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Data were pooled from multiple sources including newly collected triatomine specimens, preserved specimens, government reports, and scientific articles to create a biogeographical profile of triatomine vector species found in Texas. Triatomine specimens were documented in 97 of 254 counties, and Trypanosoma cruzi-infected specimens were reported from 48 counties. Triatomine specimens were distributed in 11 of the 12 ecoregions in Texas, with all but one species found in multiple ecoregions. Of the 241 newly collected specimens, 50.74% were infected with T. cruzi. Triatoma gerstaeckeri was the most frequently collected and most geographically dispersed species followed by T. sanguisuga. Three species, T. gerstaeckeri, T. sanguisuga, and T. lecticularia, were associated with human dwellings, and over half of the new specimens found inside or near houses were infected with T. cruzi. Chagas disease vectors in Texas are widely distributed and have adapted to ecologically diverse settings. The high T. cruzi infection prevalence of specimens found in close proximity to human settings suggests the presence of an active peridomestic Chagas disease transmission cycle.

The fine structure of the reproductive system of Chrysomya megacephala (Fabricius), a blow fly species of medical importance, was studied using scanning electron microscopy (SEM) to contribute detailed morphological information on the external sexual organs or genitalia of this species. Analysis of the male genitalia or hypopygium revealed that the epandrium is a broad organ resembling a crescent shape, while the ejaculatory apodeme and aedeagal apodeme show similarity in their lengths. The cercus is significantly longer than the surstylus with its apical end being more or less rounded. Dense patches of long bristles, morphologically similar to the sensilla chaetica and sensilla trichodea, were found along the lower half of the cercus. The surstylus has a stout triangular shape, and the proximal half is greatly endowed with sensilla thought to be sensilla chaetica and sensilla trichodea. The aedeagus per se is prominent and has a clavate shape formed by the base theca and elongated phallus. The vesica of the phallus is a smooth bilobed structure, which curves inward. The juxta and juxta process are armed with many rows of strong spines resembling thorns in their appearance. The harpe is slender, recurved anteriorly, and distally pointed like a sickle. Regarding the female genitalia or ovipositor, SEM observation of the supraanal plate revealed it to be sclerotized and more or less triangular-shaped, lying between a pair of short cerci. Several types of sensilla were found on the supraanal plate, subanal plate and cercus, including the sensilla trichodea, sensilla basiconica, sensilla placodea, and probably, sensilla styloconica. The possible functions of sensilla distributed in particular regions of the fly genitalia are discussed.

Knowledge of the behavioral responses of medically important flies to natural stimuli is critical for the development of vector control strategies. We designed, constructed, and operated the dual-choice wind tunnel to investigate the behavioral responses of the blowfly, Chrysomya megacephala (Diptera: Calliphoridae), toward two important extrinsic factors (wind speed and olfactory stimuli) that affect the flight behavior of these flies. The dual-choice wind tunnel appeared as a "T-box," consisting of two stimulus partitions and one median release partition. The correlation between wind speed and fly response showed a marked relationship, with the wind speed set at 0.5 m/s being the optimal speed. Of the 72 natural products tested, 24--all having high protein content--attracted flies at the level of greater than 50% in the rearing cages during preliminary tests, thus allowing further investigation in the dual-choice wind tunnel to further assess these responses. The behavioral response between flies exposed to the screening odors in a rearing cage and those exposed in the dual-choice wind tunnel showed a similar trend. One-day-tainted pork viscera yielded the greatest positive response among natural products tested, attracting greater than 90% of the flies included in the test population. One-day-tainted pork viscera exhibited the highest potency (1.578), exceeding 1-day-tainted beef liver, which is commonly used as the standard bait for blowflies. The usefulness and practical applications of the dual-choice wind tunnel for further investigations are also discussed.

This paper presents and discusses 30 cases of cadavers that had been transferred for forensic entomology investigations to the Department of Forensic Medicine, Faculty of Medicine, Chiang Mai University, northern Thailand, from 2000 to 2006. Variable death scenes were determined, including forested area and suburban and urban outdoor and indoor environments. The fly specimens found in the corpses obtained were the most commonly of the blow fly of family Calliphoridae, and consisted of Chrysomya megacephala (F.), Chrysomya rufifacies (Macquart) Chrysomya villeneuvi Patton, Chrysomya nigripes Aubertin, Chrysomya bezziana Villeneuve, Chrysomya chani Kurahashi, Lucilia cuprina (Wiedemann), Hemipyrellia ligurriens (Wiedemann), and two unknown species. Flies of the family Muscidae [Hydrotaea spinigera Stein, Synthesiomyia nudiseta (Wulp)], Piophilidae [Piophila casei (L.)], Phoridae [Megaselia scalaris (Loew)], Sarcophagidae [Parasarcophaga ruficornis (F.) and three unknown species], and Stratiomyiidae (Sargus sp.) were also collected from these human remains. Larvae and adults of the beetle, Dermestes maculatus DeGeer (Coleoptera: Dermestidae), were also found in some cases. Chrysomya megacephala and C. rufifacies were the most common species found in the ecologically varied death scene habitats associated with both urban and forested areas, while C. nigripes was commonly discovered in forested places. S. nudiseta was collected only from corpses found in an indoor death scene.

