Interactions betweenPleolophus basizonus andLophyroplectus luteator [Hym.: Ichneumonidae], two parasites ofNeodiprion sertifer [Hym.: Diprionidae]

Females ofPleolophus basizonus (Gray.) show a very strong avoidance of cocoonedNeodiprion sertifer (Geoff.) prepupae in which there are eggs, larvae or prepupae ofLophyroplectus luteator (Thunb.). When multiparasitism does occurP. basizonus is the successful competitor but adults are much smaller than those from hosts that were not multiparasitized.     

Effects ofBathyplectes curculionis andBathyplectes anurus [Hym.: Ichneumonidae] on the growth and development ofHypera postica [Col.: Curculionidae]

Observations, linear measurements, dissections, and histological preparations were made of parasitized and nonparasitized larvae of the alfalfa weevil,Hypera postica (Gyllenhal), on a daily basis. The observed developmental period lasted from 24 h after oviposition byBathyplectes curculionis (Thomson) orBathyplectes anurus (Thomson) until parasite larvae emerged from their hosts. Adult and larval parasites significantly altered growth and development ofH. postica larvae.B. curculionis andB. anurus caused 24 and 29% greater premature mortality in young host larvae than that observed in the unparasitized controls. Rate of development for parasitized larvae during the 1st 12 days was essentially the same as for nonparasitized larvae. Nonparasitized larvae reached maximum size in 17–18 days, whereas larvae parasitized byB. curculionis andB. anurus required 14–21 and 19–22 days, respectively. Larvae parasitized byB. curculionis are smaller in overall lengths, widths and head capsule widths than nonparasitized larvae and those parasitized byB. anurus.     

Hypersensitivity,resulting from host-unsuitability,as exemplified by two parasite species attackingSpodoptera littoralis [Lepidoptera: Noctuidae]

Spodoptera littoralis Boisd. is an unsuitable host for 2 parasite species,Bracon hebetor Say andPalexorista laxa. (Curran).B. hebetor is an exernal parasite that paralyzes its hosts prior to oviposition. In the case ofS. littoralis, parasitization often causes death rather than paralysis and consequently the parasite is unable to reach maturity. The death is not caused by the feeding of the parasite larvae.P. laxa is an internal parasite ofHeliothis spp. that oviposits readily onS. littoralis, but fails to develop therein. It was suggested that the untimely death of the hosts with their parasites prevents control of the former's population by the latter's and, therefore, may be compared to the phytopathological phenomenon of hypersensitivity.     

Interspecific competition among endoparasitoids of tobacco budworm larvae [Lep.: Noctuidae]

The ability of female larvae endoparasitoids [Microplitis croceipes Cresson:Cardiochiles nigriceps Viereck andCumpoletis sonorensis (Carlson)] to distinguish between unparasitized tobacco budworm,Heliothis virescens (F.), larvae andH. virescens larvae parasitized by the egg-larval parasitoidChelonus insularis,Cresson, was determined in laboratory studies. The 3 species of larval endoparasitoid females did not appear capable of distinguishing between unparasitized andC. insularis parasitized larvae resulting in multiple parasitoidism. The results of the ensuing competition between the 3 species for possession of the host demonstrated that bothC. sonorensis andM. croceipes were intrinsically superior toC. insularis. Both larva endoparasitoids destroyed the olderC. insularis larvae by physically attacking the latter. The presence ofC. insularis larvae in the host was found to prevent the hatch of compeatingC. nigriceps eggs through physiological suppression. The results show that the early attack of a host, as in the egg-larval parasitoid habit, is not necessarily advantageous.     

The parasite complex ofSaissetia nigra in Malaysia

The percentage parasitism ofSaissetia nigra (Nietner) by chalcidoid parasites and the relative abundance of individual parasites were studied in the field usingHibiscus rosa-sinensis L. as the host plant. In order of abundance (on the basis of percentage recorded) the primary parasites wereAnysis saissetiae Ash.,Aneristus ceroplastae How., andMicroterys newcombi (Gir)., while the hyperparasites wereMarietta exitiosa Comp.,Cheiloneurus saissetiae Noyes & Chua andEupelmus catoxanthae Ferr. The efficiency ofA. saissetiae (the larvae of which feed on the scale eggs) to control the scale population is doubtful because it is often parasitised by all 3 hyperparasites mentioned and each larva during development causes only 58% egg mortality of the parasitised host, leaving many scale eggs unconsumed.A. ceroplastae appears to be more useful parasite because it attacks the 2nd instar scales which cause significant damage to the host plant and it is free from attack by hyperparasites.     

