摘要:

To describe parasitoids of grape berry moth,Endopiza viteanaClemens, infested grapes were collected during two seasons in three grape habitats: wild grapes (the native host), organically managed commercial vineyards, and conventionally managed commercial vineyards. Three species of egg and larval parasitoids were prominent among the (eight) species collected.Trichogramma pretiosumRiley, an egg parasitoid, was collected only during the second season whenE. viteanapopulations were high and was responsible for a large proportion of parasitoid-induced mortality that season. The larval parasitoidsGlypta muticaCushman andApanteles polychrosidisViereck caused low levels of mortality during both seasons. All of the major parasitoid species were collected in each habitat type. Neither levels of parasitism nor the number of parasitoid species collected were consistently higher in the more diverse wild grape habitat compared with the two grape monocultures, although on average, levels of parasitism were slightly higher in the wild grape habitat.G. muticawas responsible for a higher proportion of the overall parasitism in the wild than in the cultivated habitats, whereasA. polychrosidiswas responsible for a higher proportion of the parasitism in the cultivated habitats. The proportion of overall parasitism contributed byT. pretiosumwas equivalent across habitats. GatedE. viteanacohorts were used to estimate generational mortality in the egg and larval stages. Parasitoids were responsible for 12–42% mortality in three cohorts. Total mortality for the egg and larval stages was between 63 and 72%. The parasitoid complex and resulting level of parasitism at individual sites are influenced by factors independent of those we used to define the habitat types. No generalizations can be made about the expected species composition or level of parasitism in any of the habitats examined.

ISSN:0046-225X    

DOI:10.1093/ee/19.3.764

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Estimates of parasitoid-induced mortality obtained from the rearing or dissection of samples of hosts may underestimate the actual mortality attributable to parasitoids. In this study, the use of appropriate unparasitized control hosts allowed the authors to apply Abbott's formula to estimate total parasitoid-induced mortality. Gypsy moth,Lymantria dispar(L.), larvae at the age of 0, 3, 6, or 9 d were stung by the solitary endoparasitoid,Cotesia melanoscela(Ratzeburg). There were significant curvilinear relationships between host age at the time it was stung and parasitoid emergence and parasitoid-induced nonemergence mortality. Emergence rates were lowest and parasitoid-induced nonemergence mortality rates were highest among hosts stung on days 0 and 9. The negative effect of parasitism on growth rates was greatest among hosts stung on days 6 and 9, and parasitoid development time was longest within hosts stung on days 0 and 9.

ISSN:0046-225X    

DOI:10.1093/ee/19.3.771

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Phytophagous insects in five orders, 50 families, 101 genera, and 114 species constitute the insect fauna ofMimosa pigraL., a weed introduced into northern Australia from tropical America. Most insect species attackingM. pigrain Australia were rarely or only occasionally encountered, are native or naturalized, polyphagous, and feed externally on the woody stems and mature foliage. Seventy-one species (62.3%) were known to breed on the plant, but only 13 (11.4%) were endophagous. No species were endophagous on flowers, fruit, seeds, or leaves. Thirty species (26.3%) are known pests of cultivated plants. Insects introduced into Australia for the biological control ofM. pigrawill find largely unexploited food sources, especially on new growth or inside the reproductive structures.

ISSN:0046-225X    

DOI:10.1093/ee/19.3.776

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

The virulence of six isolates ofBeauveria bassiana(Balsamo) Vuillemin to the Russian wheat aphid,Diuraphis noxia(Mordvilko), was bioassayed. All the isolates tested were capable of infectingD. noxia, but their virulence, determined by LC50's and LT50's, varied. An aphid-derived isolate had the lowest LC50, 0.57 × 105conidia/ml, and among the shortest LT50's at all five concentrations of conidial suspension. Two isolates from nonhomopteran hosts and one from an homopteran also displayed significant virulence and were very similar to one another, whereas two Homoptera-derived isolates were significantly less virulent. Log-transformed concentrations and post-treatment time (days) were correlated with probit-transformed mortality induced by each of the isolates. The resulting models, using third-order polynomials, gave good predictions of mortality within the range of concentrations tested. Colony growth rates for four isolates were relatively similar. Differences in virulence among the tested isolates are discussed in conjunction with their geographic origins, insect hosts, and growth and sporulation characteristics.

ISSN:0046-225X    

DOI:10.1093/ee/19.3.785

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

LC50values were determined for six populations (two laboratory and four wild-type) of Indianmeal moth,Plodia interpunctella(Hübner), to peroral inoculations of a granulosis virus. Various biological parameters of the populations were measured to determine similarities or differences among the moth populations tested. A significantly (P<0.05) higher LC50value was measured for two of the wild-type populations (one from the west coast and one from the east coast) compared with the others. These two populations also had significantly (P0.05) different among them, but showed them to be more susceptible to the virus and with shorter developmental times compared with the two wild-types discussed above.

