This paper is the result of research started on the Campus of the Utah State Agricultural College in the Spring of 1928. It is the intention of the writer to give the economic importance of the insect in the state, kind and extent of damage life history and control as far as it has been found.

Grain sorghum is a drought tolerant crop used in the Mid-south region in rotation with corn, cotton, soybeans, and corn. In 2015 and 2016, research was conducted to determine the influence of insecticide treatment, planting date, planting population, hybrid, and environmental temperatures on sugarcane aphid, Melanaphis sacchari (Zehntner), populations and yield in grain sorghum, Sorghum bicolor (L.) Moench. In general, cooler temperatures had a negative effect on sugarcane aphid control with sulfoxaflor and flupyradifurone. Additionally, there was a negative relationship between grain sorghum plant population and sugarcane aphid densities per plant. These data suggest management of sugarcane aphid with insecticide seed treatments and foliar sprays is critical for maximizing grain sorghum yields. Additionally, growers should wait for warmer temperatures to ensure optimum control.

No description available.

The tobacco-adapted form of the green peach aphid, Myzus persicae (Sulzer), is one of the most important insect pests of tobacco in the United States and around the world. Insecticides play a major role in controlling the aphid on tobacco because natural enemies usually fail to maintain its populations below damaging levels. The aphid has a history of developing resistance to many insecticides. Therefore, baseline information on the aphid's susceptibility to imidacloprid and other insecticides is critical for developing future resistant management programs to minimize losses attributed to the aphid. Studies were conducted on colonies of the tobacco-adapted form of the green peach aphid collected from nine states in the eastern United States in 2004-2007. The susceptibility of 151 colonies to imidacloprid was determined in serial leaf-dip bioassays. When combined over the four years, 18, 14, and 4% of the colonies had 10- to 20-fold, 20- to 30-fold, and 30- to 90-fold resistance ratios, respectively, suggesting that high levels of resistance to imidacloprid are present in field populations of the aphid. A colony collected near Clayton, NC had the highest LC50 value (31 ppm) combined over six tests and three years, but the average resistance ratios for the first three runs was over 130-fold (48 ppm). Geographic location had little effect on susceptibility to imidacloprid. Aphid colonies (136) including red, green, and orange color morphs were screened for total esterase activity using microplate assay with 1-Naphthyl acetate as the substrate. The green morphs generally had lower esterase levels than the red and orange morphs. All orange morphs had among the highest esterase activities. Esterase activities of red and green morphs were positively correlated with LC50 values as determined by leaf-dip bioassays for acephate and methomyl. All 25 colonies tested for esterase gene amplification had either E4 or FE4 gene amplification. The amplification of both E4 and FE4 seen as an 865-bp band characteristic of the FE4 gene and an additional 381-bp band characteristic of a deleted upstream region of the E4 gene occurred in all (4) orange morphs and one (1 of 9) green morph. Target-site insensitivity of acetylcholinesterase (AChE), as modified AChE resistance (MACE) was assessed in 65 colonies of field-collected tobacco-adapted forms of M. persicae. Eight colonies over a range of AChE activity were selected to study inhibition of AChE in the presence of two carbamate insecticides, methomyl and pirimicarb. IC50 values for methomyl ranged from 0.35 to 2.4 μM while six of eight colonies had lower values with a range of 0.16 to 0.30 μM for pirimicarb. Two colonies that were inhibited by methomyl had very high IC50 values of 40.4 and 98.6 μM for pirimicarb. Such insensitivity may be due to mutations in the ace2 gene, but this needs to be confirmed by genetic and molecular analysis. Glutathione S- transferases (GSTs), isoenzymes that are involved in the metabolism and detoxification of many xenobiotic compounds were quantified for 100 colonies by CDNB conjugation. There was a wide range of GST activity for the red (8 to 343 pmol/min/mg protein) and green (15.3 to 330 pmol/min mg protein) morphs, but all six orange morphs collected in 2007 had a narrower range (160 to 211 pmol/min/mg protein). About 45% of the red morphs had GST activity from 200-300 pmol/min/mg of protein, while 53% of the green morphs had a range of 100-200 pmol/min/mg protein. The influence of temperature-mediated synergisms on the toxicity of insecticides in red and green color morphs of the tobacco-adapted from of M. persicae were evaluated using leaf-dip bioassay procedures in laboratory incubators. Post-exposure temperatures of 15, 20, and 25°C were evaluated for four classes of insecticides, acephate, imidacloprid, lambda-cyhalothrin, and methomyl. The temperature change from 15 to 20°C caused almost a 3-fold increase in toxicity to the red and green color morphs for methomyl, acephate, and imidacloprid. In contrast, the toxicity of lambda-cyhalothrin decreased as the temperature increased, showing a negative temperature coefficient. Bioassay experiments conducted with the red morph for indirect estimates of imidacloprid concentrations in flue-cured tobacco showed that leaf position, imidacloprid rate and time after application affected the concentration of the toxicant in the leaf. The differences in aphid mortality between the lower and upper leaf positions indicate that the concentration of imidacloprid and its metabolites were unevenly distributed with the lowest mortality for aphids feeding on the younger, upper leaves and the highest for those feeding on the older, lower leaves. In field experiments, higher aphid populations occurred on tobacco treated with imidacloprid less than the field recommended rate of 41.4 ml/1,000 plants. The development of aphid populations in the field was consistent with the laboratory bioassays. Field trials were conducted to evaluate the performance of various insecticides currently registered for aphid control on tobacco. Imidacloprid applied as a tray drench treatment and acephate as foliar sprays were the most effective treatments. Moderate declines in control with imidacloprid were observed at 75-87 d after transplanting in 2006 and 2007. Aldicarb gave good to excellent control in one of three years, but only fair to poor control in the other two years. Methomyl and lambda-cyhalothrin gave good control in all three years except the residual was shorter. The poor performance of aldicarb in the two years may have been related to the presence of E4 or FE4 resistance in the naturally occurring TGPA in the experimental plots. / Ph. D.

