beneficial for the offspring.
4. Inseminated female wasps chose more 17-day-old hosts than 12-day-old hosts, but more 13-day-old hosts than 17-day-old hosts in each pair-wise choice. Virgin females chose the smaller hosts in both situations.
5. Virgin females, having greater longevity than inseminated females, laid larger numbers of eggs than the inseminated females during their lifetime by adopting an energy-saving host choice that had little effect on male offspring fitness.     

Huffmanela cf. carcharhini (Nematoda: Trichosomoididae: Huffmanelinae) from skin of a sandbar shark, Carcharhinus plumbeus, in the Pacific Ocean

Eggs of Huffmanela cf. carcharhini from the skin of an aquarium-held, juvenile sandbar shark, Carcharhinus plumbeus , from the Pacific Ocean were studied using light and scanning electron microscopy. Grossly, eggs imparted a scribble-like skin marking approximately 130 × 60 mm on the right side of the shark's snout adjacent to its eye and nostril. Fresh (unfixed) eggs were elliptical, 75-95 μm long (xˉ = 85 μm, SD = ±4.5; n = 75), 48-63 μm wide (53 ± 3.4; 75), 8-10 μm in shell thickness (9 ± 1.3; 27), 45-68 μm in vitelline mass length (52 ± 6.9; 8); had a smooth shell surface and nonprotruding polar plugs 8-13 μm wide (10 ± 1.5; 73); lacked thin filaments, superficial envelope, and shell spines; sank in 35 ppt artificial seawater; and did not spontaneously hatch after 12 hr in 35 ppt artificial seawater. Formalin-fixed eggs measured 193 days postfixation were 75-95 μm long (84 ± 3.9; 150), 45-60 μm wide (50 ± 2.2; 150), 5-10 μm in shell thickness (8 ± 1.2; 87), 45-60 μm in vitelline mass length (51 ± 3.0; 92), and 30-40 μm in vitelline mass width (33 ± 2.0; 84), and had nonprotruding polar plugs that were 10-15 μm long (11 ± 1.4; 93) and 8-10 μm wide (9 ± 1.1; 108). Forcibly hatched first-stage larvae (unfixed) were filiform, 188-273 μm long (212 ± 25.5; 13), 8-13 μm wide (10 ± 1.2; 13), and had fine transverse striations. Eggs infected the epidermis only. Histology revealed intra-epithelial inflammation with eosinophilic granulocytes and hyperplasia, plus dermal lymphofollicular hyperplasia associated with the infection. The eggs of H. cf. carcharhini likely undergo considerable ex utero development before being sloughed (unhatched) from the host, along with epidermal cells.     

Impact of mating status on egg-laying and superparasitism behaviour in a parasitoid wasp

Most parasitoid female wasps can distinguish between unparasitized and parasitized hosts and use this information to optimize their progeny and sex allocation. In this study, we explored the impact of mating on oviposition behaviour (parasitism and self‐ and conspecific superparasitism) on both unparasitized and already parasitized hosts in the solitary parasitoid wasp Eupelmus vuilleti (Crw.) (Hymenoptera: Eupelmidae). Virgin and mated females had the same oviposition behaviour and laid eggs preferentially on unparasitized hosts. The sex ratio (as the proportion of females) of eggs laid by mated females in parasitism and conspecific superparasitism was 0.67 ± 0.04 and 0.57 ± 0.09, respectively. Likewise, females laid more eggs in conspecific superparasitism than self‐superparasitism under our experimental conditions. These experiments demonstrate that E. vuilleti females can (i) discriminate between unparasitized and parasitized hosts and adapt the number of eggs they lay accordingly, and (ii) probably discriminate self from conspecific superparasitized hosts. Finally, mating does not appear to influence the host discrimination capacity, the ovarian function, or the oviposition behaviour.     

Prosorhynchus crucibulum (Digenea: Bucephalidae) miracidium morphology and its passive transmission pattern

The characterization of Prosorhynchus crucibulum (Rudolphi, 1819) Odhner, 1905 egg and miracidium is important in order to better understand the transmission dynamics between the definitive host and the primary host, the mussel. In this way, the objective of this work was to study the miracidia morphology, in order to evaluate if this species belongs to the group of passive or active transmission larvae. The morphology of eggs is similar to the ones presented by other Prosorhynchus species, with a small size of 26 × 17 μm, and four-five times smaller than the ones of Fasciola hepatica. The number of eggs produced per worm was around 6,760 (4,236-8,401), which was four-five times higher than in F. hepatica. The miracidia presented small dimensions 24 × 15 μm (23-25 × 13-15 μm range), a long stylet, two ciliated epithelial plates, very long cilia (12.7 μm) and absence of terebratorium and eyespots. Those features of the miracidia suggest that P. crucibulum belongs to the group of passively infecting larvae.     

