Root Aphid Research Articles

Cytogenetic investigations on the holocentric chromosomes ofTetraneurella akinire(Sasaki) (Homoptera, Pemphigidae)

SUMMARYThe karyotype of the root aphid Tetraneurella akinire was analysed by means of C, G, and NOR banding. The overall base pair distribution was investigated after CMA3 and DAPI fluorochrome staining. Both C and G treatments revealed a well defined banding pattern on the X and Al chromosomes. C-bands showed a marked polymorphism in both size and number, even within the same individual. NOR banding produced a precipitation of silver on one telomere of the X chromosome, which also showed bright fluorescence after CMA3 staining. Treatment with DAPI uniformly stained all chromosomes. Neither CMA3 nor DAPI showed bright fluorescence overlapping the C-positive bands. It can be concluded that T. akinire chromosomes present a cluster of GC-rich DNA sequences located on one telomere of the X chromosome, whereas the AT- sequences are regularly arranged along the chromosome axes and not grouped into well defined clusters.

Evaluation of Liquid Carbofuran as a Rescue Treatment for Corn Root Aphids, 1993

Abstract Field corn was planted on 10 May near Rockford, IA, in a field that was corn the previous year and a grass-alfalfa mixture 4 yr before that. No soil insecticide was applied at planting. The field was rotary hoed 3 times between the time of corn emergence and 22 Jun. Pretreatment counts were taken on 22 Jun. The plant population was highly variable and ranged from 0 to 17,000 plants per acre based on 1/1,000 acre counts. Plants were in the V2-V4 stages of growth. Fifteen randomly-selected plants were pulled from the soil and roots were examined for colonies of aphids. All 15 plants were infested with corn root aphids. Ant mounds of the symbiotic cornfield ant, Lasius alienus (Foerster), were abundant around the plants but densities were not determined. Plots 50 ft long were marked with flags and inside these plots 1/1,000 acre (17.4 ft) were staked off for the section of row to be evaluated. Live plant counts were taken in the 1 /1,000 acre plots prior to treatment. Treatments consisted of an untreated check and a rescue application of 1.0 qt of Furadan 4F (1.0 lb [AI]/acre) broadcast in 10.0 gal of water with a tractor-mounted sprayer. Treatments were replicated 6 times in a RCBD. The Furadan 4F was not cultivated into the soil. Approximately 0.2 inches of rain fell on the field 2 DAT and a total of 3.2 inches occurred between the treatment date on 22 Jun and the evaluation date on 7 Jul. Plots were evaluated 15 DAT. Live plant counts were taken within the staked 1/1,000 acre plots. Five plants, consisting of every 2nd or 3rd plant (depending on plant population), in each plot were pulled from the soil and examined for colonies of corn root aphids.

Electronically monitored feeding behaviour of the lettuce root aphid (Pemphigus bursarius) on resistant and susceptible lettuce varieties

AbstractFeeding behaviour of the lettuce root aphid Pemphigus bursarius was monitored electronically on six lettuce varieties. Aphids, monitored for a minimum of 5 h on lettuce roots, performed recognizable feeding behaviour on the susceptible varieties, Webbs Wonderful and Borough Wonder including non probing, pattern A start of new penetration, C (stylet pathway activities) sometimes including clear B‐waves (salivary sheath secretions), potential drops (intracellular penetrations), intracellular E (phloem ingestion) distinguishing E1 and E2 (Tjallingii, 1990) and occasionally xylem ingestion. Although aphid probing was recorded on the resistant varieties Lakeland and Grand Rapids continued penetration to the phloem elements was deterred and the time spent ingesting phloem was short. Aphids rarely probed the resistant varieties Avoncrisp and Avondefiance and all attempted penetrations quickly terminated.

Karyotype analysis and DNA content in two species of root aphids

SUMMARYIn this paper we describe the karyotypes of two aphid species, Tetraneurella akinire and Anoecia nemoralis, found on the roots of Graminacee. Karyotype analysis in T. akinire have shown variations in chromosome number which are discussed in relation to the evolution of aphid karyotypes. Moreover, we estimated the DNA content in somatic cells of both species. Since emission values observed in mitotic plates of T. akinire with 14-15-16 chromosomes were completely overlapping, we can conclude that these karyotype variations are solely due to chromosome fragmentation.

The potential of entomopathogenic fungi to control the lettuce root aphid,pemphigus bursarius

The lettuce root aphid,Pemphigus bursarius, is a commercially important pest of lettuce and occupies a niche amenable to the action of entomopathogenic fungi. As the first stage of a biological control programme, a bioassay was developed against adult apterousP. bursarius. An isolate ofMetarhizium flavoviride was pathogenic toP. bursarius and sporulated abundantly upon aphid cadavers. However, two isolates ofVerticillium lecanii, pathogenic against glasshouse whitefly and aphids, were only weakly pathogenic toP. bursarius.

