Disease-parasitoid relationships in natural populations ofLymantria dispar [Lep.: Lymantriidae] in the Northeastern United States

ImmatureLymantria dispar L. were collected from 6 geographically distinct populations over 2 years to determine correlations between parasitoid and disease incidences. Incidence of the nuclear polyhedrosis virus disease (NPV) was found to be positively correlated with incidences of the parasitoidsApanteles melanoscelus (Ratzeburg) andParasetigena silvestris (Robineau-Desvoidy).     

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).     

Spatial distribution of the gypsy moth [Lepidoptera: Lymantriidae] and some of its parasitoids within a forest environment

Aspects of the microhabitat distributions of the gypsy moth,Porthetria dispar (L.) (Lepidoptera: Lymantriidae), and some of its parasitoids were investigated in the field by means of sticky panels and gypsy moth egg masses exposed at different heights in trees, by egg masses exposed within forested and cleared areas, and by gypsy moth pupal collections from different heights in trees.Ooencyrtus kuwanai (Howard)(Hymenoptera: Encyrtidae), Apanteles melanoscelus Ratzeburg (Hymenoptera: Braconidae), and gypsy moths were caught most frequently on stickly panels placed in upper portions of trees. In contrast,Apanteles laeviceps Ashmead, a parasitoid of cutworms, was most often caught near the forest floor.O. kuwanai attacked equally egg masses exposed at different heights in trees, but parasitized those in a clearing less often than those within the forest prosper.Brachymeria intermedia (Nees) (Hymenoptera: Chalcididae) emerged mostly from pupae collected near the tops of trees and not at all from those collected below 5 m. The results are discussed as they relate to field sampling procedures, behavioral activities of gypsy moth and parasitoid adults, and integrated control possibilities for the gypsy moth.     

Impact of aerially appliedBacillus thuringiensis and carbaryl on gypsy moth [Lep.: Lymantriidae] and adult parasites

In 1973, Dipel^® (Bacillus thuringiensis Berliner) and Sevin^® 4 oil (carbaryl) were applied aerially on a dense population of gypsy moths,Lymantria dispar (L.), to evaluate the effect of these biological and chemical insecticides on gypsy moth larvae and adult parasites. Both insecticides provided excellent protection of foliage (29 % average defoliation) and gypsy moth population reduction (99 %). Significantly fewerBrachymeria intermedia (Nees), andApanteles melanoscelus (Ratzeburg),Parasetigena silvestris (Robineau-Desvoidy) andCompsilura concinnata (Meigen) adult parasites were captured in the blocks treated with Sevin 4 oil or Dipel than in the control block during the treatment year and in 1974, respectively.     

The establishment of two imported parasitoids of potato tuber moth [Phthorimaea operculella] in South Africa

Two parasitoids of the potato tuber moth (Phthorimaea operculella) (Zeller)[Lepidoptera: Gelechiidae], Copidosoma uruguayyensis Tachikawa andApanteles subandinus Blanchard, originally from South America, have been successfully established in South Africa. Recoveries many kilometers from the original release sites are common. In the Transvaal these two parasitoids have shown, by replacing the indigenous parasitoids, that they can possibly achieve better control of the potato tuber moth. The more efficient use of ridging and the complete discontinuation or reduction of insecticide applications to one or two carefully timed sprays could achieve better use of biological control.     

Mortality factors of satin moth,Leucoma salicis [Lep.: Lymantriidae], in aspen forests in Maine