The blow flies, Phaenicia eximia (Wiedemann) and Cochliomyia macellaria (F.), oviposited nocturnally on ground beef under artificial lighting of at least 1,500 footcandles at temperatures 26°C or higher during onsets of low-atmospheric pressure at study sites near Snook, Texas, during 2003. Nocturnal oviposition was replicated five times during 14 spring season experiments and three times during 14 summer season experiments conducted under similar conditions.

The results of laboratory tests indicated the average survival rates for Psorophora columbiae eggs remained quite high for all of the egg populations exposed to a temperature of 27°C (range 83.0–100.0% survival) after 96 days of exposure, except for the non-diapausing eggs on dry soil (66.3%). In regard to the exposure of egg populations to moderately cold temperatures (i.e. 8°C, 4°C and −2°C) for periods of up to 16 days, survival rates for egg populations exposed to 8°C continued to remain relatively high (average >85%) for the remainder of the experimental exposure period (i.e. 96 days). Diapausing Ps. columbiae eggs were more tolerant (82.0% survival) to low temperatures (−2°C) than non-diapausing eggs (2.4% survival) for 64 days, particularly at temperatures of and below 4°C. Diapausing and non-diapausing eggs were similar in their ability to survive under high temperatures (34°C and 38°C). High soil moisture (30–40%) or substrate moisture (95% relative humidity) content appeared to enhance the ability of the mosquito eggs to survive both low and high temperature extremes.

Activity of adult female populations of Culex salinarius, as determined by light trap collections, was studied in Chambers County, Texas, from June 1988 to July 1990. Overall, Cx. salinarius was the predominant species collected by light traps. Female Cx. salinarius were present in every month of the 2-year study period, with spring peaks in April and May and autumn peaks in September and October. Traps set in southern and central areas collected more specimens of Cx. salinarius than did those located in western areas, especially during spring, summer, and fall seasons. Females with longest wing lengths were collected in cooler winter months and those with shortest wing lengths were collected in warm summer months. Females having the longest wings tended to be collected at trap sites in coastal marsh areas of Chambers County, irrespective of when collections were made. Dipper samples taken on a monthly basis from fixed sites in upland agricultural and coastal marshland areas indicate that larvae of this species were present at more sampling sites during cooler months than in the warmest months of June, July, and August.

Examination of the puparia of the housefly, Musca domestica L. and blowfly Chrysomya megacephala (F.), through scanning electron microscopy (SEM), revealed many differences in the profile of their morphology. Special attention was focused on puparial characteristics used to differentiate between the two fly species studied, and between other forensically important flies. Results of this study indicate that the housefly puparia are almost evenly rounded at both ends and the anterior spiracle bears six papillae. A pair of pupal respiratory horns is found laterally before the posterior boundary of the first abdominal segment, bearing numerous papillae that have a longitudinal opening along the oval convex base. The peritreme of each posterior spiracle forms a crude forward or reverse D-shape, encircling three sinuous slits. The blowfly pupariums anterior spiracle contains 8-12 papillae. The pupal respiratory horns protrude slightly and in some specimens a group of approximately 38 globules on the bubble-like membrane may be observed. Each of the posterior spiracles is more or less an oval- shaped peritreme, encircling three straight spiracular slits. The anatomical features presented herein allow for the differentiation of puparia of the two fly species studied and could prove useful in future forensic entomological assessments.