The overall goal of this research was to determine the effects of spirea aphid, Aphis spiraecola Patch, feeding and nitrogen fertilization on net photosynthesis (Pn), leaf chlorophyll content and greenneess, growth, dry matter accumulation, and carbohydrate concentrations of young apple trees, with comparisons to apple aphid, Aphis pomi DeGeer. Trees were artificially infested and grown in an unheated greenhouse with screened ends. The spirea aphid responded differently to various nitrogen treatments. Aphid density increased at a faster rate on trees receiving higher nitrogen application. The leaf nitrogen concentration increased significantly and linearly with increasing amount of urea application in both infested and control leaves. Also, a significant difference in leaf nitrogen concentration was found at each urea application rate between infested and control leaves. Spirea aphid feeding and sooty mold accumulations caused significant reductions in photosynthetic rates, leaf chlorophyll content, and greenness. Pn increased linearly with increasing chlorophyll content and greenness; nitrogen rates caused an increase in Pn and leaf greenness. Aphid-days accumulations were strongly correlated to Pn and greenness at each nitrogen rate applied. Accumulation of callose at the phloem sieve plates in response to spirea aphid feeding occurred but to a lesser degree than from other aphids reported on apple and pecan leaves. Accumulation of fresh and dry weights in all tree parts (leaves, lateral shoots, trunk, rootstock, and roots) during the growing season were affected by both spirea aphid and nitrogen fertilization. The spirea aphid reduced accumulation of fresh and dry weights in all tree partitions when trees were harvested at the end of the first growing season. These reductions were still lower than the control when trees were harvested at the ten-leaf stage the following spring. The spirea aphid caused a significant reduction in lateral shoot growth at the end of the growing season and at the ten-leaf stage. Fresh and dry weights of all tree partitions tended to increase with increasing rates of nitrogen. The percentage and the amount of nonstructural carbohydrates (NSC) in all tree partitions were reduced by spirea aphid feeding and were positively related to nitrogen rate. At the ten-leaf stage in the second season, similar results were obtained. Development of spirea aphid and apple aphid was similar on trees fertilized with a moderate rate of nitrogen. Pn and leaf greenness declined to a similar extent with accumulated aphid-days, for both aphid species. Aphid species did not affect any of tree growth or NSC accumulation. / Ph. D.

