Laboratory Colonization of the Blow Flies, Chrysomya megacephala (Diptera: Calliphoridae) and Chrysomya rufifacies (Diptera: Calliphoridae).

Chrysomya megacephala (F.) and Chrysomya rufifacies (Macquart) were colonized so that larval growth rates could be compared. Colonies were also established to provide insight into the protein needs of adult C. rufifacies and developmental rates of the ensuing larvae. The C. megacephala and C. rufifacies laboratory colonies were reared for five and six generations, respectively, at 28°C. C. megacephala developmental mean rate from egg to adult was 20.4 ± 0.38 d. First-instar larvae emerge in 1.4 ± 0.24 d, second-instar larvae develop in 2.6 ± 0.38 d and third instars occur at 6.3 ± 0.72 d. Development from egg to pupation occurred in 12 ± 1.10 d. C. rufifacies developed at a mean rate of 16.2 ± 0.78 d from egg to adult emergence. Each stage occurred in succession from first-instar larvae 1.1 ± 0.25 d, second-instar larvae developed 2.3 ± 0.25 d later, and the third-instar larvae developed 5.7 ± 0.41 d later. The larvae pupated 10.0 ± 0.57 d after oviposition. Both of these flies can be collected in the wild and easily colonized using conditioned chicken as an oviposition and larval medium. C. megacephala apparently prefers a lower development and maintenance temperature than C. rufifacies, as evidenced by the high pupal mortality. Laboratory-reared C. rufifacies benefited from bloodmeal as a protein supplement to enhance egg production. C. rufifacies larvae were not observed preying on each other and additional larval species were not provided to serve as prey.

Four additional hepatozoon species (Apicomplexa: Hepatozoidae) from north Florida ratsnakes, genus Pantherophis.

Records from a colubrid host are reported for Hepatozoon horridus, described originally from a viperid snake. Hepatozoon horridus in Pantherophis guttatus (Colubridae) has gamonts 14-18.0 by 4.0-5.5 microm, with length by width (LW) 60-99 microm2, and L/W ratio 2.5-3.9. Spherical to elongate, usually ovoid oocysts with L/W ratio 1.0-3.7 contain 16-160 spherical to usually ovoid sporocysts 15-31 by 14-26 microm, with L/W ratio 1.0-1.4, that contain 5-24 sporozoites. Two additional Hepatozoon species are described from ratsnakes in north Florida. Hepatozoon quadrivittata n. sp. from Pantherophis obsoletus quadrivittatus has gamonts 12-17 by 4-6 microm, LW 56-102 microm2, and L/W ratio 2.6-3.8. Nearly spherical oocysts with L/W 1.0-1.1 contain 5-227 spherical to slightly ovoid sporocysts 20-48 by 19-45 microm, with L/W ratio 1.0-1.4, that contain 13-48 sporozoites. Hepatozoon spiloides n. sp. from Pantherophis obsoletus spiloides forms gamonts 12-15 by 4-5 microm with LW 48-75 microm2 and L/W ratio 2.6-3.5. Occasionally rounded but usually elongate oocysts, with L/W ratio 1.0-2.7, contain 5-21 spherical to elongate sporocysts 28-43 by 18-35 microm, L/W ratio 2.5-3.9. In the distinctive Hepatozoon sp. present in Pantherophis obsoletus spiloides, gamonts are 13-17 by 5-10 microm, with LW 75-140 microm2 and L/W ratio 1.4-3.0. Infected erythrocytes are always distorted and enlarged on average 2.5 times the size of uninfected cells, with nuclei enlarged by one-third and broadly elongated. Gamonts often stained deep blue, and cytoplasm of erythrocytes infected with mature gamonts was always dehemoglobinized. Sporogony could not be obtained in three feedings by hundreds of Aedes aegypti, which usually died within the first 24-48 hr.

Lutzomyia spp. (Diptera: Psychodidae) response to olfactory attractant- and light emitting diode-modified Mosquito Magnet X (MM-X) traps.

