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Further research on the production, longevity and infectivity of the zoospores of Leptolegnia chapmanii Seymour (Oomycota: Peronosporomycetes)
Ist Teil von
Journal of invertebrate pathology, 2008-07, Vol.98 (3), p.314-319
Ort / Verlag
Amsterdam: Elsevier Inc
Erscheinungsjahr
2008
Quelle
MEDLINE
Beschreibungen/Notizen
The effect of temperature on the production, survival and infectivity of zoospores of an Argentinean isolate of
Leptolegnia chapmanii was determined under laboratory conditions. Production of zoospores of
L. chapmanii
in vitro and
in vivo upon first and fourth instars larvae of the mosquito
Aedes aegypti was studied at three different temperatures. Zoospores from infected larvae were infective to mosquito larvae for 51, 12, and 5 consecutive days when maintained at 25, 35, and 10
°C, respectively. Maximum zoospore production in infected fourth-instar larvae was 9.6
±
1.4
×
10
4 zoosp/larva at 48 h at 25
°C. The average number of zoospores produced by individual fourth-instar
Ae. aegypti larvae infected with
L. chapmanii was 3.57
±
0.46
×
10
5 zoospores during 6 consecutive days at 25
°C. Zoospore production
in vitro was also affected by temperature with a maximum of zoospores (
n
=
47,666/ml) produced at 25
°C. When zoospores produced
in vitro were used as inoculum against
Ae. aegypti larvae at 25
°C, larval mortality was recorded for 5 consecutive weeks. The encystment process for zoospores took 17–20
min; the germination of cysts (excystment) occurred 5
min after exposure in water to mosquito larvae. The minimal time of contact between zoospores and mosquito larvae to develop infection was two minutes. Infection took place by zoospore attachment onto and then penetration through the larval cuticle or by ingestion of cysts as was confirmed by histological studies. Temperature directly affected infectivity and production of zoospores
in vivo and
in vitro although
L. chapmanii zoospores tolerate a wide range of temperatures.