Aphid Counts Research Articles

Soil Treatments for Control of Aphids and Beetles, Test 4, 1977

Abstract ‘Russet Burbank’ potatoes were planted in furrows on April 20, 1977, in Ritzville silt loam soil at Yakima, Washington. Plots were 2 rows wide, 1.72 m, and 15.2 m long. Furrow applications of granular insecticides were made by dribbling the materials through a hand-operated, funnel-type applicator over still uncovered potato seed pieces; then the seed pieces were covered with soil. Sidedress applications were made June 3, when about 75% of the plants had emerged; these applications were made with a tranctor-mounted Gandy applicator in about 5-cm bands, 10 cm to each side of the plants and about the depth of the potato seed pieces. Topical applications were also made June 3 but with a hand-operated applicator in about 25-cm bands over the top of the emerging potato plants; then the granules were lightly incorporated into the soil with a Lilliston cultivator. Each treatment was replicated 3 times in a randomized complete block design. The crop was sprinkler irrigated: 38 cm of water was applied between May and September. Aphid counts were made from 20 compound potato leaves in June and from 15 such leaves in July. The percent of plants damaged by the Colorado potato beetle was recorded on July 7, 18, and August 19. The data were subjected to analysis with Duncan’s Multiple Range Test.

Green Peach Aphid Control, 1977

Abstract ‘U&I Hybrid 8’ sugarbeets were planted May 6, 1966, in Ritzville silt loam at Yakima, Washington, in plots 6 rows wide and 50 ft long. Each treatment was applied to 4 plots. The plants were irrigated with line sprinklers that provided 1/2 inch of water/h. In the tests with foliar spray, 40 gpa (60 psi) were applied July 6 with D2-13 TEEJET hollowcone nozzles mounted 11 inches apart on a rear-mounted boom sprayer fitted to a JD-420 tractor traveling at 2.75 mph. The boom height was adjusted to provide optimum coverage of the foliage as the plants grew. Ortho X-77 spreader was used with all materials. After 2 days and then each week for 3 weeks aphids were counted on 25 leaves from each plot. In the tests with systemics, granules were applied with a tractormounted Gandy applicator at planting time 4-6 inches deep and 2 inches to one side of the seeds. Aphid counts were delayed until a popu-lation developed. In the spray tests, Pirimor at 2 and 3 lb/acre was equal to the Thimet standard at 1 lb/acre (Table 1). In the systemic tests, both Bay Hox 3298 and Furadan were effective (Table 2). No phytotoxicity was observed in the tests.

Green Peach Aphid Control on Potatoes, 1977

Abstract Seed pieces were planted 4 inches apart in marl soil November 15, 1976. The plots were single rows, 30 ft long, planted on 3-f t centers. Treatments were applied January 6 and replicated 4 times in a completely random design. Applications were made by hand with a CO2-charged, 2½-gallon sprayer with a single nozzle. Apterous aphid counts were made 1 and 6 days posttreatment by randomly selecting 10 lower leaves per plot. The aphid population was smaller than usual when the treatments were made. Means were separated by Duncan’s Multiple Range Test.

Insect Control in Sweet Peppers, Delaware, 1977

Abstract Treatments were replicated 3 times, in 3-row, 40-ft-long plots in a randomized complete block design. Transplants were set out on May 20. Sprays were applied using a 2-gallon, CO2-pressurized sprayer at 35 psi in 1 gallon water per treatment (= 38 gal/acre). Granular materials were applied by hand with a small shaker. Furdan 10G granules were placed in a furrow ca. 2 inches deep and 5 inches out from plant on one side of the rows; Temik 15G granules were applied in a similar manner but to both sides of the rows. Ripe (= red) pepers were sampled for “worm” infestations on August 25 and commercial size reds and greens on September 20 from the middle row of each plot. Leaves were randomly sampled each week for green peach aphid counts.

