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The ovicidal activity of 21 hyphomycete fungi species against Aedes aegypti (L.) (Diptera: Culicidae) was tested. Fungi with ovicidal activity developed on high numbers of eggs (> or =70%) during 25 d of exposure. A clear ovicidal activity with low values of hatch (1.3-40%) was observed after 25 d of incubation with Isaria farinosa (Holm: Fries) Fries, Paecilomyces carneus (Duché & Heim) Brown & Smith, Paecilomyces marquandii (Massee) Hughes, Isaria fumosorosea (Wize), Metarhizium anisopliae (Metschnikoff) Sorokin, Penicillium sp., Paecilomyces lilacinus (Thom) Samson, Beauveria bassiana (Balsamo) Vuillemin, and Evlachovaea kintrischica Borisov & Tarasov. More than 63% of eggs hatched after 25-d exposures to 11 other fungi species deemed as ineffective. These are the first results to show the effects of entomopathogenic fungi against eggs of Ae. aegypti, and they suggest their potential as control agents of this vector.

Development of Rhodnius prolixus after eclosion until the adult stage was studied at constant temperatures (T), 15, 20, 25, 28, 35°C, and relative humidities (RH), 75, 86 and 97%, and fluctuating (16/ 8 hr) temperatures, T I/II, 15/28°C, 20/25°C, 25/28°C and 25/35°C, and Refeeding was minimal at optimal conditions of T and RH for development. The most refeeding was observed at a constant 35°C. Key words: Rhodnius prolixus -development -temperature -humidityRhodnius prolixus is considered to be one of the most serious vectors of Chagas disease. All five instars including adults are obligatory hematophagous insects and potential vectors of Trypanosoma cruzi. R. prolixus is unable to molt without feeding. Nymphs need to feed at least once ad repletionem to attain the following stage. Moreover, abiotic factors such as temperature and humidity affect insect development. Under laboratory conditions, the temperature range for eclosion and molting of R. prolixus was reported to be between 16-34°C (Gomez-Nuñez & Fernandez 1963). No development was observed at 15°C and 35°C (Galliard 1935, Okasha 1964 insect habitats may differ considerably and vary according to circadian and seasonal patterns. R. prolixus is found mainly in Colombia and Venezuela from 0 to 2,600 m above sea-level, in regions with annual median temperatures from 11 to 29°C and 250 to 2,000 mm annual precipitation (Carcavallo et al. 1977, 1978, Lent & Wygodzinsky 1979. There is little information on the linked impact of cyclic conditions of temperature and humidity on development of Chagas disease vectors. Pippin (1970) showed that development of several triatomine species at unspecified fluctuating temperatures between 18 and 28°C and humidities from 15 up to 65%, was prolonged compared to 25°C and 65% humidity. More detailed investigations on R. prolixus biology in conditions reflecting the insect's natural environment are required to improve control methods. Recently Luz et al. (1998) reported an influence of fluctuating temperature and humidity on starved R. prolixus. In the present study, development of R. prolixus was examined at constant and fluctuating temperatures and humidities within a range of 15 and 35°C, and 75 and 97%. MATERIALS AND METHODSInsect rearing -R. prolixus was reared at 28 ± 1°C and 75 ± 5% humidity with a photoperiod of

The effect of relative humidity (43%, 75%, 86% and > 98%) Aedes aegypti is the principal vector of dengue viruses in tropical and subtropical regions throughout the world. This closely human-associated mosquito uses a great variety of large to small sized breeding sites and occurs year round even in semi-arid regions. Females oviposit mainly above the waterline on damp surfaces, and unhatched larvae have to hold out until immersion of eggs in water will permit eclosion and further development. Populations decline during the dryer and colder season but mosquitoes never disappear completely using subterranean and other breeding sites resulting from watering behavior by local residents (Varejão et al. 2005, Maciel-de-Freitas et al. 2007). Moreover, eggs out of water resist prolonged desiccation during distinct dry seasons, and the surviving larvae contribute to a reestablishment of vector populations at the beginning of the rainy season, thus increasing the risk of dengue epidemics (Sota & Mogi 1992, Silva & Silva 1999. Inside eggs, diapausing larvae are exposed to predation and infection by pathogens, particularly fungi that may invade eggs actively through the egg shell or affect larvae with toxic metabolites produced on the egg surface (Russell et al. 2001, Luz et al. 2007). Moisture is a limiting factor for both egg survival and fungal activity but there is still little information about the impact of relative humidity (RH) on the survival of larvae inside eggs or a possible effect of entomopathogenic fungi.We report here on the impact of RH on egg survival and an ovicidal activity of M. anisopliae under laboratory conditions. This fungal species is pathogenic to larvae and adults of A. aegypti (Scholte et al. 2004, Silva et al. 2004, and recent studies indicated that it is also effective against eggs of this vector (Luz et al. 2007). The fungal isolate tested here, IP 46, originated from a soil sample collected in 2001 in the Cerrado of Central Brazil and was stored at the IPTSP, UFG, Goiânia, Brazil. Conidia were collected from 15 days old sporulating cultures grown in Petri dishes (100 x 20 mm) at 25°C and 12 h photophase on potato-dextrose-agar; hyphal bodies were produced in liquid Sabouraud-dextrose-yeast extract medium (Goettel & Inglis 1997) for five days on a rotary shaker at 25°C and 240 rpm.The population of A. aegypti originated from virusfree larvae, collected in 1991 in Goiânia, Brazil. Mosquitoes were reared under laboratory conditions as described by Silva et al. (1998). Eggs were prepared using the method related by Luz et al. (2007), and then topically treated with 50 µl water-suspended conidia or hyphal bodies, at 5x10 6 propagules/cm 2 or with water only for the controls and incubated for up to six months at 25°C and 43%, 75%, 86% or > 98% RH regulated in the test chambers with saturated solutions of K 2 CO 3 , NaCl, KCl and K 2 SO 4 , respectively (Winston & Bates 1960). Each month, fungal development on eggs and egg viability were tested. Eggs were submerged in water and quantitative ecl...

Twenty three isolates of