摘要:

Where alternate male and female rows are used for onion-seed production it was found thatApis melliferaL., have a strong tendency to work along rows with only about 11% crossing with the row spacing used. Movement was extensive, with changing of directions frequent, but most flower-head changes were within a distance that represents width between rows. Male pollen-producing flowers were more attractive to bees than female flowers; foraging honey bees were present in greater numbers and spent longer periods on the male flower heads.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.127

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

The role of physical environmental conditions on uptake, translocation, and degradation of the32P-labelled systemic phosphonate,O-methylO-p-methylthiophenyl methylphosphonothionate, on cotton plants was investigated. Uptake, translocation, and degradation were measured by using radiochemical and bioassay techniques.A lengthening of the photoperiod from 10 to 14 hr increased rate and amount of radioactivity taken up and translocated by the cotton plants, improved insecticidal action of the systemic, and increased the degradation rate of the systemic. A further lengthening to 24 hr reversed the trends. Therefore, a point is reached at which lengthening of the photoperiod does not increase uptake and translocation of a systemic because too long a photoperiod upsets the plant's physiological functions.High humidity slowed the rate of uptake of the systemic and, in some way, reduced the chloroform-soluble fraction markedly at the 24 hr sample. At the 3-day sample, the chloroform-soluble fraction increased to about the same percentage of radioactivity as was found in the low humidity experiments, i.e., 17 and 30% higher than the 1 day sample at 65° and 80°F, respectively. High humidity slowed the rate of degradation of the chloroform-soluble fraction; the difference was greater between high and low humidity at 65° than at 80°F. For both humidities, the rate of degradation was much slower at 65° than at 80°F.Increase in temperature increased uptake and translocation of the systemic and increased the rate of degradation.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.129

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

In recent yearsAnthonomus grandisBoheman has invaded the High Plains, where it currently presents a potential threat to cotton in most of the area. A large-scale insecticidal control program was conducted during each of the years 1964–70 to control the insect. The programs were effective in preventing economic boll weevil damage to cotton in the High Plains. Despite these control efforts, low numbers of the insect advanced many miles west into previously uninfested counties of the High Plains during 1967–69. Distribution of the insect during 1964–70 in the High Plains and adjacent areas of West Texas is presented.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.136

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

Damaged squares, boll placement, total bolls, and yields from cotton given within plantings of corn, soybeans, alfalfa, peanuts, sorghum, and a check (no crop planted on either side of the cotton) were determined during 2 fruiting seasons. Two generations ofHeliothiseach year caused the greatest damage to squares in the corn treatment and the least damage in the sorghum treatment. Planting corn, alfalfa, sorghum, and peanuts adjacent to cotton increased the percent damaged squares over the check when both years were averaged.No treatment differences were observed between the number of bolls on the plants. In 1970, fewer plants per foot of cotton row produced significantly more bolls on the bottom half of the plants than did plants spaced closer together, but no differences were noted among treatments.Averaged over both years, the sorghum-treated plots produced the most seed cotton and the corn-treated plots the least. It appears that planting sorghum in a stripcropping system with cotton could be advantageous not only by encouraging and protecting beneficial insects but also by offering other desirable treatment effects.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.140

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

Predatory and harmful insects were collected from cotton planted between corn, soybeans, alfalfa, peanuts, sorghum, and a check (no crop planted on either side of the cotton). Beneficial arthropods collected in greatest numbers were lady beetles, lacewings, nabids, flower bugs,Collopsbeetles, and spiders. Destructive insects included thrips, fleahoppers, andHeliothis.Predators occurred more frequently in the sorghum, peanut, and alfalfa treatments than in the other treatments. Thrips, fleahopper, and boll weevil populations did not reach levels requiring control in any treatment. Treatment yields appeared to be affected byHeliothiswhen percent damaged squares from the treatments were compared with the check with no crop planted beside the cotton.The sorghum and check treatments produced the most and the corn treatment the least pounds of seed cotton. Sorghum appears to be the crop with the greatest potential for strip cropping with cotton.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.145

