Progress 01/01/00 to 12/31/04
Outputs
Cockroach reproductive biology: Basic studies on German cockroach egg case (oothecae) physiology indicates that the water balance of developing embryos provided by the female is most likely facilitated by a series of small 5 micron pores in the oothecal case that are in contact with the females' oothecal chamber. Experiments using radiolabeled water to examine the water balance relationships between the female and developing embryos contained in attached egg cases indicate that water-deprived females retain more water than those having access to water. Water-deprived females held at lower humidities (50 & 30 percent RH) transfer more water into their egg cases. Further, we have found that under conditions of extremely low humidity (5 percent RH) and severe dehydration (no access to water), both females and their egg cases retained proportionally more water than those allowed access to water. Our results indicate that females are able to regulate their body water
balance and contribute to water balance of the developing embryos that they are carrying under a variety of environmental conditions. Light, scanning electron, confocal, darkfield microscopic and videographic studies on the egg case have revealed that chorion covering the eggs within the egg case is quite complex. It extends into the atrium of the egg case keel, becoming structures identified as spongy bodies. This new information should help to resolve some of the controversy that has resulted from observations provided by other workers. We have developed a three dimensional representation of the structural anatomy of these structures portraying it as a system that functions allowing for air exchange (supply) to the eggs while providing for water conservation and transport within the egg case. Studies on cold adaptation in lady beetles: Studies on cold-adapted aggregated imported lady beetles Harmonia axyridis have shown that this insect can avoid freezing by super cooling their body
fluids. We found that whole body extracts from cold-adapted insects contain two polyols (glycerol and inositol) which are most likely associated with exposure to seasonal temperature changes and are involved with the frost protection phenomenon.
Impacts
Development of basic information on the physiological mechanisms linked to a better understanding of the German female cockroach and her egg case structural anatomy may provide a basis for developing improved control strategies for this urban pest. Knowledge of the basic overwintering biology of H. axyridis may provide a basis for developing management strategies that decrease the role of the beetle as a seasonal urban pest, while at the same time contributing to its more efficient use in integrated pest management.
Publications
- Perrott, R, D. M. Miller and D. E. Mullins. 2005. Inulins, Levans, Fructans and Other Smaller-Than-Cellulose Termite Feeding Attractants, and Termite Baiting. International Patent Application No. PCT/US2005/009348.
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Progress 10/01/03 to 09/30/04
Outputs
Research activities this year have included four areas: 1. Studies on coating entomopathogenic fungi, Metarhizium anislopiae spores for protection against UV-B radiation and desiccation have resulted in limited success. Although we have been able to coat these fungal spores, we have not yet demonstrated that spores are completely covered by the coating medium. 2. Evaluation of neem extraction from neem leaves has indicated that the current method used in developing countries (Mali) removes only small amounts of neem present in the neem leaves. However, the use of alcohol-based solvents appears to improve neem availabilty for use as an insecticide. 3. Laboratory experiments with potash have shown that it can act as an effective herbicide in areas which require the need for a low cost method for controlling weeds during the dry season in Mali. 4. We have completed an environmental study of pesticides in the soils from cotton growing areas of Mali. Forty-six of 60 (77
percent) samples contained detectable pesticide residues, but in relatively low amounts. The most common materials detected were p,p-DDT and its breakdown products, endosulfan(s) I and II, endosulfan sulfate and profenofos.
Impacts
Development of coating agents of entomopathogenic organisms such as M anislopiae which will promote protection from UV-B radiation and desiccation should improve their use as biocontrol agents in the field where intense sunlight and low relative humidity currently restrict their effectiveness. Studies on the use of improved neem extract preparations for insect control and potash as an herbicide, may provide farmers in developing countries with alternative, low cost pest control methods.
Publications
- No publications reported this period
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Progress 10/01/02 to 09/30/03
Outputs
Experimentation on the effects of relative humidity on the water balance of gravid female German cockroaches was continued from the last reporting period. Females carrying either 0-1 or 14-day-old egg cases were injected with tritiated water and held at a rigid relative humidity of less than 5 percent. Experimental groups of females allowed/not allowed access to water were examined at 24, 72 and 168 hours post injection. Results from these experiments indicate that under conditions of extremely low humidity and severe dehydration (no access to water), both females and their egg cases retained proportionally more tritiated water than those allowed access to water. This fits well with information we have obtained earlier in experiments with females held at higher relative humidities. Study of the German cockroach egg case internal anatomy using light and scanning electron microscopy indicates that the chorion covering the eggs is quite complex and extends into the
atrium of the egg case keel, becoming spongy bodies. From these studies, we have provided new information which should help to resolve some of the controversy that has resulted from observations made by other workers. To explain our interpretation of our data and that of these other reports, we have developed a three dimensional representation of the structural anatomy of these structures portraying it as a system that functions allowing for air exchange (supply) to the eggs while providing for water conservation and transport within the egg case. Further, we have obtained some experimental evidence using videography and darkfield illumination showing that the unique bilayer structure of the chorion can allow for air and water transport simultaneously.
