insect pests. Cockroach control has been extensive with many available types of traps, chemical

Transcription

1 INTRODUCTION When it comes to dealing with irritating insects, cockroaches are among the most loathed insect pests. Cockroach control has been extensive with many available types of traps, chemical control and even professional control; however, such methods are limited. Insect control does not ensure that every single cockroach is exterminated. In February of 2005, BBC News published a popular press article online entitled Sex hungry roaches lured to death. The article reports that the pheromone of the female German cockroach (Blattella germanica) was chemically identified and that the pheromone would be used to trap the cockroaches. In this paper, I will discuss the validity of the popular press article and address any important issues concerning the link between the popular press article and the research paper. COMPARISON TO THE ORIGINAL RESEARCH PAPER The popular press article correctly reports that the chemical pheromone of the German cockroach was localized and later chemically identified. Pheromones are special chemicals that are also used as social signals between the same sexes or opposite sex in many animals, especially insects (Birch & Haynes 1982). The original research paper, written by Satoshi Nojima et al for the February 2005 edition of Science was entitled Identification of the Sex Pheromone of the German Cockroach, B. germanica. This study focused on isolating the pheromone from B. germanica and identifying the chemical constituents using gas chromatography coupled with electroantennographic detection (Nojima et al 2005). The researchers termed the pheromone as blattellaquinone and found that its structure was similar to that of an isovalerate ester and a para-benoquinone (Nojima et al 2005). The results of the study, aside from the identification of the pheromone, showed that 93.8% of males responded to the 1

2 synthetic version of the pheromone but nymphs and adult females did not respond at all (Nojima et al 2005). When it comes to the popular press article, it does mention some important key issues but left out some important details. The article fails to properly identify the German cockroach by not including its Genus species name, B. germanica, which is a major error when reporting an important scientific find. The Genus species name was clearly part of the research paper title; however, it is possible that the unknown author of the popular press article did not read the original research paper. On page 1029 of the February 2005 edition of Science, there is a short article written by Elizabeth Pennesi that summarizes the entire research paper and includes important background information about the study as well as the role each scientist in this study. The article does not include the life history and mating ritual of B. germanica. The gland that produces the pheromone is localized on the pygidium, which is the last abdominal segment (Nojima et al 2005). When a virgin female cockroach is ready to mate, she stands on a high surface, raises her wings and releases the pheromone from the abdominal gland (Liang & Schal 1993). There are three stages in the life cycle of B. germanica: egg, nymph and adult (Jacobs 2003). After mating with a male, a female produces a capsule of eggs, in which the eggs hatch at 28 days (Jacobs 2003). After hatching, there are six to seven nymph instar stages that lasts up to 31 weeks then the nymph develops into an adult which lives for another 20 to 30 weeks (Jacobs 2003). There can be over 10,000 descendants produced in a single year, which is an essential fact for it shows how gregarious and hardy B. germanica can be (Jacobs 2003). Another major omission within this article is the failure to mention the fact that in B. germanica, only virgin female cockroaches can emit the pheromone rather than mated females, which is mentioned very clearly in the research paper by Nojima et al. The BBC article (2005) 2

3 states: the special chemical emitted by female German cockroaches and Sex pheromones, emitted by most female animals but does not clarify what type of female can emit the pheromone or whether males can emit pheromones, which is misleading to the reader. There has been evidence that male insects can emit their own pheromone. The male African cockroach (Nauphoeta cinerea) is capable of emitting a pheromone to attract females which influences female to display mating behaviour (Moore 1997). In the same study, Moore showed that in some cases, males emit pheromones as result of male versus male competition, with more dominant males emitting a more powerful pheromone than subordinate males (Moore 1997). Examples of insect species that have their male counterparts emitting sex pheromones are leaf webbers (Narayanan & Nadarajan 2005) and cabbage loopers (Heath et al 1992) and many more others. Although Nojima et al did not specify in the referring scientific paper if male B. germanica cockroaches can emit pheromones, the answer is: yes, they can. In a different study, Nojima found that males of many species in the cockroach family, including B. germanica can emit phermones from the tergal glands on the 7 th and 8 th abdominal segments (Nojima 1998). The title of the article, which is Sex hungry roaches lured to death, is considered to be misleading. There have been studies of the use of chemical pheromones other than mating purposes. A study by Wendler and Vatter was conducted in 1993, in which they found that the pheromone of B. germanica can have a direct influence on navigation for the chemical compounds are found in the feces. The issue about navigation by B. germanica through the feces will be discussed in the next paragraph. The article does not clarify how the trap will specifically work if the pheromone is used as a bait to lure sex-hungry cockroaches to their death. German cockroaches are gregarious insects whose directional locomotory behaviour is influenced by chemical compounds found in 3

