PATTERNS OF FEEDING INJURY TO POTATO BY THE POTATO FLEA BEETLE (COLEOPTERA: CHRYSOMELIDAE) IN MANITOBA

1996 ◽  
Vol 128 (5) ◽  
pp. 791-804
Author(s):  
S.F. Pernal ◽  
D.G. Senanayake ◽  
N.J. Holliday
Keyword(s):  
Vertical Distribution ◽  
Repeated Measures ◽  
Seasonal Pattern ◽  
Flea Beetle ◽  
Control Measures ◽  
Potato Plants ◽  
Flea Beetles ◽  
The Mean ◽  
The Vertical Distribution ◽  
Potato Flea Beetle

AbstractThe amount and distribution of foliar feeding injury by adult potato flea beetles, Epitrix cucumeris (Harris), were examined on individually caged potato plants grown in field plots in Manitoba. Plants were either maintained as uninfested controls, or were exposed throughout the growing season to different insect densities that mimicked the natural seasonal pattern of infestation. In 1984, a trial was conducted using cv. ‘Norland’ exposed to four different densities of potato flea beetles. In 1989 and 1990, cv. ‘Russet Burbank’ was exposed to potato flea beetles, and in some treatments, plants were exposed to early summer infestations of Colorado potato beetles, Leptinotarsa decemlineata (Say). In each trial, during the late summer period of high potato flea beetle density, the amount and distribution of flea beetle feeding injury were assessed at weekly intervals. Counts of feeding punctures in single leaflets were made from leaves in the upper, middle, and lower third of each caged plant, and these data were subjected to repeated measures analysis of variance. In each of the 3 years, increasing the number of flea beetles increased the mean number of feeding punctures per leaflet in an approximately linear fashion; however, the number of punctures per beetle varied between cultivars and years. In 1984 and 1990, the number of feeding punctures per leaflet was least in the upper third of the plants, and greater in the lower, or middle and lower, third of plants. However, in 1989, the vertical distribution of feeding punctures was relatively even. Previous feeding by Colorado potato beetles increased the mean number of flea beetle feeding punctures per leaflet and changed the vertical distribution of feeding punctures. Rainfall and temperature were correlated with patterns of flea beetle injury; injury was concentrated on lower leaflets during weeks of greater rainfall, and upper leaflets were injured most during weeks with higher average temperatures. It is concluded that flea beetles exhibit preferences for feeding in specific portions of potato plants, and that these preferences change in response to previous defoliation and are influenced by meteorological conditions. Consequently, counting feeding punctures would not be a reliable method of assessing whether control measures for potato flea beetles are justified.

THE SPATIAL DISTRIBUTION OF SPRING AND SUMMER POPULATIONS OF ADULT POTATO FLEA BEETLES, EPITRIX CUCUMERIS (HARRIS) (COLEOPTERA: CHRYSOMELIDAE), ON SMALL PLOTS OF POTATOES

1989 ◽  
Vol 121 (12) ◽  
pp. 1097-1101 ◽  
Author(s):  
Jeff G. Stewart ◽  
Leith S. Thompson
Keyword(s):  
Spatial Distribution ◽  
Flea Beetle ◽  
Regression Equations ◽  
Flea Beetles ◽  
Mean Crowding ◽  
The Mean ◽  
Potato Flea Beetle

AbstractThe spatial distribution of spring and summer populations of the potato flea beetle, Epitrix cucumeris (Harris) (Coleoptera: Chrysomelidae), on potatoes (“Superior” variety) was studied in 1987 and 1988. Slopes of the regression of mean crowding on the mean number of adults per plant were not significantly different from 1.0 except for summer populations in 1988. The y-intercepts of these regression equations were not significantly different from 0, suggesting that adults of the potato flea beetle are not aggregated. The ratios of mean crowding to mean number of adults per plant were 0.81 for spring populations and 1.02 for summer populations, also indicating that the populations were not highly aggregated. With a level of precision of 0.25, 10 samples per plot were appropriate when more than 2.8 adults per plant were present in the spring and when more than 7.2 adults per plant were present in the summer.

scholarly journals Continuous borehole optical televiewing reveals variable englacial debris concentrations at Khumbu Glacier, Nepal

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Katie E. Miles ◽  
Bryn Hubbard ◽  
Evan S. Miles ◽  
Duncan J. Quincey ◽  
Ann V. Rowan ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Water Supply ◽  
Depth Profile ◽  
Variable Thickness ◽  
Surface Melting ◽  
High Mountain ◽  
Ablation Area ◽  
The Mean ◽  
Surface Melt ◽  
The Vertical Distribution

