Polymer powder prepregging: Scoping study

Early on, it was found that NEAT LARC-TPI thermoplastic polyimide powder behaved elastoplastically at pressures to 20 ksi and temperatures to 260 degrees celcius (below MP). At high resin assay, resin powder could be continuously cold-flowed around individual carbon fibers in a metal rolling mill. At low resin assay (2:1, C:TPI), fiber breakage was prohibitive. Thus, although processing of TPI below MP would be quite unique, it appears that the polymer must be melted and flowed to produce low resin assay prepreg. Fiber tow was spread to 75 mm using a venturi slot tunnel. This allowed intimate powder/fiber interaction. Two techniques were examined for getting room temperature powder onto the room temperature fiber surface. Electrostatic powder coating allows the charged powder to cling tenaciously to the fiber, even while heated with a hot air gun to above its melt temperature. A variant of the wet slurry coating process was also explored. The carbon fibers are first wetted with water. Then dry powder is sprinkled onto the wet tow and doctor-rolled between the fibers. The wet structure is then taken onto a heated roll, with hot air guns drying and sinter-melting the powder onto the fiber surfaces. In both cases SEM shows individual fibers coated with powder particles that have melted in place and flowed along the fiber surface via surface tension

SEASONAL FLIGHT ACTIVITY OF THE MAIZE WEEVIL, \u3ci\u3eSITOPHlLUS ZEAMAIS\u3c/i\u3e MOTSCHULSKY (COLEOPTERA: CURCULIONIDAE), AND THE RICE WEEVIL, \u3ci\u3eS. ORYZAE\u3c/i\u3e (L.), IN SOUTH CAROLINA

Flight activity of Sitophilus zeamais Motschulsky (Coleoptera: Curculionidne) and S. oryzae (L.) was monitored during 1987-88 with sticky traps at three sites in South Carolina. Weevils were caught from late March to early November. The results indicate that temperature is the major factor determining seasonal flight activity of these weevils. More S. zeamais than S. oryzae were trapped at all sites. Sitophilus oryzae were abundant only at the site at which wheat was stored. There was no apparent pattern to flight activity within a storage site. The results indicate that there is little night activity around bins in which recommended pest control practices are followed

SEASONAL ABUNDANCE OF MAIZE AND RICE WEEVILS (COLEOPTERA: CURCULIONIDAE) IN SOUTH CAROLINA

Seasonal abundance of Sitophilus zeamais (SZ) and S. oryzae (SO) outside grain bins was monitored during 1986-88 with com-filled bait packets at three grain storage sites in southern South Carolina. Com was the predominant commodity stored at all sites. SZ were abundant and caught year-round at all sites, whereas SO were abundant and caught year-round only at the site at which wheat was stored regularly. Most weevils were caught during weeks when average temperatures were at or above 20°C. Catches generally peaked in fall, after newly-harvested grain was placed into storage. Catches fell during winter, began to rise in spring. peaked again during summer, and declined again in late summer. Results indicate that grain is susceptible to infestation by Sitophilus spp. year-round in South Carolina

Correlation of a-Amylase Inhibitor Content in Eastern Soft Wheats with Development Parameters of the Rice Weevil (Coleoptera: Curculionidae)

The a-amylase inhibitor content in saline extracts of 104 Eastern soft wheat cultivars was determined by assay against a purified a-amylase preparation from the rice weevil, Sitophilus oryzae (L.). A two-fold range of inhibitor levels, expressed as amylase inhibitor units per gram of dry weight (AID/g), was found across all cultivars. Inhibitory activity was lowest in cultivar \u27Augusta\u27 (5,084 ± 124 AIU/g) and highest in cultivar \u27Logan\u27 (10,410 ± 61 AID/g). No correlation of inhibitor content with progeny production (r = -0.161) or rate of emergence (r = -0.292) was found among weevils reared on 30 cultivars having relatively low, medium, and high inhibitor levels, but there was a positive correlation between inhibitor content and average number of days to adult emergence (r = 0.569). Although mean development times were significantly different on cultivars with low and high AIU/g (35.9 ± 0.2 and 36.6 ± 0.1 d, respectively), the differences were only slight and indicated that, for these cultivars of soft wheats, a-amylase inhibitors have little practical effect on initial population reductions. Nevertheless, based on a population model for S. oryzae developing on wheat at 25°C and 75% RH, the slight delay in mean development time (0.7 d) on cultivars with relatively high AIU/g results in a 20.9% reduction in total number of weevils after 180 d. Simulations also indicate that physical or biochemical resistance factors in wheat have to delay development time for about 6.2 d or reduce fecundity by about 40% to prevent wheat from being graded weevily 180 d after a single pair of weevils infests a hypothetical 6,000-bushel wheat bin

Oil-Soluble Dyes Incorporated in Meridic Diet of \u3ci\u3eDiatraea grandiosella\u3c/i\u3e (Lepidoptera: Crambidae) as Markers for Adult Dispersal Studies