Antennal sensilla of some forensically important fly species in the families Calliphoridae (Chrysomya megacephala, Chrysomya rufifacies, Chrysomya nigripes and Lucilia cuprina), Sarcophagidae (Parasarcophaga dux) and Muscidae (Musca domestica) were studied using scanning electron microscopy. Five types of sensilla were observed: trichoid, basiconic, coeloconic, styloconic and sensory pit. Only trichoid sensilla are found on the scape of the antenna, while both trichoid and styloconic sensilla are located on the antennal pedicels of all species studied. Basiconic sensilla are the most numerous of the sensilla found on the antennae of both sexes of all fly species studied and are comprised of two subtypes: large and small basiconic sensilla. Coeloconic sensilla are characterized by short pegs, with either grooved or smooth surfaces, that are sunken into deep depressions. No marked difference was observed in the number, morphological structure or distributional pattern of any of the sensilla among the species studied, with the exception of there being more numerous sensory pits detected in female P. dux compared to the other species. The suggested function of each antennal sensillum was based on comparison with results of other investigations on similar sensilla.

The surface ultrastructure of all larval instars of Chrysomya rufifacies (Macquart) is described by means of scanning electron microscopy (SEM). Morphological changes were greatest from the first to the second instar, but less from the second to the third instar. Most of these changes involved the structure of the anterior spiracle, posterior spiracle, integument of the body, and mouthhooks. Modification of the mouthhooks, especially in the third instar, are helpful in explaining the ferocious feeding ability of the older maggots. The common name of "hairy-maggot" for C. rufifacies is only appropriate for the second and third instars because of their elongated tubercles along the body, whereas this name is not descriptive of the first instar that lack tubercles.

The morphology of third-instar Piophila casei (L.) is described by means of scanning electron microscopy. Features of the anterior cephalic region and creeping welts that are used in larval skipping and creeping, respectively, are highlighted. Morphological features classically used for larval identification are also illustrated.

An antiserum raised against the peptide, culetachykinin II, immunocytochemically detected a group of neurosecretory cells in the first flagellar segment of the antennae of both males and females of the mosquito, Culex salinarius. This is the first insect species in which neurosecretory cells have been found in the antennae. The ultrastructure of these antennal neurosecretory cells (ANC) is described, as well as their relationship to other neurons in the antennae and antennal lobe of the mosquito. These tachykinin-reactive cells contain relatively small (140-220 nm) elementary neurosecretory granules. Not only do the ANC have axons that terminate on specific glomeruli of the deutocerebrum, but these neurons also have collaterals that form neurohemal terminals in the receptor lymph channels of the dendrites of the sensory neurons. Thus, the ANC not only influence higher centers of the brain that interpret signals from the antennal sensillae, but also modulate the response of the sensory receptors. To our knowledge, this is the first report of neurosecretory cells directly affecting the signal reception of sensory neurons.

Three myotropic peptides belonging to the Arg-amide insect tachykinin family were isolated from whole-body extracts of the mosquito, Culex salinarius. The peptides, APSGFMGMR-NH2, APYGFTGMR-NH2 and APSGFFGMR-NH2 (designated culetachykinin I, II, and III) were isolated and purified on the basis of their ability to stimulate muscle contractions of isolated Leucophaea maderae hindgut. Biologically inactive methionine sulfoxides of two of the three peptides were isolated using an ELISA system based upon antiserum raised against APYGFTGMR-NH2 and identified with mass spectrometry. Immunocytochemistry localized these peptides in cells in the brain, antennae, subesophageal, thoracic and abdominal ganglion, proventriculus and midgut. Nerve tracts containing these peptides were found in the median nerve of the brain, central body, nervi corpus cardiaci, cervical nerve, antennal lobe and on the surface of the midgut.

The distribution (between adult workers and worker larvae) and storage of dyed foods (one protein, two lipids, and three carbohydrates) were investigated in standardized Pharaoh ant, Monomorium pharaonis (L.), colonies (n = 250 workers, 2 queens, and 25–30 mg worker brood) in the laboratory. Two foods were in liquid form (peanut oil and 1 M sucrose) and four were in solid form (egg yolk, beef fat, table sugar, and corn starch). Workers did not actively recruit to table sugar, but in a concurrent study it was used as building material to fill nest openings. Moistened corn starch was ignored by foraging workers with little storage. Workers became satiated on 1 M sucrose before any solution was given to larvae. Peanut oil, like the 1 M sucrose solution, was rapidly distributed among and stored internally by adult workers. Unlike the 1 M sucrose solution given primarily to older larvae, peanut oil was distributed rapidly to all larval stadia. Workers showed weak recruitment to beef fat even after 7 d of starvation. Only a few workers showed evidence of feeding on beef fat and none was distributed to larvae. Storage of solid lipid (beef fat) was variable. Workers in two of five colonies stored large quantities of beef fat in piles inside their nests. In three colonies only trace amounts of beef fat were stored after 24 h. In contrast, workers consistently stored large quantities of excess solid protein (moist egg yolk powder) in piles inside their nests. Solid protein was fed to and consumed primarily by older larvae, and none was detected in young larvae or adult workers. Workers actively recruited to liquid carbohydrate (1 M sucrose) and solid protein (moist egg yolk powder) foods after 2 d of starvation. A 7-d starvation period was necessary for active recruitment to lipids (peanut oil and beef fat), but caused extremely rapid recruitment (too fast for accurate observation) to carbohydrate and protein foods. Thus, colonies were starved for 2 d prior to the introduction of protein or carbohydrate foods, and 7 d prior to lipid foods. Our results suggest that lipids may not be rapidly depleted in the metabolism of the Pharaoh ant. Thus, protein and liquid carbohydrates (using simple sugars) may play a more important role as components of insecticidal baits that are important in Pharaoh ant management. However, in field colonies that may be stressed for lack of food (which may commonly occur), an insecticidal bait formulated from oil may be readily accepted and effective.

