Primary Parasite Research Articles

INTRODUCTION, PERMANENT ESTABLISHMENT, AND DISPERSAL IN EASTERN CANADA OF OLESICAMPE GENICULATAE QUEDNAU AND LIM (HYMENOPTERA: ICHNEUMONIDAE), AN IMPORTANT BIOLOGICAL CONTROL AGENT OF THE MOUNTAIN ASH SAWFLY, PRISTIPHORA GENICULATA (HARTIG) (HYMENOPTERA: TENTHREDINIDAE)

AbstractFrom 1976 to 1978, 1300 mated females of Olesicampe geniculatae Quednau and Lim were released near Quebec City during a severe infestation of the mountain ash sawfly, Pristiphora geniculata (Hartig). Both cage and open releases were made. The interactions among the mountain ash sawfly, the imported primary parasite O. geniculatae, and the indigenous hyperparasite Mesochorus globulator (Thunb.), and the effect of O. geniculatae on the host population during and after the establishment phase, are reported. In 1984, O. geniculatae was recovered from all over southern Quebec. Parasitism ranged from 6 to 94%. Concurrently, infestation levels by the mountain ash sawfly declined significantly, and since 1985, the insect has almost disappeared in Quebec. With an annual spread of about 50 km per year after successful establishment, O. geniculatae now covers an area 1000 km in diameter. No major infestation by the mountain ash sawfly has been recorded in Quebec during the past 7 years. The introduction of O. geniculatae is rated as a complete success in classical biological control.

The Seasonal History of the White Peach Scale (Homoptera: Diaspididae) and its Hymenopteran Natural Enemies in North Carolina

Hymenopteran parasites (adults) and mobile stages (crawlers, adult males) of white peach scale, Pseudaulacaspis pentagona (Targioni-Tozzetti), were monitored biweekly (1986) or weekly (1987) in a peach orchard from April to December. The scale exhibited three peaks of crawler emergence, and a partial fourth generation was observed in both years. Three species of hymenopteran parasites consistently collected from traps were the primary parasites Encarsia berlesi (Howard) and Aphytis proclia (Walker), and the hyperparasite Marietta carnesi (Howard). Populations of all three parasites showed seasonal peaks of activity that differed in the two years of this study. Winter samples taken in 1985, and from 1987 through 1989 indicated differences between years in the ratio of parasites to hyperparasites overwintering.

Clutch Sizes and Sex Ratios in Pediobius foveolatus (Hymenoptera: Eulophidae), Primary Parasites of Epilachna varivestis (Coleoptera: Coccinellidae)

In Pediobius foveolatus (Crawford), which are primary parasites of the Mexican bean beetle, Epilachna varivestis Mulsant, mean brood sex ratio differed from 50% sons and 50% daughters. Frequency distributions of the percentage of sons differed from a random (binomial) distribution within clutches of different sizes. Clutch size predicted the percentage of sons. During single oviposition bouts, mother P. foveolatus tended to lay a mean of 12 daughter eggs followed by 2 son eggs. Oviposition duration predicted clutch size, and insemination status did not change brood size. Because offspring mortality did not occur, it was not responsible for changes in brood sex ratios or brood sizes.

Phenology and Degree-Day Relationships of the Obscure Scale (Homoptera: Diaspididae) and Associated Parasites on Pin Oak in Kentucky

Seasonal phenology of the obscure scale, Melanaspis obscura (Comstock), was monitored for 4 yr on Quercus palustris M. in Lexington, Ky., and emergence of adult males and crawlers was related to physiological time (i.e., degree-days [DD]). This scale is univoltine in Kentucky and both sexes overwinter as second instars. Date of first hatch of crawlers during 1984-1986 ranged from 22 June to 6 July, corresponding to a mean accumulation of 1,521 DDC (2,737 DDF) calculated from a base of 4.44°C (400°F). This value accurately predicted crawler hatch dates in West Lafayette, Ind., and College Park, Md., in 1986, and in Lexington in 1987. Six species of primary parasites and one hyperparasite species were reared from scale-infested twig samples. Parasite flight periods were determined from sticky trap collections within tree crowns. Application of insecticidal sprays during July for control of obscure scale crawlers would unfortunately coincide with peak activity of the scale’s primary parasites.

