Grain yield loss assessment trials were conducted between 1997 and 1999 in Samaru, Nigeria, to assess losses in millet grain caused by the stemboring crambid moth, Coniesta ignefusalis Hampson in four millet-based cropping systems. Deadhearts were scored at 35 and 45 days after planting (DAP) and bored and unbored stems at 95 DAP (harvest). Grain yield loss 35 DAP in 1997 was 265.56 kg/ha of monocropped millet and this was significantly different from the 146.29 kg/ha if millet was intercropped with cowpea. At 45 DAP in 1998, the loss of monocropped millet was 50.48 kg/ha and it was significantly higher than the 13.44 and 10.00 kg/ha of millet intercropped with groundnut or cowpea, respectively. Losses were non-significant under all cropping systems at 45 DAP in 1997 and 35 DAP in 1998. Assessing for yield losses at harvest (95 DAP) in the 3 years was difficult because in some cases, bored stems out-yielded unbored ones. However, the mean grain yields of stems bored by the stemborer under millet monocrop in 1997 (3881.37 kg/ha) and 1998 (4308.15 kg/ha) were significantly higher than those under millet intercrops in both years. Similarly, mean grain yields of unbored stems under millet monocrop were 4327.11 and 5128.78 kg/ha in 1998 and 1999, respectively, and these were also significantly different from those of unbored stems under all millet intercrops in both years. The mean grain yields of all unbored plants were non-significant in 1997. Using linear regression analysis, a significant and positive correlation was established between yield loss and larval population under millet monocrop in 1997 (r = 0.871). A similar relationship was observed between yield loss and percentage plant infestation (deadhearts) under all cropping systems in 1997 and under millet monocrop (r = 0.994) and millet–cowpea (r = 0.8487) intercrops in 1998. Percentage plant infestation rather than larval numbers was found to be the better indicator of yield loss in millet.

Studies were conducted at the ICRISAT Sahelian Centre, Niger, to assess damage and yield loss by the millet stemborer, Coniesta ignefusalis (Lepidoptera: Pyralidae) on Pennisetum glaucum (L.) R. Brown. Although 78% of stems were infested, late attack by the millet stemborer on millet plants resulted in bored stems yielding more than unbored ones. Artificial infestations with 5 and 10 larvae per plant at 2 weeks after plant emergence (WAE) resulted in 50 to 70% plants with deadhearts and 24 to 100% avoidable yield loss. At 4 weeks after plant emergence, infestations with 5 larvae and 10 larvae per plant resulted in 7% increase in yield and 16% yield loss, respectively. Therefore, both the age of plant and density of borer population at the time of infestation can influence resulting stemborer damage and yield loss on pearl millet.

Studies were conducted using a water-based trap baited with the synthetic female sex pheromone to gain further understanding on the effect of trap height and spacing in relation to crop height on catches of males of the millet stemborer, Coniesta ignefusalis (Hampson) (Lepidoptera: Pyralidae). Regardless of crop height, catches were greatest at trap heights of 0.10 and 0.50 m when the traps were stacked vertically. When traps were sited singly at 50 m spacing there was no significant difference in catches at the different heights. When trap spacing was varied from 50,15, 5,1 to 0 m, male moth catches in traps increased at lower trap heights, regardless of crop height. Comparison of catches in light traps and pheromone-baited traps showed a significant positive correlation. These findings have implications for both monitoring and development of millet stemborer control systems through mating disruption and mass trapping.

Recent studies on the identification and evaluation of the millet stemborer Contesta ignefusalis female sex pheromone have shown that pheromone technology is promising as a management component. A review of research shows that an effective pheromone trap has been developed and successfully tested in eight countries in West Africa, through the West and Central African Millet Research Network (WCAMRN/ROCAFREMI). A regional wide-scale stemborer monitoring network has been developed and is being implemented. Studies on mass trapping and mating disruption indicate that the two techniques have much potential in C. ignefusalis management. Prospects for the implementation of pheromone technology to manage C. ignefusalis in the context of an IPM scheme are discussed.

A light trap was operated in Samaru, Nigeria between 1973 and 1980 to monitor populations of Coniesta ignefusalis. Two generations of the insect/year were represented by two adult peaks in July and September. In 1974, an early peak in May resulted in three generations. In cages in the field, eggs were laid between the leaf sheath and the stem in batches of 20 to 70 with a mean of 47.5 eggs/batch. Laboratory studies conducted at 25–28°C and 75–85% r.h. showed an average developmental period of 35.5 days. The average duration of the egg, larval and pupal stages were 4.5, 21.9 and 9.2 days, respectively. Unfed adults lived for 5.3 days.

Cutting millet stem at harvest until the end of November reduced by 76 to 92.5% the number of third generation larvae of Coniesta ignefusalis entering diapause. When harvest was done after the beginning of December, reduction of diapausing larvae in millet stems did not exceed 50%. Weekly harvests from beginning of November to the end of January 1988–1989 and 1989–1990 showed an increased percentage of larvae in diapause. The percentages of larvae in diapause reached 100% at the end of January in 1988–1989 and between the end of December and beginning of January in 1989–1990. The distribution of diapausing larvae in the stems was not regular with 60% of the larvae located between 40 and 80% of the total stem height.

Pearl millet, Pennisetum glaucum (L.) R. Br. is attacked by over 100 species of insect pests, but only a few of these are of economic importance. The two major ones, the millet stem borer, Coniesta ignefusalis Hampson and the earhead caterpillar Heliocheilus albipunctella de Joannis have been the subject of research in the Sahel during the last decade. The various methods that have been suggested for the control of these species are briefly discussed. Generally, the control strategy adopted by farmers involves the use of cultural operations that will reduce insect damage. There are no control measures that have been developed for farmers. The more scientific methods that have been suggested are the results from research trials and experiments. These have several limitations. Future perspectives and considerations for developing sound and practical farmer-oriented practices are discussed.