Mosquito Magnet-X traps were modified for use with blue, green, red, and blue-green-red light-emitting diodes and olfactory attractants to determine the response of Lutzomyia shannoni (Dyar) and Lutzomyia vexator (Coquillett) (Diptera: Psychodidae) field populations to these attractants. Red and blue-green-red-baited traps captured the highest numbers of Lu. shannoni and Lu. vexator, respectively, although, there were no significant differences between the colors. Baiting the traps with CO, attracted significantly higher numbers of Lu. shannoni but showed no effect on Lu. vexator capture. In comparison with CO, alone, Lu. shannoni preferred 1-octen-3-ol and 1-hexen-3-ol (0.05 g per trap) in combination with CO.

Evaluation of the Mosquito Sentinel 360 trap in Florida residential environments.

The Mosquito Sentinel 360 (MS) trap was evaluated in back yards of 6 residences in and near Gainesville, FL. Carbon dioxide and blue-light-emitting diode-modified Centers for Disease Control and Prevention (CDC) traps were utilized as a human substitute host to provide a measure of the effectiveness of the MS trap in reducing mosquito presence at the back door area of the houses. At 5 of the 6 residences, a MS trap was operated with or without carbon dioxide, Lurex3 + octenol, or an experimental attractant. All MS traps were operated in tandem with a CDC trap, with the 6th site occupied only by a CDC trap. Over 67,000 mosquitoes from 19 species were recovered over the 12 trial days. Of these species, Anopheles crucians, An. quadrimaculatus, Coquillettidia perturbans, Culex erraticus, and Mansonia titillans were the predominant, nuisance, and medically important species captured and accounted for >92% of specimens recovered. Overall, attractant-modified MS traps captured more mosquitoes than the paired CDC trap. Carbon dioxide was found to greatly increase the capture of mosquitoes; however, the Lurex3 + octenol combination was significant with Cq. perturbans. All attractant-modified MS traps captured more Cx. erraticus and Ma. titillans than did the CDC, CO2-baited host mimic traps. The use of the MS 360 trap will undoubtedly require the addition of baits and perhaps the inclusion of a host masking or repellent approach to ensure protection from nuisance mosquitoes in residential environments.

Insecticidal potency of novel compounds on multiple insect species of medical and veterinary importance.

BACKGROUND: Vector-borne diseases continue to present significant threats to human, animal and plant health. Mosquitoes, houseflies, sand flies and stable flies are well-known vectors of several human and animal pathogens. The toxicity of selected semiochemicals with molecular structures indicative of insecticidal activity was determined against these insect species with the aim of developing novel insecticides toxic to multiple insect species. RESULTS: Three semiochemicals, namely beta-damascone, cyclemone A and melafleur, showed remarkable toxicity to three mosquitoes, Aedes aegypti L., Ae. albopictus (Skuse) and Anopheles quadrimaculatus Say, the housefly, Musca domestica L., the stable fly, Stomoxys calcitrans L., and the sand fly, Lutzomyia shannoni (Dyar). The chemicals were equally toxic to several field-collected permethrin-tolerant housefly strains. When formulated as 500 mL L(-1) emulsifiable concentrates, the chemicals demonstrated stability and toxicity on filter paper and camouflage military fabrics, with persistence up to 8 days under laboratory conditions. The chemicals were equally effective under field conditions when evaluated on unpainted plywood panels, although a higher dosage was required under field conditions to achieve similar efficacy. CONCLUSION: Laboratory quantification of LC(50) values and field efficacy of three semiochemicals as formulated compounds on mosquitoes, houseflies, stable flies and sand flies showed that these semiochemicals could serve as potent insecticides for multiple insect species.

Evaluation of semiochemical toxicity to Aedes aegypti, Ae. albopictus and Anopheles quadrimaculatus (Diptera: Culicidae).

