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Neat stuff by: Dr. Anand Titus and Geeta N. Pereira

Bacteria

There are approximately 100 species of bacteria pathogenic to insect pests but hardly one per cent among these is used as bio control agents. Bacteria belonging to the family Bacillaceae, Lactobacillaceae, Micrococacaceae, Pseudomonadaceae and Enterobacteriaceae are generally found pathogenic to insect hosts. Bacillus thuringiensis kills many larval forms of lepidopterous insects. It affects more than 175 larval species that include some of the most important economic pests. It can also be mixed with a number of commercial insecticidal formulations and is gaining ground in integrated pest management. There are many other species of bacteria which are used in biological control of insect pests such as Aerobacter aerogenes and Escherichia coli, Bacillus popillae, Bacillus sphaericus, Bacillus moritai, Bacillus lentimorbus are already used in commercial preparations. These bacteria form a toxic crystal protein which acts as a stomach poison inside the insect host resulting in the quick death of the insect. The above mentioned genus of bacteria attack mostly members of the insect family belonging to Hemiptera, Diptera, Coleoptera and Lepidoptera.

Some species of bacteria in addition to forming toxic spores produce crystalline inclusions within the sporulating cell which aids in killing the target insect.

Bacillus popillae and Bacillus lentimorbus when sprayed in the field invade the insect and gains entry into the blood system. This acts as a good medium for the growth and proliferation of the microorganism. The bacteria sporulates causing imminent death of the insect and once death occurs the bacterial spores are released into the atmosphere and soil and remain there for extended periods of time. These spores may in turn infect newly hatched beetle larvae and in turn infect it.

6/12/2009 4:00:28 PM