The release ofOpius concolor andO. Concolor var.Siculus [Hym.: Braconidae] against the spring generation ofDacus oleae [Dipt.: Trypetidae] on Corfu

Releases ofOpius concolor Szepl. andO. concolor var.siculus Mon. were carried out in the spring to determine if they could be used as a biological control agent against the heavy infestation ofDacus oleae Gmel. which occurs on Corfu at that time. At an initial density of 300–400 parasites per tree the mean parasitism rates of 3rd stage larvae ranged from 30–50% in the 1st week following the release, indicating thatOpius could work well in the spring in the tall trees with large numbers of ripe and heavily infested fruits that are found on Corfu.     

Parasites ofColeophora laricella larvae in newfoundland [Lep.: Coleophoridae]

A total of 15 species of parasites have been reared from the larch casebearerColeophora laricella (Hübner), in Newfoundland, but only 2 species,Agathis pumila (Ratzeburg) andChrysocharis laricinellae (Ratzeburg), are common. Both of these species had been introduced in the late 1940's for the biological control of the casebearer. The chalcid,C. laricinellae, was the more common parasite till the early 1970's, but since then the braconid,A. pumila, has become the most dominant, parasitizing up to 80% of the host larvae. It appears thatA. pumila is the most promising biological control agent present in Newfoundland.     

The effects of various aphids as larval prey on the development ofMetasyrphus corollae [Dipt.: Syrphidae]

The suitability of thirteen aphid species for the polyphagous larvae ofMetasyrphus corollae (Fabr.) was investigated in laboratory tests. The length of larval and pupal development, weight of puparia, mortality during larval and pupal stages were compared. Cannibalism was not observed in the larvae reared in groups on suitable food.Aphis sambuci Linneaus was not a suitable prey for the larvae.Cavariella theobaldi (Gillette Bragg) collected fromPastinaca sativa L. was toxic to larvae ofM. corollae, although it was possible to rear the larvae onAphis fabae Scopoli orAnuraphis subterranea (Walker) from the same host plant.     

The effect of population density of parasitePerisierola nephantidis [Hym.: Bethylidae] on the mortality of coconut caterpillar,Nephantis serinops [Lep.: Cryptophagidae]

The population density ofPerisierola nephantidis Mues. acts as key mortality factor in the biological control ofNephantis serinopa Meyrick. The mortality ofN. serinopa was directly proportional to the density of parasiteP. nephantidis and recorded a maximum of 96% at 1∶8 ratio of host to parasite at constant population of host. A significant inverse density-dependent action ofP. nephantidis was observed under various density ofNephantis larvae at a constant population of the parasite.     

Searching and ovipositional behavior ofAmitus hesperidum [Hym.: Platygasteridae] andEncarsia opulenta [Hym.: Aphelinidae] parasitoids of the citrus blackfly [Hom.: Aleyrodidae]

Searching behavior ofAmitus hesperidum Silvestri andEncarsia opulenta (Silvestri) for immatureAleurocanthus woglumi Ashby was similar. Both parasitoids moved unidirectionally until they encountered a host aggregation at which time they changed to a pattern of short walks with numerous turns. Parasitoid ovipositor insertion was generally at midbody between the host sternites and tergites.Amitus hesperidum females showed a significant preference for 1st instar hosts, have an ovipositional marker, do not feed on exudates from ovipositional wounds (host feed), and have significantly shorter ovipositional times and adult life spans thanE. opulenta which showed a significant preference for 2nd instar hosts, lack an ovipositional marker, and host feed.Encarsia opulenta females showed a significant preference for hosts previously parasitized byA. hesperidum but the reverse was not true. The average number of hosts parasitized by females of both parasitoid species was uninfluenced by the previous presence of the other parasitoid species on the same leaf.     

Stimulation of oviposition and successful rearing ofTelenomus heliothidis [Hym.: Scelionidae] on nonhosts by use of a host-recognition kairomone

Through use of a recognition kairomone, the parasitoidTelenomus heliothidis Ashmead is induced to oviposit and successfully develops in nonhost eggs.T. heliothidis successfully develops in the eggs ofSpodoptera frugiperda (Smith) andPhthorimaea operculella Zeller, but fails to develop in eggs ofAnthonomus grandis Boheman. Both sexes of the parasitoid are produced from the nonhosts, and development time is the same as in a natural host such asHeliothis virescens F. The use of recognition kairomones could be of great use in artificial rearing of nongeneralist parasitoids suchT. heliothidis.     

