Host Abdomen Research Articles

Noctuidonema guyanense (Nematoda: Aphelenchoididae): Population Profiles on Male and Female Fall Armyworm Moths2

The distribution of Noctuidonema guyanense Remillet and Silvain (Nematoda: Aphelenchoididae) populations on wild female, laboratory-reared female, and wild male moths of Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) was determined. Populations of all life stages of N. guyanense were aggregated (P < 0.05) on abdominal segments 7–10 of wild female and moderately infested (<100 nematodes), laboratory-reared female moths. Nematodes also aggregated on abdominal segments 7–10 on heavily infested (>300 nematodes), laboratory-reared female moths, but larger populations of all mobile life stages migrated from posterior to anterior abdominal segments of a host. On wild male moths, N. guyanense populations tended to disperse along the host's abdomen, with significant aggregates of eggs and neonates on abdominal segments 8–10 and smaller aggregates of adults and juveniles on abdominal segments 1–2. Nematodes avoided colonization of the head of nearly all hosts of either sex.

Infestation and Dispersal of Noctuidonema guyanense (Nematoda: Aphelenchoididae) on Spodoptera frugiperda (Lepidoptera: Noctuidae)

The distribution, dispersal, and population growth of an ectoparasitic nematode, Noctuidonema guyanense RemilIet & Silvain, were studied on mating pairs of Spodoptera frugiperda (J. E. Smith) in the laboratory. Nematode populations were the greatest on terminal abdominal segments of wild S.frugiperda males. Eggs and neonates were predominant on abdominal segments eight to ten, whereas juveniles were distributed widely along a host's abdomen and thorax. Although female nematodes moved from infested male moths to noninfested female moths within 15 min after initiation of host mating, male and immature nematodes often did not transfer until 1.5–2.0 h after host copulation began. Nematodes migrated anteriorly to the fifth abdominal segment of new hosts in 4–7 h. Forty-eight percent of the host-matings resulted in the transfer of an average of 5.3 nematodes to new hosts. Populations of N.guyanense on newly infested female moths increased to an average of 400 nematodes within 176 h after the initiation of mating by hosts. About 80% of the nematodes that transferred to new hosts were juveniles.

Germination and infection processes of the entomophthoralean fungus Erynia radicans on the potato leafhopper, Empoasca fabae

The germination and penetration processes of Erynia radicans on fifth instar Empoasca fabae nymphs at 20°C, 100% relative humidity, were investigated by scanning electron and fluorescence microscopy. Oval primary and secondary conidia attached to the host cuticle and germinated rapidly (60% within 2 hr). While percentage germination did not differ on the three body regions of the host, significant differences were observed in the modes of germination. The percentage of spores that produced germ tubes increased from 10% on the leafhopper head to 13% on the thorax and 22% on the abdomen, while capilliconidiophore production decreased from 88 to 84 to 71% on the respective body regions. Hyphae from spores deposited on sclerites displayed strong directional growth toward interscleral membranes, especially on the host abdomen. Penetration of the cuticle was effected by formation of appressoria. Small, globular appressoria were formed immediately adjacent to spores or on short, nonseptate germ tubes, while large, elongate appressoria were produced usually on long, but occasionally on short, septate hyphae. Approximately 3% of penetrations occurred on the leafhopper head, 16% on the thorax, and 74% on the abdomen; ca. 61% of all penetrations occurred through membranes, especially in the intersegmental folds of the abdomen. Earliest penetrations were observed 3–4 hr after inoculation, but significant numbers of penetrations were not observed until after 6 hr. The number of penetrations on individual leafhoppers was largely independent of dose (mean r 2 = 0.174), indicating substantial variability in susceptibility of individual leafhoppers. The percentage of viable oval conidia which ultimately gave rise to penetrations (either directly or indirectly via secondary spore production) was ca. 5% after 10–12 hr and 20% after 48 hr. The percentage of leafhoppers infected (percentage penetrated by one or more hyphae from a mean dose of 41 spores per insect) increased rapidly from only 2.4% at 4 hr postinoculation to ca. 60% after 8 hr. The LD50 was estimated at 4.1 spores per leafhopper.

