How can an institution go about breeding the predator itself?

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Any national plant protection service or agricultural research institution can set up mass rearing facilities. The basic equipment required comprises:

• a room with constant ambient conditions closely resembling those in the outside atmosphere
• a rack, whose legs are standing in paraffin-filled dishes to prevent ants or mites from entering the breeding jars
• I-litre screw-top glass jars, with a fine-meshed steel gauze stuck or welded into the lid. It has proven expedient to also place these jars in paraffin-filled dishes, to prevent transmigration by mites.
• sufficient untreated grain maize of a local variety for use as a nutrient medium (deep freeze for one week prior to use, in order to kill off any remaining pests or other undesired organisms!)
• a sieve set to separate the beetles from the substrate ( I 0.8 mm mesh sieve and 1 3.15 mm mesh sieve)
• sufficient P.t. and T.n. adult individuals (e.g. 3,000 P.t. and 200 T.n.)

Mass rearing involves breeding both the host (P.t.) and the predator (T.n. on P.t.). Strict measures must be taken to ensure that T.n. individuals do not get into the P.t. breeding jars. A simple breeding method would comprise the following steps:

1. Place 600 g grain maize and 500 P.t. individuals in each of 6 jars.
2. After one week, add 50 T. n. individuals each to four of the jars. These four are then the predator breeding jars, and the remaining two the host breeding jars.
3. In the 5th week, sufficient P.t. individuals will be available in the host breeding jars to start a second batch (cf. stop 1). This batch may be correspondingly larger than the first, depending on the number of beetles already produced.
4. In the 6th week, T.n. individuals can be removed from the predator breeding jars, and 50 animals transferred into each of the jars prepared for the 2nd batch (cf. step 2). Always use one-third of the jars to breed the host, and two-thirds to breed the predator.
5. Repeat steps 3 and 4 until sufficient T.n. individuals are available for release (at least 2,000).

Breeding scheme

Individuals no longer required for propagation should be kept in separate jars to maintain populations awaiting release. Constantly monitor the hygiene conditions and health status of the animals in the jars, and conduct quality control of the predators produced. More detailed recommendations on this are contained in the above-mentioned GTZ publication. The IITA "Larger Grain Borer" project also provides support in setting-up breeding activities, and will assist in staff training.

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