Secondary Parasite Research Articles

Secondary sexual characters, parasites and testosterone in the barn swallow, Hirundo rustica

Abstract. The immuno-competence hypothesis predicts that the expression of secondary sex traits should be positively related to testosterone levels, but that androgens should simultaneously have negative effects on the immune defence system. Relatively high levels of circulating androgens should therefore result in elevated levels of parasite infections. Parasite load and testosterone levels will be uncorrelated, or even negatively correlated, however, if males with high testosterone levels and large secondary sexual characters are reliable advertisers of genetic resistance to parasites. In male barn swallows, testosterone concentrations peaked during the pre-laying period. Males that had high levels of testosterone (adjusted for the stage of the breeding cycle) at one stage of the breeding cycle also had relatively high levels at other stages. The length of the outermost tail feathers, which are secondary sexual characters currently involved in sexual selection, was positively related to adjusted circulating levels of testosterone, even when potentially confounding variables were controlled statistically. The prevalence (proportion of hosts infected) and intensity (number of parasites per host individual) of ecto-parasites (two species of Mallophaga, one species of Acari) infecting barn swallows were unrelated to adjusted testosterone concentrations. Intensities of ecto-parasite infections were negatively related to tail length of male barn swallows, and unmated males had higher intensities of infections than mated males. These results are consistent with the immuno-competence version of the handicap principle.

Interactions betweenAulonium ruficorne [Coleoptera: Colydiidae] and other natural enemies of bark beetles [Coleoptera: Scolytidae

The within tree distribution of some common natural enemies of bark beetles in pine plantations in Israel and some aspects of their feeding habits were studied with special emphasis on the potential impact on the predatorAulonium ruficorne Olivier. A total of 12 predators and 2 parasite species were found associated withA. ruficorne in the natural enemy complex of bark beetles on pines. No secondary parasites were detected. The anthocoridScoloposcelis pulchella (Zetterstedt) and the dipteranMedetera striata Parent were observed feeding on immature stages ofA. ruficorne in the absence of scolytids. The associated Coleoptea:Nemosema elongatum F.,Rhizophagus bipustulatus L.,Corticeus spp.,Plastysoma spp. andPlegaderus discisus Erickson are thought to compete withA. ruficorne on larvae and pupae of bark beetles when the latter are in limited quantities (especially in the lower section of the tree). The parasites, mainlyMetacolus unifasciatuss Forster andDendrosoter caenopachoides Ruschka are assumed to compete withA. ruficorne during the larval period in the smooth bark section of the stem. Competition might occur mainly during spring and fall. Deutonymphs of the miteIpiduropoda sellnicki were detected on the abdomen ofA. ruficorne adults. Larvae of the predator were rarely infected in the field by the bacteriaSerratia sp. while laboratory cultures suffered high rate of mortality caused by this pathogen.

Secondary sexual traits, parasites, and polygyny in red-winged blackbirds, Agelaius phoeniceus

Secondary sexual traits, parasites, and polygyny in red-winged blackbirds, <i>Agelaius phoeniceus</i>

Parasites ofMonellia caryella [Hom.: Aphididae]: Phenology and effect on the aphid population in pecan orchards in Israel

One primary parasite,Trioxys pallidus (Haliday) (Hym.: Braconidae), and a secondary parasite,Aphidencyrtus sp., were identified from the blackmargined aphid,Monellia caryella (Fitch) (Hom.: Aphididae), in Israeli pecan orchards. The average total parasitism for all locations sampled was 13.5%. Although a hyperparasite was discovered, it had no significantly detrimental effect on the parasite.

Biological comparisons between arrhenotokous and thelytokous biotypes ofMesochorus nigripes [Hym.: Ichneumonidae

The host preferences and sex ratios ofMesochorus biotypes from Sweden and Colorado (U.S.A.) were studied in the field and laboratory. TheseMesochorus are secondary parasites ofBathyplectes spp., parasites ofHypera postica (Gyllenhal). The Colorado biotype is 100% thelytokous, and clearly prefersBathyplectes stenostigma (Thomson) as a host. Only an arrhenotokous biotype was positively detected in Sweden, and it appeared to preferB. curculionis (Thomson). However, some of the data suggest that the thelytokous biotype was probably also present in Sweden, at least inB. stenostigma. The behavioral differences and reproductive isolation of the thelytokous and arrhenotokous biotypes indicate that they are separate sibling species, even though they cannot yet be separated morphologically, and isozyme analyses were inconclusive (possibly due to a mixture of biotypes in Sweden).

