| Title |
Investigators | Department | Objectives | Approach Keywords | Progress Reports | Impact Statements | Publications | |
Project * COL00622 | |
| Title | Insect Pest Management with Infochemicals |
| Investigator(s) | Bjostad, LB; |
| Department | Bioagricultural Sciences and Pest Mgmt. |
| Objectives | Equal efforts in basic research and applied research will be used to identify and synthesize natural products that influence insect behavior and physiology, in order to develop novel technologies for insect pest control. 1. Isolate and identify attractive compounds from woods preferred by termites We have so far been successful in identifying an array of attractants and feeding stimulants for termites, among the most economically important insect pest species on earth, and we have developed techniques for the practical application of these compounds in pest control. We have now discovered that woods preferred by termites also contain an attractant that we have not yet identified. When wood extracts are applied to soil, termites congregate in the treated soil, a behavior that could be exploited for new techniques in termite pest control. 2. Develop methods for termite pest control based on phototoxins in their own bodies We recently discovered a key aspect of termite physiology involving norharmane, an endogenous defense with phototoxic properties, and we plan to develop several new approaches for termite pest control based on this finding. These pest control approaches would include the use of ultraviolet light or chemical inducers to activate the phototoxin, or the development of new biocontrol approaches based on the use of phototoxin-resistant microbes. A more speculative implication of this discovery is that it may prove possible to develop new therapies for human health by studying the genomics and proteomics of termite adaptations to norharmane, which has been implicated in a number of human health problems such as Parkinson's disease and alcoholism. 3. Isolate and identify volatile attractants from corn roots for corn rootworm adults We recently discovered new attractants and feeding stimulants for adult western corn rootworms in the roots of germinating corn, and we plan to complete the chemical identification, synthesis, and field testing of these new compounds. |
| Approach | . Isolate and identify attractive compounds from woods preferred by termites Activated Carbon. Collections will made with activated carbon for 1 hour. Solvent volume will be reduced under N2 and analyzed by GC/MS. Solid phase micro extraction (SPME) will also be employed to assay headspace volatiles. Steam Distillation: Steam distillation of aqueous extracts of preferred wood will be performed with with an apparatus that allows distillation at reduced. Fractions will be recovered for field-testing and chemical analysis, distillate at full reduced pressure (temp), distillate with no vacuum (97oC), and the residue water left with the wood. Chromatography. Initial separation will be performed with C-18 cartridge chromatography, eluting with blends of water, MeOH, MeCl2, and hexane. Fractions will be tested in behavioral bioassays with termites, after removal of solvent by evaporation. HPLC of the active fractions on a C18 column with a water:methanol gradient will be used for final purification. Chemical identification. Identification of the purified compounds will be carried out by GC-MS of appropriate derivatives, and by NMR, FT-IR, and other spectroscopic techniques as needed. 2. Develop methods for termite pest control based on phototoxins in their own bodies a. Ultraviolet light rapidly causes high mortality in termites, by activating the phototoxic compound beta-carboline that occurs naturally in high concentrations in their own bodies. We are in the process of determining the minimum watts per square meter required for effective termite control. b. Non-toxic chemical activators may also be able to cause termite mortality, by activating beta-carboline in a manner similar to ultraviolet light, and these non-toxic chemical activators could be used as wood treatments, soil drenches or bait additives. c. New biocontrol agents for termite pest control will be evaluated by selecting fungal and bacterial diseases that are resistant to the high levels of beta-carboline in termites. d. Non-toxic chemical suppressors may cause enhanced termite susceptibility to disease, by interfering with the ability of beta-carboline to inhibit microbes, and these non-toxic chemical suppressors will be tested as wood treatments, soil drenches or bait additives. 3. Isolate and identify volatile attractants from corn roots for corn rootworm adults As discussed above, C-18 fractions of the residue from distillation of germinating corn have been analysed by GC-MS. The MeOH fractions predominantly contained phenolics, and the water fraction contained a series of small polar molecules and oxygen heterocycles. While we have initially concentrated our attention on the MeOH fraction because of the phenolics, it is now apparent that the water fraction warrants closer inspection. We will use GC/MS to analyze for ethanethiol, methanethiol or other small molecules that have been previously found in corn and may assist elucidation of the remaining active compounds in germinating corn. |
| Keywords | rootworms, termites, corn, Diabrotica |
| Progress Reports | |
