摘要:

Vertical distribution patterns of soil-inhabiting microarthropods in an agricultural region of the San Joaquin Valley, CA, are described. Eight samples, each 122 cm deep and with surface areas of 426.5 cm2, yielded 7727 specimens with 33% from the upper 15.2 cm of the profile and 24% from the 15.2–30.5 cm depth. About 30% were collected from below 46 cm. An additional 16 samples, 4 extending to depths of ca. 250 cm and 12 to ca. 311 cm, and each encompassing a surface area of 426.5 cm2, yielded 5904 specimens. Of these, 51% was collected from the upper 15.2 cm and 21.5% from the 15.2–30.5 cm depth. About 20% of the fauna was collected from below 55 cm, and 1.8% or 109 specimens were obtained from depths below 200 cm.Distribution data are presented for the total microarthropod fauna as well as for major component taxa including Acarina, Collembola, Psocoptera, Pauropoda, Protura, Symphyla, larvae of Coleoptera and Diptera, and Japygidae (Diplura). Results are discussed in relation to sampling requirements.

ISSN:0046-225X    

DOI:10.1093/ee/6.4.575

出版商:Oxford University Press    

年代:1977

数据来源: OUP

摘要:

Three species in the native parasite guild ofSpodoptera praefica(Grote) account for 95% of the apparent mortality due to parasitization of host larvae in hay alfalfa. In field studies, parasitization did not decrease when 1, 2, or 3 parasite species were reared from hosts occurring in the same subsample. Laboratory studies indicate that intrinsic competitive ability and an index of potential reproductive capacity are inversely correlated among the 3 species. Comments are presented on the utility of the concept of r- and K- selection and the practice of releasing more than one species in biological control.

ISSN:0046-225X    

DOI:10.1093/ee/6.4.581

出版商:Oxford University Press    

年代:1977

数据来源: OUP

摘要:

Comparison of the longevity of adults ofCampoletis sonorensis(Cameron) on one nectaried and 2 nectariless strains of cotton showed a reduced longevity due to lack of extrafloral nectaries. However, the effect was considerably less when floral nectaries were available (plants in bloom stage). Male longevity was less than female longevity on both nectaried and nectariless strains, and the effect of the nectariless character was greater on males than females.Releases ofC. sonorensisagainst populations of tobacco budworm,Heliothis virescens(F.), on cotton in field cages showed that parasitism was lower on a nectariless strain than on a nectaried strain. However, rates of parasitism on both strains of cotton were relatively high, and parasites were able to maintain a generation cycle on nectariless cotton. Therefore, nectariless cotton appears to have only a slight effect on the impact of cagedC. sonorensisas a parasite of the tobacco budworm.

ISSN:0046-225X    

DOI:10.1093/ee/6.4.586

出版商:Oxford University Press    

年代:1977

数据来源: OUP

摘要:

Rabon® and the insect growth regulator, Dimilin®, were fed to pastured beef cattle in Tennessee. Manure pats were sampled bi-weekly from Apr.–Sept. Twenty-four species of insects were recovered. Of the 16 species that were analyzed, only 3 (Musca autumnalisDeGeer,Raviniasp. andSphaeridium scarabaeoides(L.)) were reduced in manure from treated cattle. One species,Ataeniussp. increased in Rabon treated manure pats. Manure pats from Rabon and Dimilin treated cattle were slower to decompose than pats from untreated cattle, but all pats had decomposed after 8 wk. Tunneling byS. scarabaeoideswas significantly reduced by both treatments.

ISSN:0046-225X    

DOI:10.1093/ee/6.4.589

出版商:Oxford University Press    

年代:1977

数据来源: OUP

摘要:

Polistes fuscatusssp.fuscatusandTherion sassacusburrow into the silken masses of active colonies ofHyphantria cuneain search of larvae, a mechanism to overcome any protective barrier function which the silk affords the caterpillar colony.

ISSN:0046-225X    

DOI:10.1093/ee/6.4.591

出版商:Oxford University Press    

年代:1977

数据来源: OUP

摘要:

Phytomyza nigraMeigen, a leafminer, is a polyphagous feeder on various grasses grown for seed. The reproductive season begins in Oct. and ends in June. Reproduction increased when adults were exposed in the laboratory to cool temperature (15°C) and short days (10 h light, 14 h dark); reproduction was reduced but did not cease when adults were exposed to cool temperatures and long days (16 h light, 8 h dark). Warm temperature (21°C) and long days drastically reduced reproduction of F1adults and completely inhibited reproduction of F2progeny. Temperature was clearly the dominant factor that influenced reproduction. Parasitism of the natural field population was less than 15% during autumn and winter but increased to 77% in Apr.

ISSN:0046-225X    

DOI:10.1093/ee/6.4.592

出版商:Oxford University Press    

年代:1977

数据来源: OUP

摘要:

Multivariate analyses are used to separate chironomid larval habitats, describe relationships between midge larval populations, and evaluate influences of biotic and abiotic variables on abundances in a lake system. Insect predators of 5 types of chironomid larvae had only a minor to moderate influence on midge densities in all habitats examined. Availability of aquatic weed did not have a major influence on abundance of larval midges. Water quality had greater influence in midwater and bottom habitats than in the surface.

ISSN:0046-225X    

DOI:10.1093/ee/6.4.595

出版商:Oxford University Press    

年代:1977

数据来源: OUP

摘要:

Parasitism ofArchips semiferanus(Walker) larvae in Pennsylvania became appreciable in early June (18.0–63.1%), which coincides with the appearance of 5th instars. Dipteran parasitism of the larvae is major (16.9–57.7%), while hymenopteran parasitism is minor (1.1–5.4%). Conversely, dipteran parasitism of the pupae is minor (0.72–2.6%) and hymenopteran parasitism is major (3.5–32.3%). Twenty-two parasites have been recovered from larvae and pupae samples, 16 of which are new host records. The major larval parasite isLypha setifacies(West) and the major pupal parasite isItoplectis conquisitor(Say).

ISSN:0046-225X    

DOI:10.1093/ee/6.4.601

出版商:Oxford University Press    

年代:1977

数据来源: OUP