Irish Potato, Control of Potato Infesting Aphids, 1976

Abstract Experiments A, B, C, D, E, and F were 7 × 6, 4 × 6, 6 × 6, 5 × 6, 7 × 6 , and 6 × 6 randomized complete block designs respectively and were conducted at Presque Isle, Maine on land that was sown to oats in 1975. The planting date was June 4, 1976 for all experiments. In each experiment the 9.1 m space between blocks and the 1.4 m space between columns and at the sides and ends of the experiments were sown to oats at planting. Each plot consisted of 4 rows of potatoes 0.9 m apart and 15.2 m long. The 57 g healthy seed pieces were hand planted 30.5 cm apart. Fertilization and hilling practices were normal for the area. Late blight control was effected by weekly foliar applications of Rohm & Haas M 45 (2242 g ai/ha July 10 through August 31, 1976). Soil applications of insecticides were made by hand with a plastic tube applying previously weighed amounts of insecticide into the furrow just prior to planting. Foliar insecticide treatments were made with a Slosser sprayer (14.1 kg/cm2 and 1.2kl/ha) in combination with the fungicide. Numbers of aphids (by species) were counted on a top, middle, and bottom leaf of 25 plants in the 2 middle rows of each plot. When date of count and application are the same, aphid counts were made prior to application of the insecticide. Analyses of variance were calculated following transformation of the raw data using log10,(x + 1)- Means of the total number of wingless aphids were compared using Duncan's new multiple range test and then reconverted as given in the Table. The soil was classified as Caribou Loam, pH 5.2. Rainfall for June, July, and August was 112, 140, and 174 percent of normal. Temperature for the same 3 months departed + 3.5°, + 1.0°, and 0.0°C from normal.

Aphid Control on Pecans, 1976

Abstract The experimental block was in an orchard of mature pecan trees spaces 47 ft x 47 ft (20 trees/acre). Two test trees were "seedlings", the remainder Schley variety. There were three to four single tree replicates per treatment. Application was with a Myers "Mity Mist" speed sprayer delivering 4.5 gallons per tree (5X). Heavy rains fell approximately three hrs after spraying. Treatment date was September 24. A pretreatment aphid count was taken on September 23 and a five day posttreatment count on September 29. The sample was from ten randomly selected compound leaves from each tree. Because of large initial differences between plots, analysis of variance was on the percent living after treatment ((post-treatment/pretreatment) × 100).

Tomato Miscellaneous Pests

Abstract Tomatoes were planted in the field from seed on May 12,1975 in 25 ft rows on 5 ft centers. Soil type was Ockley silt loam, 2 to 4% organic matter. Fifteen treatments including the check were arranged in a randomized block design, 1 row per treatment separated from the next treatment by an untreated row. Four replicates were used. Four applications were made at 10 day intervals beginning August 7 using a Back-pack mist blower (Vandermolen KWH 66), output of which was about 15 gallons per acre. Aphid counts were made by selected 10 leaves from each replicate and counting the aphids thereon. Numbers thereof were about equally divided between M.euphorbiae and M.persicae. Fruit damage by fruitworms and hornworms was assessed by examining from each replicate the first 100 fruit for characteristic feeding damage.

Tomato Miscellaneous Pests

Abstract Tomatoes were seeded in the field on May 12, 1975 in 25 ft rows on 5 ft centers. Dacamox, Di-Syston, Temik and UC 21865 were applied in a band over the row and incorporated; Furadan and Thimet were side-dressed along the row and incorporated. Twelve treatments of 4 replicates each were arranged in a randomized block design. Soil type was Ockley silt loam, 2 to 4% organic matter. Flea beetle feeding scars were counted on the leaves of 25 seedlings per replicate on June 5. On June 16 stand counts were made in on foot of row per replicate. Vigor of the young plants was evaluated on June 26 on a scale of 6 (most vigorous) to 0 (least vigorous), based on the size, color, and general appearance of the treatment replicates. Aphid counts were made on August 8 and August 22 to assess any long term value of the treatments. The crop was hand-picked on September 8 and weighed.