Parasites ofSpodoptera exigua,S. eridania [Lep.: Noctuidae] andHerpetogramma bipunctalis [Lep.: Pyralidae] collected fromAmaranthus hybridus in field corn

Three species of lepidopterous larvae were collected fromAmaranthus hybridus L. growing in field corn during 1975 and 1976 at Hastings, Florida.Spodoptera exigua (Hubner) was the predominant species in May.Spodoptera eridania (Cramer) was predominant in June andHerpetogramma bipunctalis (F.) in July and August. Nine native species of parasites, representing theBraconidae, Eulophidae, Ichneumonidae andTachinidae, emerged from these larvae.Meteorus autographae Muesebeck emerged from bothS. exigua andS. eridania. TheTachinidae, Winthemia rufopicta (Bigot),Eucelatori rubentis (Coquillett) andLespensia sp., emerged from mixtures ofS. exigua andS. eridania. Apanteles marginiventris (Cresson),Temelucha sp., andChelonus texanus Cresson emerged from bothS. exigua andH. bipunctalis larvae, andEuplectrus platyhypenae Howard andOphion sp. emerged fromS. eridania. All the species of parasites from the lepidopterous larvae that feed onAmaranthus hybridus are also reported as parasites ofS. frugiperda, a serious pest of corn. Therefore these larvae onA. hybridus may be a source of the parasites found attackingS. frugiperda.     

Trichogramma semblidis [Chalcidoidea: Trichogrammatidae] as a parasite of the bark beetle eggs [Coleoptera: Scolytidae]

It has been found thatTrichogramma semblidis (Aurv.) parasitizes the eggs ofleperisinus fraxini (Panz.),L. orni (Fuchs) andHylesinus crenatus (Fabr.) in typical variant ofCircaeo-Alnetum Oberdorfer 1953 in the Laski Experimental Forestry near Kepno. Thorough studies were conducted on exposed European ash logs and split wood in 3 methodical variants. The analysis of the galleries ofLeperisinus fraxini has showed that the average egg infestation amounted to 14.1%, 13.0% and 11.1% respectively. The egg infestation of individual gallery systems in the exposed control logs and split wood ranged between 2.7–51.2%, 1.2–44.1% and 1.7–69.2%, respectively, in different variants and the average effectiveness of the parasite amounted to 12.7% of the host egg mortality in 1970. Earlier observations and analyses of the gallery systems made on the ash trunks and branches in 1967 and 1968 showed 80.0% and 98.0% infestation of the eggs ofL. fraxini and 10.0% and 1.5% infestation of the eggs ofL. orni. Separate developmental stages of the parasite, the behaviour of the latter and penetration of the gallery systems were observed too. The most important data on the host species ofT. semblidis have been compared.     

A study of the interactions between the internal larval parasites ofRhyacionia buoliana [Lepidoptera: Olethreutidae]

The interactions of 6 species of internal parasites ofRhyacionia buoliana Schiff. in a locality in northern Germany are discussed. The occurrence of super and multiparasitism is analyzed in relation to varying host densities and different rates of total parasitism. Multiparasitism betweenOrgilus obscurator Nees and 3 other species,Temelucha interruptor Grav.,Pristomerus sp. nearorbilatis Holmgr. and biting cleptoparasitic habits. Interspecific competition occurred in the form of direct physical attack between the first instar larvae. The coexistence of the internal larval parasites ofR. buoliana provides a good example of a system of “counter-balanced competition”.O. obscurator, although inferior at the level of intrinsic competition, was the dominant species at the level of extrinsic competition.     

Host discrimination byChelonus insularis [Hym.: Braconidae], telenomus heliothidis [Hym.: Scelionidae], andTrichogramma pretiosum [Hym.: Trichogrammatidae]

The ability of female parasitoids (Chelonus insularis Cresson,Telenomus heliothidis Ashmead, andTrichogramma pretiosum Riley) to distinguish between parasitized and unparasitized tobacco budworm,Heliothis virescens (F.), eggs was determined in laboratory studies. All 3 species were relatively efficient at detecting eggs that were previously parasitized by conspecific females.T. heliothidis andT. pretiosum were able to discriminate on the basis of external examination of host eggs, whereasC. insularis appeared to examine hosts internally as well as externally. In interspecific tests, no species readily rejected eggs parasitized by the other 2 species.     