The Uganda I/CDC Strain of Plasmodium malariae in Saimiri sciureus boliviensis

The Uganda I/CDC strain of Plasmodium malariae, initially adapted to monkeys of the genus Aotus, was studied in splenectomized Saimiri sciureus boliviensis. Mean maximum parasitemia ranged from 248 to 22,134/mm3. Only 1 mosquito was infected of 2,238 examined. After the parasite was adapted to this host, infections were characterized by periods of detectable parasitemia extending up to 269 days and by sustained periods when parasite counts were greater than 1,000/mm3. After 4 linear passages, the developmental time required before the primary peak parasite count was approximately 2 mo.

Natural Mortality of the Lesser Cornstalk Borer (Lepidoptera: Pyralidae) in a Peanut Agroecosystem

Lesser cornstalk borer (LCB), Elasmopalpus lignosellus (Zeller), populations were monitored for 3 yr in commercial peanut, Arachis hypogaea L., fields in an intensively cultivated area of Comanche County, Tex. Population census raw data were standardized to make LCB density estimates comparable among generations and years. Partial ecological life tables were constructed from standardized census estimates for five pivotal stages: eggs, just-hatched larvae, medium larvae, large larvae, and pupae. Mortality factors were classified as parasitism, disease, and unexplained. Identified mortality agents included an entomopoxvirus, a fungus, 13 primary parasites, and five predators. Survivorship curves implied a constant mortality rate with total generation mortality ranging from 87.1 to 96.5%. Keyfactor analysis revealed unexplained mortality was the major contributor to overall mortality, with unexplained mortality of large larvae the key mortality factor. Three methods of analyzing mortality–density relationships showed mortality was density independent, with initial egg density rather than mortality determining the resulting larval and pupal population densities.

Introduction of beneficial insects into israel for the control of insect pests

More than 200 shipments of beneficial insects for the biological control of soft scale insects, armoured scale insects, whitefly, aphids, mealybugs and the Mediterranean fruit fly, were imported to Israel during 1976-1987 by the quarantine facility of the Israel Cohen Institute for Biological Control. Laboratory culture was initiated with 89 species of primary parasites and predators; 60 species were successfully cultured. Of these, 56 species were released in the field and 29 were recovered; six are established and have effected successful biological control ofSaissetia oleae (Olivier) andDialeurodes citri (Ashmead).

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.

Density reduction in larval mosquito (Diptera: Culicidae) populations by interactions between a parasitic ciliate (Ciliophora: Tetrahymenidae) and an opportunistic fungal (Oömycetes: Pythiaceae) parasite.

Larvae of the western treehole mosquito, Aedes sierrensis (Ludlow), are attacked in nature by the parasitic ciliate Lambornella clarki Corliss and Coats. During their attack, ciliates encyst on the larval cuticle, form a small hole in the integument, and invade the host's hemocoel. Ciliatosis is chronic and fatal; in nature, infected mosquitoes die in approximately 3 wk. Cuticular penetration provides a portal of entry for invasion by facultatively parasitic fungi and bacteria. These normally saprophytic organisms produce secondary infections that are rapidly fatal to both the host and its primary parasite. In laboratory experiments, cultures of a saprophytic oomycete, Pythium flevoense Van der Plaasts-Niterink, produced motile zoospores that encysted and germinated on cuticular cysts of L. clarki . If hyphae successfully entered the invasion hole, secondary infections of P. flevoense killed most first- and third-instar mosquitoes and their ciliate parasites within 72 h of ciliate entry into the hemocoel. In mixed populations of L. clarki-infected and uninfected larvae, P. flevoense selectively invaded L. clarki -infected larvae, resulting in reduced mosquito densities. Premature death by secondary infections of larvae infected with ciliates was positively correlated with the density of zoospores in the water.

