Darrell W. Anthony

Ultrastructural study of early development of Nosema algerae in anopheles albimanus

Abstract Early development of Nosema algerae in Anopheles albimanus was studied by electron microscopy. Sporoplasms were observed in the thorax and first three abdominal segments at 1 hr after initial exposure. The first division occurred between 30 and 36 hr. Immature spores were present at 48 hr with mature spores observed at 54 hr. By 60 hr from initial exposure, some of the mature spores had extruded and sporoplasms were seen. By 96 hr, all stages were present and development was no longer synchronous.

A laboratory evaluation of the microsporidian Vavraia culicis as an agent for mosquito control

Abstract The susceptibility of the mosquitoes Aedes aegypti, Aedes taeniorhynchus, Anopheles albimanus, Culex pipiens quinquefasciatus, Culex salinarius , and Culex tarsalis to infection by the microsporidian Vavraia culicis was determined. Using 18-hr exposures to 5 × 10 3 , 1 × 10 4 , 5 × 10 4 , and 1 × 10 5 spores/ml, C. salinarius, C. tarsalis , and A. albimanus were found to be significantly more susceptible than A. aegypti . The most severe infections were observed in C. salinarius and C. tarsalis , although heavy infections of approximately 1 million spores per adult were recorded at the higher dosages in all species tested except A. aegypti . Production trials indicated that up to 5.4 × 10 8 spores could be routinely produced in individual corn earworms, Heliothis zea . Inactivation of the spores by sunlight was measured by observing the subsequent incidence of infection and spore production in A. albimanus . These two measurements provided an LT 90 of 5.5 and 3.3 hr, respectively.

Susceptibility of spores of the microsporidian Nosema algerae to sunlight and germicidal ultraviolet radiation.

Abstract Spores of the microsporidian Nosema algerae exposed to 1, 2, and 4 hr of sunlight and 121 μW/cm 2 of germicidal ultraviolet light were fed to first-instar Anopheles albimanus . Twenty days after feeding, the incidence and intensity of infection (spores/mosquito) were recorded from adult mosquitoes. While sunlight-treated spores showed no significant decline in incidence of infection after 1-, 2-, and 4-hr exposures, intensity of infection decreased significantly after the 2- and 4-hr exposures. Incidence of infection of mosquitoes fed bactericidal ultraviolet light-treated spores declined 48.2, 76.2, and 99.9% after 1-, 2-, and 8-min exposures, respectively. Measured by intensity of infection, activity of bactericidal light-treated spores decreased 87.2% after 1 min, 91.7% after 2 min, and 99.9% after 8 min. Levels of radiation required to inactivate spores of N. algerae fell within the range reported for other Microsporidia.

Susceptibility of nontarget organisms to Nosema algerae (Microsporida: Nosematidae), a parasite of mosquitoes

Abstract Laboratory studies were conducted to determine the susceptibility of nine mosquito predators to the microsoporidian pathogen of anopheline mosquitoes, Nosema algerae . The predators tested were: Anax junius (Odonata); Hydrophilus sp., Coptotomus interrogatus (Coleoptera); Notonecta undulata, Belostoma fluminea, Ranatra australis (Hemiptera); Chauliodes rastricornis (Megaloptera); Procambarus sp. (Decapoda); and Gambusia affinis (Pisces). Of these species, only Notonecta undulata was found to be susceptible to Nosema algerae after having fed upon diseased larvae. Infection rates in four tests averaged 47.9%. The following tissues were found to be infected in the adult notonectids: gut, muscle, fat body, Malpighian tubules, tracheal epithelium, testes, brain, hypodermis, and ommatidia.

Some effects of parasitism by Babesia caballi on the tropical horse tick, Dermacentor (= Anocentor) nitens

Abstract Studies of the tropical horse tick, Dermacentor (= Anocentor) nitens, infected with Babesia caballi showed that this protozoan parasite, a causal agent of equine piroplasmosis, is also a pathogen of its vector. In all tests, some infected ticks died 7–10 days after repletion and did not lay eggs. Also infected engorged females weighed less than uninfected engorged females and produced fewer eggs than uninfected females. Mortality occurred regularly in infected eggs though only rarely in uninfected eggs. Thus, the longevity of engorged females and the reproductive potential of D. nitens is reduced by infections of B. caballi.

Scanning electron microscopy of the sporangia of species of Coelomomyces (Blastocladiales: Coelomomycetaceae)

Abstract A scanning electron microscope was used to study the sporangia of at least 6 species of Coelomomyces from 9 species of mosquitoes. The scanning micrographs obtained of (1) Coelomomyces punctatus from Anopheles quadrimaculatus , (2) C. dodgei from A. crucians , (3) C. quadrangulatus from A. crucians , (4) C. macleayae from Aedes triseriatus , (5) C. pentangulatus from Culex erraticus , (6) C. sp., probably pentangulatus , from Culex peccator , (7) C. psorophorae from Psorophora howardii , (8) C. near psorophorae from Culiseta inornata , (9) from Aedes sollicitans , and (10) from Aedes taeniorhynchus showed morphological differences in the surface microstructure of the sporangia of most species.