Laminarionema elsbetiae gen. et sp. nov. (Ectocarpales, Phaeophyceae), a new endophyte in Laminaria sporophytes

Laminarionema elsbetiae gen. et sp, nov, (Ectocarpaceae, Ectocarpales. Phaeophyceae), a new endophyte of Laminaria japonica Areschoug (Laminariales, Phaeophyceae), is described from Muroran. Hokkaido, Japan. Laminarionema elsbetiae grows in the host tissues forming networks in the epidermal and subcortical layers as well as penetrating into the cortical and medullary layers. Only phaeophycean hairs emerge from the surface of the host tissue. No reproductive cells were found in field material. However, under host-free culture the species formed three morphologically different reproductive structures. Macrosporangia containing a single large motile spore were formed under long and short day conditions below 20°C, transformed from vegetative cells, conical to elongated in shape, 50–75 μm in length and ca. 10 μm in diameter. Microsporangia were linear to lanceolate, sometimes branched, formed under long and short day conditions below 15°C. Unilocular sporangia were more or less irregular in shape, formed under short day conditions of 5–15°C, 60–75 μm in length and 40–45 μm in diameter. Sexual fusion between macro- and microspores was not seen. In mixed cultures of L. elsbetiae with young sporophytes of L Japonica Areschoug as well as Saccorhiza dermatodea (de la Pylaie) J. Agardh, L elsbetiae infected both hosts, grew in the same manner as in natural hosts, and formed macrosporangia between host epidermal cells.     

Description of Crassolabium persicum sp. n. (Nematoda, Dorylaimida, Qudsianematidae), an interesting species from Iran

A new species of the genus Crassolabium, Crassolabium persicumsp. n., collected from Arasbaran rangelands of Iran, is described and illustrated. It is characterized by its body 1.92-2.40 mm long, lip region offset by constriction and 17-19 μm wide, odontostyle 16-19 μm long with aperture occupying less than one-third (27-30%) its length, neck 428-690 μm long, pharyngeal expansion 369-390 μm long or occupying 54-56% of total neck length, female genital system amphidelphic, uterus bipartite and 162-218 μm long or 2.3-3.5 times as long as body diameter, pars refringens vaginae well developed, V = 54-57.5, vulva longitudinal, prerectum bearing a blind sac, tail conical with rounded tip to conoid (25-36 μm, c=60-69, c'=0.5-0.9), spicules 68-72 μm long, precloacal pair of supplements far (22-27 μm) from cloacal aperture, and 13-17 shortly spaced ventromedian supplements with hiatus. The new taxon is compared in depth to its relatives in Crassolabium as well as other similar species of Aporcelaimellus and Amblydorylaimus.     

Suitability of non-fertilized eggs of Homalodisca vitripennis for the egg parasitoid Gonatocerus morrilli

Gonatocerus morrilli (Howard) (Hymenoptera: Mymaridae) is an egg parasitoid used in California, USA to control glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae). Virgin GWSS females deposit non-fertilized eggs and mated females can exhaust sperm reserves for egg fertilization. However, nothing is known about Gonatocerus spp. performance when using non-fertilized GWSS eggs as hosts. Host age preference for oviposition and suitability of non-fertilized GWSS eggs as hosts for G. morrilli reproduction were investigated to determine whether non-fertilized eggs on sentinel plants could be used to monitor egg parasitoid populations. Gonatocerus morrilli parasitized all ages of GWSS eggs (1–8 days old) regardless if the host egg was fertilized or not. In choice tests (fertilized versus non-fertilized eggs), parasitoids failed to emerge as adults from non-fertilized eggs more often than from fertilized eggs. The results indicate that non-fertilized eggs were accepted by G. morrilli as suitable hosts for oviposition, but were less suitable for immature development compared to fertilized eggs.     

The influence of previous host age on current host acceptance in Trichogramma

Trichogramma principium Sug. & Sor. females were sequentially offered two portions of the grain moth (Sitotroga cerealella Oliv.) eggs, either young (1-day old) or old (eggs that had developed 6 days at a temperature of 20 °C). The probability of host acceptance depended not only on current host age, but also on the age of the previously offered host. Particularly, Trichogramma females more often oviposited in old host eggs when previously offered young eggs (35–45% of Trichogramma females laid eggs) compared to females which were sequentially offered two portions of old eggs (15–20% of Trichogramma females laid eggs). In other words, parasitization by Trichogramma was stable even when transferred from young (preferred) to old (usually rejected) eggs. Dissections showed that refusing females had significantly more mature eggs than ovipositing females, independent of host age. Among ovipositing females, wasps provided with young hosts had fewer mature ovarial eggs than wasps provided with old hosts. Supposedly, Trichogramma females offered old hosts require a higher motivation to oviposit and have a correspondingly higher egg load than females offered young (preferred) hosts.     

