摘要:

An isolate of the fungusVerticillium lecanii(Zimmerman) Viegas from Alberta, Canada, was pathogenic under controlled conditions to four species of aphids,Acyrthosiphon pisum(Harris),Metopolophium dirhodumWalker,Myzus persicae(Sulzer),Therioaphis maculata(Buckton), the grasshopperMelanoplus sanguinipes(F.), and the nabidNabis alternatusParshley. Range of population reduction of aphids caused byV. lecaniiwas 60–97% forA. pisum, 32–85% forM. dirhodum, 50–100% forM. persicae, and 37–75% forT. maculata. V. lecaniidid not significantly affect the aphidRhopalosiphon padiL., the adult of the coccinellidHippodamia quinquesignataKirby, and the larvae of the pyralidOstrinia nubilalis(Hübner).

ISSN:1754-5692    

DOI:10.1093/ee/15.2.281

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Herbivore densities, weed composition and abundance, and crop yields per land unit were compared between squash monocultures and traditional maize/legume/ squash polycultures in tropical Mexico. The most abundant insect pest in the system,Diaphania hyalinata(L.) (Lepidoptera: Pyralidae), generally had lower population densities in polycultures than in monocultures. The squash bug,Anasa tristis(De Geer) (Heteroptera: Coreidae), tended to be more common in polycultures. Reasons for the observed patterns of squash herbivore densities are discussed in terms of the “resource concentration” hypothesis. Weed height and biomass were significantly greater in monoculture and, although yields of each component crop were decreased, total crop yields were higher in polycultures when estimated as a land equivalent ratio.

ISSN:1754-5692    

DOI:10.1093/ee/15.2.285

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Cabbage was grown interplanted with several living mulches and in bare-ground monocultures in 1982 and 1983 at Freeville, N.Y. Living mulches were creeping bentgrass, red fescue, Kentucky bluegrass, and two white clovers. Populations ofPhyllotreta cruciferaeGoeze andBrevicoryne brassicae(L.) were lower on cabbage grown with any living mulch than on cabbage in bare-ground monocultures. First-generation larvae ofPieris rapae(L.) were more common on cabbage with clover living mulches, but second-generation eggs and larvae were less common on cabbage with clover living mulches. These differences in population density were probably determined by variation in herbivore colonization rates, not by variation in herbivore mortality. The data suggest that early season chemical treatments for flea beetles might be eliminated when living mulches are used. However, this potential gain may be offset by yield reduction from competition between cabbage and living mulches.

ISSN:1754-5692    

DOI:10.1093/ee/15.2.293

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Several designs for yellow sticky traps were placed on the periphery of cotton and lettuce fields and evaluated to determine the most efficient trap design for capturing bandedwinged whiteflies,Trialeurodes abutilonea(Haldeman), and sweetpotato whiteflies,Bemisia tabaci(Gennadius). Cylindrical traps caught more (55% of the total) than the other designs; upward-facing horizontal traps caught 26%, vertical traps 16%, and downward-facing horizontal traps 3%. The number of both species of whiteflies captured by the various traps placed around field periphery was then compared with the number caught on traps in lettuce field interiors; catches from cylindrical and upward-facing horizontal traps were consistently correlated at high levels. Traps placed at ground level caught a significantly higher number ofT. abutiloneaandB. tabaciwhen compared with those placed at 50 and 100 cm (82% of total versus 11 and 7%, respectively). Correlation coefficients for number of whiteflies captured at all three heights and number of whiteflies captured in the field interiors were significant. The coefficients of variation, however, were lower for the traps placed at ground level than for the two aerial heights, suggesting that traps placed at 50 and 100 cm contributed disproportionately to the variation.

ISSN:1754-5692    

DOI:10.1093/ee/15.2.300

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

A factorial experiment involving infested and noninfested wheat cullivars ‘Abe’ (H3H3, H5H5), ‘Monon’ (H3H3), and ‘Knox 62’ (H6H6); Hessian fly,Mayetiola destructor(Say), biotypes B, C, and D at larval densities of 5, 10, 20, and 30 per plant; and temperature levels of 18 and 25°C was conducted in environmental chambers. Results showed that neither larval density nor its interaction with any of the other variables had any significant effect on plant resistance based on seedling wheat growth and larval survival. A high temperature of 25°C had a significant effect on resistance of wheats having combined H3H3 and H5H5 gene pairs when infested by biotypes B and D. Biotype C was not effective against wheats having the H3H3 or H5H5 gene pairs for resistance at either temperature.

