2008 Annual Report
1a.Objectives (from AD-416)
Develop and refine boll weevil monitoring tactics to enhance suppression or eradication efforts. Develop improved and novel methods for elucidating the biology and ecology of southern green stink bugs. Improve current management strategies for cotton fleahopper through development of ecologically interpretable monitoring methods, elucidation of dispersal strategies in relation to the environment, and improved understanding of cotton fleahopper/cotton plant interactions. Identify and characterize neuropeptide hormones of arthropod pests and develop biostable, bioavailable mimics that can disrupt critical life processes to provide effective and environmentally sensitive pest control.
1b.Approach (from AD-416)
Studies will be conducted to investigate effects of diet on pheromone production by boll weevils, effects of the trap environment on boll weevil colonization patterns and captures in traps, and methods to locate and manage sources of weevil re-infestations. New methods will be developed to determine the reproductive/physiological development of southern green stink bugs and their utilization of wild host plants and crops. Dissections to identify reproductive/physiological characteristics and neuropeptide chemistry/biostable mimic technology will combine to reveal basic southern green stink bug biology and mechanisms for their behavior and ecology. This information will help determine the timing and approaches to manage southern green stink bug populations. Various pest sampling technologies and techniques will be evaluated relative to a reference sampling method in cotton to determine an efficient and effective sampling technology. Cotton fleahopper dispersal from uncultivated plants and colonization of early-season cotton fields will be determined relative to weather and physiological characteristics of the host plants. Plant stage-dependent feeding and oviposition activity, and consequent instar- or stage-dependent plant injury will be defined. Completion of the research will result in new sampling technologies and cotton fleahopper management guidelines. Knowledge of the role of neuropeptides will be developed which will lead to the development of neuropeptide mimics that resist degradation by enzymes in the digestive tract, hemolymph, and tissues. Research will be conducted to identify neuropeptides, and to develop and evaluate neuropeptide mimics that can regulate diuresis, ecdysis, diapause, and reproduction as tools to study the biology of sucking bugs and as pest insect management agents.
Work under this project during FY 2008 resulted in significant progress in identifying diverse plant habitats of cotton insect pests, and exploiting this information to define ecological processes, including dispersal. A host plant survey of wild host plants of the cotton fleahopper exposed seasonal utilization of wild hosts, which can be linked to fleahopper infestations in cotton. Further, the population dynamics and within-plant distribution of fleahoppers was described clearly to reinforce efficient and effective sampling strategies for managing fleahoppers in cotton. Food diets were correlated with reproduction in southern green stink bugs and characterized by reproductive morphology of the bugs. Analysis of three independent sets of data (pollen, winds, and population genetics) was interpreted to identify likely source areas of boll weevils that had re-infested cotton in the Southern Rolling Plains Zone of the Texas Boll Weevil Eradication Program. This information is important for the Texas Eradication Program because the source area needs additional attention and weevil control in the future to prevent such occurrences and to prevent new outbreaks of this insect pest. Significant progress was made in FY 2008 in identification of neuropeptides associated with critical life processes in stink bugs, Heliothines, and other pest arthropods. Project research has revealed functional and economic aspects of trapping within the Boll Weevil Eradication Program that may benefit from changes in trap placement, and in discontinued use of killing strips inside the traps. (NP 304, Components 2-6, Problem Statements 2.A, 3.B, 4.D, 5.D, 6.A)
Cotton Pollen as a Marker for Off-Host Boll Weevil Movement:
The boll weevil has historically been a major insect pest of cotton in the U.S. Weevil dispersal between cotton and nearby non-cotton habitats causes problems in timing of insecticide applications. Pollen can potentially be used as a marker to establish boll weevil movements between cotton and non-cotton hosts; pollen is known to be a natural marker of insect dispersal and food sources. Scientists in the Areawide Pest Management Research Unit at the Southern Plains Agricultural Research Center, College Station, Texas, showed that pollen from cotton and other plants remained in the gut of weevils, and in identifiable form, for various times after ingestion (up to 96 hours in the case of cotton pollen). This accomplishment is important because it shows that pollen in the gut of wild boll weevils can be used as a marker to indicate distance and relative time of travel from cotton to non-cotton environments, which in turn may facilitate development of protocols for successful off-cotton weevil treatments. (NP 304, Component 4, Problem Statement 4.D)
Bioavailable/Biostable Insect Neuropeptide Versions for Moth Control:
