摘要:

Nectar characteristics of six onion (Allium cepaL.) cultivars were examined to assess the potential for preferential foraging by honey bees (Apis melliferaL.). Mean nectar amounts for six cultivars ranged from 0.54 to 0.84 μl per floret per day. Onion cultivars differ in flowering potential, with cultivars varying from 176 to 359 flowers per umbel and 32 to 74 umbels per 30 onion plants. All cultivars examined contained highly concentrated nectar with total dissolved solids ranging from 52 to 65%. Onion nectar was analyzed by gas chromatography to determine qualitative sugar differences among onion cultivars. All cultivars were hexose-dominant, having sucrose ranges from 4.0 to 14.4% and nearly equal amounts of fructose and glucose. There were significant differences in sugar content between the onion cultivars. Nectar composition and honey bee visitation among the six test cultivars were compared. It was determined that honey bees foraged preferentially on some of the onion cultivars.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.327

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Pollen analysis from nest provisions of two populations ofOsmia lignaria propinquaCresson from the same valley over a 2-yr period showed a seasonal pattern beginning with willow,Salixspp. (Salicaceae), and progressing to bitter brush,Purshia tridentata(Rosaceae). Population I used twice as many pollen species but had similar niche breadths and constancy measures to Population II. There was a yearly difference in the percentage of the dominant pollens collected. The percentage of cells with one pollen showed between year, population, and season differences. There were no differences in the populations' nesting successor offspring production. The foraging differences apparently resulted from the proximity of the dominant pollens,SalixandPurshia, to the nest sites.Salixwas a minimum of 600 m (one way) from Population I, but only 300 m from Population II.Purshiawas within 200m of both populations. The increased distance traveled by Population I bees allowed foraging on other pollen sources:Camassia(Liliaceae),Ceanothus(Rhamnaceae),Delphinium(Ranunculaceae),Phacelia(Hydrophyllaceae), andPotentilla(Rosaceae). These pollen species were available within 200 m but were rarely used by Population II. Bees were using as dominant pollen sources cornucopian species in the form of shrubs or small trees having showy floral displays of flowers with exposed, erect anthers extending beyond the petals.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.332

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Preimaginal development rates (egg, larval, pupal, and egg to adult) for the strawberry leafroller,Ancylis comptana(Froelich), were determined at six constant temperatures: 14, 18, 22, 26, 30, and 34°C (±2°, 16:8 [L:D]). Total development was fastest at 30° (22.3 ± 0.2 d) and 26°C (28.1 ± 0.3 d); 108.5 ± 9.6 d were required for total development at 14°C. Survival was>75% between 18 and 30°C, but decreased to 31% at 14 and 34°C. Based on a linear model of the temperature–developmental rate relationship,Kandtvalues were 78 DD (degree-days) above 10.3° for eggs, 254 DD above 9.7° for larvae, 100 DD above 10.9° for pupae, and 431 DD above 10.2°C for total preimaginal development. A four-parameter biophysical model of the temperature–development relationship indicated that high temperature inhibition occurred from 29 to 33°C for the preimaginallife stages. Field development of second- and third-generation egg and larval stages was predicted within three calendar days. Management of the strawberry leafroller is greatly facilitated by predicting egg hatch to synchronize control measures with the first instars, which do not exhibit leaf-rolling behavior.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.339

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

The seasonal abundance and phenology of the borersDiatraea lineolata(Walker),D. saccharalis(F.), andEoreuma loftini(Dyar) were investigated on corn in northern Tamaulipas, Mexico, from 1985 to 1988.D. lineolatawas the dominant species throughout the study. The presence ofE. loftiniwas practically limited to the fall seasons, andD. saccharaliswasmostcommon during the fall of 1985. Positive interspecific associations between borer species were detected, particularly during the fall, when densities were highest. Two borer generations were detected within each corn growing season (spring or fall) for all borer species; the first generation was initially detected at middle to late whorl stage, whereas the second generation normally occurred after tasseling. All species overwintered as mature larvae in dry cornstalks, withD. lineolataalso expressing summer diapause. Plant maturation was the major factor responsible for diapause induction ofD. lineolataregardless of time of year. A minimal accumulation of heat units and contact moisture was required forD. linealatalarvae to terminate diapause. The relationship of these studies to those reported for the same species in the tropics or other species elsewhere is discussed.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.345

