J. Fargues et C. Luz, EFFECTS OF FLUCTUATING MOISTURE AND TEMPERATURE REGIMES ON SPORULATION OF BEAUVERIA-BASSIANA ON CADAVERS OF RHODNIUS-PROLIXUS, Biocontrol science and technology, 8(3), 1998, pp. 323-334
The effects of both moisture and temperature on the sporulation of an
isolate of Beauveria bassiana, highly virulent to the Chagas' disease
vector, Rhodnius prolixus, were studied in the laboratory under fluctu
ating regimes. Quantitative assays for conidial production from fungus
-killed cadavers from 10-day-old tests showed that recycling was highl
y dependent on the duration of exposure to high relative humidity (RH)
. On first-instar larval cadavers, sporulation reached more than 10(5)
conidia/nymph under most regimes with a favourable phase combining hi
gh humidity (97% RH) and temperatures of 20 or 25 degrees C for at lea
st 12 h/day. Sporulation on third- and fifth-instar nymphs required a
longer period (16 h/day or more) of favourable conditions (97% RH and
25 degrees C) per day The intensity of the conidial production from Rh
odnius cadavers was enhanced when diurnal temperatures were high (28 a
nd 35 degrees C). From a vector control standpoint, daily high humidit
y requirements appear to be a crucial constraint. The recycling abilit
y of B. bassiana on fungus-killed R. prolixus is most likely to contri
bute to the regulation of this triatomine vector if applications are m
ade during the rainy seasons and in the most favourable habitats.