Seasonal Biology of the Walnut Scale, Quadraspidiotus juglansregiae (Homo petra: Diaspididae), and Associated Parasites on Red Maple in Kentucky

Seasonal phenology of the walnut scale, Quadraspidiotus juglansregia (Com stock), was studied for 5 yr on Acre rubrum L., and emergence of adult males and crawlers was related to physiological time (i.e., degree-days [DD]). The scale is Nicoline in Kentucky, and both sexes overwinter as second-instar nymphs. This pattern differs sharply from previously published life history data for Q. juglansregiae on other hosts and suggests that the walnut scale, as it is currently understood, may actually represent a species complex. Date of first hatch of crawlers ranged from 30 May to 17 June and corresponded to a mean accumulation of 785 DD (base 4.44°C) from 1 January. Four primary parasites and two hyper parasites were found associated with Q. juglansregiae on red maple. The encyrtid Coccidencyrtus ensifer Howard, the most abundant primary parasite, emerged from first and second generation adult female scale insects. Application of insecticidal sprays in June or August for control of walnut scale crawlers will unfortunately alsocoincide with the period of peak activity of the scale’s primary parasites.

Facultative Hyperparasitism and Sex Determination of Encarsia smithi (Silvestri) (Hymenoptera: Aphelinidae)

Encarsia smithi (Silvestri) and Encarsia opulenta (Silvestri) are primary parasites of the citrus blackfly, Aleurocanthus woglumi Ashby, but E. smithi is also a hyperparasite. Diploid E. smithi larvae are primary parasites, whereas haploid larvae are parasites of conspecific diploids as well as of diploids of E. opulenta . Virgin females of E. smithi deposit haploid eggs in mature larvae or pupae of E. opulenta or E. smithi to produce male offspring by arrhenotoky. Mated females deposit diploid eggs in A. woglumi nymphs and produce female progeny irrespective of whether the hosts are already parasitized by E. opulenta or unparasitized. Diploid eggs or as many as four newly emerged larvae of E. smithi were found in A. woglumi gastric caeca. Larvae moved into the body cavity of A. woglumi as late second instars. Mated female E. smithi also have the option to produce males by ovipositing haploid eggs in A. woglumi nymphs already parasitized by either E. smithi or E. opulenta .

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.

Introduction, Recovery, and Limited Establishment of Coleophora klimeschiella (Lepidoptera: Coleophoridae) on Russian Thistles, Salsola australis, in Southern California

Although case-bearing leafmining larvae of Coleophora klimeschiella Toll were released on Russian thistles, Salsola australis R. Brown (Chenopodiaceae), at 13 locations in southern California during 1977–85, this biological control agent remained tenuously established at only one site by late 1986. Neither insectary-reared or field-collected stocks released in field cages or in the open in numbers of 100–600 per site appeared to foster colony establishment. Poor host-plant adaptation as well as predation and parasitism by indigenous natural enemies are identified as possible sources of biotic resistance to the establishment of this imported insect. The predator, Phylobacnus atriplexus (Foster) (Coleoptera: Cleridae), and the primary parasite, Macroneura sp. (Hymenoptera: Eupelmidae), found attacking C. klimeschiella, also are known from gall-midge hosts on native saltbushes (Atriplex spp., also Chenopodiaceae).

Distribution of Progeny in Two Ineffective Parasites of a Gall Midge (Diptera: Cecidomyiidae)

Rhopalomyia californica Felt is a native cecidomyiid midge that develops in multichambered, terminal galls on Baccharis pilularis DC in California. At two study sites, number of midge larvae per gall varied from 1 to >40. However, distribution of progeny for two of the midge's primary parasites, Torymus baccharidis (Huber) and Tetrastichus sp., was relatively constant, averaging between one and three individuals per gall, regardless of number of hosts per gall. Both species exploited a relatively small proportion of available galls, and, as a result, these parasites did not have a major impact on the host population. Distribution of Torymus progeny was probably the result of competitive interactions and low capacity for increase, whereas that of Tetrastichus was apparently the result of competitive interactions and hyperparasitization. It is suggested that species of parasites that are ineffective in their native homes may be of considerable value in classical biological control, especially when such ineffectiveness is due largely to interspecific interactions, rather than low reproductive capacity.