Thesis (MScAgric)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Characterizing the genetic structure of a pest population can provide an understanding of the factors influencing its evolution and assist in its ultimate control. The aim of the present study was to characterize the genetic structure of woolly apple aphid Eriosoma lanigerum (Hausmann) populations in the Western Cape Province in South Africa. Since this economically important apple pest has not previously been characterized at molecular level, it was necessary to evaluate methods for determining the genetic structure of E. lanigerum populations. Two different molecular techniques were evaluated viz. random amplification of polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP). This study represents the first application of the latter technique to members of the Aphididae. Aphids were sampled from four regions in the Western Cape in South Africa viz. Elgin, Ceres, Vyeboom and Villiersdorp. A spatially nested sampling design was used to establish the distribution of the genetic variance of aphids. A total of 192 individuals from 13 farms were analysed. Ten RAPD primers were chosen for analysis from an initial assay of 25 after fragment reproducibility had been confirmed. For AFLP analysis three different rare-cutting restriction enzymes were evaluated for AFLP analysis, viz. EcoRI, SseI and MluI. The latter yielded the best results in combination with the frequent-cutting enzyme MseI. Twenty-five AFLP selective primer pairs were evaluated, out of which five were chosen for analysis of the total population. Two hundred and fifty AFLP fragments and 47 RAPD fragments were scored for analysis. Both analyses indicated that a low level of genetic variation was apparent in E. lanigerum populations and that no differentiation resulted from geographic isolation. From RAPD analyses it was deduced that all variation could be attributed to differences between individuals. AFLP analysis indicated that, whereas genetic differences in E. lanigerum populations between orchards were negligible, a significant portion of genetic variation could be attributed to differences between farms and individuals within farms. Therefore, AFLP analysis allowed for finer discrimination of the genetic structure of E. lanigerum populations than RAPD analysis and is recommended for studies of other aphid species. The fact that most of the genetic variation present in E. lanigerum populations could be found on small spatial scales indicated that sampling individuals over a wide geographic area was an ineffective way of detecting the genetic diversity present in E. lanigerum populations. The low level of variation in populations is most likely due to the exclusive occurrence of parthenogenetic reproduction, founder effects (including distribution of infested plant material from a limited source) and selective factors such as the use of resistant rootstocks or pesticides. Furthermore, the low level of variation found indicated that the possibility of controlling E. lanigerum in the Western Cape using host plant resistance is favourable. Thus, plant breeders developing resistance to E. lanigerum can expect plant entries to be exposed to most of the genetic diversity present in Western Cape populations, regardless of location. / AFRIKAANSE OPSOMMING: Die bepaling van die genetiese struktuur van 'n landboukundige plaagpopulasie kan lei tot begrip van die faktore wat die populasie beïnvloed en kan uiteindelike beheer vergemaklik. Die doel van die huidige studie was om die genetiese struktuur van die appelbloedluis Eriosoma lanigerum (Hausmann) in die Wes-Kaap Provinsie van Suid-Afrika te bepaal. Aangesien hierdie belangrike appelplaag nie van tevore op molekulêre vlak bestudeer is nie, was dit nodig om metodes vir die bepaling van die genetiese struktuur van E. lanigerum populasies te evalueer. Twee molekulêre tegnieke is geëvalueer, nl. lukraak geamplifiseerde polimorfiese ONS (RAPD) en geamplifiseerde fragment-lengte polimorfismes (AFLP). Hierdie studie is die eerste om laasgenoemde tegniek te gebruik om lede van die Aphididae te bestudeer. Plantluise is verkry van vier verskillende gebiede in die Wes-Kaap Provinsie van Suid-Afrika nl. Elgin, Ceres, Vyeboom en Villiersdorp. 'n Hierargiese sisteem is gebruik om die verspreiding van die genetiese variasie van plantluise te bepaal. In totaal is 192 individue van 13 plase geanaliseer. Tien RAPD inleiers is gekies uit 'n analise van 25 verskillende inleiers nadat fragment reproduseerbaarheid bevestig is. Drie verskillende restriksie ensieme is geëvalueer vir AFLP analise nl. EcoRI, SseI en Mlul. Die beste resultate is verkry toe MluI saam met MseI gebruik is. Vyf-en-twintig AFLP selektiewe inleier pare is geëvalueer waarvan vyf gekies is vir analise van die totale populasie. Twee-honderd-en-vyftig AFLP fragmente en 47 RAPD fragmente is gedokumenteer vir analise. Beide RAPD en AFLP analises het getoon dat daar 'n lae vlak van genetiese variasie in E. lanigerum populasies is en dat geen differensiasie as gevolg van geografiese isolasie ontstaan het nie. Uit RAPD analise is daar afgelei dat al die variasie toegeskryf kon word aan verskille tussen individue. AFLP het aangetoon dat alhoewel verskille in E. lanigerum populasies tussen boorde laag was, kon 'n hoë persentasie van die variasie toegeskryf word aan verskille tussen plase en individue binne plase. AFLP analise het meer insig in die genetiese struktuur van E. lanigerum populasies verskaf, en word dus aanbeveel vir studies van ander plantluise. Omdat meeste van die genetiese variasie oor klein geografiese afstande verkry word, is steekproefueming oor groot gebiede 'n ondoeltreffende manier om die genetiese variasie binne 'n monster te meet. Die lae vlak van genetiese variasie is waarskynlik te wyte aan partenogenetiese vermeerdering, stigter gevolge (insluitend verspreiding van geïnfesteerde plantmateriaal vanaf 'n beperkte bron), sowel as selektiewe faktore soos die gebruik van bestande onderstokke en insekdoders. Verder dui die lae vlak van variasie aan dat die moontlikheid vir beheer deur gasheerplantbestandheid goed is in die Wes-Kaap. Planttelers kan verseker wees dat hulle plante blootgestel sal wees aan meeste van die genetiese variasie in die Wes-Kaap appelbloedluis populasies ongeag hulle ligging.