AbstractSurface melting of High Mountain Asian debris-covered glaciers shapes the seasonal water supply to millions of people. This melt is strongly influenced by the spatially variable thickness of the supraglacial debris layer, which is itself partially controlled by englacial debris concentration and melt-out. Here, we present measurements of deep englacial debris concentrations from debris-covered Khumbu Glacier, Nepal, based on four borehole optical televiewer logs, each up to 150 m long. The mean borehole englacial debris content is ≤ 0.7% by volume in the glacier’s mid-to-upper ablation area, and increases to 6.4% by volume near the terminus. These concentrations are higher than those reported for other valley glaciers, although those measurements relate to discrete samples while our approach yields a continuous depth profile. The vertical distribution of englacial debris increases with depth, but is also highly variable, which will complicate predictions of future rates of surface melt and debris exhumation at such glaciers.

scholarly journals On the spatial variability of the regional aerosol distribution as determined from ceilometers

2020 ◽  
Author(s):  
Matthias Wiegner ◽  
Alexander Geiß ◽  
Ina Mattis ◽  
Fred Meier ◽  
Thomas Ruhtz
Keyword(s):  
Vertical Distribution ◽  
Mixing Layer ◽  
Data Set ◽  
Integrated Backscatter ◽  
Aerosol Distribution ◽  
Mixing Layer Height ◽  
Aerosol Sources ◽  
The Mean ◽  
Two Parameters ◽  
The Vertical Distribution

Abstract. Measurements of the vertical distribution of aerosol particles are typically only available at selected sites leaving the question of their representativeness for urban and regional scales unanswered. As a contribution to solve this problem we have investigated ceilometer signals from two testbeds in Munich and Berlin, Germany. For each testbed measurements of 24 months from 6 ceilometers were available. This constitutes a unique data set, in particular as the same type of instruments are deployed and the same data evaluation schemes applied. Two parameters are discussed: the mixing layer height (MLH) as an indicator for the vertical distribution and the integrated backscatter as a proxy for the amount of aerosols in the mixing layer. The MLH was determined by the COBOLT algorithm, the integrated backscatter from the Klett (backward and forward) inversion scheme. It was found that the mean difference of the MLH at two sites within a testbed typically only varies by less than 50 m, slightly increasing with the distance of the corresponding sites. Almost 60 % of all intercomparisons agree within ±100 m. MLHs are typically correlated with R > 0.9 in particular for the Berlin-testbed. With respect to the integrated backscatter the correlation is in the range of 0.7 < R < 0.9. This is expected from the diversity of local aerosol sources within a given testbed. We conclude from our data that the MLH determined from a single ceilometer is applicable for a whole metropolitan area. However, the integrated backscatter of particles within the mixing layer exhibits a variability of 15–25 % suggesting that one ceilometer is not representative, especially if atmospheric processes shall be investigated.

Travelling disturbances in the ionosphere

1950 ◽  
Vol 202 (1069) ◽  
pp. 208-223 ◽  
Keyword(s):  
Seasonal Variation ◽  
Vertical Distribution ◽  
Sudden Change ◽  
Frequent Occurrence ◽  
Vertical Movements ◽  
Short Period ◽  
The Mean ◽  
The Vertical Distribution

Methods have been developed for the examination of the horizontal and vertical movements of short-period disturbances in the ionosphere. It has been found that quasi-periodic travelling disturbances with periods of from 10 to 60 min. are of frequent occurrence in the F region by day. They appear as temporary variations in the vertical distribution of ionization which show a horizontal progression and a vertical progression downwards. The horizontal directions of travel have a well-defined mean direction on most days. The mean direction shows a marked seasonal variation with a sudden change at each equinox. The horizontal rate of travel is usually between 5 and 10 km./min., and the rate of vertical progression downwards is approximately half the horizontal rate. The disturbances are considered to be variations of a compressional type in the atmosphere resulting in changes in the distribution of ionization.

DISSEMINATION OF HOWARDULA SP. NEMATODES BY ADULT TOBACCO FLEA BEETLES (COLEOPTERA: CHRYSOMELIDAE)

1977 ◽  
Vol 109 (9) ◽  
pp. 1283-1285 ◽  
Author(s):  
Kent D. Elsey
Keyword(s):  
Adult Male ◽  
Average Rate ◽  
Flea Beetle ◽  
Nematode Parasite ◽  
Free Living ◽  
Flea Beetles ◽  
The Mean

AbstractA Howardula sp. nematode parasite of the tobacco flea beetle, Epitrix hirtipennis (Melsheimer), was able to utilize the adult male to disseminate juveniles. At 27°C the mean total number of juveniles released per beetle was 369 for female beetles and 377 for males at an average rate of ca. 37 per day from both sexes. A cooler temperature retarded the onset of dissemination but did not affect the rate of release. Fifty-nine per cent of the free-living nematodes survived for 5–6 days, but none survived beyond 13 days. Seventy-nine per cent of the free-living nematodes were female.