Stimuli inducing detachment of larvalArrenurus danbyensis (Hydrachnidia: Arrenuridae) from adultCoquillettidia perturbans (Diptera: Culicidae)

In this study, potential cues for detachment of parasitic larvalArrenurus danbyensis Mullen mites fromCoquillettidia perturbans (Walker) mosquitoes were investigated. Contact with water did not induce a dramatic rate of dissociation. Crushing the host's abdomen was not as effective as crushing the head or thorax; although general body trauma has an effect, it is not sufficient to explain these results. Crushing the host's head following application of a ligature slowed the rate of mite detachment. We infer that haemolymph-borne cues, possibly hormones, are released by crushing the head or thorax of the host and induce rapid mite detachment. External application of Ringers solution or body fluids from mosquitoes significantly increased rate of mite detachment. It is possible that two separate mechanisms stimulate detachment of mites: external haemolymph reception signifying damage to the host and internal reception of haemolymph-borne cues associated with oviposition behavior.

Parasitic flies (Conopidae, Diptera) may be important stress factors for the ergonomics of their bumblebee hosts

Bumblebees harbour a wide range of parasitic organisms that attack all stages of their life cycles (reviews in Postner, 1951; Pouvreau, 1973, 1974; Alford, 1975; Kistner, 1982). Among them, conopid flies (Conopidae, Diptera) are particularly interesting because they attack foraging bumblebees which are handling flowers, or even on the wing (Frison, 1926; Cumber, 1949; Postner, 1951; Howell, 1967; Askew, 1971). A single egg is attached to (Frison, 1926; Plath, 1934; Cumber, 1949) or inserted into (DeMeijre, 1904; Howell, 1967) the host's abdomen, where the larva hatches and feeds on haemolymph and internal organs. Within 6–10 days the larva passes through three recognizable stages (Pouvreau, 1974) before the fly pupates in situ within the abdomen. The host bee dies shortly before the parasite pupates (Postner, 1951; Smith, 1966) and the parasite overwinters in its puparium; the adult fly then emerges in early summer (Frison, 1926; Townsend, 1935; Cumber, 1949; Postner, 1951). Conopid flies as parasites of bumblebees are known from all major habitats where the hosts occur (e.g. Kröber, 1939; Smith, 1966). However, the effect of parasitism on distribution and abundance of bumblebees is not known. In this preliminary note we have estimated degrees of infestation and concomitant reduction of life span in affected workers. The results are compared with literature reports on infestation levels in Europe.

Torrubiella Ratticaudata Sp. Nov. (Pyrenomycetes: Clavicipitales) and Other Fungi from Spiders on the Solomon Islands

Torrubiella ratticaudata sp. nov. is described from salticid spiders from the Solomon Islands. The anamorph of this fungus, Gibellula clavulifera var. alba var. nov., produces ovoid conidia on phialides on penicilloid conidiophores and bacilliform conidia from polyblastic conidiogenous cells arising directly from the mycelium. Both teleo- and anamorphic states occur on spiders bearing a single, whiplike fungal stroma projecting from the tip of the host's abdomen. Gibellula is extended and emended to include species of Granulomanus, which is regarded as a synonym of Gibellula. The different conditions under which morphologically distinct synanamorphs may reasonably be amalgamated in a single genus or should be retained in separate genera are discussed. Nomuraea atypicola and Gibellula pulchra were also found on the spiders; no teleomorphic state for either of these species was present.

Two remarkable new species of scuttle‐fly (Diptera: Phoridae) that parasitize termites (Isoptera) in Sulawesi

ABSTRACT. Diplonevra mortimeri sp.nov. and D.watsoni. sp.nov. are described from specimens caught at Nasutitermitinae termite colonies in Sulawesi. The female of both species has a remarkable pre‐oviposition behaviour in which she lures a worker termite into following her away from the colony. She then oviposits in the termite's abdomen. Pupation takes place within the remains of the host's abdomen. Both species only mature a single egg at a time. The female probably guards the comatose host termite during the period of larval development. The morphology of the male hypopygia of the new species allows reinterpretation of the peculiar anal tube in typical male Diplonevra. Furthermore the suggested homologies reinforce the view that the epandrium (tergite 9) has not been replaced by a periandrium (fused gonocoxites) in the Cyclorrhapha and consequently the latter cannot be derived from the Empidoidea.