Natural control agents of the satin moth,Leucoma salicis (L.) were examined in 2Populus grandidentata Michaux stands. Highest mortality occurred in overwintering larvae, with the causal agents 2 fungi,Paecilomyces sp. andHirsutella gigantea Petch, a factor causing death symptomatic of a pathogen, the parasiteEupteromalis hemipterus (Walker) and death from unknown causes. Mortality fromPaecilomyces sp. andE. hemipterus was reduced where overwintering sites were covered with burlap cloth. Parasites recovered from larvae and pupae included the braconidsApanteles melanoscelus (Ratzeburg) andMeteorus versicolor (Wesmeal), the ichneumonidCoccygomimus pedalis (Cresson), the tachinidsCompsilura concinnata (Meigen),Carcelia laxifrons Villeneuve,Tachinomyia variata Curran, and the sarcophagidsSarcophaga aldrichi Parker andAgria housei Shewell. Larval and pupal predators included the carabidCalosoma frigidum Kirby, pentatomids, and birds, particularly black-billed cuckoos,Coccyzus erythrophthaimus (Wilson). Eggs were parasitized by the scelionidTelenomus prob.californicus Ashmead and the trichogrammidTrichogramma minutum (Riley). Predators of adult satin moths included the hermit thrush,Hylocichla guttata (Pallas), and pentatomid bugs.     

Introduction and establishment ofApanteles flavipes [Hym.: Braconidae] onDiatraea saccharalis [Lep.: Pyralidae] in texas

The braconid parasite,Apanteles flavipes (Cameron), was introduced into the Lower Rio Grande Valley of Texas in 1977 and has become established onDiatraea saccharalis (F.) attacking 4 species of host plants. Approximately 71% of the 26,971 adult parasites released were released in sugarcane,Saccharum officinarum L., with the remainder being released on field corn,Zea mays L., broomcorn,Sorghum vulgare technicum (Koern.) and Johnson grass,Sorghum halepense (L.). Recoveries indicate dispersal of at least 4 km from release sites.     

Developmental interactions between the army wormLeucania separata [Lep.: Noctuidae] and its parasiteApanteles ruficrus [Hym.: Braconidae]

The developmental interactions between the gregarious endoparasitoidApanteles ruficrus Hal. and the army worm,Leucania separata Walker were investigated. The parasitoid preferred young host larvae and developed in 9.5 days irrespective of host age at the time of parasitization. The growth of parasitized host larvae were depressed. The net maximum weight of the host larva was positively correlated with the number of parasitoid eggs laid when the 2nd instar was parasitized. And when parasitizing in 2nd instar, the weight of parasitoid was negatively correlated with the number of eggs laid. The parasitoid has an ability to regulate the size of the host and the parasitoid itself according to the number of eggs laid when the host larva is very small.     

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.     

Biological control ofMythimna separata [Lep.: noctuidae] in New Zealand and its bearing on biological control strategy

A survey of parasites ofAgrotis spp. was carried out in Pakistan to find promising species for trial against noctuids especiallyAgrotis spp. andMythimna separata (Walker) in New Zealand. The parasites recorded wereApanteles ruficrus Haliday,Macrocentrus collaris Spinola,Periscepsia carbonaria Panzer,Turanogonia smirnovi,Rohdain,Ctenichneumon panzeri Wesmael andAnthrax sp. All exceptAnthrax sp. were supplied to New Zealand whereA. ruficrus andM. collaris were released in large numbers.A. ruficrus became established and is giving excellent control ofM. separata resulting in enormous economic gains. Recently it has also been recovered fromAgrotis spp. This example of biological control is significant in thatM. separata has been controlled by a parasite that was previously known from it in New Zealand. The specific status of the “A. ruficrus” already present in New Zealand requires investigation.     

Vectoring gypsy moth nuclear polyhedrosis virus byApanteles melanoscelus [Hym.: Braconidae]

Gypsy mothLymantria dispar L. larvae were exposed toApanteles melanoscelus (Ratzeburg) females contaminated with nuclear polyhedrosis virus. Three methods of contamination (ovipositor, total body surface, and exposure to infected hosts) and two exposure periods (2 and 24 hours) were tested. A significantly greater incidence of larval mortality caused by virus occurred among larvae exposed to contaminated than among larvae exposed to uncontaminated parasites for 2 and 24 hours. No significant differences occurred in larval mortality caused by virus for the 3 methods of contamination for the 2- and 24-hour tests or in parasite emergence from larvae parasitized by contaminated or uncontaminated parasites.     