The use of polyacrylamide gradient gel electrophoresis to identify variation in isozymes as markers for Lactuca species and resistance to the lettuce root aphid Pemphigus bursarius

This paper describes simple, routine polyacrylamide gradient gel electrophoresis of allozyme patterns surveyed in wild populations of four Lactuca species, obtained from the Wellesbourne Vegetable Gene Bank. Using multivariate statistical techniques, four allozyme bands were identified, which distinguished the four species, and an additional two bands, which were related to the resistance of Lactuca species to the lettuce root aphid.

Chemical Control of PPGA, 1988:

Abstract Cabbage was planted in Hidalgo fine sandy loam soil on 13 Oct 1987 at Rio Farms in Monte Alto, Tex. Row culture was 2 rows 10 inches apart on 40-inch beds. Plants within a row were thinned to a 12-inch spacing on 30 Oct. There were 6 treatments arranged in a randomized complete block experimental design and replicated 4 times. Plot size was 4 beds, 70 ft long with 10 ft alleys separating replications. The crop was irrigated as needed to avoid water stress. Insecticides were applied when plants were at the 5-leaf stage on 4 Nov. Either a soil application (sidedress) made in combination with a liquid fertilizer (32-0-0) or a foliar application was used. A commercial liquid fertilizer applicator equipped with 3 shanks per bed and calibrated to discharge 25 gal/acre delivered the sidedress treatments 1-3 inches below the soil surface. Outside shanks were positioned 3-6 inches from the crop plants. Soil temperature at the time of application was 26°C. Foliar applications consisted of a selective systemic aphicide applied using a tractor-mounted CO2-powered sprayer fitted with a single-cone nozzle/bed and calibrated to deliver 20 gal/acre on a 20-inch band. The adjuvant Triton AG-98 Ag Emulsifler (0.125% vol/vol) was applied with the foliar sprays. Root aphid density was estimated using a simple flotation technique; roots from 5 randomly selected plants were immersed in a calcium chloride solution (1 tablespoon CaCl in 1 gal water), and insects floating to the surface were counted. Sampling commenced 2 wk after insecticide applications and continued at 2-wk intervals until harvest. Three 5-plant samples were taken from each plot. Yields were determined by hand-harvesting heads of commercially acceptable size in a 15-ft area in one bed near the center of each plot. Plots were harvested 4 times, and yield data were combined for each successive harvest to provide cumulative totals. Following the final harvest of marketable heads on 29 Feb, all remaining heads from the harvest area were cut. Yield data from that harvest were combined with total marketable yield to produce total yield values. All data were analyzed using ANOVA, and means were separated using LSD.

Chemical Control of Cabbage Root Aphids 1987

Abstract Cabbage was planted in Hidalgo fine sandy loam soil on 11 Nov 1986 on the Agricultural Research Farm of Rio Farms in Monte Alto, Tex. Row culture was double-row with 40-inch spacing between beds. Plants were thinned to a 12- inch spacing on 12 Dec. The experiment was arranged as a randomized complete block with 4 treatments and 4 replications. Plots consisted of 2 adjacent beds 70 ft long; 10-ft alleys separated replications, insecticides were applied in a liquid fertilizer (N-32) solution and were injected as a side-dressing on 8 Jan 1987. A commercial liquid fertilizer applicator equipped with 3 shanks per bed and calibrated to discharge 25 gal/acre delivered the treatment solutions ca. 4 inches below the soil surface. Soil temp was 20°C. Root aphid population density was estimated using a simple flotation technique. Roots from 3 randomly selected plants were washed in a CaCl solution (1 tablespoon CaCl/gal water), and insects floating to the surface were counted. Surveys were made pretreatment on 8 Jan and at 2 and 5 weeks, posttreatment on 23 Jan and 13 Feb. Two 3-plant samples were taken randomly per plot. Yields were determined by hand-harvesting both beds in a 15-ft section near the center of each plot. Only cabbage heads of commercially acceptable size were harvested during each of 3 harvests; thus, weight per head was consistant among treatments. Following the final harvest of marketable heads, all cabbage from the harvest area was cut; these yield data were combined with total marketable yield to produce total yield values. All data were analyzed by ANOVA, and means were separated by LSD.