Bibliography: leaves 196-210 / xi, 256, [85] leaves : (ill. (some col.) ; 31 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Entomology, Waite Agricultural Research Institute, 1985

Please read the abstract in the section 07chapter7. / Dissertation (MSc (Genetics))--University of Pretoria, 2002. / Genetics / unrestricted

Master of Science / Department of Entomology / John C. Reese / The soybean aphid, Aphis glycines Matsumura, arrived first to North America during the midst of 2000. It is a very fast spreading insect and causes a high yield loss of above 50% in most of the soybean growing tracts of United States. Another important economic threat is it’s ability to transmit some viruses to soybean. Studies to control this exotic pest started early during the year of its arrival. But a complete integrated pest management (IPM) approach that includes a combination of different control measures has yet to be completely developed. Host plant resistance is one component of integrated pest management and is more sustainable than any other control methods against this insect. In the first study, more than 80 genotypes were screened with two given aphid biotypes, biotype 1 and biotype 2. It was found that the genotypes that were earlier resistant to biotype 1 (K1639, K1642, K1613 K1621, Dowling and Jackson) were susceptible to the new biotype 2 with large populations developing on these genotypes. But we found three new Kansas genotypes that showed resistance only against biotype 1, but not against biotype 2. However, the two of the Michigan genotypes (E06902 and E07906-2) showed resistance to both biotype 1and biotype 2. In second study, the feeding behavior analyses of aphid biotypes were done using the EPG, Electrical penetration graph, technique for a recorded 9 hrs probing time. The resistant and susceptible genotypes show significant differences in their EPG parameters, especially for the sieve element duration in both biotypes. Most of the aphids reached sieve element phase (> 90%) in susceptible genotypes, but only few (<30%) were reached in resistant genotypes. But, no differences were found in any other probing phases between resistant and susceptible genotypes, except the number of potential drops (PDs) in biotype 2. Thus, it is concluded that resistance is largely associated with phloem tissues and there could be some biochemical, physical or morphological factors that affect the stylet penetration in aphids.

Master of Science / Department of Entomology / John C. Reese / The soybean aphid, Aphis glycines is documented to have arrived in North America in mid 2000 and has ever since established itself as a formidable pest of soybeans, with the capacity to cause immense crop losses. This formidable pest with its complex life cycle and habits represents a current threat to soybean production. Host plant resistance is a promising avenue that can offer considerable control over the soybean aphid problem. Antibiosis being the most effective host plant resistance category, this study was aimed at attempting to understand the effects of induction on the antibiosis levels of soybeans. In the first set of experiments, different soybean genotypes and two soybean aphid biotypes were tested to comprehend if and how the genotypes and biotypes affected the survival and reproduction of the aphid. The experiments revealed mixed results that can be attributed to the genotypes tested and the biotypes used. While some genotypes showed no significant changes due to previous infestation, K1621 suggested signs of induced resistance to biotype 1 and PI567301B showed induced resistance to biotype 2, while K1639 pointed towards induced susceptibility to biotype 2. A follow up feeding behavior study with Electrical Penetration Graph (EPG) technique was carried out on PI567301B to elucidate if the induced resistance was tissue-specific, which could affect the feeding behavior of the aphid (biotype 2); but the results showed no appreciable differences in the feeding behavior of the aphids on clean vs. infested plants. Induced response studies shed light on how plants respond to herbivory and help us identify how changes in plant physiology affect the various herbivores that visit it for food and shelter. This knowledge can thus be applied to the development of superior varieties of crops that can defend themselves better against recurring infestations.