| 1993 | We have continued the isolation and identification of corn semiochemicals for western corn rootworm larvae, to be used as insecticide baits and for larval monitoring. Abou-Fakhr E, Hibbard BE, Bjostad LB (1994) Tolerance of western corn rootworm larvae (Coleoptera: Chrysomelidae) to 6-methoxybe nzoxazolinone, a corn semiochemical for larval host location. Journal of Economic Entomology, accepted for publication September 1993. Hibbard BE, Peairs FB, Pilcher SD, Schroeder ME, Jewett DK, and Bjostad LB (1994) MBOA (6-methoxy-2-b enzoxazolinone): an attractant for western corn rootworm (Coleoptera: Chrysomelidae) soil insecticides. Journal of Economic Entomology, submitted September 1993. Hibbard BE, Bernklau EJ, and Bjostad LB (1994) Long chain free fatty acids : semiochemicals for host location by western corn rootworm larvae (Coleoptera: Chrysomelidae). Journal of Chemical Ecology, submitted December 1993. |
| 1994 | We have continued the isolation and identification of corn semiochemicals for western corn rootworm larvae, and have developed techniques for their use in insect control. The following manuscript has been accepted for publication by the Journal of Economic Entomology: Hibbard BE , Peairs FB, Pilcher SD, Schroeder ME, Jewett DK, and Bjostad LB (1994) MBOA (6-methoxy-2-benzoxazolinone): an attractant for western corn rootworm (Coleoptera: Chrysomelidae) soil insecticides. Journal of Economic Entomology, accepted for publication. We chemically identified and synthesized the sex pheromone of the caddisfly Hesperophylax occidentalis, an attractant that may be useful for biomonitoring of water quality. We submitted two manuscripts on this work to the Journal of Chemical Ecology: Bjostad LB, Jewett DK, Brigham DL. (1994) Sex pheromone of the caddisfly Hesperophylax occidentalis.(Trichoptera: Limnephilidae). J. Chem. Ecol., submitted Jan. 1995. Jewett D, Brigham DL, Bjostad LB. (1994) Hesperophylax occidentalis (Trichoptera: Limnephilidae) sex pheromone structure-activity study with electroantennograms. J. Chem. Ecol., submitted Jan. 1995. |
| 1995 | We chemically identified and synthesized the sex pheromone of the caddisfly Hesperophylax occidentalis, an attractant that may be useful for biomonitoring of water quality. Two manuscripts on this work have been accepted for publication by the Journal of Chemical Ecology: Bjostad LB, Jewett DK, Brigham DL. (1996) Sex pheromone of the caddisfly Hesperophylax occidentalis. (Trichoptera: Limnephilidae). J. Chem. Ecol., accepted Sept. 1995. Jewett D, Brigham DL, Bjostad LB. (1996) Hesperophylax occidentalis (Trichoptera: Limnephilidae) sex pheromone structure-activity study with electroantennograms. J. Chem. Ecol. , accepted Sept. 1995. We have demonstrated that dichloromethane and a related set of haloalkanes are powerful attractants for western corn rootworm larvae. We have hypothesized that these synthetic compounds mimic carbon dioxide in their interaction with the insect chemoreceptors, because carbon dioxide is the only volatile compound from corn roots that attracts the larvae. We have submitted two publications on this work: Jewett DK, and Bjostad LB (1995) Dichloromethane attracts corn rootworm larvae in a laboratory behavioral bioassay. Journal of Chemical Ecology, submitted July 1995. Jewett DK, and Bjostad LB (1995) Structure-activity study with haloalkane attractants of western corn rootworm larvae using a behavioral bioassay. Journal of Chemical Ecology, submitted July 1995. |
| 1996 | Carbon dioxide produced by corn roots is strongly attractive to western corn rootworm larvae, and we have completed the first definitive study of the optimum concentration range for larval attraction. We have also shown that no compounds other than carbon dioxide are involved in larval attraction to corn roots. With these two key pieces of information, we are now developing microbial and chemical sources of carbon dioxide as new, environmentally-safe pest management tools for the control of western corn rootworm larvae, one of the most economically important pests in North America. Organic solvent extracts of mature brown corn silks elicit strong electroantennogram (EAG) responses from western corn rootworm adult males and females. The young green silks do not elicit this strong EAG response. The active compounds were separated by chromatography, and the fractions were tested for EAG activity. The compounds in the EAG-active fractions were chemically identified. |
| 1997 | Disruption of western corn rootworm host orientation with CO2: Field experiments were conducted in cornfields with artificial sources of CO2 in the soil, intended to confuse WCR larvae and prevent them from using CO2 gradients to locate corn roots. Formulations developed in our laboratory for generating CO2 in the soil were effective in providing a statistically significant improvement in root ratings. The insecticide COUNTER 20CR (6 oz./1000 feet) significantly improved root ratings, as indicated by the Iowa 1-6 scale for root ratings. Our best treatment (yeast-nutrient granules) produced the same root rating (2.5, SE 0.2) as the COUNTER 20CR root rating (2.5, SE 0.1). Both these treatments gave substantial improvements in root ratings relative to the untreated corn, which had root ratings of 3.9, SE 0.2. Yeast-nutrient pellets were also tested, approximately 1 cm in diameter, with the