摘要:

Two techniques, sweeping with a canvas net and night trapping with a portable trap, were compared as means of sampling Acridid grasshoppers in burned and unburned tallgrass prairie in eastern Kansas. Mark-release experiments revealed that night traps on both burned and unburned sites throughout the summer captured roughly three-fourths of the grasshoppers when the weather was clear and warm; thus, the technique provides good estimates of seasonal change in absolute density. Ability to capture grasshoppers on unburned vs. burned prairie differed for sweep sampling(in contrast to night trapping); only 30 to 40% as many grasshoppers (per grasshopper present) were collected by sweeping on unburned vs. burned sites. Furthermore, grasshoppers were captured more readily by sweeping as they grew older. Therefore, sweeping provided poor estimates of how the relative abundance of grasshoppers (1) changed seasonally at a site, and (2) differed between burned and unburned sites. Sweeping and night trapping provided similar estimates of the relative abundances of individual species present at anyone place and time on either burned or unburned prairie.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1449

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Two temperature-dependent models have been derived for use in management of the alfalfa blotch leafminer,Agromyza frontella(Rondani), in eastern Ontario. A linear function, designed for grower use and based on heat units above 5°C, will give accurate predictions of the seasonal occurrence of the life stages together with critical biological events such as adult emergence, hatch, and larval dropout. A nonlinear function, based on a polynomial algorithm, will give even more precise simulations and is amenable to computerized forecasting.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1455

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Adult bean leaf beetles,Cerotoma trifurcata(Forster), were trapped as they entered Illinois woodlots during October 1979 and 1980. Soil litter samples and emergence traps detected the presence and distribution of overwintering beetles within woodlands. Spring beetle emergence from overwintering sites began in April and extended through May. In 1980 the majority of beetles emerged in May, but in 1981 the majority emerged during April. Beetle emergence and soybean planting dates were well synchronized in 1980, and poorly synchronized in 1981, resulting in a population crash. A simple predictive model for beetle emergence based on degree-day accumulation was developed. This proved superior to simple calendar date predictions of peak colonization flights.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1459

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Population densities of the minute pirate bug and its prey, the western flower thrips, were monitored in squash monocultures and tricultures with corn and cowpea intercropped. The predator exhibited a more rapid colonization rate in tricultures, and the thrips densities on squash were lower and fell earlier in the season in these systems. The capacity for thrips control byOriuson squash was demonstrated in predator inclusion-exclusion cage experiments. The earlier colonization of triculture byOriuswas probably due to the greater attractiveness of the mixed-crop habitat.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1464

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Laboratory, small-field plot, and commercial-scale experiments were completed, using Connecticut, Rhode Island, and New York Colorado potato beetle, (CPB)Leptinotarsa decemlineata(Say), populations to determine if “antifeedant fungicides” might reduce the suitability of potato for CPB while simultaneously protecting potato from early and late blight. In the laboratory, fungicides formulated from triphenyltin hydroxide (TPTH) or Cu(OH)2, reduced CPB feeding 95 and 61%. In small-field plots, CPB larval densities were significantly reduced where TPTH and Cu(OH)2, were used regularly. In commercial-scale experiments,L. decemlineatapopulations were significantly reduced and required fewer insecticide applications for acceptable control where TPTH was used regularly.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1470

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

The number of “gossypol” glands in cotton anthers and chemical composition of these glands vary among different cotton lines. The glands contain mostly gossypol but also contain other terpenoid aldehydes, and each gland is enveloped by tissues containing an anthocyanin. Although youngHeliothis virescens(F.) larvae (Lepidoptera: Noctuidae) avoid feeding on the glands of anthers, their ability to penetrate the mass of anthers and feed on female reproductive structures of cotton does not appear to be affected by the presence of glands.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1478