Determination of host range in relation to systematics forPeristenus stygicus [Hym.: Braconidae], A parasitoid ofMiridae

Peristenus stygicus Loan develops inMirinae speciesLygus hesperus,Knight,L. lineolaris, (Palisot de Beauvois) andPolymerus basalis (Reuter),Orthotylinae speciesLabopidicola geminata (Johnston),Phylinae speciesPseudatomoscelis seriatus (Reuter) and partially develops in the mirineDichrooscytus sp. The parasitoids attackMicrophylellus maculipennis (Knight) (Phylinae) and another orthotyline species, but do not develop in these.Taedia johnstoni (Knight) (Mirinae), 2 species ofBrycorinae and 3 species ofLygaeidae are not acceptable as hosts. Olfactometer studies show the parasites are significantly more attracted to lygus nymphs whenPhaseolus vulgaris L. is present than either the nymphs or bean alone. Host color, mobility, size, previously infested plant material, and host plant species are rejected as host selection criteria.     

Parasitism ofPhthorimaea operculella [Lep.: Gelechiidae] larvae in Queensland

Parasitism ofPhthorimaea operculella (Zeller) larvae on potato foliage was examined intensively in the Lockyer Valley, south-eastern Queensland from 1975–78 and extensively from other hosts and areas of Queensland. The % parasitism in the Lockyer Valley exceeded 50% in 29 of the 36 collections. The parasite species were dominated by the introducedCopidosoma desantisi Annecke & Mynhardt (Encyrtidae) andOrgilus lepidus Muesebeck (Braconidae) which together accounted for 92.6% of parasite numbers recorded. In more northern areas of Queensland, the dominant parasite species found was the introducedApanteles subandinus Blanchard (Braconidae). Other hymenopterous parasites found wereMicrochelonus curvimaculatus Cameron (Braconidae), Elasmus funereus Riek (Elasmidae) andTemelucha minuta (Morley) (Ichneumonidae).     

Natural control ofLiriomyza sativae [Dip.: Agromyzidae] in pole tomatoes in southern California

Liriomyza sativae Blanchard and its associated parasites were monitored during the growing season on untreated fresh market tomatoes in southern California in 1978.Chrysonotomyia (Achrysocharella) punctiventris (Crawford) andChrysocharis parksi Crawford were the predominant larval and larval-pupal parasites, respectively, parasitizing the leafminer. A significant linear relationship was found between the percentage parasitization of viableL. sativae larvae byC. parksi and the number ofL. sativae viable pupae per sampling unit.     

Biological and ecological studies of the parasitoidChelonus inanitus [Hym.: Braconidae] in Israel

Only one species ofChelonus Panzer,Chelonus inanitus (L.), was found to be widespread in all areas of Israel. The parasitoid was particularly widespread in alfalfa fields but also was present in cotton, sugar beet, artichoke and corn. Spodoptera littoralis (Boisd) andS. exigua (Hbn.) were the main hosts ofC. inanitus although it might develop in other Lepidoptera species. A study of its population showed that adults were present in the spring, summer and autumn but not during the winter. In most cases the population density of the parasitoid appeared to be related to that of the hosts. Parasitism and sex ratio ofC. inanitus in alfalfa fields were studied. The number of males (average of 75%) was higher than that of the females. Percentage of parasitism in larvae ofS. littoralis andS. exigua reached up to 39.8% and 13.5% respectively. The parasitism values in eggs ofS. littoralis were up to 71%.     

Predation byXylocoris flavipes [Hem.: Anthocoridae]: Influence of stage,species and density of prey and of starvation and density of predator

When the efficacy of the predaceous bugXylocoris flavipes (Reuter) was tested in the laboratory as a biological control agent against stored-product insects, it attacked eggs more than larvae, pupae, or adults and early-stage larvae ofTribolium castaneum (Herbst) more than late-stage larvae. The predator also killed more larvae ofT. castaneum than larvae ofAttagenus megatoma (F.). The density of predator and prey regulated the capture rate of the predator. Predation byX. flavipes was uninfluenced by starvation for as much as 96 hr.