The forensic entomology case described herein is the first such case documented in Thailand. A mummified corpse of a 32-yr-old man was discovered in a forested habitat, with the larvae of six species of flies (Diptera) found in association with the corpse at the time of its discovery, i.e., those of Hydrotaea (=Ophyra) spinigera Stein (family Muscidae), Piophila casei (L.) (family Piophilidae), Megaselia scalaris (Loew) (family Phoridae), Sargus sp. (family Stratiomyidae), and larvae of two unidentified flesh fly species (family Sarcophagidae). The presence and age of the larval specimens of P. casei, M. scalaris, and H. spinigera gave entomological evidence that the postmortem interval for the corpse was 3–6 mo. This report also documents some of the forensically important fly species that occur in Thailand.

Organisms highly similar to Blastocrithidia triatomae, a pathogenic parasite of Chagas disease triatomine bug vectors, were detected using polymerase chain reaction amplification and DNA sequence analysis of a segment of the small subunit rRNA gene in 3 of 203 triatomine specimens collected in Texas from June 2005 to October 2006. The parasite was identified in three species of triatomine bugs (Triatoma gerstaeckeri, T. indictiva, and T. neotomae) collected from three distinct geographic locations. Flagellated organisms indistinguishable from Trypanosoma cruzi were observed by direct microscopy in hindgut material of two of the three specimens. Coinfection with T. cruzi and Blastocrithidia was detected by molecular methods in one of the specimens. Parsimony analysis provided strong support for clustering of the new sequences within a Blastocrithidia group, clearly separated from other flagellated protozoans. Confirmation of Blastocrithidia in U.S. triatomine species complicates microscopic diagnosis of T. cruzi due to the morphologic similarity of the parasites.

Chrysomya megacephala (F.) (Diptera: Calliphoridae) is the most medically important blow fly species in Thailand as the adults are a mechanical vector of various pathogens and a nuisance pest, while the larvae can cause myiasis. Biological information on this fly species is limited, thus this study presents the ultrastructure of the testes using light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscope (TEM). This information may be particularly important for future systematic study of this species. Thirty adult C. megacephala males aged three- and seven- days-old were used in this study. Light microscopic observations revealed that the color of the testes changes from pale orange at emergence to a reddish orange color in 1 old-day flies, and remains this color throughout the entire adult stage. The shape of the testes correlates closely with the age of the fly. SEM imaging showed that the testes are a paired structure, which has a smooth surface and is occasionally penetrated by tracheoles. TEM analysis revealed that the testes of 3 day-old are characterized by three stages of developing spermatids. The first stage is the beginning of the first division of maturation, and the spermatid has a pear-shape with a large nucleus (the ratio of nucleus and cytoplasm is 1:1), that is profuse with dense chromatin material dispersed inside the nucleus (Figure 1). The second stage has a nucleus with elongated clusters of chromatin in the globular cell. The ultrastructure of the tail or flagellum includes a spherical nucleus, but the axonemal model is indistinguishable. In the testes of 7 old-day males, the spermatozoa are regularly arranged. The spermatozoa consist of two regions: the head, formed by an acrosome and nucleus, and the tail consisting of two mitochondrial derivatives, an axoneme and an accessory body (Figure 2).

