Trogoderma granarium and Trogoderma versicolor are some of the most dangerous insects for stored products. Their larvae damage seeds of a great number of crops, products and materials of plant and animal origin. These species are quarantine pests for Bulgaria.
A laboratory population of T. versicolor was used in bioassays originating from samples of foreign wheat varieties stored in the Plant Protection Institute (Bulgaria). The lethal effect of mycoses caused by one Metarhizium anisopliae and ten Beauveria bassiana isolates to adult insects was studied under laboratory conditions. The insects were treated with conidial suspensions (1х109conidia/ml). The dead individuals were placed in a humid chamber. The lethal effect was evaluated as a percentage of the cumulative daily mortality due to mycosis after correction with the mortality in the control variant.
The highest lethal effect (100%) was recorded on the second day after the treatment with isolates 667Bb of B. bassiana and 619Ma of M. anisopliae, followed by mortalities of 97.56%, 95.13% and 93.90% caused by isolates 666Bb, 660Bb and 655Bb. The lowest lethal effect (24.39%–26.82%) was caused by 433Bb and 559Bb on the same day. Mortality caused by all isolates, except 563Bb, was 100% on the 5th day.
This is the first report in Bulgaria on bioassays with fungal pathogens against T. versicolor adults.