PRIMARY HYMENOPTEROUS PARASITES OF NANTUCKET PINE TIP MOTH, RHYACIONIA FRUSTRANA (COMSTOCK)1

Nantucket pine tip moth (NPTM), Rhyacionia frustrana (Comstock), is a pest of several members of the genus Pinus, including commercial and ornamental species. A rather large parasitoid complex is associated with NPTM, but collecting and rearing techniques have not clearly defined the true or primary parasites attacking the NPTM. Incorrect associations may have been assumed. This report defines known primary hymenopteran parasites attacking NPTM including records for Arkansas.

FINAL-INSTAR LARVAE OF NATIVE PUPAL PARASITES AND HYPERPARASITES OF OPEROPHTERA SPP. (LEPIDOPTERA: GEOMETRIDAE) ON SOUTHERN VANCOUVER ISLAND

AbstractThree native species of parasites and 3 hyperparasites were reared from pupae of the European winter moth, Operophtera brumata (L.), and the Bruce spanworm, O. bruceata (Hulst), collected in the Victoria area of Vancouver Island, British Columbia, in 1981. Two of the pupal parasites also attacked other species of Geometridae. Two species of hyperparasites attacked Cyzenis sp., and the third parasitized ichneumonid primary parasites of Operophtera spp. The hyperparasites may have a negative impact on the biological-control agents, Cyzenis albicans (Fall.) and Agrypon flaveolatum (Grav.). Total parasitism by pupal parasites of the Operophtera host complex was about 4%. Descriptions and illustrations of cephalic structures of final-instar larvae of the parasites and a key for their separation are given.

Parasitism of Aphids (Homoptera: Aphididae) Associated with Texas Sorghum

More than 7,700 greenbug and nearly 2,200 corn leaf aphid mummies were collected from sorghum grown in the six vegetational regions of Texas. Adult parasites emerged from 5,635 of the collected greenbug mummies and 1,468 of the collected corn leaf aphid mummies. Of the mummies producing adult parasites, 4,040 resulted in three species of hymenopterous primary parasites, Lysiphlebus testaceipes (Cresson) and Diaeretiella rapae (M'Intosh) (Braconidae), and Aphelinus varipes (Foerster) ( =A. nigritus Howard) (Aphelinidae). The remaining 3,064 emerged adults represented five species of hymenopterous hyperparasites, Pachyneuron siphonophorae (Ashmead) and Asaphes lucens (Provancher) (Pteromalidae), Alloxysta sp. ( megourae complex) (Cynipidae), Aphidencyrtus aphidivorus (Mayr) (Encyrtidae), and Tetrastichus minutus (Howard) (Eulophidae). About 43% of the 7,103 aphid mummies produced hyperparasite species, or ca. 45% of the greenbug mummies and 35% of the corn leaf aphid mummies. Alloxysta sp. was always most common from L. testaceipes-produced mummies, and A. aphidivorus was usually most common from A. varipes -produced mummies. P. siphonophorae was nearly always the most common hyperparasite regardless of region or host aphid, Alloxysta sp. was usually second most common, and A. aphidivorus third most common. The survey did not recover any of the six species of exotic greenbug parasites previously imported from Europe and released in Texas or Oklahoma. These exotic parasite species are either not established or not yet exerting a significant influence on the greenbug.

