Ultrastructural studies on the fungus, Nomuraea rileyi, infecting the velvetbean caterpillar, Anticarsia gemmatalis

Germination, penetration, and invasion ofBeauveria bassianaon silkworm,Bombyx mori, causing white muscardine

“…Pekrul & Grula (1979) observed that the penetration of hypha of B. bassiana occurs within 16-18 h after infection in the corn earworm Heliothis zea, while Lecuona et al (1991) reported that the conidia of B. bassiana germinated within 18 h after inoculation on Ostrina nubilalis larvae. Similar variations have been observed in the case of Nomuraea rileyi where the conidial germination period varies from 8 to 48 h in different insect larvae (Kish, 1975;Mohamed et al, 1978;Boucias & Pendland, 1982;Thorvilson et al, 1985;Kumar et al, 1997). Similar to the observation of Pekrul & Grula (1979) on O. nubilalis, in the present study on B. mori, though the conidia of B. bassiana were found more concentrated near the nodules, they were able to germinate on all regions of the cuticle.…”

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“…The detection of endocuticular cell lysis prior to the invasion of hyphae into the epidermis was similar to phenomena described by Getzin 3 and Mohamed. 4 By contrast, Boucias 8 and Thorvilson 5 did not find lysis of the endocuticle.…”

“…Germination of the conidia on the integument of S. litura (46 to 48 hr) was similar to that reported for Heliothis zea 4 and on Spodoptera frugiperda 10 but slower than that reported for Pseudoplusia includens (less than 8 hr) 7 and Anticarsia gemmatalis (6 to 18 hr). 8 These differences in time could be attributed to the variation in the composition of the integument of different larvae. Germination of N. rileyi conidia was induced by the addition of larval cuticle and yeast extract to minimal medium.…”

Characterization of a Germination-Accelerating Factor from the Silkworm (Bombyx moriLinnaeus) of Entomopathogenic FungusNomuraea rileyi(Farlow) Samson

“…Successful fungal infection is affected by environmental (e.g., temperature, humidity and sunlight) and biological (e.g., sensitivity and ecdysis) factors. 29) This shows that the conidia of an entomopathogenic fungus attach to and invade an insect only when nearly 100% humidity [30][31][32][33][34] and an appropriate temperature [35][36][37][38][39] are maintained for 16-41 h. [40][41][42] These requirements are not easily achieved in a field environment, and this is considered to be one of the reasons for the unstable effects of fungal pesticides. We have proved that GAF induced the germination of N. rileyi conidia, and it will reduce the time between conidial attachment and their invasion into the insects.…”

“…[2][3][4] It has also been reported that N. rileyi conidia attached to the surface of the host insect required a shorter time for germination, 5,6) as did those cultured on culture media containing a cuticle extract. These differences in germination behavior depending on the presence or absence of host insectderived ingredients might play an important role in the host recognition mechanism of N. rileyi, although the factor responsible for this mechanism has yet to be identified.…”