rationale that the larger size may facilitate longer term release of CO2, and we found that these larger yeast-nutrient pellets also gave us a statistically signicant improvement in root ratings (3.0 , SE 0.2), significantly better than untreated corn. Effervescent tablets composed of sodium hydrogencarbonate and citric acid were tested as a non-microbial treatment capable of generating CO2, and we obtained statistically significant improvements in root rating (2.8, SE 0.3). The root ratings for yeast alone (3.3, SE 0.3) were not significantly better than those for the untreated corn, nor were the root ratings for sucrose alone (3.8, SE 0.3), and these results imply that the details of CO2-generating formulations are apparently important. Termite Attractants: We are the first laboratory to show that CO2 is attractive to any termite species. We showed in laboratory behavioral bioassays that the termite species Reticulitermes flavipes and Reticulitermes tibialis are attracted to CO2, in which we used a test concentration of 5 mmol/mol, or 0.5% CO2 in air. Our behavioral bioassay design involved a glass T-tube (5 mm ID), modified with a laboratory torch so that the ends of the two choice arms projected down at 45 degree angles from horizontal, to provide pitfalls after the termites made a choice. A syringe pump was used with two 35 ml polyethylene syringes, one filled with ambient air and the other filled with 5 mmol/mol CO2 in air, to convey the odors to the two arms of the T-tube, at 1.0 ml/min into each arm. We plan to use these results to develop several different approaches useful in termite pest management, including use of CO2 to attract termites to traps for monitoring the presence or abundance of termite, use of CO2 to attract termites to sources of insecticide, use of CO2 to attract termites to sources of food or other materials that arrest termite movement, use of CO2 to disrupt the orientation behavior of termites behaviorally rather than acting as a physiologically deleterious fumigant , use of CO2 as co-attractant for termites along with other attractive materials that may have fundamentally different chemistry. |
| 1998 | A behavioral bioassay was developed to test responses of newly hatched (neonate) larvae of western corn rootworm Diabrotica virgifera virgifera LeConte to volatile compounds from corn plants, a major host for this insect. A glass Y-tube filled with glass beads was used to allow choice tests in a vertical direction and to reproduce the thigmotactic cues available to larvae in their natural soil environment. A syringe pump was used to provide slow, consistent delivery of candidate compounds to the 2 sides of the apparatus. Significantly more larvae were attracted to the side containing a germinating corn seed than to the side containing ambient air. In addition, significantly more larvae were attracted to the side containing cut corn roots than to the side containing an ambient air control. Carbon dioxide (CO2) from corn roots previously has been implicated as an attractant for the larvae, and dose--response curves for larval attraction to CO2 were obtained using different sources (different dilutions of carbonated water, the headspace over a carbonated water dilution, and different concentrations of CO2 in air). The CO2 concentrations for all sources were measured by mass spectrometry with selected ion monitoring at m/e 44. Neonate larvae were significantly attracted to concentrations of CO2 as low as 1.125 SE 0.04 mmol/mol (concentration of CO2 in ambient air on the control side was 0.99 SE 0.02 mmol/mol). Larvae were optimally attracted to 2.51-4.20 mmol/mol CO2, but they were attracted to concentrations as high as 100 mmol/mol. Larvae were not attracted to 300 or 900 mmol/mol CO2, and they exhibited toxic symptoms at these high concentrations. The concentration of CO2 in soil near growing corn roots was 4.36 SE 0.31 mmol/mol, which was consistent with the behavioral optimum for the larvae. The concentration of CO2 in soil that contained no corn was 1.38 SE 0.03 mmol/mol and the concentration in ambient air was 0.94 SE 0.01 mmol/mol. |
| 1999 | Field tests were conducted with a total of 22 granular formulations applied to the soil for western corn rootworm control, including 17 behaviorally active formulations based on CO2-generating materials to attract the larvae. Some of the behaviorally active formulations contained small amounts of insecticides in conjunction with feeding stimulants to induce ingestion. Several CO2-generating formulations gave significant improvements in root ratings compared to untreated control plants, including some formulations containing insecticides and others lacking insecticides. Previous work in our laboratory has shown that CO2 is the only volatile compound from corn roots that attracts western corn rootworm larvae, suggesting the possibility that CO2-generating formulations applied to the soil may cause behavioral disorientation and prevent larvae from locating corn plants, providing a new method for pest control. Field tests were also conducted with CO2-generating formulations materials in traps for termites. Our laboratory was the first research group to show that CO2 is attractive to termites in the laboratory, and we have now demonstrated that traps emitting CO2 are attractive to termites in the field. |