Impacts
The physiology of the embryos contained in the cockroach egg case is quite complex. The structural relationships of the internal anatomy which provide for water balance of the developing embryos contributes significantly to the reproductive success of this insect. Development of basic information on the physiological mechanisms linked to a better understanding of the egg case structural anatomy may provide a basis for developing improved control strategies for this urban pest.
Publications
- Leland J. E., D. E. Mullins, and D. F. Berry. 2003. The fate of 14C-Diazinon in compost-amended soil, and uptake by earthworms. J. Environ. Sci. Health B38(6) (In press)
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Progress 10/01/01 to 09/30/02
Outputs
We are studying the effects of relative humidity on the water balance of gravid female German cockroaches. Females carrying either 0- to 1-day-old egg cases or 14-day-old egg cases were injected with tritiated water and held at rigid relative humidity regimes (30, 50 and 70 percent). The amount of (tritiated) water contained in the females and their egg cases were examined after 24, 72 and 168 hour intervals. The results from these experiments indicate that water deprived females retain more tritiated water than those having access to water. In addition, the water deprived females held at the lower humidities (30 and 50 percent) transferred more (tritiated) water into their egg cases. It appears that females are able to regulate their body water balance and contribute to water balance of the egg case that they are carrying.
Impacts
Water balance of the cockroach egg case is known to be important in the reproductive success of this species as indicated by its influence on the ability of the eggs contained in the egg case to develop and hatch. Basic information on the respiratory and water balance mechanisms utilized by German cockroach oothecae may provide a basis for developing new control strategies for this important urban pest.
Publications
- Mullins, D. E., K. J. Mullins and K. R. Tignor. 2002. The structural basis for water exchange between the female cockroach (Blattella germanica) and her ootheca. J.exp. Biol. 205:2987-2996
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Progress 10/01/00 to 09/30/01
Outputs
Structural studies the German cockroach egg cases (oothecae) have provided new evidence that oothecal water balance mechanisms mediated by the female are most likely facilitated by the presence of a series of small, 5 micron pores in the oothecal case that are in contact with the female oothecal chamber. Confocal microscopy has confirmed that these pores penetrate the oothecal case and are associated with the water distribution system within oothecae. Scanning and transmission microscopy has provided new evidence that the spongy bodies and the associated chorion contained within oothecae form a structural basis for oothecal water conservation during respiration of developing embryos contained within oothecae. We have found that cold-adapted aggregated imported lady beetles Harmonia axyridis showed significant increases in their ability to supercool during cold temperature exposure. Comparisons of individuals collected from a natural aggregation in Cary, NC. in
February, 2001 had lower SCP's (-14.4 + 0.6 degrees C;) than in April 2001 ( -9.2 +0.3 degrees C). Analysis of H. axyridis whole body extracts indicated significant changes in two polyols (glycerol and inositol) associated with exposure to seasonal temperature changes. H. axyridis is an effective predator in agroecosystems but a seasonal urban pest during autumn and winter when large numbers alight on buildings, then move into interior spaces to overwinter.
Impacts
Basic information on the respiratory and water balance mechanisms utilized by German cockroach oothecae may provide a basis for developing new control strategies for this important urban pest. Knowledge of the basic biology of H. axyridis may provide a basis for developing management strategies that decrease the role of the beetle as a seasonal urban pest, while at the same time contributing to its more efficient use in integrated pest management.
Publications
- No publications reported this period
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Progress 10/01/99 to 09/30/00
Outputs
We are studying water balance of the cockroach egg case. Cockroaches can regulate the amount of water contained in their egg cases by several means. We have developed some new approaches for measuring water exchange in maturing American cockroach egg cases. Using traditional gravimetric measurements, egg cases held in environments higher than 50% relative humidity increased in weight (water content). However, we have been unable to corroborate these results with experiments using radiolabeled water (tritiated water). A second work area involves studies on the cockroach digestive system to improve our knowledge on the uptake of materials that these insects ingest during feeding. We have developed a method using radiolabeled materials that allows for determination of food material uptake rates in the cockroach gut.
Impacts
Information obtained on the water balance processes in maturing egg cases might be used to develop methods which disrupt these processes, providing an effective means for their control. Likewise, information obtained from studies on gut uptake of food materials may allow for improving the uptake rate and efficiency of pesticides contained in pesticide baits, rendering them more effective.
Publications
- Bentz, Barbara and D. E. Mullins. 2000. Ecology of the Mountain Pine Beetle Cold Hardiness in the Intermountain West. Enviro. Entomol. 28:577-587.
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