Mark-release-recapture experiments to study insect dispersal require the release of marked insects that can be easily identified among feral conspecifics. Oil-soluble dyes have been used successfully to mark various insect species. Two oil-soluble dyes, Sudan Red 7B (C.I. 26050) and Sudan Blue 670 (C.I. 61554), were added to diet of the southwestern corn borer, Diatraea grandiosella Dyar, and evaluated against an untreated control diet. Survival, diet consumption, larval and pupal weight, development time, fecundity, longevity, and dry weight of the adults were measured. Adults reared on the three diets were also tested for mating success. Some minor effects were observed for southwestern corn borers reared on the marked diets. Eggs, larvae, pupae, and adults were all reliably marked and readily identifiable. Adults retained color for their entire life span. Adults from each diet mated successfully with adults from the other diets. F1 progeny from the different mating combinations survived to the second instar but tended to lose the marker after 3-4 d on untreated diet. Both Sudan Red 7B and Sudan Blue 670 can be used to mark southwestern corn borer adults and thus should be useful for mark-release-recapture dispersal studies. The dyes will also be useful for short-term studies with marked larvae and oviposition behavior

Freezing for control of stored-product psocids

A series of studies was conducted by exposing young and old eggs, nymphs, and adults of the psocids Liposcelis bostrychophila (Badonnel), L. paeta (Pearman), L. decolor (Pearman), and L. entomophila (Enderlein) to -18°C for various time intervals. Survival was assessed as initial and final, at different times depending on the life stage. Young eggs of L. bostrychophila were the most tolerant life stage of any of the species, with scattered survival out to 120 h of exposure to -18°C. Eggs were the most tolerant life stage for each species, requiring 24, 12, and 2 h of exposure for complete kill of L. paeta, L. decolor, and L. entomophila, respectively. Nymphs and adults of all species were far more susceptible than eggs, with no final survival after two hours of exposure. Results show the extreme variation between different psocid life stages and species to cold temperatures, and provide guidelines for using cold as a control strategy for psocids. Our results show that 24 h at -18°C is sufficient to kill all life stages of the psocid species tested, except for young L. bostrychophila eggs which will require at least 128 h of exposure at -18°C for complete mortality

Dispersal of Adult \u3ci\u3eDiatraea grandiosella\u3c/i\u3e (Lepidoptera: Crambidae) and Its Implications for Corn Borer Resistance Management in \u3ci\u3eBacillus thuringiensis\u3c/i\u3e Maize

Dispersal of the southwestern corn borer, Diatraea grandiosella Dyar, was examined by release and recapture of dye-marked adults and by capture of feral adults in and around 50-ha center pivot irrigated fields of Bacillus thuringiensis (Bt) maize. Pheromone and blacklight traps were used to capture the adults. In 1999, 2000, and 2001, a total of 177, 602, and 1,292 marked males, and 87, 231, and 1,045 marked females were released in four irrigated Bt maize fields, respectively. Recapture beyond release point was 2.13, 6.17, 3.16, and 17.91% for males and 0, 0, 2.23, and 4.18% for females in the four fields, respectively. One male was recaptured over native vegetation outside the field perimeter, and one was caught in a neighboring maize field, 457 m from the release point. An exponential decay function explained recapture of marked adults across the dispersal distance. More than 90% of adults were recaptured within 300 m of the release point. Large numbers of feral adults were captured throughout the study fields and over native vegetation between fields. The feral adult dispersal could be described with a linear model. Virgin females (38% marked and 14% feral) were captured throughout the study fields. The recapture of marked insects suggests that the dispersal was limited. However, capture of feral adults throughout Bt maize fields indicates that the actual dispersal may be more extensive than indicated by recapture of marked adults. Potential refuge sources for the feral adults were 587-1,387 m from the edge of the fields. There seems to be some dispersal of D. grandiosella from the nontransgenic “refuge” fields into the transgenic fields, which may allow for some genetic mixing of the Bt-resistant and -susceptible insects to help suppress potential evolution of pest resistance to transgenic maize. However, it is not clear whether the dispersal recorded in this study is sufficient to support the current resistance management strategy for corn borers

Rubidium Chloride and Cesium Chloride Sprayed on Maize Plants and Evaluated for Marking \u3ci\u3eDiatraea grandiosella\u3c/i\u3e (Lepidoptera: Crambidae) in Mark–Recapture Dispersal Studies