Longidorus ferrisi n. sp. from California Citrus

In October 1999, the authors received fixed specimens of a species of Longidorus from Howard Ferris found about the roots of a citrus tree in Oakville, Napa County, CA. After determining it to be new a species, we requested additional specimens. The samples contained roughly equal numbers of males and females. Longidorus ferrisi n. sp. is most similar to L. elongatus, but can be distinguished by a greater c-ratio (111-187 vs 73-141), a lesser c′ (0.7-1.1 vs 1.0-1.3), a more offset head, a more posterior guide ring (35-40 vs 30-33 μm), the presence of sperm in the uterus in mature females, and the approximate 1:1 ratio of females to males. Other similar species include L. artemisiae, L. crassus, L. glycines, and L. milanis. Longidorus ferrisi n. sp. differs from L. artemisiae by a lesser a-ratio (74-102 vs 109-155), a lesser c′ value (0.7-1.1 vs 1.0-1.6), a more posterior guide ring (35-40 vs 27-34 μm), a longer odontostyle (91-108 vs 84-98 μm), a wider lip region (16-19 vs 14-17 μm), wider mid-body (53-69 vs 41-52 μm), and longer spicules (57-65 vs 39-49 μm). The new species differs substantially from L. crassus by its lip shape and the presence of males, and differs from L. glycines by a shorter body (4.33-5.97 vs 6.14-8.31 mm), a lesser c′ value (0.7-1.1 vs 0.9-1.4), a narrower lip region (16-19 vs 20-23 μm), wider mid-body (53-69 vs 39-57 μm), longer spicules (53-69 vs 45-53 μm), and fewer supplements (7-11 vs 11-17). Longidorus ferrisi n. sp. differs from L. milanis by a longer body (4.33-5.97vs 3.00-4.90 mm), a greater c value (111-187 vs 86-130), a wider mid-body (53-69 vs 43-56 μm), a different head shape, and longer spicules (53-69 vs 41-54 μm). The nuclear 18S ribosomal DNA sequence of this species revealed that this species is unique with respect to all sequenced Longidorus species.     

Host stage preference for depositon of male eggs byCoccophagus cowperi [Hym.: Aphelinaidae]

VirginCoccophagus cowperi Girault females were allowed to deposit male eggs on a complete series (egg to nearly fully-formed adults) of developing female individuals of their own species, these females developing as primary, internal parasites of their scale hosts. Dissections of a subsample of this material indicated that the virgin females expressed a host stage preference for the large larval and prepupal stages. A large proportion of the eggs were deposited on mature primary parasite larvae prior to their expulsion of the meconium. The male eggs were directly anchored to the primary parasite.     

Transmission experiments on the host specificity of Heterophyes species in 16 potential definitive hosts

Sixteen different species of piscivorous mammals and birds were tried as experimental definitive hosts for Heterophyes heterophyes, H. aequalis and H. dispar. The hosts were classified in four categories, by fluke longevity, recovery and size, and the number of uterine eggs (embryonated/unembryonated): (1) Canidae and the cat were highly susceptible hosts for all three species of Heterophyes; (2) several mammals and herons showed a reduced susceptibility to infection (H. aequalis, 6 species; H. dispar, 1 species; H. heterophyes, 0 species); (3) In a group of hosts specific to each trematode, flukes were recovered up to 14 days post infection, but their uterine eggs did not become embryonated; (4) In a fourth category of hosts, chiefly Mustelidae, flukes could not be recovered. Taking also the literature into account it is concluded that man is a highly susceptible host for H. heterophyes, and that probably H. aequalis and H. dispar may reach reproductive maturity in humans also. The described wide host range of H. aequalis appears to be more typical for Heterophyidae than the comparably narrow host range of H. heterophyes.     