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Aedes canadensisandAedes stimulansadults probed the flowers of seven plant species in woodlands. Of the 217 males and females collected, 159 (73.3%) were sighted during 1700 to 1930 h (EDT). An anthrone reagent detected fructose or sucrose in newly emerged adults (53.2∼ of 124 A.canadensis, 45.1% of 142 A.stimulans) and in blood-seeking females (50.1% of 515 A.canadensis, 49.3% of 600 A.stimulans)collected during diurnal and crepuscular periods (0930 to 1930 h). Sugar positivity rates peaked for both species (53.7 to 63.6%) during 1700 to 1930 h, a time when the majority of adults was observed on blossoms. Average amounts of total available energy reserves, determined by bichromate and spectrophotometric assays, were greater in blood-seekingA.stimulansfemales (mean range = 6.2−11.4 cal per female) than in both sexes ≤ 12 h old (mean = 0.8−2.7 cal per insect). The presence of fructose or sucrose in newly emerged males and females reinforces the importance of these sugars for insect survival during early adulthood.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1482

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Adult seedcorn maggot,Delia platuraMeigen, populations were determined in 1980 and 1981 in relay intercropped soybeans, in soybeans for which a wheat cover crop had been disked into the soil, and in soybeans planted without wheat. Influence of planting date on seedcorn maggot populations also was evaluated for early-, mid-, and late-May plantings. Seedcorn maggot populations were not increased in relay intercropped soybeans in either year, but were 8.5 times greater in wheat disked areas compared with soybeans planted without wheat. Fewer seedcorn maggots were collected in late May compared with early and mid-May in both years. Reductions in soybean stands, caused by seedcorn maggot, occurred only in 1981.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1487

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

Diapause pink bollworm,Pectinophora gossypiella(Saunders), larvae in cotton,Gossypium hirsutumL., bolls buried in soil during March exited the bolls and tunneled to within 0 to 1.7 cm of the soil surface under laboratory conditions. Higher percentages of the larvae exhibited this behavior when bolls were buried in moist (11 to 15%soil moisture)than in dry(2%soil moisture) soil or when bolls were left on the soil surface. Higher percentages of the exited larvae pupated as compared with pupation of larvae remaining in the bolls. Adult emergence occurred more rapidly when larvae in bolls was buried in moist soil (12% soil moisture) than when larvae in bolls were buried in dry soil (4% soil moisture). In an outdoor insectary (1979), the first pupa from diapause pink bollworm larvae was obtained between 15 and 22 March 1980. Pupation increased thereafter to95%during 24 to 31 May. Adult emergence was first observed 5 to 12 April, and92%emergence occurred from 24 to 31 May. In 1981, adult emergence began on 20 April, with 100% emergence occurring by 23 June.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1490

出版商:Oxford University Press    

年代:1983

数据来源: OUP

摘要:

The suitability of rice,Oryza sativa(L.), sorghum,Sorghum bicolor(L.) Moench, and vasey grass,Paspalum urvilleiStuedel, as host plants of the rice stink bug,Oebalus pugnax(F.), were determined at 21, 24, 27, and 30°C. At 21, 24, and 27°C there were no significant (P<0.05) differences in the weight of 10-day-old nymphs reared on the three hosts, but at 30°C, weights of nymphs reared on grain sorghum were significantly (P<0.05) greater than those reared on rice or vasey grass. Weights of 15-day-old nymphs followed the same pattern, but there were no significant (P<0.05) differences between weights of insects reared on rice and grain sorghum at 30°C. At 24 and 30°C, weights of adults were significantly (Pvasey grass), but at 21 and 27°C weights of adults from rice and grain sorghum were similar. Nymphal survival was significantly (P<0.05) greater on rice and grain sorghum than on vasey grass at each temperature except 21°C, where there was no difference between insect survival on vasey grass and grain sorghum. At 21 and 27°C, development time (egg to adult) was significantly (P<0.05) shorter on grain sorghum than on rice or vasey grass, but at 24 and 30°C no differences in developmental time existed. The mean development time from egg to adult on rice, sorghum, and vasey grass at 30°C was 22.9 days, 20.7 days, and 22.3 days, respectively.

ISSN:0046-225X    

DOI:10.1093/ee/12.5.1496

出版商:Oxford University Press    

年代:1983

数据来源: OUP