Cabbage Root Aphid Control 1986

Abstract 'Sanibel' variety cabbage was planted 7 Oct into double-row beds with 40-inch centers at the Hoblitzelle Research and Demonstration Farm, Mercedes, Tex. Soil type was an Hidalgo sandy clay loam. Plants were thinned to a 6-inch spacing on 1 Nov, and 60 lb N-32 fertilizer was side-dressed on 3 Dec. Two separate experiments were conducted, one to evaluate efficacy of foliar-applied insecticides, and one to evaluate side-dressed insecticides for control of poplar petiole gall aphids (cabbage root aphids). Experimental design for both tests was a randomized complete block with 4 replications. The plots measured 2 beds by 30 ft (foliar test) or 4 beds by 30 ft (side-dress test) with a buffer row between plots. Side-dress treatments were applied on 3 Dec, and foliar sprays were begun 24 Dec. The RH-7988-treated plot received 1 foliar application, the other 2 insecticides were sprayed twice at a 7-day interval. Soil injections were applied with a liquid fertilizer applicator, and foliar sprays were discharged through a COzpowered, backpack sprayer calibrated to spray 10 gal/acre (30 psi, 4 flat-fan nozzles per plot). Efficacy was evaluated by removing the roots of 4 plants from each plot and washing them in 1 gal of water containing 1 tablespoon of CaCl. Dislodged aphids were counted as they floated to the surface of the water. Cabbage heads were harvested on 13 ft, 2 inches of row per plot to determine yield. Data were analyzed for treatment differences with ANOVA, and means were separated with Duncan's New Multiple Range Test.

A Simple Rearing System for Cereal Aphids, Especially Suited to Transmission Studies With Barley Yellow Dwarf Virus.

A simple and versatile system is described for rearing cereal aphids. The rearing unit consists of a disposable 35 ml polystyrene cup, with cardboard lid, which contains a young cereal seedling growing on a cottonwool ball saturated with nutrient solution. The units have been used successfully for maintaining virus-free colonies of aphids, conducting transmission tests for barley yellow dwarf viruses with several species of aphids, assessing the infectivity of aphids (alatae and apterae) collected in the field, and for biological investigations of root aphids.

Intensity of radicle fluorescence as related to the resistance of seedlings of lettuce to the lettuce root aphid and carrot to the carrot fly

SUMMARYA technique is described which indicates by u.v. fluorescence the concentration of caffeoylquinic, chlorogenic and isochlorogenic acids in roots of germinating lettuce and carrot. The surface fluorescence of radicles from lettuce root aphid (Pemphigus bursarius) resistant seedlings was more intense than for susceptible seedlings, attributable to the higher concentration of isochlorogenic acid. In contrast, radicles of carrot seedlings resistant to carrot fly (Psila rosae) were less fluorescent than susceptible seedlings, corresponding to the lower concentration of chlorogenic acid in resistant seedlings. The technique is non‐destructive and has been developed to distinguish between cultivars or breeding lines potentially resistant to these insect pests.

Corn Root Aphid-Nematode Control, 1980

Abstract Experiments were conducted in Phelps County, NE, to evaluate 3 insecticides for reducing corn root aphids and/or nematode damage to corn. Plots were 2 rows (spaced 0.9 m), 10.7 m long arranged in a Latin Square design Experiment 1 was located in an area of the field that had severe stand reduction in 1979. Experiment 2 was in an area that did not have severe stand reduction in 1979. The granular insecticide/nematicides were applied after planting but before corn was emerged with a Noble metering device mounted on a manually operated planter press wheel to give an 18-cm band over the planted furrow. Pretreatment and posttreatment nematode soil samples were taken with a 2.5 × 20-cm soil probe. Corn root aphids are transported from plant to plant by ants (Lasius neoniger Emery). To prevent disrupting the experiment by digging plants and counting aphids, insect control was based on number of active anthills/row. Yields were determined by hand harvest.

Phenolic acids associated with the resistance of lettuce cultivars to the lettuce root aphid

SUMMARYPhenolic acids, particularly caffeoylquinic acids, in lettuce root extracts were analysed by high pressure liquid chromatography (hplc), gas liquid chromatography (glc) and ultra‐violet (uv) absorbance to seek a relationship with the resistance of certain lettuce cultivars to lettuce root aphid, Pemphigus bursarius. Although consistent results were obtained by each method, glc estimates of isochlorogenic acid tended to be low and uv estimates high. Hplc results were intermediate and since it was the easiest technique to perform routinely it was preferred.Isochlorogenic acid was the only caffeoylquinic acid detected in quantity and there were greater concentrations in resistant than in susceptible cultivars. Phenylalanine‐ammonia lyase (PAL), the first enzyme in the phenyl propanoid pathway, is more active in resistant cultivars. Although these cultivars also had a greater tendency to browning when damaged, it was not due to greater polyphenol oxidase activity but probably to the presence of more isochlorogenic acid substrate.The results were consistent with an association between isochlorogenic acid concentration, PAL activity and resistance to P. bursarius.