The role of 20-hydroxyecdysone in the moulting of Biosteres longicaudatus, a parasite of the Caribbean fruit fly, Anastrepha suspensa

Ecdysteroid levels in whole body extracts of parasitized and unparasitized Anastrepha suspensa peaked 24 h after initial puparium formation. Six to eight-hour old first instars of the parasite, Biosteres longicaudatus, dissected from the host 16–18 h prior to its ecdysteroid peak never moulted in 20-hydroxyecdysone free media, while > 15% removed 6–12 h afterwards (i.e. at 24–36 h old) did. Isolation of 6–8-h old parasites within ligated abdomens of pre-wandering host larvae inhibited the parasites' moult. However, topical applications of 20-hydroxyecdysone (1.3 μg) to each host abdomen 24 and 48 h after ligation elicited host pupariation and larval-pupal apolysis as well as parasite moulting. Pre-treatment of host larvae with 2.7 μg/g hydroprene prior to parasitization and ligation prolonged host larval life. Subsequent 20-hydroxecdysone therapy of these hydroprene-treated, ligated abdomens increased parasite moult above that of abdomens receiving 20-hydroxyecdysone treatments alone. Six to eight-h old parasite first instars incubated for 4 days in 20-hydroxyecdysone-free medium increased in length by 78.3% and in head-capsule width by 23.8%. After a 24-h pulse of 10 −6 M 20-hydroxyecdysone only those that exceeded 1400 μ [X̄ = 14.1 ± 0.9 μ (SD)] in length and 250 μ in headcapsule width, moulted. A comparison of parasite growth in vivo and in vitro suggested that size may also affect moulting competence.

Apolysis without ecdysis in larval development of a strepsipteran, Elenchus tenuicornis (Kirby)

Prcvious uncertainty concerning the numhcr of larval stages in a strepsipteran (Elenchus tenuicornuj was resolved by transmission and scanning electron microscope observations. The first larval instar (triungulinid) is free-living: after entering the host (a delphacidj it undergoes a normal ecdysis. The resulting second instar larva undergoes two further apolyses without ecdysis. In the male, the cuticle of the fourth instar larva tans to form the puparium, while the female becomes sexually mature without a further moult after extrusion of the cephalothorax through the host cuticle. The discarded exuviae of the triungulinid remain in the host abdomen; subsequent larval staging is made possible by the retention of thr cxuviae ensheathing the larva as rach apolysis is accomplished. ~ ecdysis ~ larval instars - Strepsiptera ~ cuticle.

The preservation of infective spores of Octosporea muscaedomesticae in Phormia regina, of Nosema algerae in Anopheles stephensi, and of Nosema whitei in Tribolium castaneum by lyophilization

Infective spores of three species of microsporidia were subjected to the lyophilization process by employing varying media as cryoprotectants. The infectivity of the lyophilized spores was then tested against a standard fresh spore preparation in the appropriate host insect. Spores of Octosporea muscaedomesticae served as an experimental model and were rendered noninfective in host Phormia regina (Calliphoridae: Diptera) after lyophilization with the following cryoprotective agents: skim milk (12%), ascorbic acid (5%) combined with thiourea (5%), glycerol (10%), mesoinositol (5%), and equine serum. Spores of O. muscaedomesticae lyophilized or vacuum-dried in 50% sucrose as well as in the hosts' tissues remained highly infective for as long as 2 years at a dose of 10 6 spores/fly and a trial length of 12 days. At a dose of 5 × 10 4 spores/fly there was a slight decrease in infectivity of the spores which had been lyophilized in the host's abdomen after a 2-year storage period compared with that of fresh, nonlyophilized spores. Naked spores of Nosema algerae suspended in 50% sucrose and lyophilized produced infection in 50% of the host population of Anopheles stephensi (Culicidae: Diptera) compared with 70% infection produced by fresh non-lyophilized spores. Spores of Nosema whitei lyophilized within its host larva Tribolium castaneum (Tenebrionidae: Coleoptera) remained 100% infective at a dose of 5 × 10 5 spores/gram diet. It is concluded that an aqueous solution of 50% sucrose and/or the host's tissues are excellent protectants for the cryogenic or vacuum-drying process of the above-named spores, and their protective function may apply also to other microsporidian species.

