摘要:

A protozoan disease caused byNosemasp. was eliminated from a quarantine culture ofGaleruca rufaGermar by segregation of adults and cohorts of progeny, by sanitation, and by destruction of all cohorts containing the pathogen. A significant reduction in egg production by diseased, versus healthy, adults revealed the debilitating effect of the disease. A brief review of weed-feeding insects known to have protozoan diseases is presented.

ISSN:1754-5692    

DOI:10.1093/ee/10.2.143

出版商:Oxford University Press    

年代:1981

数据来源: OUP

摘要:

Newly hatched larvae ofAedes triseriatus(Say) collected from treeholes displayed a seasonally variable sex ratio. The initial spring hatches of overwintered eggs were predominantly males, and subsequent hatches produced progressively smaller proportions of male larvae until females were the dominant sex. Primary sex ratios of geographic strains ofA. triseriatusor progeny of male-predominant spring broods were not distorted. Ovitrap studies showed that females deposited equal numbers of male and female eggs throughout the year. Exposure to a hatching stimulus in the laboratory resulted in more rapid response by male embryos than females. Overwintered eggs in treeholes hatch in installments because hatching stimuli and/or conditioning factors are suboptimal, and the more ready hatching of males generates the seasonally characteristic sex ratios. Male and female embryos also show slight differences in photoperiodic response which do not contribute to seasonal distortion of sex ratio.

ISSN:1754-5692    

DOI:10.1093/ee/10.2.147

出版商:Oxford University Press    

年代:1981

数据来源: OUP

摘要:

Seventeen Kentucky bluegrass,Poa pratensisL., cultivars were evaluated for tolerance to feeding by adult hairy chinch bugs,Blissus leucopterus hirtusMontandon. Adults were confined on one month-old plants within a 10 cm diam × 20.3 cm high cylindrical plastic cage for 17–19 days. Cages were divided longitudinally so that 1/2 of the plants in each pot were infested. Tolerance was evaluated as differences between infested and uninfested plants for height of regrowth, dry weight, yield of clippings, root length and weight, plant survival, tillering, and % dry matter. Regrowth, yield of clippings, root length, and plant survival were significantly reduced and % dry matter significantly increased in almost all cases by adult feeding. Dry weight, root weight, and tillering of plants were not significantly changed by feeding. Significant differences were found in tolerance among Kentucky bluegrass cultivars. Differences in cultivar regrowth, yield, and % dry matter were the most useful criteria for measuring tolerance.

ISSN:1754-5692    

DOI:10.1093/ee/10.2.153

出版商:Oxford University Press    

年代:1981

数据来源: OUP

摘要:

Two tractor-mounted devices collected about 83,500 stilt bugs,Jalysus spinosus(Say) from ca. 25 ha of tobacco during the fall of 1972 and 1973. Due to rapid growth of microorganisms collected with the bugs, only 1% of the stilt bugs stored at 12.8°C survived 83 days. However, 19% of the stilt bugs stored in outside cages at ambient temperature survived 160 days.

ISSN:1754-5692    

DOI:10.1093/ee/10.2.158

出版商:Oxford University Press    

年代:1981

数据来源: OUP

摘要:

A trap is described for field testing scolytid pheromones that has several advantages including avoidance of sticky materials and less time spent evaluating treatments. The new trap was as effective as a conventional sticky screen trap in catching the pine engraver,Ips piniSay.

ISSN:1754-5692    

DOI:10.1093/ee/10.2.161

出版商:Oxford University Press    

年代:1981

数据来源: OUP

摘要:

The pheromone 3,13-Octadecadien-1-ol acetate (principally theZ,Zisomer), even at low density of sources, reduced captures of males and mating activity ofSynanthedon exitiosa(Say) moths in a test of disruption of mating communication. Data from 2 methods of evaluation, (1) male trapping and (2) virgin female mating observations, were parallel and confirmed the effectiveness of disruption.

ISSN:1754-5692    

DOI:10.1093/ee/10.2.164

出版商:Oxford University Press    

年代:1981

数据来源: OUP

摘要:

The effectiveness of the attractant blend,Z-5- andE-7-tetradecenyl acetates in a microgram ratio of 50:950 for adult males of army cutworm,Euxoa auxiliaris(Grote), was enhanced by the addition of trace quantities (0.13–2.5 εg or 0.013–0.25%) ofZ-7-tetradecenyl acetate, but the addition of 2% of this isomer reduced the trap catches.An alternate specific attractant, developed by field testing highly purified chemicals, consisted of a 3-component blend ofZ-5-,Z-7-, andZ-9-tetradecenyl acetates. In a microgram ratio of 100:1:10 on rubber septa, this attractant was effective in the field for at least 24 days. The trap catches. were reduced as the quantities of theZ-7- orZ-9-tetradecenyl acetates in this blend were increased to 8 and 33%, respectively. The 3-component attractants for the army cutworm were both strongly inhibited by less than 0.4%Z-5-dodecenyl acetate which is the main component of the redbacked cutworm pheromone.

ISSN:1754-5692    

DOI:10.1093/ee/10.2.167

出版商:Oxford University Press    

年代:1981

数据来源: OUP

摘要:

The citrus rust mite game (CRM GAME) is an interactive simulation algorithm for estimating citrus yield loss to the rust mite. Losses occur due to increased fruit drop and decreased fruit size of damaged (russetted) fruit. There is no single economic threshold of mites at which a pesticide should be applied. Instead, a range of damage thresholds can equal a spray cost depending upon crop value, timing of pest attack, timing of harvest and temperature. Mean percent surface damage of 5 to 20% equals the cost of a pesticide application depending upon the particular situation. Since the emphasis must be onpreventionof the loss, predictive capability of the pest population is implicit in the concept of economic thresholds for agricultural pests.

ISSN:1754-5692    

DOI:10.1093/ee/10.2.171

出版商:Oxford University Press    

年代:1981

数据来源: OUP

摘要:

Field developmental times, expressed in day-degrees above 12.6°C, were estimated for the larval and pupal (i.e., prepupal plus pupal) stages ofHellothis zea(Boddie) andH. virescens(F.) reared on cotton. Means for larvae, female pupae, and male pupae were 238.9, 205.9, and 229.8, respectively, forH. zea; and 225.2, 211.8, and 233.7, respectively, rorH. virescens. The interspecific difference in mean larval developmental times was significant. For both species, the variance of pupal developmental times was significantly larger for females than for males, and adult females began emerging well before the males. No significant interspecific differences in pupal developmental times occurred. Some implications of the results with regard to population dynamics studies and modeling are discussed.

ISSN:1754-5692    

DOI:10.1093/ee/10.2.177

出版商:Oxford University Press    

年代:1981

数据来源: OUP

摘要:

Citrus groves in Indian River County in Florida, irrigated by crown-flooding, have provided an extensive new habitat for the mosquitoAedes vexans(Meigen).Eggs are laid mainly under tree canopies at the crowns of citrus grove furrows and require inundation as a hatching stimulus. Normal rainfall provides insufficient water depth in the furrows to hatch many eggs, but crown-flood irrigation hatches large numbers. Therefore, irrigation during periods of drought stimulates mosquito production.

ISSN:1754-5692    

DOI:10.1093/ee/10.2.180

出版商:Oxford University Press    

年代:1981

数据来源: OUP