Experiments were undertaken to determine the potential for using rubidium chloride (RbCl) or cesium chloride (CsCl) to mark southwestern corn borer, Diatraea grandiosella Dyar, for use in applied ecological studies. Maize, Zea mays L., plants were sprayed with aqueous solutions of RbCl or CsCl at rates of 100, 1000, or 10,000 µg/g and inoculated with D. grandiosella neonates. Rubidium and cesium were successfully absorbed and translocated in maize plants. There were only a few minor effects of the treatment on maize or on southwestern corn borers.Rb and Cs were detected in plants, but not in insects, by using Flame atomic absorption spectrophotometry. Graphite furnace-atomic absorption spectrophotometry (GF-AAS) and neutron activation analysis (NAA) allowed identification of Rb and Cs in adults. Rb and Cs were detected by GF-AAS in feral unmarked adults, and they contained higher levels of Rb than Cs. Males and females contained similar amounts of Rb, but Cs levels were higher in males than in females. Adults recovered from field maize treated with 1000 µg/g Cs had higher levels of Cs than did those from untreated plants. Using NAA, neither Rb nor Cs was detected in adults recovered from greenhouse-grown untreated maize. Males and females recovered from maize treated with 1000 µg/g RbCl and CsCl contained similar amounts of Rb, but females contained more Rb than Cs. We conclude that application of 1000 µg/g RbCl or CsCl on plants is effective in marking adults of D. grandiosella with Rb or Cs and would be useful for mark-recapture dispersal studies

Cold temperature disinfestation of bagged flour

We conducted studies using a commercial freezer maintained at -17.8°C to determine the time needed to kill Tribolium castaneum eggs in a pallet of flour. Each bag weighed 22.7 kg, and there were 5 bags in each of 10 layers. The dimensions of the pallet were 109-cm wide by 132-cm long by 123-cm tall, and the weight of the stacked pallet was approximately 1152 kg. We conducted tests for nine internal goal temperatures of -12, -10, -8, -6, -4, -2, 0, 4 and 8°C. Internal temperatures in the most central location of the flour pallet reached: -11.0, -9.4, -6.9, -5.0, -3.5, -1.6, -0.1, 3.3, and 5.6°C and were achieved after 11.0, 9.1, 8.9, 7.2, 6.7, 5.8, 5.5, 5.2, and 4.2 days, respectively. For treatments where the goal temperature for the center bag ranged from -12 to 4°C, egg mortality was 100% in bags located in both the periphery and in the center of the pallet. When the temperature goal for the center bag was 8°C, 7 ± 2.5% of the eggs survived in bags located near the center of the pallet. Our data showed that temperatures that follow the dynamic temperature curve that takes place over 24.2 days (cool down and warm up for the 0°C temperature goal) resulted in 100% mortality of T. castaneum eggs. The reason for the difference in mortality for a static compared to a dynamic temperature treatment may be due to the fact that the dynamic temperature treatment occurs over a much longer duration. The fact that the treatment only required 5.5 days in the freezer before it could be shipped makes it a practical method to disinfest pallets of flour, especially because the bags do not need to be removed from the pallet and no chemicals are used

Insect-Attracting and Antimicrobial Properties of Antifreeze for Monitoring Insect Pests and Natural Enemies in Stored Corn

Insect infestations in stored grain cause extensive damage worldwide. Storage insect pests, including the Indianmeal moth, Plodia interpunctella (Hubner) (Lepidoptera: Pyralidae); Sitophilus spp. (Coleoptera: Curculionidae); and their natural enemies [e.g., Cephalonomia tarsalis (Ashmead) (Hymenoptera: Bethylidae), and Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae)] inhabit a temporary, but stable ecosystem with constant environmental conditions. The objective of the present experiment was to assess the efficacy of using ethylene glycol antifreeze in combination with nutrient solutions to monitor storage insect pest and natural enemy populations in three bins of corn, Zea mays L. The treatments were deionized water, a diluted (1:5 antifreeze:water) antifreeze solution, 10% honey, 10% honey in the diluted antifreeze solution, 10% beer in the diluted antifreeze solution, 10% sucrose in the diluted antifreeze solution, and a commercial pheromone trap suspended in a 3.8-liter container filled with 300-ml of diluted antifreeze solution. The seven treatments captured storage insect pests and their natural enemies in the bins at 33-36°C and 51-55% RH. The pheromone trap in the container with the diluted antifreeze captured significantly more P. interpunctella than the other treatments, but a lower percentage (7.6%) of these captures were females compared with the rest of the treatments (\u3e40% females). All trapping solutions also captured Sitophilus spp. and other beetle species, but the captures of the coleopteran pests were not significantly different among the seven treatments (P \u3e 0.05). Two parasitoid wasps also were captured in the study. The number of A. calandrae was different among the seven treatments (P \u3c 0.05), whereas the number of C. tarsalis was not different among the treatments (P \u3e 0.05). Most A. calandrae adults were captured by the 10% honey in the diluted antifreeze, whereas the fewest were captured in the deionized water. Microbial growth was observed in the 10% honey solution, but no microbial growth occurred in the rest of the treatments, including 10% honey in the diluted antifreeze solution. The results of insect captures and microbial growth demonstrated that antifreeze could be used as a part of storage insect monitoring and/or control programs