Protective immunity to Brugia malayi larvae in BALB/c mice: potential of this model for the identification of protective antigens.

Protective immune responses against the infective larvae of Brugia malayi have been demonstrated in BALB/c mice. Various factors governing resistance to reinfection have been examined to provide baseline data for use of this model in studies of immunoprophylaxis. Parasites that established following a primary infection survived for approximately 10 days, following which numbers declined rapidly to a low level. Resistance was evidenced by a more rapid clearance of secondary infection parasites. The degree of immunity expressed was not related to the route of administration of the initial infection (subcutaneous, intravenous, intramuscular, or intraperitoneal). However, both the level of resistance and the rapidity of its expression were dependent on dose, with as few as 2 larvae stimulating measurable immunity. Sensitization with living male or female adult worms, fourth stage larvae or microfilariae of B. malayi, or infective larvae of B. pahangi conferred substantial resistance to larval challenge. Significant levels of immunity were also induced by dead B. malayi larvae (46%) and their aqueous extracts (76%), but not with the corresponding insoluble fraction. We suggest that this experimental system is ideally suited to aid in the identification of putative protective antigens in brugian filariasis.

PRIMARY AND SECONDARY PARASITES OF AN ALFALFA-INFESTING APHID, THERIOAPHIS SP., IN MANITOBA

In 1984 and 1985 a total of 51 mummies of the genus Therioaphis sp. (Hornoptera: Aphididae) were collected on alfalfa, Medicago sativa L., in several localities in southern Manitoba: Glenlea, Oakbank, Rosenort, St. Adolphe, and Ste. Agathe [status of North American species of Therioaphis is uncertain; some workers regard Therioaphis on alfalfa and those on clover as different species, whereas others regard those found on alfalfa as merely strains of the species from clover (A.G. Robinson, personal comrnunication)]. The mummies were held in gelatin capsules at 20°C and a 16L:8D cycle, and 44 parasite adults that emerged were identified. Two primary parasites pecies. Praon exsolelurn (Nees) and Binodoxys sp. (Hymenoptera: Aphidiidae), were recorded (Table 1). Cocoons from which adults of P. exsoleturn emerged were formed between the mummy and the substratum, whereas cocoons of the two Binodoxys specimens were inside the mummies. The three secondary parasite species (Table 1) emerged only from the hosts with external cocoons and presumably had developed on P. exsoleturn. Each of the seven hosts from which no parasites emerged had an external cocoon which contained a decomposed parasite larva, either P. exsoletum or one of the secondary species.

チャの新梢枯死症の原因

The shoot blight of tea plant causing sever damage to tea production in Japan was etiologically investigated. This disease was found to be caused by the tea gray blight fungus, Pestalotia longiseta. The tea brown blight fungus, Glomerella cingulata, was often detected on the diseased shoots, but it was considered to be a secondary parasite.

Interaction of Laterispora brevirama and the mycoparasites Sporidesmium sclerotivorum and Teratosperma oligocladum

Laterispora brevirama, a fungus found in association with the Sclerotinia mycoparasites Sporidesmium sclerotivorum and Teratosperma oligocladum, was markedly similar in morphology to the other two fungi yet differed in its parasitic activity. Laterispora brevirama colonized and proliferated on sclerotia of Sclerotinia minor which had been infected first by Sporidesmium sclerotivorum or T. oligocladum but did not do so in the absence of these specific mycoparasites. Macroconidia of L. brevirama germinated in soil in response to sclerotia infected by Sporidesmium sclerotivorum, and to hyphae of Sporidesmium sclerotivorum. Aqueous extracts of hyphal mats of Sporidesmium sclerotivorum stimulated maximal germination of macroconidia in vitro, although other nutrients also supported germination to a lesser extent. In culture and in its parasitic phase in soil, L. brevirama formed specialized contact cells on the hyphae of Sporidesmium sclerotivorum and T. oligocladum, but never appeared to invade hyphae. Laterispora brevirama added to soil at 1000 macroconidia/g, along with Sporidesmium sclerotivorum at the same concentration, did not influence the rate of infection and destruction of sclerotia of Sclerotinia minor by Sporidesmium sclerotivorum. The resulting numbers of new macroconidia of Sporidesmium sclerotivorum formed in the soil from energy derived from the infected sclerotia, however, were reduced by the presence of L. brevirama. Laterispora brevirama is either a direct parasite of Sporidesmium sclerotivorum and T. oligocladum or is a secondary parasite of Sclerotinia spp. that is active only in association with either of the two primary mycoparasites.