Green Peach Aphid Control, 1975

Abstract ‘U&l Hybrid 8’ sugarbeets were planted April 1, 1975, in Ritzville silt loam at Yakima, Washington, in plots six rows wide and 50 ft long. The plants were irrigated with sprinklers providing one-half inch of water/hr. Four plots were treated on July 22 with each material at 40 gpa (60 psi) through D2-13 “TEEJET” hollowcone nozzles mounted 11 inch apart on a rear-mounted boom sprayer fitted to a JD-420 tractor travelling at 2.75 mph. Ortho X-77 spreader was used with all materials. The boom height was adjusted to provide optimum coverage of the foliage as the plants grew. In addition to the experimental compounds, all beets were treated with MAG 6 at 3 lb/A on July 16 to reduce a powdery mildew infection. Three days and each week after treatment aphids were counted on 25 leaves from each plot. Treatments were applied May 30, July 7, and July 22, but because of the low and uneven population on sugarbeets there was no significant difference in the aphid counts until after the last treatment. For two weeks following the last treatment all treated plots had less aphid than check plots. On August 13, 20, and 27 mites (Tetrgnychusurtica Koch) were also counted in the aphid experiments.

Apple Insect Control, 1975

Abstract Experimental insecticides were evaluated for control of several fruit insect pests using four (4) Cortland apple trees/treatment. Insecticides were applied to run-off with the use of a truck-mounted Myers hydraulic sprayer operating at 450-500 psi. Applications were made on May 22 (petal-fall), June 2, 17, July 1, 15, and 31. One additional cover spray was added on August 26 to all Lannate plots. Cyprex 65 WP at 0.5 lbs/100 was added to all plots (except the check) on all application dates. Apple aphid counts were made by walking around each replicate tree and counting the total number of infested terminals per tree. Infested terminals consisted of those with over 25 aphids/terminal. Fruit infestation ratings were obtained by picking (at random) 2 bushels of fruit per replicate tree (8/treatment) at normal fruit harvest dates and counting fruit injury by specific insects.

The use of weather data and counts of aphids in the field to predict the incidence of yellowing viruses of sugar‐beet crops in England in relation to the use of insecticides

SUMMARYPartial regression equations were calculated that relate the mean percentage of plants infected with yellowing viruses (beet yellows and beet mild yellowing viruses) in sugar‐beet crops at the end of August to the number of days during January, February and March when temperatures fell below – 0.3 °C (31‐5 °F) and the mean temperatures in April, for the 21 yr, 1951–71, using weather records from Rothamsted Experimental Station. Regression analyses were also made to find the effect of other factors including mean and minimum temperatures for the same months, and also mean counts of ‘green aphids’, mainly of the vector Myzus persicae, on sugar‐beet plants during May and June. Significant relationships were established with all factors, but ‘frost‐days’ and April mean temperatures accounted for the greatest percentage of the variance in yellows incidence.The calculations were made separately for the years from 1951 to 1958, when no routine advice was given to farmers about aphid control, and 1959–71 when a ‘spray‐warning scheme’ was in operation, and many crops were sprayed at critical times to prevent aphid‐ and virus‐spread. Weather factors had the same effects in both periods, but for any particular weather less virus was spread in the second period than in the first, although there were sufficient aphids, i.e. the numbers expected from the prevailing weather conditions. There was no evidence that insecticide treatment used in any one year affected aphid‐incidence in subsequent years.Regression analyses on weather variables were also calculated separately for each of seventeen beet‐sugar factory collection‐areas, using weather records from local weather stations, and also the Rothamsted weather records. Unexpectedly, the fit of the regressions was always better with Rothamsted weather data than with local weather records. Mean yellows‐incidence for the different factory areas declined from south to north, and there was a linear relationship with the square root of the latitude above 50 °C. At the same time the correlation coefficients relating yellows‐incidence to ‘frost‐days’ became smaller and less significant, and those showing dependence

Aphidophagous Cecidomyiidae (Diptera): taxonomy, biology and assessments of field populations