Some factors affecting the respiration of intertidal Asterina gibbosa (Echinodermata: Asteroidea)

1987 ◽  
Vol 67 (4) ◽  
pp. 717-727 ◽  
Author(s):  
Christine T. Murphy ◽  
M. B. Jones
Keyword(s):  
Vertical Distribution ◽  
Neap Tide ◽  
High Water ◽  
Rocky Shores ◽  
Rock Pools ◽  
Factors Affecting ◽  
Upper Limits ◽  
The Mean ◽  
The Vertical Distribution ◽  
Inadequate Food Supply

In Britain, the cushion star Asterina gibbosa Pennant 1897 (Echinodermata, Asteroidea) is confined to the west coast, where it occurs on rocky shores, often sympatrically with the closely related Asterina phylactica Emson & Crump 1979 (Crump & Emson, 1983; Emson & Crump, 1984). The vertical distribution of A. gibbosa extends from about 100 m depth, into the intertidal; however, littoral cushion stars occupy rock pools and relatively damp habitats such as gulley walls, crevices, overhangs and the underside of boulders, generally on the lower shore (Emson, 1979). On shores with rock pools, cushion stars may extend their upper limits of vertical distribution but not beyond the mean high-water neap-tide level (Crump & Emson, 1978). Absence of A. gibbosa from higher shore levels has been related to intolerance to desiccation and high temperature, inadequate food supply, and complex behavioural responses to gravity and light (Crozier, 1935; Emson, 1979; Crump & Emson, 1983). Prior to the present study, it has not been possible to discuss the influence of respiratory requirements on the vertical distribution of this species.

RESISTANCE OF TRANSGENIC POTATOES TO ATTACK BY EPITRIX CUCUMERIS (COLEOPTERA: CHRYSOMELIDAE)

1999 ◽  
Vol 131 (4) ◽  
pp. 423-431 ◽  
Author(s):  
Jeff G. Stewart ◽  
Jennifer Feldman ◽  
Debby A. LeBlanc
Keyword(s):  
Transgenic Plants ◽  
Prince Edward Island ◽  
Flea Beetle ◽  
Transgenic Potato ◽  
Growth Stages ◽  
Potato Plants ◽  
Transgenic Potato Plants ◽  
Transgenic Potatoes ◽  
Choice Feeding ◽  
Potato Flea Beetle

AbstractPotato plants (Solanum tuberosum, cv. Russet Burbank) genetically altered to produce the CryIIIA protein from Bacillus thuringiensis var tenebrionis were tested for susceptibility to attack by the potato flea beetle, Epitrix cucumeris (Harris), on Prince Edward Island, Canada, from 1993 to 1996. Average weekly damage to the fourth terminal leaf of transgenic potato plants was 31% lower in 1993 and 20% lower in 1994 compared with nontransgenic plants. Transgenic plants had 29% fewer potato flea beetle adults when compared with nontransgenic plants in 1994, although no difference was detected between the two plant types in 1993. Recovery of potato flea beetle pupae in the soil was noticeably lower from transgenic plants expressing the CryIIIA protein in all parts of the plant (Construct No. RBBT02-10Y1) than from either the transgenic plants that expressed the CryIIIA protein primarily in the green foliage (Construct No. RBBT04-01) or the nontransgenic plants. Adult potato flea beetles, when given a choice between transgenic and nontransgenic leaf material, fed preferentially on nontransgenic material. In contrast, when adults were not given a choice, feeding damage was similar between treatments. These results suggest that the reason for reduced feeding on transgenic potato plants by the potato flea beetle is, at least in part, due to some toxicity of the plants to immature growth stages and a preference for adults to feed on nontransgenic material when it is available.

Submersible observations on the daytime vertical distribution of Aequorea ?forskalea off the west coast of southern Africa

2005 ◽  
Vol 85 (3) ◽  
pp. 519-522 ◽  
Author(s):  
Conrad Sparks ◽  
Andrew S. Brierley ◽  
Emmanuelle Buecher ◽  
Dave Boyer ◽  
Bjøern Axelsen ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Southern Africa ◽  
West Coast ◽  
Sea Surface ◽  
The West ◽  
Spatial Overlap ◽  
The Mean ◽  
The Vertical Distribution

The vertical distribution of the hydromedusa Aequorea ?forskalea was investigated using observations from the research submersible ‘Jago’ collected during 36 dives off the west coast of southern Africa during November 1997 and April 1999. The mean population depth of Aequorea ?forskalea deepened with increasing sea surface temperature. We suggest that this behaviour enables individuals to avoid offshore advection, to minimize spatial overlap with other large medusae and to maintain their position over the middle of the shelf.

Sign in / Sign up

Export Citation Format

Share Document