Neuropeptides are short chains of amino acids that regulate critical life functions in insects. However, biostable and bioavailable versions of neuropeptides, which can both resist degradation by enzymes and penetrate either the outside surface or gut wall in insects, will be required in order for neuropeptide technology to be developed for effective pest insect control. Scientists in the Areawide Pest Management Research Unit at the Southern Plains Agricultural Research Center, College Station, Texas, in collaboration with scientists in England, developed novel versions of insect neuropeptides of the allatostatin class that involve incorporation of non-natural components to create the bioavailable/biostable versions. The analogs were shown to both retain activity and to cross the digestive system of an immature moth intact, and were found to be stable to internal degradation factors that inactivate the natural neuropeptides. This accomplishment is important because it brings us one step closer to the development of practical neuropeptide-like substances that will disrupt normal development and reproduction and effectively control lepidopteran pest insects in an environmentally friendly fashion. (NP 304, Components 2, 5, Problem Statements 2.A, 5.D)
Improved Detection of Reproducing Boll Weevils in Cotton:
The boll weevil has historically been a key pest of cotton in the U.S., warranting national boll weevil eradication efforts. A critical component of eradication efforts is the detection of reproductive populations of boll weevils; researchers currently rely on only one type of egg-laying puncture to detect these populations. Scientists in the Areawide Pest Management Research Unit at the Southern Plains Agricultural Research Center, College Station, Texas, identified three different types of egg-laying punctures that can reflect boll weevil reproduction. This accomplishment is important because it provides more accurate detection of reproductive weevil populations and will facilitate success in boll weevil eradication programs. (NP 304, Component 4, Problem Statements 4.A, 4.D)
Effectiveness of Boll Weevil Pheromone Traps With and Without Kill Strips:
Boll weevil eradication programs typically equip pheromone traps with an insecticide-impregnated device (kill strip) to kill captured insects. Despite their widespread use in eradication programs, the effectiveness and benefits associated with the use of kill strips have not been clearly established. Scientists in the Areawide Pest Management Research Unit at the Southern Plains Agricultural Research Center, College Station, Texas, in collaboration with scientists at the ARS Weslaco, Texas, Location, showed that the use of kill strips did not influence weevil captures or simplify trap servicing, although their use did result in a small reduction in weevil predation and trap obstruction. This accomplishment is important because it provides solid data for use in eradication program decision-making regarding the appropriateness of using kill strips in traps; a significant reduction in trapping costs may be achievable. (NP 304, Component 4, Problem Statement 4.C)
Regulatory Insect Neuropeptides from Stink Bugs:
Neuropeptides are short chains of amino acids that regulate critical life functions in insects. Neuropeptide technology offers great promise in effective and environmentally sensitive control of pest insects. Scientists in the Areawide Pest Management Research Unit at the Southern Plains Agricultural Research Center, College Station, Texas, in collaboration with scientists in Germany and at Texas A&M University, used state-of-the art analytical techniques to identify novel neuropeptides native to several species of agriculturally important stink bug species. Maps of the locations of each of the neuropeptides within the nervous system of the stink bugs were generated. These neuropeptides have been associated with the regulation of developmental, reproductive, energy utilization, water balance, and digestive processes in other insect species. This accomplishment is important because it brings us one step closer to the development of practical neuropeptide-like substances that will disrupt normal life processes and effectively control stink bugs in an environmentally friendly fashion. (NP 304, Component 2, Problem Statement 2.A)
Accurate Nymphal Instar Assignment in the Cotton Fleahopper:
The cotton fleahopper is an important insect pest of cotton, particularly in production areas where the cotton boll weevil has been eradicated. Accurate assignment of the development phases of this insect is critical to sound scientific research aimed at development of improved control methods. Current guidelines for distinguishing the five nymphal instars of the cotton fleahopper are based on the developmental progression of wing pads; however, inexperienced observers often have difficulty determining the instars of nymphs because wing pads on earlier instars are difficult to discern and because distinguishing characteristics among these instars are subtle. Scientists in the Areawide Pest Management Research Unit at the Southern Plains Agricultural Research Center, College Station, Texas, developed guidelines for accurately distinguishing nymphal instars based on head capsule width. This accomplishment is important because these new guidelines provide more accuracy in nymphal instar assignment regardless of the skill of the individual involved, and will significantly enhance the scientific validity of scientific research that is dependent upon accurate instar assignment. (NP 304, Component 2, Problem Statement 2.A)
Improved Sampling of Fleahoppers in Cotton:
The cotton fleahopper is an important pest of cotton grown in the U.S. The standard practice for determining cotton fleahopper abundance in fields involves direct counts of fleahoppers on plants, which can be laborious and time consuming. Consequently, many producers avoid or neglect sampling for fleahoppers, which can lead to critical delays in detection of economic outbreaks. Scientists in the Areawide Pest Management Research Unit at the Southern Plains Agricultural Research Center, College Station, Texas, showed that samples collected with a hand-held pneumatic sampling device, the Keep-It-Simple-Sampler (KISS), accurately and precisely reflect field population levels of adult fleahoppers; however, the KISS did not provide accurate estimates of nymph populations. This accomplishment is important, despite the shortcoming of not adequately sampling nymphal populations, because it provides researchers and producers an alternative, very predictive method for estimating adult fleahopper population levels in cotton. (NP 304, Component 3, Problem Statement 3.B)
Structural Requirements for Diapause-Break Activity of a Neuropeptide in Heliothine Moths:
Neuropeptides are short chains of amino acids that regulate critical life functions in insects. However, biostable versions of neuropeptides that can resist degradation by enzymes in insects will be required in order for neuropeptide technology to be developed for effective pest insect control. Scientists in the Areawide Pest Management Research Unit at the Southern Plains Agricultural Research Center, College Station, Texas, in collaboration with scientists at the Ohio State University, identified critical chemical and structural requirements for a neuropeptide to successfully break diapause in Heliothine insects such as the cotton bollworm. This knowledge is critical for the future design and development of biostable neuropeptide versions that incorporate non-natural stabilizing components. The accomplishment brings us one step closer to the development of practical neuropeptide-like substances that will disrupt normal diapause activity and effectively control Heliothine pest insects in an environmentally friendly fashion. (NP 304, Component 2, Problem Statement 2.A)
New Weed Host of the Cotton Fleahopper:
The cotton fleahopper is a serious, early-season pest of cotton that can develop on alternate early-season hosts and, when it infests cotton, can reduce cotton fruit set and eventually cotton yield. More needs to be known about weed hosts of the fleahopper so that better predictions can be made concerning the fleahopper’s subsequent movement to cotton. Scientists in the Areawide Pest Management Research Unit at the Southern Plains Agricultural Research Center, College Station, Texas, identified turnipweed as a previously unreported host for the cotton fleahopper. This accomplishment is important because it provides new information on weed hosts of the fleahopper that is important in understanding the dynamics of subsequent cotton infestations by this insect pest. (NP 304, Component 3, Problem Statement 3.B)
Pollen Contamination of Boll Weevil Traps:
Pollen that is incidentally deposited (by wind or otherwise) on boll weevil traps may serve as a source of nutrients for weevils and may also give false indications of weevil origins and dispersal. For trap pollen to be of predictive value in research or monitoring activities, it is important to establish if pollen found on or in trapped weevils is incidental or is representative of the plants upon which the weevils fed or visited. Scientists in the Areawide Pest Management Research Unit at the Southern Plains Agricultural Research Center, College Station, Texas, showed that weevil traps placed in or near cotton fields contained almost no pollen, indicating that weevils are not likely to become contaminated with non-food pollen while remaining in the traps. This accomplishment is important because it demonstrates parameters by which data on trap pollen can be predictively used in establishing the origin and dispersal routes of the weevil, ultimately facilitating development of more efficient management or eradication strategies. (NP 304, Component 4, Problem Statement 4.D)
Molecular Markers for Genetic Differentiation of the Cotton Fleahopper:
The cotton fleahopper is an important pest of cotton grown in the U.S.; typically, the fleahopper moves to cotton once preferred weed hosts begin to mature and become less attractive. Information on the sources of fleahoppers entering cotton is critical to understanding the ecology of the insect and in developing improved control strategies; little is presently known on this issue. Scientists in the Areawide Pest Management Research Unit at the Southern Plains Agricultural Research Center, College Station, Texas, in collaboration with scientists at Texas A&M University, developed molecular markers (Amplified Fragment Length Polymorphisms, AFLPs) to identify genetic similarities and differences among fleahopper populations. This accomplishment is important because it provides methodology for detailed genetic comparisons of cotton fleahopper populations in cotton and weed hosts; such comparisons will facilitate studies of fleahopper movement and identification of weed sources responsible for the majority of fleahoppers in cotton. (NP 304, Components 2, 3, Problem Statements 2.A, 3.B)
|Number of Web Sites Managed||1|
|Number of Non-Peer Reviewed Presentations and Proceedings||2|
Predel, R., Russell, W.K., Russell, D.H., Lopez, J., Esquivel, J.F., Nachman, R.J. 2008. Comparative peptidomics of four related hemipteran species: Pyrokinins, myosuppressin, corazonin, adipokinetic hormone, sNPF, and periviscerokinins. Peptides. 29:162-167.