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

When supplemental releases of the host,Pieris rapae(L.), and two of its parasites,Trichogramma evanescensWestwood andApanteles rubeculaMarshall, were made in cabbage fields in Missouri, the host population was controlled sufficiently that larval damage remained below the level causing economic injury. All check plots had populations that exceeded this level.Natural populations ofT. evanescenswere ineffective in controlling early generations of the host.Natural populations ofA. rubeculaapparently do not overwinter successfully at Columbia, Missouri, but when this parasite was released during late September and October, the progeny did overwinter. Releases ofA. rubeculaat a rate of about 5000 adults per acre were sufficient to control populations of host larvae. Releases ofA. glomeratus(L.) were ineffective when populations ofA. rubeculawere present.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.150

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

The European corn borer first appeared in the southeast corner of Minnesota in 1943. It spread northward throughout Minnesota except the extreme north and northeast, and westward through corn-growing areas in South Dakota. This report reviews the history and some biological characteristics of the dispersion of the insect in the 2 States from 1945 to 1970.There was a high population build-up, or a “population swell” just behind the front of distribution. This phenomenon was shown by populations differing at only a subspecies level. On the basis of the population swells which occurred during the 26-year period, it is suggested that after the initial invasion in 1943, distinctly different populations could have invaded Minnesota in 1952 and again in 1966.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.157

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

Optimum conditions were determined for capturing.Anthonomus grandisBoheman in traps baited with males. Metal wing traps were painted daylight fluorescent yellow over a white undercoat (about 4×6-m. wings × 9-in. base) and were coated With an adhesive. Traps were baited with male boll weevils which were held in a container with a single layer of screen and placed at heights of 1–3 ft above ground around a cotton field adjacent to overwintering sites. This system, or a slight modification, would be useful in subsequent surveys and for control or possible eradication of the boll weevil with traps.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.162

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

Oviposition and egg hatchability of once-mated, nondiapauseHypera postica(Gyllenhal) were studied for 35 weeks under constant temperatures (10, 23, and 30°C) and alternating temperatures (4.5 and 15.5°C each 12 hours). Maximum oviposition (1788 eggs per female) occurred at alternating temperatures (4.5–15.5°C). Oviposition at 10 and 23°C, though not significantly different from each other, was significantly less than oviposition at 4.5–15.5°C. A temperature of 30°C was unfavorable for oviposition.The maximum number (1022 eggs per female) and percent (90%) of viable eggs occurred at 23°C, indicating that an intermediate temperature was optimal for fertilization. Egg hatchability at 4.5–15.5°C was reduced to 36% because 4.5° apparently disrupted sperm activity and because sperm were depleted in late oviposition. Egg hatchability at 10°C also was reduced (32 % ). Egg hatchability at 30°C was reduced to 0 after 4 weeks. Females which had been at 30°C laid viable eggs when they were remated after 8 weeks and held at 23°C.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.166

出版商:Oxford University Press    

年代:1972

数据来源: OUP

摘要:

A predaceous mite,Typhlodromus occidentalisNesbitt (Acarina: Phytoseiidae), was incapable of maintaining population densities of the twospotted spider mite,Tetranychus urticaeKoch, and McDaniel spider mite,T. mcdanieliMcGregor, beneath levels that produced foliage injury on apples.T. occidentaliswas an effective predator early in the season, but it was unable to maintain itself in sufficient numbers during early summer to prevent strong resurgences of twospotted spider and McDaniel spider mites during –September.By employing selective pesticides in commercial orchards, predatory mites can be maintained and can exert effective late-season control of tetranychid spider mites during August–October. One or more summer applications of selective acaricides which result in a more favorable predator:prey ratio is required to insure effective late-season predation byT. occidentalis.The cyclical nature of the predator:prey relationship may be due to lack of an alternate prey species such as the apple rust mite,Aculus schlechtendali(Nalepa), which is virtually absent in commercial orchards. Attempts to establish the apple rust mite as an alternate prey forT. occidentalisby deleting fungicidal applications for 3 years in 1 orchard were unsuccessful.

ISSN:1754-5692    

DOI:10.1093/ee/1.2.169

出版商:Oxford University Press    

年代:1972

数据来源: OUP