Takeshi Saika

Development of Biorational Pest Control Formulation against Longicorn Beetles Using a Fungus, Beauveria brongniartii (Sacc.) Petch

Abstract Some basic experiments were performed in order to develop a biocidal formulation which is lethal to certain species of longicorn beetle. The entomopathogenic filamentous fungus, Beauveria brongniartii could be grown aerobically in the presence of 4% corn steep liquor and 2% glucose at 25°C with a minimum doubling time of 7 h. Depletion of glucose and the onset of the stationary phase occurred within 48 h. Application of a diluted aliquot of this culture to a nonwoven pulp fabric sheet resulted in the growth of B. brongniartii on the surface of the fabric. The conditions for the growth of cultures on fabric sheets were optimized and large-scale cultivation of the cultures on fabric was achieved in a specially designed chamber. The cultures covered with conidia could be stored sealed in polyethylene bags for more than 400 d at 5°C without loss of infectivity, while storage at room temperature resulted in a gradual decrease in the number of viable cells. Infectivity was lost when the population of cells decreased below 107 cells/cm2. However, when water was added to dried cultures which had been stored at 25°C for an extended period of time, the number of viable cells recovered and the infectivity of the cultures could be restored. Under field conditions, periodic rainfall which moistens the sheet cultures may help to sustain the infectivity of this agent. When the effects of this biocide were probed in field tests using tangerine crops, it was observed that the use of this agent prevented the proliferation of beetles, in addition to killing adult insects.

Development of an adhesive sheet for direct counting of bacteria on solid surfaces

An adhesive sheet was developed for direct counting of microorganisms on solid surfaces. The sheet consists of a polyurethane film base and water insoluble adhesive. SYBR Green II (for total direct counting) or 6-carboxyfluorescein diacetate (6CFDA) (for fluorescent vital staining) was used for fluorescent microscopy of bacteria collected on the adhesive face of the sheet. Adhesive sheet sampling showed a higher recovery rate for microbial enumeration than conventional swab method or stamp agar. This method is simple, rapid, inexpensive and reproducible.