Natural Enemies of Oak Lecanium (Homoptera: Coccidae) in Eastern Virginia

Twigs of willow oak, Quercus phellos L., infested with oak lecanium, Parthenolecanium quercifex (Fitch), were collected during 1980–83 to determine the identity and role of natural enemies of the oak lecanium. Five Hymenoptera and their effectivenesswere identified: Encyrtus fuscus L. and Blastothrix sp. as internal parasites of the adult female; Coccophagus lycimnia (Walker), an internal parasite of the immature stages; Eunotus lividus Ashmead, an egg predator; and Pachyneuron altiscutum Cook, a secondary parasite. Rates of parasitization varied among locations, and ranged from 10 to 60%. Two Coleoptera were identified: Hyperaspis signata (Oliver) (Coccinellidae) and Tricorynus confusus (Fall) (Anobiidae), the latter species being observed for the first time as a predator.

Sludge Application to Land Compared with a Pasture and a Hayfield: Reduction of Biological Health Hazard Over Time

AbstractEconomic and environmental pressures favor the disposal of sewage sludge on agricultural land. In order to assess this hazard, this study investigated the occurrence and survival of primary and secondary bacterial pathogens, parasite eggs, and enteroviruses in sludge injected by machine into a fallow field, sludge spread on a grass plot (Poa spp. and Fescue spp.), a pasture grazed by cows (Bos taurus), and on soil taken from a control hayfield (dominated by Bromus spp.). It was assumed that the unsludged hayfield represented an acceptable level of “risk.”The sludged plots compared favorably with the control hayfield with respect to the occurrence and survival of nematode parasites, enteroviruses, and primary bacterial pathogens. Secondary bacterial pathogens persisted on all fields throughout the study, but levels declined more slowly on the sludged grass plot than the injected sludge field, the pasture, or the control hayfield. Despite the persistence of secondary pathogens (which are normally present on grazed fields), the health hazards to humans and animals were judged to be comparable to those on a hayfield and a pasture that had not been sludged.

Composition and Relative Abundance of Parasites Associated with Aphid Populations on Strawberry in Southern California

Four primary parasites and seven secondary parasites (hyperparasites) were reared from mummies of five species of aphids collected from winter plantings of strawberries in southern California in 1981 and 1982. In order of abundance, the primary parasites were Lysiphlebus testaceipes Cresson, Aphelinus semiflavus Howard, Aphidius urticae Haliday, and Ephedrus californicus Baker. L. testaceipes accounted for 47.8 and 77.1% of all primaries in 1981 and 1982, respectively, and was reared most commonly from the strawberry aphid, Chaetosiphon fragaefolii (Cockerell), in 1981 (56.3%) and from the melon aphid, Aphis gossypii Glover, in 1982 (74.5%). Dendrocerus aphidum (Rondani) and Alloxysta magourae “complex” were the most common secondary parasites, accounting for 34.6 and 19.2% of all secondaries, respectively, in 1981 and for 55.8 and 23.4% in 1982. C. fragaefolii was the most common aphid present both years, reaching damaging populations in 1982 despite the parasite activity.

A hyperparasite of coccids develops as a primary parasite of fly puparia

Species ofPachyneuron (Hym.: Pteromalidae) have been recorded as either primary parasites or hyperparasites.P. concolor (Foerster) is a polyphagous secondary parasite, attacking encyrtid primary parasites in soft scales, mealy bugs and coccinellid larvae. It also develops as a tertiary parasite.

Observations on the biology ofCinara ponderosae(Williams) (Homoptera: Aphididae) in the westside forests of the Sierra Nevada

Observations on the biology and population dynamics of Cinara ponderosae Williams) in the westside Sierra Nevada forests of California are presented. The species is believed to be anholocyclic, because sexuales, eggs, and fundatrices were absent. In the spring following winter survival on ponderosa pine (Pinus ponderosa Lawson) in the foothills, populations migrated up the west slope of the Sierra Nevada. The local population in Blodgett Forest, Eldorado County, began in May with the number of aphids and colonies expanding throughout June and collapsing by the end of July. Detailed study of instar distribution, based on a sampling every four days, showed a gradual increase in older instars until population collapse. First generation 4th instars and apt era e moved throughout the tree and began new colonies. Predators, primary and secondary parasites, and ant associates were noted and discussed.

