| Photodynamic Effect on Light on Insects |
| Deer Ticks and Lyme Disease |
| Scanning Electron Microscopy |
| Spiders of Central PA |
The term "photodynamic action" probably was used first by Tappeiner (Blum 1941) to denote the effect of light on biological materials following treatment with fluorescent dyes. Blum reviewed reports of experimentally and naturally induced photodynamism in a large variety of noncellular systems and uni- and multicellular organisms excluding insects.
In 1966, C.K. Dorsey of West Virginia University (unpublished data) observed high mortality in Drosophila that were fed fluorescent dyes in population dispersal studies. As a graduate student at WVU, I proposed a research project to study this phenomenon in insects and attempt to determine the mode of action.
Preliminary studies of 7 dyes and their effects on the house fly, Musca domestica was conducted at the Department of Entomology in 1970. The experimental procedure was to feed the flies a solution of milk sugar with various concentrations of dyes. All flies were kept in darkness from 3 hours to overnight. After the dark period, some flies were exposed to natural light, some to artificial light, while others remained in darkness.
The results demonstrated very little mortaliy in those insects fed dyes but not exposed to light. One hundred percent mortality was observed with three of the dyes after an exposure of 1-3 hours in natural or artificial light (Yoho 1971).
The results of a more in-dept-study of six dyes were published in 1973 (Yoho 1973). It was determined that the only wavelengths of light participating in the phenomenon were those in the normally nondestructive visible range.
Fourteen dyes sanctioned by the FDA for use in foods, drugs and cosmetics were tested and the results published in 1974 (Yoho 1974). Mortality was observed in 11 of the 15 dyes with noticable behavioral changes in flies within 5-10 minutes of exposure to light. One of the most active dyes was FD&C red #3. This research in part resulted in the banning of that dye by the Food and Drug Administration.
In unpublished data (Yoho), hemolymph levels in the body cavity and appendages of house flies were observed to decrease dramatically while the crop contents increased.
In a published study (Weaver, Butler, Yoho 1976), hemolymph volumes were observed to decrease significantly in the American Cockroach when fed dye and exposed to natural or artificial light.
Light microscopy and transmission electron microscopy revealed gross membrane and cellular damage in dye-fed light exposed insects (Yoho 1972)
Since the observed behavior of dye-fed light exposed insects appeared similar to that of insects exposed to neurotoxic insecticides, histochemical and spectrophotometric analyses of acetylcholinesterase was investigated. No evidence of inhibition was observed (Yoho 1972).
The research group, Yoho, Butler, and Weaver studied the possible application of active dyes as insecticides and utilized bait stations in cattle barns at West Virginia University agricultural farms. This unpublished data gave inconclusive results as to the effectiveness of this method on the fly populations. It was noted that when the barn was hosed during routine cleaning, fly defication containing dye turned the normally white walls red.
Several chemical companies expressed interest in developing the bait station method, but nothing ever came of it. It should be noted that the research group was concerned about the use of dyes as insecticides since the photodynamic phenomenon is not restricted to insects. If dyes contaminated the ennvironment, other organisms including humans could be at risk. I included a statement in the FD&C paper (Yoho 1974) as follows: "The fact that photodynamic effects have been observed in many animal systems, including man, indicates the need for more careful scrutiny of dye additives in commercial products.
Feingold (1974) a pediatrician at the Kaiser-Permanente Health Care Program at the Kaiser Research Institute in San Francisco cited our research group's work in his study of hyperactivity in children. He noted the hyperactive state of dye-fed light-exposed flies and stated: "It is almost imposible to equate the human system with that of a house fly, yet the possible and interesting implications rose again with a report from Florida in early 1974 that "hyperactivity" appeared to increase in H-LD children who studied or played in intense light. Feingold recommended that hyperactive children not consume food or drugs containing dyes.
In accepting a full-time teaching position at Lock Haven State College in 1974, I had to abandon this research because of a commitment to teaching and a lack of the necessary research equipment to continue. Others have followed in this research, but to my knowledge the specific mode of action in insects or other animals has not been determined. The main reason for including my past research information on this page is to possibly interest new or potential researchers to continue these investigations.
Blum, H.F. 1941. Photodynamic Action and Diseases Caused by Light. Reinhold Publishing Corp., New York. 309 p.
Yoho, T.P.; Butler, L.; and Weaver, J. 1971. Photodynamic Effect of Light on Dye-Fed House Flies: Preliminary Observations of Mortality. J. Econ. Entomol. 64:972-973.
Ibid. 1973. Photodynamic Action in Insects. 1. Levels of Mortality in Dye-Fed Light-Exposed House Flies. Environ. Entomol. 2: 1092-1096.
Ibid. 1974. Photodynamic Killing of House Flies Fed Food, Drug, and Cosmetic Dye Additives. Environ. Entomol. 5: 203-204.
Deer Ticks and Lyme Disease
In the summer of 1989, I had the opportunity and privilege to attend a workshop at Ohio State University in Medical-Veterinary Acarology. One of the presentors was Dr. Willy Burgdorfer, the discoverer of the Lyme spirochete, Borrelia burgdorferi. The other presentor, Dr. James Keirans was a tick systematists from the Smithsonian Institute.
As a result of this workshop, I became very interested in determining the population density of the Deer Tick, Ixodes scapularis (formally dammani) in Clinton County. Since I was on sabbatical leave this year, I spent much time attempting to survey for this tick. In spite of frequenting areas where several individuals were bitten by ticks and developed the disease, I did not find any Deer Ticks. This was good and bad news. Bad news because I had no ticks to determine population density. Good news because evidently this tick must be in a very low density in this county. This is supported by only a few reported cases 0f Lyme Disease.
As an ongoing component of work this work, I notified all physicians in Clinton and adjacent Lycoming County that I would like to have any ticks removed from patients and in turn I would provide species identification. Of the 30 ticks received to date, only two were positively identified as Deer Ticks. This data also supports the low incidence of the tick in Central Pennsylvania.
Scanning Electron Microscopy
Most of my research experience is with the transmission electron microscope at West Virginia University (Yoho 1972). Although Lock Haven University does not possess a TEM, our department does have a scanning electron microscope (SEM) which I use mainly to teach students techniques and applications of SEM. The unit is an older model JSM-25 which is more suited for teaching than research. I sponsor an average of three students a semester in a three hour independent study. Students learn theory and use of equipment and then propose a research project which requires a written scientific paper at the end of the semester. Students have investigated a variety of specimens including: insects, spiders, ticks, plants, bone, teeth, fish scales, blood, chromosomes, pollen, and various minerals.
Spiders of Central Pennsylvania
My major interest is in collecting and identifying spiders of Central Pennsylvania. As is the case for the Deer Tick, I have informed local physicians that I will identify specimens for them.
I have been especially interested in determining whether the Brown Recluse, Loxoceles reclusa is present in Clinton County. To this date, I have not identified nor am I aware of any reports of this spider in the county.