摘要:

Egg development ofHeliothis zea(Boddie) was studied under various static and fluctuating environmental regimes. Two computer-controlled environmental chambers were programmed to fluctuate temperatures through diurnal sinusoids of ±5°F (2.8°C) to ±20°F (11.1°C) using the same mean temperatures as regimes in statically controlled environmental chambers.The heat-units concept of development proved not to apply to bollworm egg development. In its stead, a hypothesis is formulated based on the egg-development curve measured in static thermal conditions.

ISSN:1754-5692    

DOI:10.1093/ee/2.4.491

出版商:Oxford University Press    

年代:1973

数据来源: OUP

摘要:

Spodoptera exigua(Hübner) on cotton in California is typically a secondary pest, likely to become abundant after insecticide applications againstLygus hesperusKnight. In this study local outbreaks were generated experimentally in an area of one square mile of cotton, subdivided into 4 randomized blocks of 4 treatments. Applications of dimethoate triggered significant increases in abundance of beet armyworm larvae. Levels up to 4 times as high as those in the untreated control were reached. Analysis of results of population censuses of both beet armyworm and its natural enemies in the experimental area, supplemented by observational evaluation of predator activities on early developmental stages, indicated impairment of predation on eggs and newly hatched larvae as the calise of outbreaks. Especially important in this context were the hemipterous speciesGeocoris pallensStål,Orius tristicolor(White), andNabis americoferusCarayon, which were severely reduced by the treatments. Another important predator of eggs and caterpillars, the larva ofChrysopa carneaStephens, appeared immune to the insecticide. Field observations further revealed some egg predation by the otherwise predominantly phytophagousL. hesperus.The relevance of this study to pest management procedures for cotton is discussed.

ISSN:1754-5692    

DOI:10.1093/ee/2.4.497

出版商:Oxford University Press    

年代:1973

数据来源: OUP

摘要:

The major fraction of the attractant “mask” or antiaggregative pheromone ofDendroctonus pseudotsugaeHopkins was identified as 3-methyl-2-cyclohexen-l-one, (MCH). The female beetles released this compound after sonic stimulus by actual male stridulation and by electronic playback of recorded male sounds, thus definitively confirming that the cue for release of MCH is the male some Signal in a novel interaction of sonically and chemically induced behavior. This natural antiaggregative pheromone can presumably be used in forest protection without ecological disruption.

ISSN:1754-5692    

DOI:10.1093/ee/2.4.505

出版商:Oxford University Press    

年代:1973

数据来源: OUP

摘要:

Laboratory arrestment tests withDendroctonus frontalisZimmerman confirmed that a high concentration of the pheromone verbenone inhibits male response to the known attractants of this beetle. However, a very low concentration of verbenone combined with these attractants elicited significantly more male arrestment than did the attractants alone. Male stridulation also differed according to the concentration of verbenone present in the pheromone mixture. A low concentration evoked the “attractant” chirp characteristic of male response to the female attractant, but a medium concentration of verbenone evoked the male “rivalry” chirp characteristic of male fighting. Since it is known that females produce a small quantity and males a large quantity of verbenone, these different effects are suggested as multiple functions of the pheromone.

ISSN:1754-5692    

DOI:10.1093/ee/2.4.511

出版商:Oxford University Press    

年代:1973

数据来源: OUP

摘要:

A pest management program on alfalfa raised for seed in Washington was developed during 1953–72. Major components include an integrated trichlorfon-predator control system for Iygus bugs,Lygus hesperusKnight andL. elisusVan Duzee, and a demeton-parasite- predator system against the aphidsAcyrthosiphon pisum(Harris) andMacro-siphum creeliiDavis. Basic selection pressure which led to development of this program was the hazard of insecticides to the essential pollinatorsMegachile rotundata(F.) andNomia melanderiCockerell.

ISSN:1754-5692    

DOI:10.1093/ee/2.4.515

出版商:Oxford University Press    

年代:1973

数据来源: OUP

摘要:

Vogtia malloiPastrana was introduced into the United States from Argentina in April 1971 as a biological control agent of alligatorweed,Alternanthera philoxeroides(Mart.) Griseb.Vogtiawere released at 10 different locations from Wilmington, North Carolina, to Ft. Pierce, Florida. Populations have become established at four of these release sites. Population studies conducted at the Lake Alice release site, on the University of Florida campus, Gainesville, Florida, indicated the new population dispersed randomly over the stand of alligatorweed.Vogtiareduced the number of aerial alligatorweed stems per square foot from 52.5 to 4.0 in four generations. The alligatorweed did not have a competitive advantage by the end of the fourth generation; mixed vegetation was replacing the deteriorating mats of alligatorweed.

ISSN:1754-5692    

DOI:10.1093/ee/2.4.519

出版商:Oxford University Press    

年代:1973

数据来源: OUP

摘要:

Mean flight activity from overwinteredApis melliferaL. colonies was usually greater and the quantity of pollen trapped was well in excess of that from disposable pollination units (DPU's). However, comparisons between individual units indicated that DPU's exhibit more uniform flight activity than colonies. Data pertinent to the effect of this atypical domiciliary crowding and colony makeup on longevity, development, and certain behaviorial adaptations of the bees are included.

ISSN:1754-5692    

DOI:10.1093/ee/2.4.525

出版商:Oxford University Press    

年代:1973

数据来源: OUP

摘要:

Several entomological techniques were combined to create a reliable method of analyzing the foraging activities of colonies ofApis melliferaL. Returning bees were periodically sampled at the hive entrance with a sweep net. Vacuum sampling from a modified auger-hole pollen trap is proposed as a means of reducing possible sampling error. The samples of bees were quick frozen in sealed plastic bags and held for subsequent laboratory analysis.The percentage of foraging bees (pollen, nectar, and both pollen and nectar collectors combined) and of nonforaging bees remained constant at all times over all days, but the ratio of nectar to pollen-collecting bees varied; an increase in one was reflected by a decrease in the other. The ratio of bees collecting both pollen and nectar to those collecting only pollen was approximately 1:3 Statistical analysis demonstrated that duplicate samples of 10 bees produced adequate data for differentiation between the foraging activities of worker bees.

ISSN:1754-5692    

DOI:10.1093/ee/2.4.531

出版商:Oxford University Press    

年代:1973

数据来源: OUP

摘要:

Tolerance to parathion in phytophagous insects is significantly influenced by the host plant. This fact was demonstrated for the European corn borer,Ostrinia nubilalis(Hübner); the imported cabbageworm,Pieris rapae(L.); and the cabbage maggot,Hylemya brassicae(Bouché).

ISSN:1754-5692    

DOI:10.1093/ee/2.4.537

出版商:Oxford University Press    

年代:1973

数据来源: OUP

摘要:

Dendroctonus ponderosaeHopkins was studied in lodgepole pine,Pinus contortaDouglas, at 4 elevations between 1923 and 2750 m in northwestern Wyoming. The beetle had a 1-year life cycle at 1923 and 2130 m. At 2450 m, part of the population completed a generation in one year, but the remainder required two years. Two years usually were required to complete a generation at 2573–2750 m. Life tables showed high mortality rates and declining populations at the 3 highest elevations, in contrast to high survival rates and increasing populations at the lowest elevation. Cool temperatures at high elevations delayed development, so the beetle overwintered in stages that were particularly vulnerable to winter temperatures. The conclusion is that mountain pine beetle populations are regulated by weather at high elevations.

ISSN:1754-5692    

DOI:10.1093/ee/2.4.541

出版商:Oxford University Press    

年代:1973

数据来源: OUP