| 2000 | Field tests were conducted with neonicotinoid insecticides in combination with CO2-generating formulations for the control of western corn rootworm larvae. Our laboratory has previously shown that CO2 attracts western corn rootworm larvae, which locate corn roots underground, and that enhanced control of the larvae can be achieved by using CO2-generating materials to attract the larvae to small amounts of insecticide. In field tests in Colorado corn fields, CO2-generating granules containing small amounts of neonicotinoid insecticides were added to the soil in the vicinity of corn seeds at planting time and/or at cultivation time. Neonicotinoid granules with CO2-generating materials added to them significantly reduced the number of larvae attacking corn plants compared to granules containing neonicotinoids alone. |
| 2001 | Baiting systems have become increasingly important in termite pest control, and we previously showed that CO2 is attractive to several species of termites, including Reticulitermes flavipes, R. virginicus, and R. tibialis. The interaction between attraction to CO2 and feeding behavior is not known, and field tests were conducted with an array of CO2-generating formulations (including loose granular materials and also pellets made with a laboratory press at 20,000 pounds per square inch) in conjunction with squares of wood available for termite feeding. Squares of wood were dried and weighed before and after each field test, to determine the amount of wood consumed. Traps were placed 2 meters from fence posts infested with Reticulitermes tibialis at ranches in Colorado. For both pelletized and loose forms of CO2-generating baits, CO2 caused significantly earlier arrival of termites than in traps without CO2 baits, caused more termites to be present than in traps without CO2 baits, and caused more wood to be consumed than in traps without CO2 baits. Wood consumption is a continuing record of termite activity in termite monitoring systems, and CO2 appears to be valuable in enhancing the likelihood that termite infestations will be detected by increasing the wood consumption that occurs. Baiting systems also rely on effective dispersal of pesticides through termite colonies by trophollaxis, or food-sharing, and CO2 is promising in enhancing effectiveness by increasing colony-wide consumption of cellulosic materials that contain pesticide. Surveys of termite-infested houses in Colorado revealed a pattern of infestation by different termite species that was not previously known. Winged aphids, or alates, were obtained from houses infested with termites in a number of communities in Colorado. Two different termite species were confirmed as pests in these communities, with a distinctive geographic distribution. In the more southern communities surveyed (Longmont, Arvada, and Boulder), Reticulitermes virginicus was identified as the pest species in each case. In the more northern communities surveyed (Fort Collins, Greeley, Loveland), Reticulitermes tibialis was identified as the pest species in each case. Reticulitermes tibialis has been historically the pest of concern in Colorado, but the finding that R. virginicus is also a significant pest in Colorado was unexpected. Species identifications of termites were confirmed with voucher specimens submitted to the Smithsonian Institution (David Nickle, termite systematist). Khapra beetle (Trogoderma granarium) is a serious grain pest not known to occur in the United States, and possible introductions are monitored each year with infochemical traps in grain facilities throughout Colorado. Although Khapra beetle was not found, the dermestid beetle species Trogoderma teukton was detected for the first time in Colorado. This species previously has been reported in the U. S. only from Iowa, Minnesota, North Dakota, and Washington. The occurrence of T. glabrum, T. granarium, T. inclusum, T. simplex, and T. variabile was also determined. |
| 2002 | Termites are known to prefer some woods over others, and we hypothesized that preferred woods may contain compounds that act as termite feeding stimulants. To examine this possibility, woods preferred by termites were extracted with hexane. Compounds in the extract were identified by gas-liquid chromatography and mass spectrometry (GC-MS) of trimethylsilyl derivatives prepared with bis (trimethylsilyl) trifluoroacetamide (with 1% dimethylchlorosilane as acid catalyst). We tested the phagostimulant activity of candidate feeding stimulants with Reticulitermes tibialis, a major structural pest in Colorado and other western states. Candidate feeding stimulants were tested with feeding bioassays on paper and on microcrystalline cellulose thin layer chromatography (TLC) plates. At ecologically relevant concentrations, R. tibialis fed significantly more on substrates containing candidate feeding stimulants than on controls. Field tests were performed on horse and cattle ranches with old wooden fenceposts, which are commonly infested with termites in Colorado. A hydraulic press was used to prepare pellets from cellulose powder impregnated with candidate feeding stimulants. The pellets were placed in perforated Nalgene jars containing moist soil, and the jars were buried beside termite-infested fenceposts. Pellets containing candidate feeding stimulants were fed upon significantly more (p < 0.05) than cellulose controls. Baiting systems have become increasingly important in termite pest control, and we previously showed that CO2 is attractive to several species of termites, including Reticulitermes flavipes, R. virginicus, and R. tibialis. Our identification of termite feeding stimulants complements our development of CO2-generating materials for termite attraction that can similarly be used for the development of new pest control approaches based on behavioral manipulation. Baiting systems also rely on effective dispersal of pesticides through termite colonies by trophollaxis, or food-sharing, and feeding stimulants may enhance effectiveness by increasing colony-wide consumption of cellulosic materials that contain pesticide. |