Parasites of rice stemborers in Sarawak (Malaysian Borneo)

Observations on parasites were made during a study of the following rice stem-borers in Sarawak (Malaysian Borneo):Tryporyza incertulas (Walker),T. innotata (Walker),Chilo suppressalis (Walker)C. auricilia (Dudgeon), andSeamia inferens (Walker). Egg-parasitism was often high, but that of the larval and pupal stages generally very low. Between 40–80% of theTryporyza eggs were parasitised byTelenomus rowani (Gahan), while 30–50% were attacked byTetrastichus schoenobii Ferrière. About 40–90% of the eggs ofChilo were parasitised byTrichogramma? japonicum Ashmead and 5–26% byTelenomus dignus (Gahan). Only 0.4–3% of theTryporyza larvae were parasitised by a Braconid,Rhaconotus schoenobivorus (Rohwer), whileBracon chinensis Szepligeti attacked 0.2–0.7% of the larvae ofC. suppressalis. Parasitism ofSesamia larvae byApanteles flavipes Cameron was equally low, never exceeding 2%. Pupal parasitism was somewhat higher.Tetrastichus israeli (Mani & Kurian) attacked 8% and 18% of the pupae ofC. suppressalis andS. inferens, respectively, while the Ichneumonid,Xanthopimpla stemmator (Thunberg) attacked up to 3% of the pupae of the former species. The immature stages of some of these parasites are described.     

The effect of prey density on the functional and numerical reponses of three species of predatory mites

Functional and numerical responses of the predators:Phytoseiulus persimilis Athias-Henriot,Metaseiulus occidentalis (Nesbitt), andAmblyseius chilenensis (Dosse) [Acarina, Phytoseiidae] were observed at prey (Tetranychus urticae Koch [Acarina, Tetranychidae]) densities up to 300 prey/6.45 cm². Neither functional nor numerical response curves revealed any prey-predator interference effects, i.e.: the dome-shaped response curves (Holling, 1961), did not occur.     

Experimental studies on parasitization byApanteles Glomeratus V. Relationships between growth rate of parasitoid and host age at the time of oviposition

The growth and development ofApanteles glomeratus L. eggs and larvae in the host larva (Pieris rapae crucivora Boisduval) was investigated by calculating their volume. WhenA. glomeratus eggs increase 90 fold in volume after being laid, larvae hatch from them. The larvae grow exponentially and the growth rate of the parasitoid is dependent on the host stage. Being laid in the 1st instar host, the parasitoids grow more slowly than those laid in 2nd–4th instar host. A pupal host stage prevents the parasitoids’ development. When larvae exceed the threshold size of 5.0×10⁸ μ³, they enter the 2nd instar. A few days after they attain the maximum size of 3.3×10⁹ μ³, they moult and egress from the host body.     

Changing status of the parasites of potato tuber mothPhthorimaea operculella [Lepidoptera: Gelechiidae] in Australia

Three introduced parasites ofPhthorimaea operculella (Zeller) are now widespread, and a fourth established in a limited area, in Australia.Apanteles subandinus Blanchard, which occurs from Tasmania to Queensland, is the most effective species and the outstanding parasite in Victoria. The extent of parasitism and the status of the various parasites were monitored from the time of their release until 1971. In many areas whereCopidosoma koehleri Blanchard was the only parasite found in 1966, a substantial increase in parasitism was recorded in subsequent years, following the liberation of other species. In the 1969–70 season there was an explosive increase inOrgilus lepidus Muesebeck, which became the dominant species in some coastal areas of New South Wales, displacingA. subandinus. Its change of status to a dominant position was associated with a change of sex ratio from 1.6 ♀: 1♂ to 1.0 ♀: 1 ♂.     

