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.     

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.     

The establishment of two parasites of the diamond-back mothPlutella xylostella [Lep.: Plutellidae] in Trinidad,W.I.

The diamond-back moth,Plutella xylostella (L.) is a major pest of cruciferous crops in Trinidad, West Indies. Pesticides are applied as a control measure but it is now resistant to several of them. Indigenous parasitesApanteles aciculatus (Ashm.),Apanteles sp. (glomeratus group),Spilochalcis hirtifemora (Ashm.) andTrichogramma brasiliensis (Ashm.) are unable to exert economic control.Apanteles plutellae (Kurdj.) andTetrastichus sokolowskii Kurdj. were introduced and are now well established. It is recommended to introduce additional parasitesMacromalon sp. andThyraeella collaris (Grav.) in order to obtain complete biological control.     

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.     

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.     

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).     

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.     

Some interactions ofSerratia marcescens nucleopolyhedrosis virus andBlepharipa pratensis [Dip.: Tachinidae] inLymantria dispar [Lep.: Lymantriidae]

The entomopathogensSerratia marcescens Bizio and nucleopolyhedrosis virus were each fed alone and in combination with the parasiteBlepharipa pratensis (Meigen) to 4th-instar gypsy moth,Lymantria dispar, (L.) larvae. At LD₃₀ for NPV, the presence of the parasite enhanced polyhedrosis about 30%, but the total number of gypsy moth larvae and pupae killed (85%) was not significantly different from the number killed by the parasite alone (93%). When the parasite was combined withS. marcencens, a strain nonpathogenic inL. dispar, total mortality was not significantly different from that in insects exposed only to the parasite (89 and 86%, respectively), but parasite survival was reduced about 12%. However, deaths not attributable to the parasite could not be ascribed to the bacterium either.     

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.     

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.     

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.     

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.     

Species ofIchneumonidae [Hym.], parasites of some lepidopterous pests of lucerne in Romania

Eleven species ofIchneumonidae were identified as parasites of lepidopterous pests of lucerne. All of the parasitized Lepidoptera are new host records for theseIchneumonidae andDiadegma variegata Szépl. is a species of parasite new to Romania.     

Low Energy Conformations for Gonadotropin-Releasing Hormone with d- and l-Amino Acid Substitutions for Gly 6: Possible Receptor-Bound Conformations

In the preceding paper, using ECEPP, including the effects of water, and the chain build-up procedure, we computed the low energy structures for GnRH and found that there were no distinct low energy structures or structures with high statistical weights. To attempt to deduce possible structures of GnRH that may bind to the GnRH receptor, we computed the low energy structures for GnRH peptides that have l- and d-amino acids substituting for Gly 6. The l-amino acid-substituted peptides (l-Ala and l-Val) have very low or no affinity for the receptor and on activity (release of FSH and LH) while the d-Ala-, d-Leu-, d-Trp- and d-Phe-substituted peptides have significantly higher relative affinities and activities than those for native GnRH; the d-Val-substituted peptide has about one-third of the affinity and activity as native GnRH. Unlike native GnRH, our computations suggest that both sets of peptides form well-defined structures in water: the l-amino acid-substituted peptides are predominantly α-helical while the d-amino acid-substituted peptides adopted E*A A A E D*(C*) A E C A(C*) and minor variants of these structures. By eliminating structures that lay in common to the d-Ala and l-Val peptides and further eliminating structures that differed between the d-Ala and d-Leu peptides, we reduced the number of possible distinct binding conformations to 254. Searching for structures among these 254 conformations that had relative statistical weights that paralleled their relative affinities, we found two candidate structures: D*E A A E C*A E C A and D*G A A E D*A E C G*, both of which have conformations for residues 3–9 that are similar to the computed most probable structures for the d-amino acid-substituted GnRH peptides in water.     

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.     

Results of a joint pesticide test programme by the Working Group: Pesticides and Beneficial Arthropods

The side effect of 20 commercial pesticides (10 insecticides/acaricides, 6 fungicides, 4 herbicides) on 6 different beneficial arthropods was tested by members of the IOBC/WPRS Working Group “Pesticides and Beneficial Arthropods” in 3 countries. The tests were done according to standardized methods based on common rules, which, among others, emphasize the reduction of the beneficial capacity as the relevant parameter for evaluation. The beneficials tested were:Trichogramma cacoeciae Marchal,Pales pavida Meig.,Phygadeuon trichops Thomson,Leptomastix dactylopii (How.),Coccygomimus turionellae (L.) andChrysopa carnea Steph. The insecticidal biopreparation Dipel, the acaricide Torque, the fungicides Nimrod, Cercobin-M, Ortho Difolatan, the herbicides Betanal and Illoxan were harmless to slightly harmful to all the natural enemies tested. These chemicals should be examined further for their possible recommendation for integrated control. Other pesticides gave less favourable results. It is hoped that the results would help other WPRS Working Groups and plant protection advisers in the development of rational control programmes.     

Survey and distribution ofCybocephalidae [Coleoptera] in Israel

Nine species ofCybocephalus were found in a survey conducted throughout Israel:C. micans (Reitter),C. nigriceps nigriceps (J. Sahiberg),C. nigriceps sinister Endrödy-Younga,C. aegyptiacus Endrödy-Younga,C. mediterraneus Endrödy-Younga,C. pullus Endrödy-Younga,C. fodori minor Endrödy-Younga,C. membranaceus (Reitter) andCybocephalus sp. n.C. micans andC.n. nigriceps are the most prevalent: the former in the Coastal Plain on citrus and the latter in the Arava region on date palms. In most cases the population density of the predator appeared to be related to that of the prey. Armoured scale insects(Homoptera: Diaspididae) were the main prey ofCybocephalus.     

Parasitoids and hyperparasitoids ofZeiraphera diniana [Lep., Tortricidae] and their pole in population control in outbreak areas

There are 109 species of primary and secondary parasitoids associated withZeiraphera diniana Guénée in the Central European Alps. Ninety species are primary, 6 facultative secondary and 13 obligate secondary parasitoids. At family level, the composition of the complex seems to be the same in every outbreak area of the host, with ichneumonids predominating. In the Upper Engadine Valley (Switzerland), where intensive studies were conducted over a period of 3 consecutive outbreak periods (28 years), 65% of the complex is represented. The nomenclature ofZ. diniana parasitoids has been clarified as far as possible. Many species names cited in the literature are synonyms or misidentifications. The complex of parasitoids, together with the associated predators ofZ. diniana, is unable to slow down the rate of density increase of the host in outbreak areas. This fact has stimulated investigations on the most important parasitoid species, i.e.Phytodietus griseanae Kerr. (Ichneumonidae), Sympiesis punctifrons Thomson,Dicladocerus westwoodii West. andElachertus argissa Walker (Eulophidae) over a period of about 10 years. Recent research has demonstrated that immigration ofZ. diniana moths into the outbreak areas during the phase of host density increase is very important. The rate of increase of the natural enemies — which are univoltine —can never equal or exceed that of their host; consequently, control by these natural enemies alone is not possible.     

Observation of algal colonization on Acropora aspera killed by Acanthaster planci

Algae started colonizing branches of the coral Acropora aspera (Dana) killed by the sea star Acanthaster planci (Linnaeus) within less than 24 hours. Two blue-greens ((Microcoleus lyngbyaceus (Crouan) Ag. and Hormothamnion solutum B. & F.)) dominated the early community but became less abundant than a brown ((Giffordia indica (Sonder) Papenfuss & Chihara)) after 26 days.