| 2003 | Termites are known to prefer some woods over others. Aspen (Populus tremuloides Michx.) is one of the preferred woods fed upon by Reticulitermes spp., and waferboard and flakeboard made from aspen are highly susceptible to termite damage. Chemical analysis of termite-resistant woods has led to the discovery of several termite feeding deterrents. We reasoned conversely that preferred woods may be particularly rich in compounds that act as termite attractants. Because termites are often found in moisture damaged wood, water extracts of aspen were tested for termite attraction. Blocks of aspen lumber were soaked 24 hours in distilled water, and this aqueous extract was tested in a behavioral bioassay. Two glass tubes (1 cm diameter, 30 cm high) were filled with soil. The aqueous extract of aspen was added to the top of one of the soil filled tubes, and water (control) was added to the top of the other. Equal amounts of liquid were added to both tubes, until liquid could be seen coming out of the bottoms of the tubes. The two tubes were then connected vertically through two holes in the lid of a plastic tub in order to make good surface contact with the soil in a plastic tub (100 ml) containing 100 termites workers. The tubes were checked for termites and termite activity after 24 hours. Data collected included both termite distance and number of termites. The distance the termites went up the soil filled tube was measured by recording the height of the termite tunnels in the tube. The number of termites present was measured by emptying the soil in the tubes into a water bath and counting the floating termites present. In tests with Reticulitermes virginicus and Reticulitermes flavipes workers, the aqueous aspen extract was significantly preferred over the control. Steam distillates of aspen wood were tested similarly, and in tests with Reticulitermes virginicus and Reticulitermes flavipes workers, the steam distillate was also significantly preferred over the control. |
| 2004 | To extract free fatty acids and hydrocarbons from the surfaces of honey bees, we added 1.0 ml 1M sodium hydroxide and 1.0 ml dichloromethane and shook with medium vigor for 2.0 min, to limit extraction to the surface of the bee. The dichloromethane extracts hydrocarbons and other less polar compounds from bee surface. The 1.0 M sodium hydroxide solution contained salts of free fatty acids from the surface of the bee. For analysis of the free fatty acids we added 2.0 ml 1 M hydrochloric acid to the 1 ml sample of 1 M sodium hydroxide containing the acids and extracted with dichloromethane to recover the free fatty acids. Eicosane ( 5 micrograms) was added as an internal standard. Methyl esters were prepared with boron trifluoride-methanol. Analysis was done by gas-liquid chromatography and compounds were identified by comparison of mass spectra and retention times with those of authentic standards . Field bioassays assessed the behavior of a pair of bees, a guard and a forager, from different honey bee colonies. Guards were identified at hive entrances and foragers were collected by identifying bees returning from foraging flights. Each bee was placed in a separate plastic bag. The forager was then dipped in a 1.0 M sodium hydroxide solution for 2 to 3 s., shaken to remove excess fluid, dipped a second time, and returned to her bag for 5 to 10 min to dry. After drying, the bees were placed together in a 10 cm. petri dish and their behavioral interactions observed for five min and are scored as described above. The null hypothesis (no effect of the wash) was that the bees would fight at the same rate as control pairs in which the forager was not washed. The alternate hypothesis was that sodium hydroxide treatment removes the free fatty acids by converting them to soluble salts; this deactivates their role in nestmate recognition and fewer fights would be expected. Newly emerged worker bees had substantially less total free fatty acids and total hydrocarbons on their surface than do older workers. The newly emerged workers did not differ significantly among colonies in total hydrocarbons or total fatty acids. We detected palmitic acid , palmitoleic acid, stearic acid, oleic acid), linoleic acid, linolenic acid, tetracosanoic acid, the 21, 23, 25, 27, and 29 carbon n-alkanes, and the corresponding alkene for each of the n-alkanes on the newly emerged bees and on older bees. Hexadecanoic acid concentrations are significantly lower on the surface of newly emerged bees than on foragers. Principal components analysis of FFA concentrations shows that newly emerged bees all have quite similar scores on the first principal component, and are substantially different from foragers. Sodium hydroxide washes significantly increased the probability of acceptance of foragers by guards from other colonies; 60% of guards rejected foreign foragers, while 32% of sodium hydroxide washed foragers were rejected. Guards rejected control bees washed in distilled water 57% of the time ; the distilled water controls did not differ significantly from the untreated controls. |