ISSN:1754-5692    

DOI:10.1093/ee/15.2.305

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Field studies carried out at Fredericton, New Brunswick, Canada, between 1982 and 1984 show that an important proportion of overwintered Colorado potato beetles,Leptinotarsa decemlineata(Say), colonizing the young potato plants in late plantings originate from the earlier plantings. Results of a concurrent insectary test suggest that these beetles have a 15% higher total fecundity than the beetles that stayed on the older plants. Reasons for the relocation of the beetles remain, however, to be fully determined. The late planting was colonized more heavily than the early planting in 1982 and 1983 but not in 1984. The seed spacings of 15 and 36 cm had no effect on the colonization by the beetles. The numbers of adults, egg masses, and larvae were larger in the weed-free plots than in the plots with weeds except in the widely spaced late plantings. The importance of these results for the management of the beetle is discussed.

ISSN:1754-5692    

DOI:10.1093/ee/15.2.311

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

A sex pheromone component for the southern pine coneworm moth,Dioryctria amatella(Hulst), was identified as Z-11-hexadecenyl acetate (Z11–16:0Ac) and was attractive to male moths in loblolly pine,Pinus taedaL., seed orchards. Male moth catches in Pherocon 1C traps baited with a rubber septa loaded with 10, 100, 300, or 1,000 µg of Z11–16:0Ac were as good as or better than traps combining two liveD. amatellafemales, Field tests in Alabama, Georgia, and Texas throughout the entire growing season showed that baits with 100 µg generally would be best for a monitoring trap.

ISSN:1754-5692    

DOI:10.1093/ee/15.2.316

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Leaf burial by the earthworm,Lumbricus terrestrisL., is a significant mortality factor for the spotted tentiform leafminer (STLM),Phyllonorycter blancardella(F.), and its braconid parasites,Pholetesor ornigis(Weed) andPholetesor pedias(Nixon). In apple orchards with high earthworm densities, and in years with relatively warm springs,P. blancardellaemerges before all leaves are buried by earthworms. In years with cool springs, STLM development is prolonged and almost all leaves are buried before STLM emergence. In both cases, however, braconid parasites of STLM that overwinter in leaves do not emerge until most leaves have been buried, and, hence, suffer a high mortality. In another orchard with very low earthworm densities, leaf burial was negligible and not a significant mortality factor for STLM or its parasites.

ISSN:1754-5692    

DOI:10.1093/ee/15.2.321

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Fall armyworm (FAW),Spodoptera frugiperda(J. E. Smith), oviposition on paper towels treated with water extracts of corn leaves, FAW larvae, larval frass, and artificial diet was reduced significantly compared with towels treated only with the solvent. Carrageenan was the component in the artificial diet responsible for oviposition deterrence. Aqueous extracts from two sweet corn cultivars grown outdoors in pots deterred oviposition, but only one, ‘Pioneer X304C’, a FAW-resistant cultivar, did so when grown outdoors or in the greenhouse. Extracts of ‘Pioneer X304C’ leaves with other solvents also deterred FAW oviposition. In field-cage experiments, oviposition was reduced significantly on ‘Pioneer X304C’ corn plants sprayed with aqueous extracts of either ‘Silver Queen’ or ‘Pioneer X304C’ leaves.

ISSN:1754-5692    

DOI:10.1093/ee/15.2.327

出版商:Oxford University Press    

年代:1986

数据来源: OUP

摘要:

Two methods of trappingPholetesor ornigis(Weed) adults were investigated. Sticky traps of different colors were tested, and lemon yellow was most attractive to the parasitoids. Other traps were baited with live parasitoids. Live virgin females were very attractive to males, whereas few parasitoids were caught in traps baited with virgin males, mated females, or no insects. Both types of traps were used for season-long monitoring ofP. ornigisin three orchards in 1984. Yellow traps caughtP. ornigismainly during the midsummer generation, whereas traps baited with live virgin females showed flight periods corresponding to each generation of the host insect, the spotted tentiform leafminer,Phyllonorycter blancardella(F.).

ISSN:1754-5692    

DOI:10.1093/ee/15.2.331

出版商:Oxford University Press    

年代:1986

数据来源: OUP