出版商:Oxford University Press    

年代:1990

数据来源: OUP

ISSN:1754-5692    

DOI:10.1093/ee/19.2.346

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Distribution of pear psylla,Cacopsylla pyricola(Foerster), eggs on dormant and developing pear budwood was quantified for field and laboratory material. Most eggs were deposited in the grooves just beneath buds, particularly beneath the terminal bud. Preference changed seasonally, and subterminal buds became increasingly preferred as shoots became more phenologically advanced. On the more advanced shoots, psylla laid eggs extensively on newly flushed tissue. Egg survival was affected by location on the shoot, with eggs deposited directly on buds having higher rates of mortality than those deposited adjacent to buds or in lenticels (30–50% versus 18–25% mortality). Development rates of eggs were not noticeably affected by location of eggs on shoots. Data weakly suggest that eggs deposited at the terminal and first subterminal bud were first to hatch in the field. In laboratory tests oviposition rates of similarly aged psylla increased linearly with phenological age of budwood. A conditioning experiment provided no evidence that previous contact with leaf tissue induced low rates of oviposition on dormant budwood (compared with foliage) in no-choice tests. Oviposition rates were about two times higher on foliage of forced shoots than on dormant budwood regardless of previous exposure. However, psylla conditioned on foliage had significantly lower rates of oviposition (on either host tissue) than psylla conditioned on dormant budwood. These results are interpreted as evidence that psylla “waif” for phenologically more advanced shoots before reproductive activity is fully engaged.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.357

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

The seasonal occurrence ofPhyllonorycter elmaellaDoganlar&Mutuura, a tentiform leafminer, and its parasitoid,Pnigalio flavipes(Ashmead), in insecticide-free blocks located in commercial apple orchards was determined.P. elmaellahad three complete generations each year; population densities increased in each generation.P. elmaellasap feeders (first to third instars) were “abnormally” abundant in the blocks at the end of each season, possibly because of a delay in their development.P. flavipeshad at least the same number of generations asP. elmaella. Parasitoid activity decreased as the season progressed. Phenology data showed adultP. flavipesemerged almost concurrently with adultP. elmaelladuring the spring and summer generations, 2–3 wk before tissue feeders (fourth and fifth instars), were present in the orchard. This emergence pattern may be caused by a reproductive advantage for femaleP. flavipesto feed on sap feeders before oviposition. The number of individuals ofP. elmaellathat are able to overwinter successfully, rather than the seasonal levels of parasitism, seems to determine the leafminer's year-to-year population dynamics. However, parasitoid activity reduced the leafminer's intraseasonal population increase and kept its densities below treatment threshold levels in all orchard blocks examined.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.362

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Populations of the gypsy moth (Lymantria dispar(L.)) have been monitored in Michigan since 1985 using a permanent statewide grid of more than 2,000 pheromone traps. Trap catch data were analyzed using a computerized Geographic Information System (GIS). Using trap catch data from 1985 to 1987, a regression model (R2= 0.79) was developed to predict adult male moth catch for 1987 using three risk levels of gypsy moth population densities (low, medium, and high). Trap catch data and data on defoliation were combined in the GIS, demonstrating that adult male moth catch can be a good indicator of potential defoliation in the following year. The regression model was then used to predict low, medium, and high risk areas for moth populations for the next year.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.370

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Taylor's power law and Iwao's patchiness regression were used to analyze spatial distributions of broad mite,Polyphagotarsonemus latus(Banks), and citrus rust mite,Phyllocoptruta oleivora(Ashmead), on lime trees during winter, spring, summer, and fall between 1985 and 1987. Taylor's power law generally provided a better description of variance-mean relationships for both species than did Iwao's patchiness regression. Both species exhibited aggregated patterns of spatial distribution, but patterns of distribution differed among species. Sample size requirements for fixed levels of precision were determined by using estimated variance-mean relationships obtained from Taylor's power law regressions.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.378

出版商:Oxford University Press    

年代:1990

数据来源: OUP

摘要:

Prepupae of the Mediterranean fruit fly,Ceratitis capitata(Wiedemann), exhibited a significant mortality response under field conditions when exposed to concentrations of 5,000, 1,500,500, and 150 infective juveniles/em2of the insect parasitic nematode,Steinernema feltiaeFilipjev (Mexican strain). Additionally, concurrent field exposures of mature larvae (500 nematodes/em2) yielded significantly higher mortalities in the soil than in a vermiculite overlay. Fly mortality responses to nematodes produced in vivo or in vitro were not significantly different at the median exposure concentration. The estimated LCO50response of 38 nematodes/em2soil surface area indicates that these nematodes may offer a nontoxic alternative to soil treatments for Mediterranean fruit fly control programs.

ISSN:1754-5692    

DOI:10.1093/ee/19.2.383

出版商:Oxford University Press    

年代:1990

数据来源: OUP