Allophryxus malindiae gen.nov., sp. nov., a hemiarthrinid bopyrid parasitic upon the pontoniinid shrimp Coralliocaris superba (Dana)

Allophryxus, a new genus of hemiarthrinid isopod, is described. The only species, A. malindiae, is a parasite of the common Indo-West Pacific coral-associated shrimp Coralliocaris superba (Dana). The parasite attaches to the anteroventral aspect of the host's abdomen. Allophryxus is the only hemiarthrinid genus definitely known to have seven pereiopods on the short and four on the long side of the body. The presence of four pairs of biramous pleopods and the absence of telson and uropods from the abdomen distinguish this parasite from related forms.

Mermithid and microsporidan parasitism of blackflies (Diptera: Simuliidae) in the vicinity of Churchill Falls, Labrador

Neomesomermis flumenalis (Welch) infected 11.2% of 3144 blackfly larvae from five localities. Thelohania bracteata (Strickland) and Pleistophora simulii (Lutz &Splendor) and P. multispora (Strickland) parasitized 4.9% of the larval population. The mermithid infected the larvae of Prosimulium mixtum Sime &Davies and Simulium corbis Twinn, S. decorum Walker, and S. venustum Say. The larvae of the last three species were also infected with at least one of the species of Microsporida. Joint infections of T. bracteata and P. simulii occurred in S. venustum. Only 5 of 18 localities had infected blackfly populations. One nematode per host occurred most often, and emergence was from the host abdomen.

A TACHINID PARASITE OF DASYBASIS OCULATA (RICARDO) AND DASYBASIS HEBES (WALKER) (DIPTERA, TABANIDAE)

AbstractLarvae of a species of Bactromyiella Mesnil, possibly B. ficta (Walker), were found singly in the abdominal haemocoel of four female Dasybasis oculata and one female Dasybasis hebes. The parasite prepupa escaped from the host's abdomen, pupated within 6–8 hours and a single adult fly was reared after a pupal term of 27–30 days.

Site Selection by Larval Water Mites Parasitic on the Damselfly Cercion Hieroglyphicum Brauer

Two species of Arrenurus commonly parasitize a population of the damselfly Cercion hieroglyphicum. The incidence of the thoracic parasite, A. mitoensis Imamura and Mitchell, is low. Mite larvae preferentially clump together on the host mesothorax and at peaks of mite abundance may kill hosts. The abdominal parasite, A. agrionicolus Uchida, is abundant and locates 98% of the hosts. Larvae attach to the venter of the abdomen; the first mite usually attaches 0.50 mm anterior to the tip of segment 7 and subsequent attachments are anterior to this point with the mites usually keeping 0.10 mm apart. Responses to crowding cause mites to move to new sites, which tends to produce equal numbers on the two sides of the host abdomen, as well as forcing mites to more anterior attachment sites. These two parasites show the contrasting adaptations of a clumped parasite versus those of a more uniformly distributed parasite that is usually abundant enough to show intraspecfic competition for host resources.

The Strepsiptera are a True Order, Unrelated to Coleoptera

The reduction of the Strepsiptera to a family of Coleoptera in a recent textbook on beetles of the United States is found untenable. The Strepsiptera have a unique hypermetamorphic development, carried on entirely in the bodies of other insects of the orders Zygentoma (Lepismatidae), Orthoptera, Homoptera, and Hymenoptera. The female of Eoxenos (a parasite of Lepisma ) redevelops legs and emerges from the host to free her young; in all other members of the order the females are legless sacs, with cephalothoracic plates protruding from the host abdomen to receive sperm from the male and to permit exit of the active first larvae. Males all are winged, and are separated into families and super-families on the bases of reduction of tarsal joints, antennal joints, and wing veins; the tarsi are isomerous, never heteromerous as in the Coleoptera to which Strepsiptera have been referred. Pupal development of the males with a puparium with detachable cephalotheca does not occur in Coleoptera, but is found in Strepsiptera, Aleurodoptera, Coccoptera, and cyclorrhaphous Diptera. Free first larvae also occur in other orders, and do not constitute a valid character for uniting Strepsiptera with Coleoptera. The strepsipterous metathorax has the same parts as in the Aleurodoptera, and is totally unlike the coleopterous thorax. The simple wing venation is distinctive; the mouthparts are nonfunctional and very distinct from those of Coleoptera; the raspberrylike compound eyes are similar to those of Coccoptera, some Diptera, and a few other groups, but not like those of Coleoptera.