| 2005 | The fluorescent alkaloid norharmane has been isolated from Reticulitermes termites and characterized by H-1 NMR, UV/Vis, mass spectrometry, and gas chromatography/mass spectrometry . Norharmane was uniformly present at approximate to 1 ng/mg in Reticulitermes tibialis Banks workers, soldiers, and alates; Reticulitermes flavipes (Kollar) workers; and Reticulitermes virginicus (Banks) workers. Subterranean termites contend with substantial microbial disease pressure due to their soil habitat and social behavior, and the fluorescent alkaloid norharmane, known from several Reticulitermes spp., may be a critical defense in countering this pressure. Termite hemolymph containing norharmane and synthetic norharmanc at ecologically relevant concentrations both showed antimicrobial activity against the entomopathogenic fungus Metarhizium anisopliae (Metschnikoff). A qualitative survey of 18 termite genera showed universal norharmane presence. Norharmane was absent from five closely related taxa that were also analyzed. GC/MS analyses further showed that norharmane was biosynthesized as a metabolite from endosymbionts cultured in isolation from Reticulitermes tibialis and R. flavipes termites. Actinomycetes bacteria are likely candidates as the endosymbionts that biosynthesize norharmane, because they arc components of the termite gut and are the only microbes known to produce norharmane. Subterranean termites, Reticulitermes spp., were attracted to carbon dioxide (CO2) in laboratory and field tests. In behavioral bioassays, Reticulitermes flavipes (Kollar), Reticulitermes tibialis Banks, and Reticulitermes virginicus Banks were attracted to CO2 concentrations between 5 and 50 mmol/mol. In field tests, stations containing CO2-generating baits attracted R. tibialis away from wooden fence posts at rangeland sites in Colorado. For all of the CO2 formulations tested, termites foraged in significantly more bait stations at treatment fenceposts than in bait stations at the control fenceposts. CO2 used as an attractant in current baiting systems could improve their effectiveness by allowing earlier exposure of termites to an insecticide. Amounts of the insecticide thiamethoxam required for 50% mortality of western corn rootworm larvae, Diabrotica virgifera virgifera LeConte, were reduced 100-fold when extracts of germinating corn, Zea mays L., were used to entice neonate larvae to feed on it. In behavioral bioassays, neonate rootworm larvae fed vigorously on filter paper disks treated with liquid pressed from corn roots. Larvae wandered away from filter paper disks treated with distilled water without feeding. For solutions containing 10 ppm thiamethoxam, 95% larval mortality occurred after 30 min of exposure when corn extract was present, but only 38% mortality occurred when the same concentration of insecticide alone (no feeding stimulants) was tested. Thiamethoxam did not deter larval feeding on corn extract, even at the highest concentration of thiamethoxam tested. |
| 2006 | Termite bait stations with or without a CO2-generating bait (Focus Termite Attractant, produced by Brotica, Inc., Fort Collins, Colorado, and distributed by Ensystex Australasia) were tested at tree and house locations in Australia. The termite species Coptotermes acinaciformis (Froggatt) (Isoptera: Rhinotermitidae), Schedorhinotermes intermedius (Brauer) (Isoptera: Rhinotermitidae), Microcerotermes turneri (Froggatt) (Isoptera: Termitidae), and Nasutitermes exitiosus (Hill) (Isoptera: Termitidae) discovered more monitoring stations when the CO2-generating bait was present, and also discovered the monitoring stations more quickly when the CO2-generating bait was present. Reticulitermes tibialis Banks, R. flavipes (Kollar) and R. virginicus (Banks) termites contain the phototoxic alkaloid norharmane, and ultraviolet light exposure experiments (60 and/or 30 W/m(2)) caused high autophototoxic mortality in all three species. This may be the first known instance of autophototoxicity in nature. Norharmane has been previously reported as a phototoxin when fed to other insects, and this termite endosymbiont-produced beta-carboline may be the causal agent in Reticulitermes spp. autophototoxic mortality. Regardless of mechanism, the observed UV-induced termite mortality suggests novel pest control possibilities. UV exposure bioassays with half-covered arenas showed that Reticulitermes termites are negatively phototactic to ultraviolet light. Additionally, mortality was significantly reduced in half-covered arenas compared to uncovered controls and this may be a mechanism by which the termites avoid autophototoxicity. Norharmane transfer between trophic levels was observed in saprophagous Tyrophagus sp. mites, associated with laboratory colonies of Reticulitermes, which become fluorescent after ingesting norharmane from termite cadavers. In contrast to termites, these mites showed no mortality when exposed to UV light. No UV-mediated mortality was observed in pavement ants, Tetramorium caespitum L., fed on sucrose and norharmane, discounting the hypothesis that norharmane may play a role in predation protection. |