Parasites of Blackmargined Aphids 1 and their Effect on Aphid Populations in Far-West Texas 2

One primary parasite, Aphelinus perpallidus (Gahan), and five previously unreported secondary (suspected) parasites, Alloxysta schlingeri (Andrews), Aphidencyrtus spp., Chartocerus spp., Dendrocerus spp., and Pachyneuron spp., were identified from black margined aphids, Monellia caryella (Fitch) (Homoptera: Aphididae), in far-west Texas pecan orchards. Aphelinus perpallidus was found in significant numbers, but populations varied greatly among orchards. During most of the growing season, less than 6% of collected M. caryella specimens were parasitized by A. perpallidus , but up to 52% were parasitized in one orchard in October. Other species parasitized <1% of M. caryella populations.

Ecology ofRhopalomyia californicaFelt (Diptera: Cecidomyiidae) and its parasites in an urban environment

The ecology of an endemic gall midge, Rhopalomyia californica Felt, and its larval parasites was studied over a 3-year period in the city of Davis, California. Six species of parasites were associated with larvae of the midge: Torymus koebelei (Huber), T. baccharidis (Huber), Platygaster california (Ashmead), Zatropis capitis Burks, Mesopolobus sp., and Tetrastichus sp. However, the midge was from four to ten times more abundant in Davis than in the endemic environment. In Davis, neither parasitization by any given species nor by the aggregate of species was a consistent regulating factor. These results suggest that, whereas parasite guilds in urban environments may be structurally similar to their non-urban counterparts, adequate or comparable levels of natural biological control of the host will not necessarily result. Thus, the use of native plants in urban environments may not always minimize attendent pest problems. The data obtained provide some empirical support for multiple-species introductions in classical biological control and illustrate the utility of facultative secondary parasites. A method for assessing competitive interactions among parasites before introduction is described, and the relevance of the theory of r- and K-selection to biological control is assessed.

Status of the subfamily names Charipinae and Alloxystinae (Hymenoptera: Cynipidae)

Abstract. The Alloxystinae (= Allotriinae) comprises three genera (Alloxysta, Phaenoglyphis and Lytoxysta) of secondary parasites on aphids. Charipinae comprises a single monobasic genus (Dilyta # Charips = Glyptoxysta), a primary parasite of a psyllid. The relevant subfamily and generic synonymies are listed. Lectotypes are designated for Dilyta subclavata Förster and Charips microcera Haliday which are newly placed in synonymy.

Utility of Facultative Secondary Parasites in Biological Control

The effect of Zatropis capitis Burks, a facultative secondary parasite, on Torymus koebelei (Huber) and Platygaster californica (Ashmead), primary parasites of Rhopalomyia californica Felt, is used to illustrate how a facultative secondary parasite can be of value in biological control. Parasitization by either of the primary parasites was greatest when these species occurred alone compared to when they occurred in combination with Z. capitis ; however, total parasitization was greatest when the primaries occurred with the facultative secondary parasite. It is suggested that a facultative secondary parasite is of value in biological control when (1) the impact on host density produced by a primary parasite and a facultative secondary one acting in concert is greater than that produced by the primary parasite acting alone and (2) the facultative secondary parasite does not have a deleterious effect on other parasite guilds in the environment.

New genera and species of Eurytomidae (Hymenoptera: Eurytomidae)

The economically important family Eurytomidae which include both primary and secondary parasites as well as phytophagous species hasnot been well understood. In this paper an effort has been made to key out tribes. Several new genera and new species have been described and these are mostly from the New World.

THERMAL CONSTANTS FOR DEVELOPMENT OF THE PEA APHID (HOMOPTERA: APHIDIDAE) AND SOME OF ITS PARASITES

AbstractThe relationship between the temperature and the speed of development is described for the Kamloops ‘biotype’ of the pea aphid, Acyrthosiphon pisum, and some of its associated hymenopterous parasites. The primary parasites are: Aphidius ervi ervi, A. ervi pulcher, A. smithi, and Praon pequodorum; and the secondary parasites are: Asaphes lucens and Dendrocerus niger. For each species the lower temperature threshold for development and the time-to-adult was determined under constant laboratory conditions using field-grown alfalfa as a host plant for the pea aphid and the first-generation offspring of field-collected aphids and parasites. The thermal constants enable the prediction of aphid and parasite population growth, as influenced by temperature, on a physiological time-scale.