The parasitoid complex of three noctuids [Lep.] in a northern Florida cropping system: Seasonal occurrence,parasitization, alternate hosts,and influence of host-habitat

Parasitoids of the cabbage looper,Trichoplusia ni (Hübner), the soybean looper,Pseudoplusia includens (Walker), and the tobacco budworm,Heliothis virescens (F.) were characterized in a 3.2-ha model of a north Florida (U.S.A.) cropping system (including tobacco (Nicotiana tabacum L.), soybeans (Glycine max (L.)Merr. and 18 other crops) not treated with chemical pesticides. The study was for a 2 yr-period; a minimum of three 0.0004-ha sections of row, or 0.0001-ha sections in broadcast or drilled crops were sampled weekly. In addition, sweeps with a net and some other sampling techniques were used in some crops.Litomastix truncatella (Dalman),Meteorus autographae Muesebeck, andVoria ruralis Fallen were the most important larval parasitoids recovered from cabbage loopers;Trichogramma spp. were by far the major egg parasitoid. Parasitization of eggs and larvae in crucifers (Brassica oleracea L.) ranged from 0 to 55% and 0 to 100%, respectively, and was generally highest during the spring and fall. Parasitization of cabbage looper immatures was highest in tomatoes (Lycopersicon esculentum Mill.). Parasitism by the parasitoid complex for the soybean looper larvae was high but eggs in soybeans were seldomly attacked by parasitoids. Tobacco budworm eggs were rarely parasitized in tobacco but were frequently parasitized in tomatoes and okra (Abelmoschus esculentus (L.)Medik). Parasitization of tobacco budworm larvae in tobacco was usually over 50% and was mostly byCardiochiles nigriceps Viereck; fewC. nigriceps were found from the other plants.     

Biology ofPyemotes parviscolyti [Acarina: Pyemotidae]

Pyemotes parviscolyti Cross & Moser is phoretic only onPityophthorus bisulcatus Eichhoff; it attacks all stages of this insect except the adult. Females, which contain little or no venom, prey on other scolytids if galleries overlap. Males copulate with females ofPyemotes ventricosus Newport and vice versa, but only males of the mother species result. Copulation withPyemotes scolyti Oudemans was not successful.     

Host-parasite relationship 2- cholinesterase activity of the larvae of the rice mothCorcyra cephalonica [Lep.: Pyralidae] parasitized byBracon hebetor [Hym.: Braconidae]

The parasitic waspBracon hebetor Say paralyses its host, the larvae of the rice mothCorcyra cephalonica Staint, before oviposition. The effect of injected venom on the activity of cholinesterase was studied. The ChE activity of the paralysed larvae showed a partial inhibition of about 40% than that of the normal larvae. Such inhibition in ChE activity interferes with the synaptic transmission and/or may result in neuromuscular block causing the observed paralysis.     

Plagiprospherysa trinitatis [Dipt.: Tachinidae], A parasite ofElasmopalpus lignosellus [Lep.: Phycitidae] in Trinidad,W. I.

Increased damage to sugarcane byElasmopalpus lignosellus associated with preharvest burning in Barbados, has prompted an investigation of its natural enemies in Trinidad. Three parasitesPlagiprospherysa trinitatis Thompson,Macrocentrus sp. andAgathis rubricinctus Ashmead were reared. Laboratory techniques for breedingP. trinitatis as well as its host are described. Attempts to utilize related species for biological control are reviewed and the possibilities of utilizingp. trinitatis are discussed briefly.     

Population dynamics ofTelenomus fariai [Hym.: Scelionidae], a parasite of chagas' disease vectors VIII. Morphological and ecological comparison between two allopatric populations under laboratory conditions

Telenomus fariai Lima ranges from Argentina and Chile to Mexico; some ecological parameters and morphological characters were compared between tropical (Costa Rica) and temperate (Argentina) populations, as reared on tropical and temperate hosts. The results of the 4 combinations between the 2 parasite populations and the 2 host species (Triatoma phyllosoma pallidipennis Stal) andTriatoma infestans Klug) [Hym.: Reduviidae] showed that only the parasite's geographical origin was statistically significant when evaluated through adult female life expectancy at time of emergence from the host, development time, total progeny per host per female 0–24 h old, and generation time. No difference was found between parasite populations with respect to total progeny per female and net reproductive rate. The morphometry proved statistically significant for all body measurements except the antennae.