Comparative studies on Tetrastichus hagenowii (Ratzeburg) and T. asthenogmus (Waterston), two primary parasites of cockroach oothecae, and on their hyperparasite Tetrastichus sp. (T. miser (Nees) group) (Hymenoptera: Eulophidae)

AbstractTetrastichus hagenowii (Ratz.) and T. asthenogmus (Wtstn.) are parasitic in cockroach oothecae and may themselves be attacked by a species of Tetrastichus of the group of T. miser (Nees). In Bangalore in 1976–79, the primary parasites were reared from oothecae of Periplaneta americana (L.), P. australasiae (F.) and P. brunnea Burm., and laboratory colonies of them were established on oothecae of P. americana. The hyperparasite, reared from field-collected oothecae of Periplaneta spp., was bred in the laboratory on oothecae of P. americana containing larvae of T. hagenowü. The immature stages of the three species of parasites were compared and their biologies studied. The eggs of the three species can be differentiated on the basis of their shape as can the pupae, but the larvae of the two primary parasites are indistinguishable. The duration of the developmental stages of the three species overlapped but the hyperparasite had a slightly shorter pupal period. Host finding by the T. hagenowii female was investigated. The two primary parasites were similar in most of their biological attributes. However, T. asthenogmus was inherently superior to the Bangalore strain of T. hagenowii in having lower levels of female sterility and its greater preference for the oothecae of P. brunnea, the predominant species of cockroach in Bangalore. T. hagenowii proved to be more tolerent of low temperatures than T. asthenogmus. The hyperparasite had an advantage over the other two species in possessing longer life-span and synovigenic females, and individual females parasitised more oothecae in their life-span than the primary parasites; but it was unable to distinguish healthy oothecae from those containing larvae of the other two species until it had drilled into them.

HYPERPARASITISM OF THERIOAPHIS TRIFOLII F. MACULATA (HOMOPTERA: APHIDIDAE) IN SOUTH AUSTRALIA

Abstract Trioxys complanatus Quilis (Hymenoptera: Aphidiidae) was introduced into South Australia in August 1977 as a primary parasite of the spotted alfalfa aphid Therioaphis trifolii (Monell) f. maculata. The first hyperparasites of T. trifolii f. maculata were not recorded from field‐collected T. complanatus pupae until April 1978, some 8 months after the initial releases of T. complanatus. Four species of aphid hyperparasites have been found attacking T. complanatus viz. Dendrocerus aphidum (Rondani), Pachyneuron aphidis Bouche, Phaenoglyphis villosa (Hartig) and Myiocnema sp.

Parasitization of Larvae of Paropsis Atomaria Ol. (Coleoptera: Chrysomelidae) in the Australian Capital Territory.

Parasites of the larvae of the eucalypt-defoliating chrysomelid Paropsis atomaria Ol. in the Australian Capital Territory, Australia, in 1975-77 included the hymenopteran primary parasite Eadya paropsidis Huddleston & Short, the hyperparasites Perilampus tasmanicus Cam. and Mesochorus sp., and the tachinids Anagonia anguliventris (Mall.) (Froggattimyia anguliventris), F. tillyardi Mall. and Paropsivora sp. For the December-January 1st-generation larvae of Paropsis atomaria in 1976-77, E. paropsidis achieved an average 49% parasitism, and the tachinids 19%; the two kinds of parasites occurred together in 18% of parasitised larvae. Planidia of Perilampus tasmanicus attacked an average of 68% of the tachinid larvae and 70% of the larvae of E. paropsidis. Mesochorus occurred only in tachinid larvae, with a mean parasitism of 35% over the season, but it was not found after early January; multiparasitism with P. tasmanicus was found in 24% of parasitised tachinids. The number of progeny of the primary parasites deposited in one chrysomelid larva rarely exceeded 5 for tachinids and 6 for E. paropsidis. This occurred whether the parasites were intra- or interspecifically competing. The exceptionally high reproductive capacity of P. tasmanicus was related to poor survival: up to 50 planidia were found inside a single chrysomelid larva, in a phoretic relationship awaiting primary parasite larvae.