First release of Teretriosoma nigrescens Lewis (Col., Histeridae), the predator of Prostephanus truncatus (Horn) (Col. Bostrichidae), and follow‐up investigations in southern Togo

Abstract

The predator Teretriosoma nigrescens Lewis was released in southern Togo for the first time in 1991. Followup storage trials were carried out after this first release of the predator in order to investigate effects on its prey, the storage pest Prostephanus truncatus (Horn), in maize stores. Two trials were installed in the same villages (Tsagba as release village and Dafo as control), one in the storage season 1990/91 and the other in 1992/93. A third trial was set up in Moretan (release village) and Akaba (control) in 1993 together with the second release of T. nigrescens. The storage period lasted 8 months with sampling every 2 months. The number of P. truncatus was reduced by 56.4% in stores with presence of T. nigrescens as compared to the control after 8 months of storage in 1990/91. Damage and losses of stored maize cobs were 40.7% and 47.4% smaller than without the predator. One year after the release, larger numbers of the predator were observed in stores. Again, P. truncatus was reduced by T. nigrescens, but this was not as visible as before.In the third trial in Moretan, 1993, shortly after the second release of T. nigrescens, again a decrease of numbers of the Larger Grain Borer was observed in stores after 8 months of storage, together with a reduction of damage and losses.

Teretrius nigrescens against larger grain borer Prostephanus truncatus in African maize stores: biological control at work?

“…(1997) looked for an effect on S. zeamais numbers but found none. Altogether, although these results were seen as ‘encouraging’ (Richter et al . 1998), they do support our conclusion that control of P. truncatus inside the store to a satisfactory level is, in general, not achievable with T. nigrescens alone.…”

“…This was accompanied by a reduction in final loss but not in final damage. Finally, Richter et al . (1998) in 1990–92, again in Togo, made pair‐wise comparisons of villages over three storage seasons with and without T. nigrescens .…”

“…This was accompanied by a reduction in final loss but not in final damage. Finally, Richter et al (1998Richter et al ( ) in 1990 in Togo, made pair-wise comparisons of villages over three storage seasons with and without T. nigrescens. In all three cases, P. truncatus numbers were reduced by T. nigrescens, but final damage was reduced in only one of these (from 50% to 30%).…”

“…A campaign of classical biological control was launched, with the first releases of the histerid beetle Teretrius (earlier Teretriosoma ; Mazur 1997) nigrescens (Lewis) in Kenya and Togo in 1991 (Giles et al . 1996; Richter et al . 1998), and has since been ongoing in Africa (Henning‐Helbig 1995; Bell et al .…”

Solvent extraction of cues in the dust and frass of Prostephanus truncatus and analysis of behavioural mechanisms leading to arrestment of the predator Teretrius nigrescens

“…After establishment of initial populations, it has spread out from the sites of introduction (Farrell, 2000) and is now regarded as the most serious pest of stored maize on the continent (Hodges et al ., 1983; Dick, 1988). In an attempt to control this pest, the Mesoamerican predator, Teretrius nigrescens (Lewis) (Coleoptera: Histeridae), was released into Africa in 1991 for classical biological control (Richter et al ., 1998).…”