AbstractLarvae of Aphidoletes Kieffer and Monobremia Kieffer feed exclusively as predators on aphids. The taxonomic status of these genera and their included species is reviewed and new generic and specific synonymies are given. A. aphidimyza (Rondani), A. urticariae (Kieffer), A. abietis (Kieffer), A. thompsoni Möhn and M. subterranea (Kieffer) are accepted as good species and a neotype is designated for A. urticariae. Diagnostic characters of these species are indicated and characters of the male genitalia, female wings and larval skins are illustrated. Published information on their biology, particularly of the commonest species A. aphidimyza, is summarized and includes details of host ranges and geographical distribution. Lestodiplosis grassator (Fyles), L. pini Barnes, Trilobia aphidisuga Del Guercio, Uncinulella eriosomiperda Del Guercio, Trilobiella siphae Del Guercio and Adelgimyza strobilobii Del Guercio probably prey on aphids but have not been recognized since they were originally described. Comparative assessments of field populations of Aphidoletes by examination of aphid colonies in the field, by incubation of samples in polythene bags and by laboratory examination of samples fixed in 70% ethyl alcohol showed that only the last gives accurate counts of eggs and larvae. Counts of aphids, Aphidoletes, Syrphids, Coccinellids and Anthocorids in 35 samples taken from aphid colonies occurring at Wisley in 1970–72 are tabulated, together with seven samples from other localities. Aphidoletes (mainly A. aphidimyza) was numerically the dominant predator in all three years at Wisley and was about ten times more numerous on wild plants than on cultivated plants.

Spring Populations of the Green Peach Aphid 1 on Peach Trees and the Role of Natural Enemies in Their Control 23

A 2-year study of the spring population of Myzus persicae (Sulzer) on peach trees showed that the number of surviving fundatrices reaching reproductive maturity represented less than 2% of the overwintering eggs. Colonies established from surviving fundatrices protected from natural enemies by slecve cages displayed a tremendous numerical recovery. For example, in a protected environment (cage) the average number of alate aphids per stem mother was 3596 in 1970, and 1080 in 1971. In contrast, on unprotected twigs the natural enemies, primarily coccinellid and syrphid predators, played a major role in reducing the production of alate aphids by an estimated 95% in both years (based on counts of immature aphids).

Insect Predators for Controlling Aphids on Potatoes. 3. In Small Plots Separated by Aluminum Flashing Strip-Coated with a Chemical Barrier and in Small Fields1

In 1966, 8-in, aluminum flashing standing on edge proved effective as a barrier to interplot movement of the larvae of Coccinella septempunctata L. when introduced sequentially into 0.014-acre plots of potatoes; notwithstanding, the small plots proved unsatisfactory for evaluating effectiveness of the introduced predators, chiefly because of the habits of the predators. The flashing had a 1-1½-in, band at the top on each side coated with Fluoro Glide®, technical grade. Approximately square ¼-acre fields were superior to 12x50 ft plots for evaluating effectiveness of manual introductions of 2nd and 3rd instars of C. septempunctata or 2nd instars of Chrysopa spp. against aphids on potatoes. In small fields having light-to-moderate aphid infestations, better control was obtained from sequential introductions of Chrysopa spp. at 88,100 larvae/acre than from 4 applications of C. septempunctata at 30,500 larvae/acre. However, the best all-season control was achieved where introductions of both predators at these rates were made in the same field. Best all-season control ranged from 33 to 97%, depending upon species of aphid; for all species of aphids combined, it was 58. The abundance of predaceous stages of coccinellids and chrysopids during the summer on sample aphid count leaves in the fields or plots was not well correlated with the numbers of C. septempunctata or Chrysopa spp. introduced into the plantings.

Growth characteristics of potato plants useful in studies of population dynamics and biological control of aphids

During three growing seasons, certain information was recorded weekly that was related to several characteristics of the aerial growth of five varieties of field-growing potatoes, viz. the number of stems and leaves per plant, the length of stems, and leaf area. Conversions of aphid numbers recorded from stratified subsamples of plants in the field to the number of aphids per plant or per unit of leaf area became possible by knowing the number of leaves and the leaf area per plant at the time of each aphid count. The numbers and areas of leaves per plant varied greatly among varieties as well as within and among years. The range in average maximum area of leaves per plant was 533 to 2,523 in.2 for the years 1967 to 1969. The comparable range for number of leaves per plant for the years 1967 and 1969 was 53 to 145. Consideration was given to the probable influence upon the magnitude of errors of estimate of aphid abundance that might result in making conversions of field counts of aphids to the numbers of aphids per plant or per unit of leaf area.

