摘要:

Viviparous green anholocyclic clones of the green peach aphid (GPA),Myzus persicae(Sulzer), displayed lower mortality and higher reproductive rates than the yellow holocyclic strain at 5 and 10° C, whereas nymphal development rates were similar. Results indicate that the anholocyclic strain, which overwinters in the viviparous stage, has evolved some degree of cold tolerance.

ISSN:1754-5692    

DOI:10.1093/ee/11.1.231

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

In the Yakima Valley of Washington there are two distinct strains of the green peach aphid (GPA),Myzus persicae(Sulzer): a holocyclic yellow morph and an anholocyclic green morph. These two distinct color morphs were maintained for over 20 generations in the greenhouse on a number of different host plants. In tests with non-viruliferous GPA feeding on diseased sugarbeet,Beta vulgaris(L.), or hoary cress,Cardaria draba(L.) Desv., the holocyclic strain was slightly more successful in transmitting beet western yellows virus (BWYV) to an indicator plant, shepherdspurse,Capsella-bursa pastoris(L.) Medic., than the anholocyclic strain. However, viruliferous GPA of the holocyclic strain was less successful in transmitting BWYV to indicator plants after first feeding on noninfested sugarbeet or hoary cress plants (83 and 66% efficiency, respectively), whereas the anholocyclic strain was able to transmit BWYV at lesser rates (98 and 96%, respectively). These differences may have arisen because of selective factors resulting from the different winter hosts normally associated with the two populations.

ISSN:1754-5692    

DOI:10.1093/ee/11.1.234

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

Prevalence of the nuclear polyhedrosis virus (NPV) granulosis virus (GV) was determined in populations of fall armyworm,Spodoptera frugiperda, in southeastern Louisiana. Both diseases reached their peak mean infection rates in mid-August in fall armyworms infesting pastures, the NPV at 50.8% and the GV at 2.8%. NPV prevalence in some pastures peaked at 60 to 68%. Infection rates by NPV in fall armyworms infesting corn and sorghum were initially lower than in pastures but were similar after mid-July (corn) or late July (sorghum). Infections by a mermithid nematode, an entomogenous fungus, and a microsporidium were rare.

ISSN:1754-5692    

DOI:10.1093/ee/11.1.239

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

Oviposition by the corn earworm,Heliothis zea(Boddie), on peanuts,Arachis hypogaeaL., was studied in the laboratory and in field cages. Highly significant differences in location of eggs were found. Numbers of eggs deposited in the peripheral, middle, and inner portions of the plant, respectively, occurred in a mean ratio of 9.9:4.9:1.0. Leaves were chosen ca. 86.5% of the time as oviposition sites compared with stems. In addition, the bottom leaf surface was selected over the top leaf surface by a 2.1:1.0 ratio. The least preferred sites for oviposition were stems and the lower portion of the plant. 1st-instar larvae exhibited a distinct preference for terminals as feeding sites.

ISSN:1754-5692    

DOI:10.1093/ee/11.1.243

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

We examined predictions of the theory of energy maximization for a field population of several species of bees foraging for nectar and pollen on a planting of six male-sterile and one male-fertile sunflower,Helianthus annus, cultivar. Honey bee and bumble bee workers gathered only nectar from sunflowers and mostly visited the two male-sterile cultivars that supplied the greatest caloric rewards; pollen was collected from other sources. Individuals of nonsocial species such asMelissodes agilispreferred the male-fertile cultivar (the only one supplying pollen), although it was lowest in caloric reward, because of their requirement for pollen for brood provisioning. Specialized workers of social species typically collect either nectar or pollen and presumably maximize caloric or nutrient acquisition. In contrast, individuals of nonsocial bee species forage for a mixed currency (energy and nutrients) and should not be expected to behave as predicted by the theory of energy maximization.

ISSN:1754-5692    

DOI:10.1093/ee/11.1.246

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

This paper reports the within-plant distribution of cabbage looper on cotton through time. Mainstem leaves receive the largest percentage of eggs. Increased plant density results in a greater proportion of eggs being oviposited on mainstem leaves, and closer to the mainstem terminal. As the plants age and increase in size, the eggs are found higher on the plant. The larvae appear to prefer leaves 5 to 10 nodes from the terminal. The average age of leaves being consumed by cabbage looper is estimated. A sampling plan for cabbage looper eggs based on mainstem leaves for estimating the optimal sample size for a given level of reliability is presented, taking into account plant age, plant density, and sampling cost (time).

ISSN:1754-5692    

DOI:10.1093/ee/11.1.251

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

Insect populations in grass grass-broadleaf weed swards without legumes or seeded to legumes by minimum tillage were sampled by sweep net. Seeded legumes were Viking birdsfoot trefoil, Arlington red clover, and Saranac AR alfalfa. Swards without legumes received 168 kg of nitrogen per ha per year. Samples taken at five plantings at 11 separate collections are summarized for totals collected of each of 93 insect species for each sward type. Data indicate that common species tend to be grass specialists with little known affinity for legumes, or generalists which may switch to legumes as those plants become dominant community components. Roles of grassor weed-feeding species in reducing plant competition during legume establishment may result in a net beneficial effect of insect populations.

ISSN:1754-5692    

DOI:10.1093/ee/11.1.255

出版商:Oxford University Press    

年代:1982

数据来源: OUP

摘要:

The larvae ofTetralopha euphemellaHulst are leaf tiers on the foliage of mesquite,Prosopisspp. Larvae completed their entire development on honey mesquite,P. glandulosaTorrey var.glandulosa, western honey mesquite,P. g.var.torreyana(L. Benson) M. C. Johnston, velvet mesquite,P. velutinaWooten, and white mesquite,P. albaGrisebach, but not on screwbean mesquite,P. pubescensBentham. Adults emerged from overwintering pupae in April and May. Populations of larvae in the field were always low, and larvae caused little damage to mesquite trees. Parasitism of larvae in the field reached 20% during the last two instars, mostly from tachinid flies. Each larva ate ca. 26 cm2of leaf surface (about one mesquite leaf) during its life. In the laboratory, adults laid an average of 152 eggs each. Four days were required for the egg stage, 27 days for the larva, 11 days for the pupa, and 3 days for adults to reach peak oviposition, for a generation time of ca. 45 days.

ISSN:1754-5692    

DOI:10.1093/ee/11.1.261

出版商:Oxford University Press    

年代:1982

数据来源: OUP

ISSN:1754-5692    

DOI:10.1093/ee/11.1.268

出版商:Oxford University Press    

年代:1982

数据来源: OUP