Federico, P., Hallam, T.G., McCracken, G.F., Purucker, S.T., Grant, W.E., Sandoval, A.C., Westbrook, J.K., Medellin, R.A., Cleveland, C.J., Sansone, C.G., Lopez, J., Betke, M., Moreno-Valdez, A., Kunz, T.H. 2008. Brazilian free-tailed bats (Tadarida brasiliensis) as insect pest regulators in transgenic and conventional cotton crops. Ecological Applications. 18:826-837.
Downer, K.E., Nachman, R.J., Stoffolano, Jr., J.G. 2007. Effect of seasonality and perisulfakinin on engorgement by Tabanus nigrovittatus (Diptera: Tabanidae) in the laboratory. Annals of the Entomological Society of America. 100:251-256.
Kim, Y., Nachman, R.J., Aimanova, K., Gill, S., Adams, M.E. 2008. The pheromone biosynthesis activating neuropeptide (PBAN) receptor of Heliothis virescens: Identification, functional expression, and structure-activity relationships of ligand analogs. Peptides. 29:268-275.
Coast, G.M., Nachman, R.J., Schooley, D.A. 2007. An antidiuretic peptide (Tenmo-ADFb) with kinin-like diuretic activity on Malpighian tubules of the house cricket, Acheta domesticus. Journal of Experimental Biology Online. 210:3979-3989.
Audsley, N., Matthews, J., Nachman, R.J., Weaver, R.J. 2007. Metabolism of cydiastatin 4 and analogues by enzymes associated with the midgut and haemolymph of Manduca sexta larvae. General and Comparative Endocrinology. 153:80-87.
Zhang, Q., Zdarek, J., Nachman, R.J., Denlinger, D.L. 2008. Diapause hormone in the corn earworm, Helicoverpa zea: Optimum temperature for activity, structure-activity relationships, and efficacy in accelerating flesh fly pupariation. Peptides. 29:196-205.
Audsley, N., Matthews, J., Nachman, R.J., Weaver, R.J. 2008. Transepithelial flux of an allotostatin and analogs across the anterior midgut of Manduca sexta larvae in vitro. Peptides. 29:286-294.
Taneja-Bageshwar, S., Strey, A.A., Kaczmarek, K., Zabrocki, J., Pietrantonio, P., Nachman, R.J. 2008. Comparison of insect kinin analogs with cis-peptide bond, type VI-turn motifs identifies optimal stereochemistry for interaction with a recombinant arthropod kinin receptor from the southern cattle tick, Boophilus microplus. Peptides. 29:295-301.
Alstein, M., Ben-Aziz, O., Zeltzer, I., Bhargava, K., Davidovich, M., Strey, A.A., Pryor, N.W., Nachman, R.J. 2007. Inhibition of PK-PBAN-mediated functions in insects: Discovery of selective and non-selective inhibitors. Peptides. 28:574-584.
Taneja-Bageshwar, S., Strey, A.A., Zubrzak, P., Williams, H., Reyes-Rangel, G., Juaristi, E., Pietrantonio, P., Nachman, R.J. 2008. Identifications of selective and non-selective, biostable beta-amino acid agonists of recombinant insect kinin receptors from the southern cattle tick, Boophilus microplus, and mosquito, Aedes aegypti. Peptides. 29:302-309.
Spurgeon, D.W. 2008. Seasonal patterns in host-free survival of the boll weevil (Coleoptera: Curculionidae) in the subtropics. Journal of Entomological Science. 43(1):13-26.
Westbrook, J.K. 2008. Noctuid migration in the nocturnal aeroecological boundary layer. Integrative & Comparative Biology. 48:99-106.
McCracken, G.F., Gillam, E.H., Westbrook, J.K., Lee, Y., Jensen, M., Balsley, B. 2008. Brazilian free-tailed bats (Tadarida brasiliensis: Molossidae, Chiroptera) at high altitude: Links to migratory insect populations. Integrative & Comparative Biology. 48:107-118.
Pietrantonio, P.V., Junek, T.A., Parker, R., Mott, D., Siders, K., Troxclair, N., Vargas-Camplis, J., Westbrook, J.K., Vassiliou, V.A. 2007. Detection and evolution of resistance to the pyrethroid cypermethrin in bollworm, Helicoverpa zea (Lepidoptera, Noctuidae) in Texas. Environmental Entomology. 36:1174-1188.