Experimental studies on the distribution of the aphid counts

SummaryThe present paper dealt with the sequential changes of the distribution pattern of apterous females aphid populations, that were artificially settled at the beginning on the experimental barley ‘field'. The aphids were settled at random or even with a fixed denisty per plant. For five or six days after the settling, the number of individuals followed the negative binomial distributions in all cases while the parameters k and p were varying. The estimated values of k were rather small for the first one week after the settling, which may suggest that the number of moving aphids between plants was relatively small and the degree of concentration expressing the intrinsic increase was high. After that, as the number of individuals increased, the number of moving aphids between plants would be considered to be increased. It was found that with the lapse of time the degree of concentration decreased or k became larger.The distribution of aphids per blade in a plant was also described briefly.

The incidence ofRhopalosiphum padi(L.) and Barley Yellow Dwarf Virus in Canterbury wheat crops in 1962 and 1963

Abstract A survey of the incidence of cereal aphid infestation in wheat crops during the last two seasons was carried out in Canterbury. This survey revealed large differences in aphid populations, in different districts where varying environmental conditions affected crop growth. Early sowing, vigorous growth, and adjacent shelter led to high aphid numbers in the 1962 season. Cold damp conditions during the winter and spring of the 1963 season prevented any build up of aphid populations and resulted in low levels of barley yellow dwarf virus (BYDV) infection in the following summer. Aphid counts in the spring months were directly related to the subsequent levels of BYDV infection in January. Low crop yields were associated with high virus counts in the 1962 season, particularly in districts which experienced low rainfall in early summer, e.g., Rangiora-Oxford. A high BYDV incidence did not reduce yields below about 35 bushels/ac on the moister and more fertile soils of the Lincoln-Southbridge districts.

Determination of Aphids in Hops

Abstract This year’s study on samples of high and low aphid count hops evidenced a wide variation in results. Changes in the testing program prior to next year’s study are presented.

Seasonal Biology of the Balsam Woolly Aphid on Mt. Mitchell, North Carolina

Studies of the seasonal biology of the balsam woolly aphid, Chermes piceae Ratzeburg (Adelgidae: Homoptera), were carried out in 1960 following discovery of a severe infestation of this insect on Mt. Mitchell. Observations of aphid development were made in the field on 3- by 3-inch plots of bark on living trees. In addition, microscopic counts of aphids on bark samples were made at frequent intervals in the laboratory. Observations within the plots revealed as many as three generations per year. Data obtained from bark samples showed that most of the aphid population completed two generations.

Preliminary Investigations on the Biology and Ecology of the Parasites and Predators ofBrevicoryne brassicae(L.)

During 1953 and 1954, experimental plots were set up on two sites in eastern England and regular fortnightly samples were taken in an attempt to evaluate the degree of control of the Cabbage Aphid,Brevicoryne brassicae(L.), exerted by its parasites and predators.The plot at each site consisted of a block of 5 rows of 40 plants and each main sample consisted of a sample of three leaves (one upper, one middle and one lower leaf) from 25 per cent. of the plants. Two such samples (A & B) were taken at each visit and were so arranged that the plants were sampled in strict rotation. The leaves were taken back to the laboratory and sample A was used to assess the number of Aphids, the other for an assessment of parasitism. The Aphids were removed from sample A and put into 95 per cent. alcohol and counted. The mummies were removed from sample B and put into labelled tubes. The leaves from sample B were then kept in insect-proof containers and examined daily for the next fortnight. All mummies which formed were removed and sorted. The insects which emerged from the mummies were killed, sexed and recorded. Predators taken from this sample were identified and recorded and used for further experiments. The validity of counting Aphids from one sample and parasites and predators from another was investigated by a series of “check-samples” taken from arbitrary plots in the fields. A shorter method for assessing parasitism was tried, using a sub-sample of the main sample, and an explanation is given for the disparity between the two sets of results.