Discovery of Maritrema obstipum (Digenea: Microphallidae) from migratory birds in Korea

Adults of Maritrema obstipum (Digenea: Microphallidae) were found in the intestines of 4 species of migratory birds, including the sanderling (Crocethia alba), Kentish plover (Charadrius alexandrines), Mongolian plover (Charadrius mongolus), and red-necked stint (Calidris ruficollis), collected from Yubu Island, Chungcheongnam-do, Korea. The worms of were 451 × 265 μm in size, and were easily identifiable as Maritrema species by the presence of the cirrus sac, and the ring-like distribution of the vitellaria. More specifically, the ejaculatory duct curved posteromedially, and the 2 parts of vitelline follicles were found to be distinct at the posterior end. The eggs were brown-colored, and 19.8 × 12.3 μm in size. All these findings implicated M. obstipum as the pertinent species of the worms. Beside these, adult worms of Gynaecotyla squatarolae, Parvatrema duboisi, and Acanthoparyphium sp. were also discovered. This is the first report establishing migratory birds as the natural definitive hosts for M. obstipum.     

Factors contributing to the in vitro development of Ascaris suum from second-stage larvae to mature adults

When a three-step roller culture system was used, second-stage larvae of Ascaris suum, artificially hatched from eggs, developed in high numbers to the fourth stage, and a few to young and mature adults. The culture system consisted of (1) Medium KW-2 supplemented with 10 mM L-cysteine for the first 4 days, and with 5 mM L-cysteine for the following 7 days; (2) followed by Medium API-18 for 7 days; and (3) thereafter, by Medium API-1 supplemented with hemin (bovine) at a concentration of 24 micrograms/m1. Cultures were gassed with 95% nitrogen-5% carbon dioxide for the first 4 days and 85% nitrogen-5% oxygen-10% carbon dioxide thereafter, and incubated at 39 C. Two mature females that produced unfertilized eggs and a mature male with spermatozoa were the most advanced stages attained. The mature females were obtained in 67 and 73 days; and the largest female measured 110 mm. The latter produced 1,356,000 unfertilized eggs, from days 67 to 125. The mature male was obtained in 80 days; it measured 77 mm long and had paired spicules that were 1.5 mm long. Development of A. suum in three other culture systems showed that deletion of Medium API-18 or its substitution by Medium KW-2 limited development to late fourth stage and early, young adults, respectively; and the use of Medium API-1 without hemin limited development to early fourth stage.     

Activity patterns and oviposition rates of Aphytis lingnanensis females,a parasitoid of California red scale Aonidiella aurantii: implications for successful biological control

1. Activity patterns of Aphytis lingnanensis Compere (Hymenoptera: Aphelinidae) females were determined. Females have a preovipositional period of 2–6.5 h and oviposit daily until they die. The average lifetime fecundity was 191 eggs (n = 10 females), with a maximum of 13 eggs per day, but usually far fewer. Females do not lay eggs at night as low light levels reduce the propensity to oviposit. 2. Aphytis lingnanensis females showed a repeatable pattern of activity during the course of the day, ovipositing actively during the first 1.5 h of their 7 h exposure to hosts. Thereafter, activity levels decreased sharply and females spent relatively long intervals resting. Activity occurred in fairly discrete bouts, with long periods of inactivity, ranging from 12 to 231 min between bouts. 3. Each day, females laid most eggs during their first bout of oviposition, with availability of mature eggs in the ovaries dictating the duration and intensity of ovipositional bouts. Once females completed a bout of oviposition in the laboratory, they moved away from the hosts even though many suitable hosts remained. They stood immobile, sheltering, until they matured more eggs. 4. These results suggest how general biological control models and dynamic state variable models of behaviour can be made more realistic. In particular, the behaviour of females does not remain constant over extended periods, particularly because of egg depletion, which suggests that the interaction between the ovipositional history of the individual and its physiological capabilities dictates the response of females to particular circumstances, and thus contributes to patterns of parasitism in the field. 5. It is predicted that A. lingnanensis females in the field are inactive at night and begin ovipositing when it becomes light enough in the morning. Egg depletion is likely if enough hosts are available, but should occur later in the day than was recorded in the laboratory. Egg-depleted females are likely to shelter while they mature more eggs, but may undertake interpatch movement.     

Vittatidera zeaphila (Nematoda: Heteroderidae), a new genus and species of cyst nematode parasitic on corn (Zea mays)

A new genus and species of cyst nematode, Vittatidera zeaphila, is described from Tennessee. The new genus is superficially similar to Cactodera but is distinguished from other cyst-forming taxa in having a persistent lateral field in females and cysts, persistent vulval lips covering a circumfenestrate vulva, and subventral gland nuclei of the female contained in a separate small lobe. Infective juveniles (J2) are distinguished from all previously described Cactodera spp. by the short stylet in the second-stage juvenile (14-17 μm); J2 of Cactodera spp. have stylets at least 18 μm long. The new species also is unusual in that the females produce large egg masses. Known hosts are corn and goosegrass. DNA analysis suggests that Vittatidera forms a separate group apart from other cyst-forming genera within Heteroderinae.