BACKGROUND: Mosquitoes are the most important vectors of human pathogens. Wide-scale use of pesticides has led to the development of resistance to most common insecticide groups. The need to develop novel products that have a low impact on human health and the environment is well established. The toxicity of selected semiochemicals with molecular structures indicative of insecticidal activity was determined against adult Aedes aegypti (L.) and Anopheles quadrimaculatus (Say). The two most active insecticides against Ae. aegypti were also evaluated against Ae. albopictus (Skuse). RESULTS: Fifteen semiochemicals classified as terpenoid alcohols, ketones or carboxylic esters showed toxicity to both mosquito species. Geranyl acetone (LC(50) = 38.51 microg cm(-2)) followed by citronellol (LC(50) = 48.55 microg cm(-2)) were the most toxic compounds to Ae. aegypti, while geraniol and lavonax, with LC(50) values of 31.88 and 43.40 microg cm(-2), showed the highest toxicity to An. quadrimaculatus. Both geranyl acetone and citronellol were highly toxic to Ae. albopioctus. No semiochemical showed fumigation activity against either species. All semiochemicals persisted for less than 24 h when tested on filter paper. CONCLUSION: Quantification of LC(50) values of several semiochemicals against Ae. Aegypti, An. quadrimaculatus and Ae. albopioctus showed that semiochemicals not only modify insect behaviors but also hold potential as potent insecticides for mosquito control programs.

Evaluation of semiochemical toxicity to houseflies and stable flies (Diptera: Muscidae).

BACKGROUND: The housefly, Musca domestica L., and stable fly, Stomoxys calcitrans (L.) are cosmopolitan pests of both farm and home environments. Houseflies have been shown to be resistant to a variety of insecticides, and new chemistries are slow to emerge on the market. Toxicities of selected semiochemicals with molecular structures indicative of insecticidal activity were determined against adults from an insecticide-susceptible laboratory strain of houseflies. The three most active semiochemicals were also evaluated against recently colonized housefly and stable fly strains. RESULTS: Nineteen semiochemicals classified as aliphatic alcohols, terpenoids, ketones and carboxylic esters showed toxicity to houseflies and stable flies. Rosalva (LC(50) = 25.98 microg cm(-2)) followed by geranyl acetone and citronellol (LC(50) = 49.97 and 50.02 microg cm(-2)) were identified as the most toxic compounds to houseflies. Permethrin was up to 144-fold more toxic than rosalva on the susceptible strain. However, it was only 35-fold more toxic to the insecticide-tolerant field strain. The compounds generated high toxicity to stable flies, with LC(50) values ranging from 16.30 to 40.41 microg cm(-2). CONCLUSION: Quantification of LC(50) values of rosalva, citronellol and geranyl acetone against susceptible housefly and field-collected housefly and stable fly strains showed that semiochemicals could serve as potent insecticides for fly control programs.

Susceptibility of Aedes aegypti and Aedes albopictus larvae to Ascogregarina culicis and Ascogregarina taiwanensis (Apicomplexa: Lecudinidae) from Florida.

The susceptibility of Aedes aegypti to Ascogregarina culicis and Aedes albopictus to Ascogregarina taiwanensis was examined with mosquito and parasite strains from Tampa, FL. When each host was bioassayed with its natural gregarine, the infection intensity indicated that Ae. aegypti was 59% more susceptible to A. culicis (87 gamonts/larva) than Ae. albopictus to A. taiwanensis (47 gamonts/larva). Infections in single and mixed host populations exposed to 100 oocysts/larva of one and both parasites demonstrated that Ae. aegypti harbors higher A. culicis gamont loads than Ae. albopictus of A. taiwanensis. In dual gregarine exposures of single host populations, the A. culicis infection intensity in Ae. aegypti was reduced by approximately 50%. A. taiwanensis exhibited the same capability of infecting Ae. albopictus in single and dual exposures. In mixed host populations there were no cross infections, but A. taiwanensis in Ae. albopictus produced an infection intensity of approximately 70% lower than that of A. culicis in Ae. aegypti.

Artificial feeding of Amblyomma cajennense (Fabricius, 1787) (Acari: Ixodidae) through silicone membrane

An artificial feeding system was used where citrated bovine blood was offerred to male and female Amblyomma cajennense. Vestiges of blood, sweat, hair and exfoliated skin were used as phargo-stimulants placed on the surface of the silicone mambrane. The ticks were collected, as engorged nymphs, from naturally infested equines, with the ecdysis occurring in the laboratory. Four hundred ticks were used, 50 per cent being female, at three to four weeks post-ecdysis. Vestiges of blood on the silicone membrane were the most efficient phago-stimulant and the association of vestiges of blood and sweat residue smears yielded better results compared to the other phargo-stimulants used.