Morphology of the alimentary canal of the mature third instar larva of the blow fly, Chrysomya megacephala (F.), was examined using light, scanning, and transmission electron microscopy. Salivary structures consist of a single median deferent duct that bifurcates into efferent ducts connected to paired, tubular salivary glands comprised of closely packed conical-shaped epithelial cells with large nuclei. The crop occurs as a large, swollen diverticulum of the digestive tube and is lined internally with convoluted cuticle (epicuticle and endocuticle). The esophagus is a simple, straight tube internally lined with cuticle and externally encompassed by muscle fibers. The cardia is a bulb-like structure composed of anterior foregut tissue and posterior midgut tissue from which the peritrophic membrane (PM) is produced. The midgut begins within the cardia which is flanked posteriorly by four tubular gastric caeca that are lined internally with four to five layers of cuboidal epithelial cells bearing microvilli. Midgut tissue is lined with simple cuboidal epithelium whose cells are filled with numerous secretory granules and possessed long microvilli facing the lumen. A peritrophic membrane is contained within the midgut lumen. The larval hindgut consists of the pylorus, Malpighian tubules, ileum, colon, rectum, and anus, posteriorly. The pylorus is characterized by a single layer of epithelial cells encircled by a muscular layer and the presence of PM within the lumen. Malpighian tubules each diverge into two tubular structures totalling four long tubules of long chained cuboidal cells bearing microvilli internally. The wall of the ileum is comprised primarily of a monolayer of cuboidal epithelial cells with large oval nuclei and more intense muscular fibers surrounding the periphery. A cuticular layer surrounds the lumen containing the PM. This inner cuticle consists of a thin epicuticle that is electron-dense; whereas, the endocuticle is much thicker but less electron-dense. Myo-epithelial cells are dense in the anal region, where the PM persists.

Fly eggs found in corpses can be utilized as entomological evidence in forensic investigations of deaths if the species of fly and the developmental rate at a temperature similar to the death scene are known. The species identification of fly eggs is particularly important, and previously, scanning electron microscope has been used for this purpose. Herein, we report a simple technique, using light microscopy, to identify forensically important eggs of Chrysomya rufifacies (Macquart), Chrysomya megacephala (Fabricius), Chrysomya pacifica Kurahashi, Chrysomya nigripes Aubertin, Aldrichina grahami (Aldrich), Lucilia cuprina (Wiedemann), Musca domestica L. and Megaselia scalaris (Loew). A 1% potassium permanganate solution was used to stain egg surfaces for 1 min, followed by dehydration in 15, 70, and 95%, absolute alcohol (each solution for 1 min) and the eggs were permanently mounted. The characteristics are based on the width of plastron, morphology of plastron area surrounding the micropyle and chorionic sculpturing, with the length of egg being used as supplemental feature.

Cuticular development of Aedes aegypti larvae was examined by electron microscopy and comparisons were made between larvae exposed to methoprene, isopropyl (E, E)-11-methoxy-3, 7, 11-trimethyl-2, 4-dodecadienoate, those treated with the fluorescent insect growth regulator, 5-[[[5-(dimethylamino)-1-naphthalenyl]-sulfonyl]amino]-1, 3-benzodioxole (DNSAB), and untreated larvae. Larvae of all three groups were routinely fixed at 24, 48, and 72 hr posttreatment. Thin sections of the sixth-abdominal segment, anal papillae, midgut tissue, and Malpighian tubules were examined for morphological variations from controls.

A compound was synthesized that fluoresces in the visible spectrum and has the properties of an insect juvenile hormone. When it was assayed against Aedes aegypti larvae, it produced larval-pupal and pupal-adult intermediates; when injected into allatectomized adult females, it restored normal egg development. The fluorescent insect growth regulator (5-[[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]amino]-1,3-benzodioxole) when injected into females, could be traced into eggs and newly hatched larvae. Microspectrofluorometric and chromatographic studies indicate that it is metabolically stable. Fluorescent insect growth regulators constitute new tools for the investigation of the action of insect growth regulators in general.

The formation of new mitochondria in insect tissues occurs during discrete periods of cell growth associated with the molting cycles or metamorphosis. Acriflavine and ethidium bromide are known to disrupt replication, transcription and translation of circular, mitochondrial DNA during mitochondriogenesis. Injection of acriflavine into Heliothis zea during metamorphosis resulted in adult deformities and the loss of flight ability in normal appearing individuals. A 45% mortality rate was found for doses of 20 μg acriflavine/individual. Both acriflavine and ethidium bromide were toxic to neonate Aedes aegypti larvae. Acriflavine was most toxic with an LD 50 of 0.48 ppm, and larvae required only 12 hr of exposure for a maximal mortality response. Surviving larvae took up to three times longer to reach the pupal stage.