4 their fecal material (Wendler and Vlatten 1993). Cody Schal, a scientist that was involved in the study, suggested that a population of German cockroaches could be exterminated or controlled by utilizing a pheromone trap laced with a poisonous compound (Pennisi 2005). Since cockroaches use fecal matter as a source of navigation, the poison from the pheromone trap would be transferred through the feces to females and nymphs in the colony since females and nymphs are unresponsive to the pheromone (Pennisi 2005). IMPROVING THE POPULAR PRESS ARTICLE The content of the popular press article is for the most part, valid and accurate. However, it lacks detail and clarification. An interview with Dr. Wendell Roelofs takes up most of the article. It is important for journalists to know that when conducting an interview with an esteemed person, the person may not always give out all the information required to write an article. Therefore, it is essential to do research on background information on the subject that correlates with the primary information given in an interview, as well as including the background information in the article itself. It should be mentioned that the article is fascinating and even though it includes a personal interview with one of the scientists, it can potentially leave the reader disappointed and confused. The article ends abruptly with no mention of future plans of controlling the German cockroach population using pheromones. The ending of the article is considered to be unprofessional and amateurish. Therefore, the article could have been improved by supporting the interview with Dr. Roelofs by inserting necessary background information as well as clarifying key facts and lastly, including a clincher sentence that would have made the article a successful read. Kathleen Wren of MSNBC wrote a similar article on the same topic and in 4

5 comparison to the BBC News article, Wren s article is more professional and includes every single information fact, down to how the experiment was conducted, how the poison can be transferred to other cockroaches through the feces, and even the mating ritual of the female cockroach. If any suggestions were to be made to the unknown author of the BBC News article, it would be simple: read the MSNBC article for it is a work of professionalism and contains all the information required to understand the topic. CREDENTIALS OF AUTHORS Dr. Wendell Roelofs is a highly esteemed professor of insect biochemistry at Cornell University in New York. He has won numerous awards and is a member of many professional societies such as American Chemical Society and Entomological Society of America. Dr. Coby Schal is a professor of entomology at North Carolina State University specializing in urban entomology and has over 150 research papers published. There is not much information on Satoshi Nojima. He is a former post-doctoral assistant to Dr. Wendell Roelofs and has published several papers on B. germanica. Dr. Nojima currently works at Shin-Etsu Chemical Co. in Tokyo, Japan. Dr. Francis X. Webster is a professor working within the Faculty of Chemistry at the State University of New York. Aside from the German cockroach, he has conducted similar experiments with the brown-banded cockroach (Supella longipalpa). Lastly, Dr. Richard G. Santangelo is a research technician at North Carolina State University within the Department of Entomology. 5

6 REFERENCES Sex hungry roaches lured to death. BBC News, UK edition. URL: [ Birch, M.C., and Haynes, K.F Insect pheromones. London: Edward Arnold Publishers Ltda Heath, R.R., Landolt, P.J., Dueben, B.D Identification of male cabbage looper sex pheromone attractive to females. Journal of Chemical Ecology 18: Jacobs, Steve Entomological Notes: German Cockroaches. Penn State, College of Agricultural Sciences. URL: [ Liang D. and Schal, C Female calling behavior of the German cockroach, Blattella germanica (Dictyoptera: Blattellidae). Journal of Insect Behavior 6: Moore, Allen J The evolution of social signals: Morphological, functional, and genetic integration of the sex pheromone in Nauphoeta cinerea. Evolution 51(6): Narayanan, U.S. and Nadarajan, L. Evidence for a male-produced sex pheromone in sesame leaf webber, Antigastra catalaunalis Duponchel (Pyraustidae, Lepidoptera). Current Science (4): Nojima, S., Schal, C., Webster, F.X., Santegelo, R.G., Roelofs, W.L Identification of the sex pheromone of the German cockroach, Blattella germanica. Science 307: Nojima, S., Nishida, R., Kuwahara, Y Nuptial feeding stimulants: A male courtship pheromone of the German cockroach, Blatella germanica (L.) (Dictyoptera: Blattellidae). Naturwissenschaften 86: Pennisi, E Irresistible Lure for Cockroaches Determined. Science 307: 1029 Wendler, G., and Vlatten, R The influence of aggregation pheromone on walking behavior of cockroach males (Blattella germanica L.). J. Insect Physiol. 39: Wren, K Sexy perfume lures cockroaches to their doom. MSNBC. URL: [ 6