This work presents the ultrastructure of testis of the medically important blow fly, Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae) using light microscopy and electron microscopy. Reproductive organ of males was dissected to determine the testis in the pupal stage, 3-day-old flies and 7-day-old flies and observed under scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM displayed a smooth surface which is occasionally penetrated by tracheoles. TEM of the testis in the pupal stage presents the thick testis wall covering underdeveloped cells containing a variable size of an electron-dense globule. For the 3-day-old males, the testicular wall is formed by an external layer, a peritoneal sheath, a muscular layer, a basement membrane, and a follicular epithelium. Follicular epithelium presented developing spermatozoa. Regarding the 7-day-old males, development of spermatozoa is apparent, displaying nucleus, centriolar adjunct, axoneme, and mitochondrial derivatives, with the 9 + 9 + 2 microtubule pattern of axoneme. 1. Introduction Chrysomya megacephala (F.) is the medically important blow fly species in many parts of the world including Thailand. Larvae of this species have been reported in association with human corpses in several case situations [1]. Not only have their specimens been used to estimate the postmortem interval (PMI) in cases [2], but also to detect organophosphate poisoning in a putrefying body through larval analysis [3]. In Thailand, C. megacephala has been the primary species of fly found at death scenes involving exposed, burned, hanging, or floating corpses, in which the types of environment were quite varied, including forested, urban, and suburban areas [1]. The biology, particularly, the reproductive morphology of blow fly has been documented as the basic research in some species. Examples of this are provided by investigation under light microscopy in Chrysomya pinguis, Chrysomya defixa [4], Calliphora pubescens, Calliphora testaceifacies [5], and Onesia accepta [6]; while scanning electron microscopic (SEM) study has been employed for researches in Lucilia cuprina [7], Cochliomyia hominivorax, and Cochliomyia macellaria [8]; most of such works have involved the taxonomic identification. Regarding applied research, the research involving bacterium, Rickettsiella in the ovary of the Oriental cockroach, Blatta orientalis [9], insect virus Hz-2V in the reproductive organs of the female corn earworm moth, Helicoverpa zea (Lepidoptera), and infection of the endobacterium was exemplary [10].
References
[1]
K. Sukontason, P. Narongchai, C. Kanchai et al., “Forensic entomology cases in Thailand: a review of cases from 2000 to 2006,” Parasitology Research, vol. 101, no. 5, pp. 1417–1423, 2007.
[2]
M. L. Goff, A. I. Omori, and K. Gunatilake, “Estimation of postmortem interval by arthropod succession. three case studies from the Hawaiian Islands,” American Journal of Forensic Medicine and Pathology, vol. 9, no. 3, pp. 220–225, 1988.
[3]
K. Gunatilake and M. L. Goff, “Detection of organophosphate poisoning in a putrefying body by analyzing arthropod larvae,” Journal of Forensic Sciences, vol. 34, no. 3, pp. 714–716, 1989.
[4]
H. Kurahashi, N. Benjaphong, and B. Omar, “Blow flies (Insecta: Diptera: Calliphoridae) of Malaysia and Singapore,” Raffles Bulletin of Zoology, vol. 45, supplement 5, pp. 1–88, 1997.
[5]
N. R. Norris, “Lectotype designation and characterisation of the Australian blowflies Calliphora pubescens Macquart and Calliphora testaceifacies Macquart (Diptera: Calliphoridae),” Australian Journal of Entomology, vol. 35, no. 1, pp. 49–59, 1996.
[6]
K. R. Norris, “Synonymy, distribution and bionomics of the Australian blowfly Onesia accepta (Malloch) (Diptera: Calliphoridae),” Australian Journal of Entomology, vol. 41, no. 4, pp. 354–356, 2002.
[7]
D. J. Merritt, “The morphology of the phallosome and accessory gland material transfer during copulation in the blowfly, Lucilia cuprina (Insecta, Diptera),” Zoomorphology, vol. 108, no. 6, pp. 359–366, 1989.
[8]
A. C. R. Leite, “Ultrastructure of the male terminalia of Cochliomyia hominivorax and C. macellaria,” Memórias do Instituto Oswaldo Cruz, vol. 90, pp. 475–481, 1995.
[9]
R. Radek, “Light and electron microscopic study of a Rickettsiella species from the cockroach Blatta orientalis,” Journal of Invertebrate Pathology, vol. 76, no. 4, pp. 249–256, 2000.
[10]
C. P. Rallis and J. P. Burand, “Pathology and ultrastructure of the insect virus, Hz-2V, infecting agonadal male corn earworms, Helicoverpa zea,” Journal of Invertebrate Pathology, vol. 80, no. 2, pp. 81–89, 2002.
[11]
K. Hori, “Comparative anatomy of the internal organs of the Calyptrate muscoid flies I. Male internal sexual organs of the adlt flies,” Science Report Kanazawa University, vol. 7, pp. 23–83, 1960.
[12]
J. M. Valdez, “Ultrastructure of the testis of the Mexican fruit fly (Diptera: Tephritidae),” Annals of the Entomological Society of America, vol. 94, no. 2, pp. 251–256, 2001.
[13]
A. M. Fausto, M. Belardinelli, R. Fochetti, J. M. Tierno de Figueroa, and M. Mazzini, “Comparative spermatology in plecoptera (Insecta). II. An ultrastructural investigation on four species of systellognatha,” Arthropod Structure and Development, vol. 31, no. 2, pp. 147–156, 2002.
[14]
E. Paccagnini, L. De Marzo, F. Giusti, and R. Dallai, “The aberrant spermatogenesis of the Haplothrips simplex (Buffa) (Thysanoptera): ultrastructural study,” Tissue and Cell, vol. 38, no. 3, pp. 177–186, 2006.
[15]
K. P. O. Name, J. R. Pujol-Luz, and S. N. Báo, “Structure and ultrastructure of spermatozoa of Chrysomya megacephala (Diptera: Calliphoridae),” Micron, vol. 41, no. 7, pp. 853–860, 2010.
[16]
R. Dallai, P. L. Bellon, S. Lanzavecchia, and B. A. Afzelius, “The dipteran sperm tail: ultrastructural characteristics and phylogenetic considerations,” Zoologica Scripta, vol. 22, no. 2, pp. 193–202, 1993.
[17]
F. D. Warner, “The relationship between matrix structure and the microtubule component of the axoneme,” Journal of Cell Biology, vol. 47, no. 1, pp. 159–182, 1970.
[18]
K. T. Tokuyasu, “Spoke heads in sperm tail of Drosophila melanogaster,” Journal of Cell Biology, vol. 63, no. 1, pp. 334–337, 1974.
[19]
K. Ilango, “Structure and function of the spermathecal complex in the phlebotomine sandfly Phlebotomus papatasi Scopoli (Diptera: Psychodidae): II. Post-copulatory histophysiological changes during the gonotrophic cycle,” Journal of Biosciences, vol. 30, no. 5, pp. 733–747, 2005.
[20]
J. Jean-Lou and M. Xavier, “Ultrastructure of the spermatozoon of the mosquito Toxorhynchites (Diptera, Culicidae),” Zoologica Scripta, vol. 17, no. 3, pp. 289–291, 1988.