| Impact | |
| 1999 | Western corn rootworms are the most damaging insect pests in corn ($1 billion annually, and we are developing less toxic means for the control of these pests by manipulating their behavior with CO2, a non-toxic compound. This is consistent with the goals of the Food Quality Protection Act. We have now demonstrated that CO2-emitting traps are effective in attracting and catching termites in the field. This will be useful in developing improved baiting technology for termites, the most successful and environmentally benign new technique for termite control that is on the market. |
| 2000 | Neonicotinoid insecticides are among the newer classes of environmentally benign materials that are encouraged by the Food Quality Protection Act, with better differential toxicity and residue properties than older classes of insecticides. Western corn rootworms are among the most damaging insect pests in corn, responsible for more than $1 billion annually in the United States in combined damage and control costs. |
| 2001 | Termites are among the most serious pests worldwide, and CO2 baits have considerable promise in improving the efficacy of newly-developed baiting systems for their control. Khapra beetle trap data is useful in export enhancement. |
| 2002 | Termites are among the most serious pests worldwide, and baits that contain behaviorally active compounds have considerable promise in improving the efficacy of newly-developed baiting systems for pest control. |
| 2003 | Termites are among the most damaging structural pests, responsible for more than $11 billion annually in the United States in combined damage and control costs (Su. 2002. Sociobiology 40: 95-101). Termite attractants can be used to monitor adult populations to assess damage potential, and can also be combined with pesticides to minimize the amounts required for control. |
| 2004 | Special features facilitate the admission of new members, such as neonates, to otherwise closed animal societies. In eusocial insects, such as honeybees and paper wasps, young adults acquire a colony recognition phenotype from other colony members or nesting materials. Older adults must exempt them from expulsion during the acquisition period. Newly emerged adult honeybees gain tolerance in their colony before their acquisition of the colony recognition phenotype by presenting a blank slate, absent recognition cues. This makes them generically acceptable in honey bee colonies. This strategy is analogous to the easily recognizable phenotypes associated with juvenility in birds and mammals. |
| 2005 | 1. Our discovery that termites are attracted to CO2 can be used in the development of improved monitoring and pest management techniques for termites. 2. Our discovery that termites contain a high concentration of norharmane means that termites can be used as a model system to study the effects of the toxin norharmane in human health. 3. Our discovery that feeding stimulants allow a 100-fold reduction in the amount of insecticide required to control corn rootworms can be used to improve the environmental quality of agroecosystems. |
| 2006 | 1. Our discovery that 6 species of termites in Australia are attracted to CO2 can be used in the global development of improved monitoring and pest management techniques for termites. 2. Our discovery that ultraviolet light causes high mortality in termites, due to the high concentration of the phototoxin norharmane that termites naturally contain, means that a new method of termite pest control is now possible. |
| Publications | |
| 1993 |
ABOU-FAKHR, E. 1993. Physiological and behavioral effects of secondary plant compounds on western corn rootworm, Diabrot ica virgifera virgifera. Masters thesis, Colorado State Univ ersity. BJOSTAD, L.B., B.E. HIBBARD, & W.S. CRANSHAW. 1993. Applic o f semiochem. in IPM programs. Chap 17 in Pest Control Agents & Tech with Reduced Environ Impact. S.O. Duke, J.J. Menn, & J.R . Plimmer, eds Amer Chem Soc Symp Ser. WA,D.C CARMICHAEL, L.M., J. MOORE & L.B. BJOSTAD. 1993. Parasitism and decreased response to sex pheromones in male Periplaneta americana (Dictyoptera: Blattidae). J. Insect Behavior 6:25 -32 . JEWETT, D.K. 1993. Sex pheromones of the trichoptera. Master s thesis, Colorado State University. |
| 1994 |
ABOU-FAKHR, E., B.E. HIBBARD, & L.B. BJOSTAD. 1994. Tolerance of westrn corn rootworm larvae (Coleoptera:Chrysomelidae) to 6-methoxy-2-benzoxazolinone, a corn semiochemical for larval host location. J. of Econ Entomol 87: 647-652 DONG, H., J.S. QUICK, D.L. BRIGHAM, L.B. BJOSTAD, J.B. RUDOLPH, & F.B. PEAIRS. 1994. Leaf unrolling of three wheat genotypes in Russian wheat aphid extracts. Cereal Research Communications 22: 375-379 HIBBARD, B.E., E.J. BERNKLAU, & L.B. BJOSTAD. 1994. Long chain free fatty acids: semiochemicals for host location by western corn rootworm larvae (Coleoptera: Chrysomelidae). Journal of Chemical Ecology 20: 3335-3344 |
| 1996 |
