摘要:

The species composition and habitat associations of spiders were studied in one abandoned and 5 commercial apple orchards in central Virginia. Sixty-eight identifiable species were recorded from all orchards. The abandoned orchard contained 63 species while 11–17 species were found in individual commercial orchards. The Salticidae, Philodromidae, Thomisidae, Theridiidae, Anyphaenidae, and Dictynidae comprised 75–92% of the total spiders collected from each orchard. The proportions of hunting spiders found in all but one commercial orchard were similar to that found in the abandoned orchard. The many species of spiders encountered in each orchard exhibited specific habitat preferences and segregated the tree into numerous niches. Since many orchard insect pests often occupy several of these niches, different spider species may act in a complementary manner to suppress such insect pest populations.

ISSN:1754-5692    

DOI:10.1093/ee/9.2.247

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

In a uniform infestation with eggs of the western corn rootworm,Diabrotica virgiferaLeConte, the root damage rating was found to be a more sensitive measurement of root worm damage than vertical pulling weight, root lodging and goosenecking, plant stunting, or adult recovery. Also, root damage ratings, unlike vertical pulling weight, were independent of the size of the root system.Adult insects began to emerge from the artificial infestation at the same time as from a nearby natural infestation. The maximum damage the test corn hybrids were able to sustain was reached at ca. 1200 eggs/30.5 cm of row (row-ft); any increase beyond this level resulted in a decrease in the number of adults recovered. The relationship established between yield reduction and a known number of corn rootworms showed that even with almost ideal growing conditions, as few as 100 eggs/30.5 cm of row caused a highly significant reduction.

ISSN:1754-5692    

DOI:10.1093/ee/9.2.253

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

There was no association between lesions of apple scab incited byVenturia inaequalis(Cke.) and damage done to unsprayed harvested mature fruit of ‘Jonathan’, ‘Golden Delicious’, and ‘Gallia Beauty’ apples(Malus domesticaBorkh) by codling moth,Laspyeresia pomonella(L.), apple maggot,Rhagoletis pomonella(Walsh), plum curculio,Conotrachelus nenuphar(Herbst), or redbanded leafroller,Argyrotaenia velutinana(Walker). However, there was a negative association of apple scab and damage by rosy apple aphid,Dysaphis plantaginea(Passerini) with ‘Jonathan’. When scab infestation was prevented by weekly spraying of half of each tree with dodine, the insect species tended to damage more sprayed than unsprayed fruit. Plum curculio showed a significant ovipositional preference for scabfree (sprayed) ‘Golden Delicious’ and ‘Rome Beauty’. In unsprayed, detached ‘Jonathan’ apples in trays, fruit with scab lesions had significantly more redbanded leafroller feeding scars than fruit without scab lesions.

ISSN:1754-5692    

DOI:10.1093/ee/9.2.258

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

Hydroprene terminatedMicroctonus aethiopoidesLoan diapause when topically applied to hostHypera postica(Gyllenhal). Concentrations of 1, 5, 10, or 50 μg/host terminated diapause in at least 97% of the parasites. Parasite survival and morphological condition were influenced by hydroprene concentration. One μg had no adverse effects other than 8% deformed adults and had no carry-over effect on F1generation. Five μg did not affect pupation or adult eclosion but caused 31% deformed adults and some deformed adults in F1generation. Ten μg did not affect pupation, reduced adult eclosion, caused 82% deformed adults, and had a carry-over influence on the Fl generation where there were fewer parasitized weevils, decreases in adult eclosion, and increases in number of deformed F1M. aethiopoidesadults. Fifty μg decreased successful pupation and caused 100% pupal mortality.

ISSN:1754-5692    

DOI:10.1093/ee/9.2.262

出版商:Oxford University Press    

年代:1980

数据来源: OUP

摘要:

Studies conducted from May through Nov., 1979 determined that the distribution and abundance ofScaphylopius acutus acutus(Say) (Homoptera: Cicadellidae), a vector of peach (Prunus persicaBatsch) X-disease, in a Connecticut peach orchard were related to the distance from wild host species at the orchard edge and to the relative abundance of wild host plants in the orchard ground cover. Greatest numbers of adultS. acutusfor spring and summer generations were captured on yellow sticky traps located among wild host plants at the orchard edge while fewest were caught on traps in peach trees furthest from the edge. Density of nymphs and adults on peach trees and in ground cover in 32 plots along a transect through the orchard increased with the relative abundance of wild host plants in the ground cover and decreased with distance from the orchard edge.Host preference experiments conducted in the laboratory revealed that both generations ofS. acutuswere most highly attracted to red clover,Trifolium pratenseL. (Leguminosae), for feeding and oviposition. However, this plant comprised less than 1% of the orchard ground cover. Peach was preferred as a food host by both generations over 8 wild host species, which comprised 94% of the ground cover. Oviposition preference experiments indicated that peach was among the least preferred hosts for both generations while several rosaceous species, in particular strawberry,Fragaria virginianaDuchesne and blackberry,Rubus allegheniensisPorter, comprising 65% of the ground cover, were most highly preferred for oviposition. The differential utilization of peach and wild rosaceous hosts byS. acutusfor feeding and oviposition would encourage frequent movement of adults between peach and the ground cover.

ISSN:1754-5692    

DOI:10.1093/ee/9.2.265

出版商:Oxford University Press    

年代:1980

数据来源: OUP