Wednesday, December 13, 2006 - 1:47 PM

Using house fly wings as insect cuticle to test temperature and relative humidity effects on conidial germination of insect-killing fungi

Mohammed El Damir,, Guardian Pest Control, Inc, 701 East Fourth Street, Duluth, MN

Sunn Pest, Eurygaster integriceps Puton, is an important insect pest of wheat and barley in the Near and Middle East. Using entomopathogenic fungi in Sunn Pest management is environmentally friendly and economically viable. The objectives of this study were to test the use of a forewing of the house fly (Musca domestica L.), strength sabauroud dextrose agar (SDAY/4), and dry agar-agar as substrates to assess the effect of relative humidity (RH) (91, 95, 98 and 100 1%) and temperature (15, 20, and 30 1C) on spore germination of Beauveria bassiana 5672 and Metarhizium anisopliae 1080 isolates at 24, 48 and 72 h post exposure. In all treatments tested, similar influences of temperature and %RH were observed when conidial germination of 5672 and 1080 was tested on SDAY/4 and fly forewing, whereas little or no germination occurred with agar-agar as a substrate. Conidial germination occurred at temperatures of 15-30C and ≥95% RH and temperatures of 20-30C and >95% RH for B. bassiana 5672 and M. anisoplia 1080, respectively. At 100% RH, 30C and 72 h exposure period, the highest germination rates of 1080 were 99 and 96% on SDAY/4 and fly forewing, respectively. We concluded that the SDAY/4 medium triggered the conidial germination of these fungi similar to the house fly forewing cuticle. This suggests that SDAY/4 medium is useful as a substitute substrate of cuticle when examining the influence of temperature and %RH on conidial germination. The SDAY/4 medium is also nutritive and supplies a substrate for growth and sporulation. This technique provides a tool for predicting the epidemiology of these fungi in the field for an IPM program of Sunn Pest.


Species 1: Hemiptera Scutelleridae Eurygaster integriceps (Sunn pest)
Species 2: Diptera Muscidae Musca domestica (house fly)

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