ISSN:0046-225X    

DOI:10.1093/ee/19.3.791

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Arthropods of French Guiana were examined to delineate the host range of a newly described species of an ectoparasitic nematode,Noctuidonema guyanenseRemillet&Silvain, of adult Lepidoptera. Moths in five families (Lasiocampidae, Noctuidae, Notodontidae, Pyralidae, and Sphingidae) harboredN. guyanense. Twenty-five species of Noctuidae were infected. Multiple species ofSpodopteraandMocisserved as hosts forN. guyanense. The most commonly infected hosts wereLesmone formularisHübner,S. dolichos(F.),S. frugiperda(J. E. Smith), andXanthopastis timais(Cramer). Lepidoptera in 19 families, including 121 species of Noctuidae, did not harborN. guyanense. Also, arthropods in 12 orders and 70 families of non-lepidopteran insects, 2 orders of Arachnida, and 5 families of Araneae were not infected byN. guyanense. It appears thatN. guyanenseis primarily an ectoparasite of moths in Noctuidae.

ISSN:0046-225X    

DOI:10.1093/ee/19.3.795

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

The South American weevilNeohydronomus affinisHustache was first released in North America as a biological control for waterlettuce,Pistia stratiotesL., at Kreamer Island, Lake Okeechobee, Fla., on 29 April 1987. Releases were made at six additional sites in southern Florida. Periodic observations at several of these sites indicate the weevils have become established and are dispersing. At some sites, weevil-infested plants are exhibiting symptomology typical of plants in other countries whereN. affinishas been used successfully to control this aquatic weed.

ISSN:0046-225X    

DOI:10.1093/ee/19.3.799

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

The different types of parasitoid-induced mortality, host stage preferences, and sex ratio exhibited byPnigalio flavipes(Ashmead) to its host,Phyllonorycter elmaellaDoganlar&Mutuura, was investigated in commercial apple orchards in central Washington. The parasitoid-induced mortality ofPhyllonorycter elmaellaconsisted on average of 57.2% host stinging with oviposition, 32.7% host feeding, and 10.1% host stinging without oviposition.Pnigalio flavipeslaid eggs onPhyllonorycter elmaellatissue feeders (fourth and fifth instars) an average of 5.4 times more than it did on sap feeders (first-third instars), but host-fed on sap feeders an average of 12.1 times more than on tissue feeders. When healthy tissue feeders became scarce late in the season,Pnigalio flavipesbegan to lay eggs on previously attacked tissue feeders (superparasitize) and then switched to laying eggs on sap feeders. The sex ratio (M:F) ofPnigalio flavipesreared from tissue feeders was almost 1 to 1. Only malePnigalio flavipeswere reared from sap feeders.

ISSN:0046-225X    

DOI:10.1093/ee/19.3.803

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Reproductive capacity and activity patterns of native screwworm (Cochliomyia hominivorax(Coquerel)) males were evaluated by release and recapture of sterile females in central Belize. On six occasions 4,000 virgin, 1-d-old sterile females were released at a central location. A total of 382 sterile females and 66 native females were recaptured on sentinel sheep at four locations. Ratios of virgin to mated recaptured females were used to calculate an estimated number of matings per release. During the 65-d period of the test, numbers of recaptured females and mating percentages increased, then decreased for the last release. Location of sentinel animals, day after release, and individual releases were significant factors explaining capture rates for mated and nonmated released females and captures of native females. Mating capacity for the native population of screwworm males over the 10-d recapture period was estimated to range from 70 to 1,735 matings for the dispersal area of these females. These data and estimates suggest that although screwworm males have relatively low population densities, they have significant excess mating capacity, and that production and release of competitive sterile males is important for the success of the screwworm eradication program.

ISSN:0046-225X    

DOI:10.1093/ee/19.3.808

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

An aphid-derived isolate ofBeauveria bassiana(SGBB8601) andVerticillium lecanii(DNVL8701) were bioassayed against six species of globally distributed cereal-infesting aphids under controlled conditions. Aphids were immersed in conidial suspensions at concentrations ranging from 104to 108conidia/ml, each concentration being replicated six times with 20 aphids treated per replicate. Pathogenicity of both fungal species was confirmed on all the aphids tested, but in most cases,B. bassianawas more virulent thanV. lecanii. The LC50values forB. bassianaandV. lecaniiwere 8.2 × 104and 4.1 × 105conidia/ml, respectively, onDiuraphis noxia; 2.1 × 105and 9.8 × 105onSchizaphis graminum; 3.3 × 105and 7.0 × 105onMetapolophium dirhodum; 1.1 × 105and 1.3 × 106onSitobion avenae; 2.1 × 106and 8.9 × 105onRhopalosiphum maidis; and 3.3 × 106and 6.9 × 106onR. padi. Statistical analysis indicated that there were substantial differences in susceptibility to the two pathogens and in virulence of each fungus to different aphid species. The LT50values at all concentrations varied between the pathogens and among the aphid hosts withB. bassianatending to kill aphids more rapidly. The mortality data were probit transformed, and a third-order polynomial model was fit to the data to describe responses of each host to conidial concentration and time after treatment. The potential for use ofB. bassianafor aphid control is discussed.

ISSN:0046-225X    

DOI:10.1093/ee/19.3.815

出版商:Oxford University Press    

年代:1990

数据来源: OUP