Structure and Diversity of Ant Communities in Successive Coastal Dune Valleys

SUMMARY (1) The composition, density and diversity of ant communities, and the potential level of resources supporting the ant communities were compared in three successive dune valleys on the Dutch Wadden island Schiermonnikoog; the three dune valleys 'Strandvlakte' (SV), 'Kobbeduinen' (KBD) and 'Kooiduinen' (KID) represent a pioneer and two advanced stages in primary and secondary succession, respectively. (2) The number of ant species increased from four in Strandvlakte to eleven in Kobbeduinen and eighteen in Kooiduinen. (3) Ant species diversity was positively related to structural diversity of soil and vegetation; a negative relationship was found between ant species diversity and the abundance of the pioneering ant Lasius niger. (4) Rank-abundance curves of ant species in Kobbeduinen and Kooiduinen approximately agreed with lognormal distributions, although a tendency was observed for ant species in Kooiduinen to converge to a broken stick distribution. (5) Microhabitat niche breadth of ant species in the advanced communities Kobbeduinen and Kooiduinen was found to be positively correlated with worker density; this was particularly true in Kobbeduinen, where the highest overall densities of ant workers, root aphids and potential prey (except soil Collembola) were found. (6) In the most diverse but moderately dense Kooiduinen community, only part of the ant species had niche breadths, which were in the same degree proportional to worker density as in Kobbeduinen.

Effects of the Subterranean Aphid [Geoica utricularia (Passerini)] on Forage Yield and Quality of Sand Lovegrass

In 1977 at Mead, Nebraska, replicated plots in two sand lovegrass (Eragroslis trichodes) nurseries naturally infested with root aphids (Geoica ufricularia Passerini) were treated with soil drenches of carbofuran and disulfoton (2.24 kg/ha AI) toquantify the economic importance of these aphids. In a nursery of ‘Nebraska 27’ sand lovegrass, the carbofurnn and disulfoton treated plots produced 45% and 16% more forage, respectively, than the untreated plots. In a nursery of another Nebraska experimental strain, the treated plots produced more forage than the untreated plots but the differences were not significant. There were no differences among treated and control plots in either nursery for dry matter, protein, and in vitro dry matter digestibility percentages.

An association between resistance to root aphid (Pemphigus bursarius L.) and downy mildew (Bremia lactucae Regel) in lettuce

Many lettuce cultivars (Lactuca sativa L.) with high resistance to lettuce root aphid (Pemphigus bursarius L.) also carried the gene Dm-6 for specific resistance to downy mildew (Bremia lactucae Regel). This suggests the possibility of linkage between this gene and root aphid resistance. The origin of this association is discussed.

A British Record of the Rice Root Aphid.

A British Record of the Rice Root Aphid.

Control of the Lettuce Root Aphid in Massachusetts

Journal Article Control of the Lettuce Root Aphid in Massachusetts Get access A. G. Gentile, A. G. Gentile Search for other works by this author on: Oxford Academic PubMed Google Scholar A. W. Vaughan A. W. Vaughan Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Economic Entomology, Volume 67, Issue 4, 1 August 1974, Page 556, https://doi.org/10.1093/jee/67.4.556 Published: 01 August 1974

Lettace Root Aphid Control by Means of Plant Resistance

SUMMARYAt Wellesbourne, Warwick, in 1968, not all plants of the lettuce cv. Webb's Wonderful protected against lettuce root aphid. Pemphigus bursarius (L.), by diazinon pre‐sowing treatments remained uncolonized throughout a relatively light aphid attack but no colonization of unprotected plants of cv. Avoncrisp occurred. In a second experiment in 1972, in which plants were untreated and exposed to an intense aphid attack, the lettuce cvs. Mildura, Borough Wonder, Webb's Wonderful, Avoncrisp and Avondefiance all attracted similar large numbers of winged root aphid rnigrants. No root colonies formed on the resistant CVS. Avoncrisp and Avondefiance. All plants of the other cultivars became severely damaged and most were killed.

Study on inheritance of resistance to root aphid, Pemphigus bursarius, in lettuce

SUMMARYThe inheritance of resistance to lettuce root aphid, Pemphigus bursarius, was studied in lettuce using the Wellesbourne cultivars Avondefiance and Avoncrisp as resistant parents and Borough Wonder and Webb's Wonderful as aphid‐susceptible parents. All four cultivars were crossed in all possible combinations including reciprocals and the response to root aphid of plants in the P1F1F2 and BC generations was assessed using apterae of P. bursarius from the lettuce cv. Iceberg. Resistance to attack was clearly inherited and the parents appeared to be homozygous for their resistance or susceptibility. In the F1 generation, however, in all crosses between resistant and susceptible parents, segregation into susceptible, resistant and some slightly less resistant plants occurred. This and the highly significant differences in segregation between pairs of reciprocal crosses in the F1 and other generations indicate that the inheritance of resistance to root aphid is controlled by extra‐nuclear factors. Modifying genes might also be involved but there appears to be no linkage of root aphid resistance with resistance to downy mildew, for which the Wellesbourne lettuces were bred.