Abou-Fakhr E, Hibbard BE, Jewett DK, Bjostad LB. 1996. Electroantennogram responses of western corn rootworm (Coleoptera: Chrysomelidae) adults in relation to maize silk morphology and phenology. Environ. Entomol. 25:430-435 Bjostad LB, Jewett DK, Brigham DL. 1996. Sex pheromone of the caddisfly Hesperophylax occidentalis.(Banks)(Trichoptera: Limnephilidae). J. Chem. Ecol. 22: 103-122 Jewett D, Brigham DL, Bjostad LB. 1996. Hesperophylax occidentalis (Banks)(Trichoptera: Limnephilidae) sex pheromone structure-activity study with electroantennograms. J. Chem. Ecol. 22: 123-138 Jewett DK, and Bjostad LB. 1996. Dichloromethane attracts diabroticite larvae in a laboratory behavioral bioassay. Journal of Chemical Ecology 22:1331-1344 |
| 1997 |
Bernklau, E.J. 1997. Infochemicals and host location by western corn rootworm larvae. M.S. Thesis. Colorado State University Hibbard, B.E., Jewett, D.K., Bjostad, L.B. 1997. Pentanoic acid attracts Olcella parvis (Adams)(Diptera: Chloropidae) in Colorado corn fields. J. Kansas Entomol. Soc. 70: 67-69 Hibbard, B.E., T.L. Randolph, E.J. Bernklau, & L.B. Bjostad. 1997. Electroantennogram-active components in buffalo gourd root powder for western corn rootworm adults. Environ. Entomol. 26: 1136-1142 Hibbard, B.E., T.L. Randolph, E.J. Bernklau, E.M. Abou-Fakhr & L.B. Bjostad. 1997. Electroantennogram-active components of maize silk for adults of the western corn rootworm (Coleoptera: Chrysomelidae). Environ. Entomol. 26: 285-296 Jewett DK, and Bjostad LB. 1997. Structure-activity study with haloalkane attractants of western corn rootworm (Coleoptera: Chrysomelidae) larvae using a behavioral bioassay. J. Entomol. Sci. 32: 91-105 |
| 1998 |
Bernklau, E.J., and Bjostad, L.B. 1998. Behavioral responses of first-instar western corn rootworm to carbon dioxide in a glass bead bioassay. J. Econ. Entomol. 91:444-456 Bjostad, L.B. 1998. Electrophysiological methods. Chapter 9. Methods in Chemical Ecology. J.G. Millar and K.F. Haynes, eds. ISBN 0-412-08071-0. Kluwer Academic Publishers, Norwell, Massachusetts |
| 1999 |
Bjostad LB, Bernklau EJ, Fromm EA. Filed 19 November 1998. Method and Device for Attracting Insects. U. S. Patent Provisional Application 60\107,285 Bjostad LB, Bernklau EJ, Fromm EA. Filed 4 November 1999. Method and Device for Attracting Insects. Patent Cooperation Treaty Application PCT/US99/26074 |
| 2000 |
Bjostad LB, Bernklau EJ, Fromm EA, Morton V. Filed 26 June 2000. Method and Device for Attracting Insects. PCT Patent Application No. PCT/US00/13477. |
| 2001 |
Bishop, R.J., Bernklau, E.J., Bjostad, L.B. 2001. A new state record for Trogoderma teukton (Coleoptera : Dermestidae) in Colorado with notes on other Trogoderma species. Entomological News 112 (4): 281-284. |
| 2002 |
Bjostad, L.B., Bernklau, E.J., Fromm, E.A. 2002. Patent Application 2730-65-PZA (South Africa) , Serial No. 2001/3584 Bjostad, L.B., Bernklau, E.J., Fromm, E.A. 2002. Patent Application 2730-65-PROV (Provisional) , Serial No. 60/107,285 Bjostad, L.B., Bernklau, E.J., Fromm, E.A. 2002. Patent Application 2730-65-PUS (United States), Serial No. 09/831,094 Bjostad, L.B., Bernklau, E.J., Fromm, E.A. 2002. Patent Application 2730-65-AR (Argentina), Serial No. P990105629 Bjostad, L.B., Bernklau, E.J., Fromm, E.A. 2002. Patent Application 2730-65-PEP (Europe), Serial No. 99961587.5 Bjostad, L.B., Bernklau, E.J., Fromm, E.A. 2002. Patent Application 2730-65-PJP (Japan), Serial No. 2000-580439 Bjostad, L.B., Bernklau, E.J., Fromm, E.A. 2002. Patent Application 2730-65-PBR (Brazil), Serial No. PI 9915306-8 Bjostad, L.B., Bernklau, E.J., Fromm, E.A. 2002. Patent Application 2730-65-PAU (Australia), Serial No. 18134/00 Bjostad, L.B., Bernklau, E.J., Fromm, E.A. 2002. Patent Application 2730-65-PCT (International), Serial No. PCT/US99/26074 |
| 2003 |
Bjostad, L.B., Bernklau, E.J., Fromm, E.A. 2003. Patent Application 2730-65-PZA (South Africa) , Serial No. 2001/3584 Bjostad, L.B., Bernklau, E.J., Fromm, E.A., Morton, H. V. 2003. Patent Application 2730-65-CIP-PZA (South Africa), Serial No. 2002/3664 |
| 2004 |
Breed MD, Perry S, Bjostad LB Testing the blank slate hypothesis: why honey bee colonies accept young bees Insectes Sociaux 51 (1): 12-16 2004 |
| 2005 |
Bernklau, E.J., and Bjostad, L.B. 2005. Insecticide enhancement with feeding stimulants in corn for western corn rootworm larvae (Coleoptera : Chrysomelidae) J. of Economic Entomology, 98 (4):1150-1156. Aug. Bernklau, E.J., Fromm, E.A., Judd, T.M., and Bjostad, L.B. 2005. Attraction of subterranean termites (isoptera) to carbon dioxide. J. of Economic Entomology. 98 (2):476-484. Apr. Siderhurst, M.S., James, D.M., Blunt, T.D., and Bjostad, L.B. 2005. Antimicrobial activity of the termite (Isoptera) alkaloid norharmane against the entomopathogenic fungus Metarhizium anisopliae. Sociobiology, 46 (3):563-577. Siderhurst, M.S., James, D.M., Blunt, T.D., and Bjostad, L.B. 2005. Endosymbiont biosynthesis of norharmane in Reticulitermes termites (Isoptera : Rhinotermitidae) Sociobiology. 45(3):687-705. Siderhurst, M.S., James, D.M., Rithner, C.D., Dick, D.L., and Bjostad, L.B. 2005. Isolation and characterization of norharmane from Reticulitermes termites (Isoptera : Rhinotermitidae). J. of Economic Entomology. 98 (5):1669-1678 Oct. |
| 2006 |
Broadbent S., Farr M., Bernklau E.J., Siderhurst M.S., James D.M., Bjostad L.B. 2006. Field attraction of termites to a carbon dioxide-generating bait in Australia (Isoptera). SOCIOBIOLOGY 48 (3): 771-779 Siderhurst M.S., James D.M., Bjostad L.B. 2006. Ultraviolet light induced autophototoxicity and negative phototaxis in Reticulitermes termites (Isoptera : Rhinotermitidae). SOCIOBIOLOGY 48 (1): 27-49 |