L’arbre. Les arbres du genre Carapa (Meliaceae) sont présents dans toutes les forêts d’Afrique tropicale au niveau de l’équateur, du rift d’Albertine jusqu’au Sénégal et au Mali pour sa distribution la plus septentrionale. En Afrique comme en Amérique tropicale, le carapa est une source importante de Produits Forestiers ligneux (bois) et Non-Ligneux (PFNL). Le fruit et les graines. Le fruit typique de carapa est une capsule à quatre ou cinq valves qui renferment chacune deux à cinq graines, soit un total de huit à vingt graines par fruit. L’extraction de l’huile. Les villageois ramassent les graines tombées au sol avant qu’elles ne soient parasitées ou germées, ce qui est défavorable à la production d’une huile de qualité. L’extraction de l’huile se fait par ébouillantage des graines. L’huile extraite, polyvalente, est la substance issue de la plante qui est la plus utilisée devant les extraits de feuilles, d’écorce et de racines. Le marché. En Afrique, le commerce de l’huile de carapa est essentiellement local et reste une activité très marginale. Une demande accrue émane toutefois de l’utilisation de cette huile comme insecticide naturel dans la culture du coton biologique. Discussion. Compte tenu du potentiel économique de l’huile de carapa, sa commercialisation devrait respecter une rétribution équitable des paysannes afin de mieux rentabiliser la production. Des mesures de protection des arbres de carapa et de leur habitat doivent également être prises pour permettre une gestion de la production d’huile à long terme. La plantation semble être une option durable en vue de la conservation des peuplements naturels de carapa.

The bioefficacy of various plant extracts, namely Azadirachta indica A. Juss, Khaya senegalensis Desrousseaux (A. Jussieu) and Hyptis suavuolens (L.) Poit, either alone or in combination with half the recommended dose of synthetic pesticides, was studied with farmers to find a more sustainable strategy for the management of bollworms in cotton. A number of treatments were farmer innovations. The treatments were compared six times during the season to the application of the fully recommended dose of synthetic pesticides and to a control with no pesticide application. Applications of either the fully recommended dose of the synthetic pesticides or the combinations with a neem seed extract (6 kg/ha) were most effective in reducing bollworm incidence and damage. Both the treatments gave the highest yields of cottonseed, the latter being the most cost-effective. All the pesticides used, except neem alone, had a toxic effect on bollworm predators. This study has increased farmers' confidence in endogenous technology. The researcher's interaction among the local learning group members, who conducted the experiments, facilitated the introduction of a cost-effective alternative to the standard full-dose synthetic pesticide recommendation.

The incidence of the American serpentine leafminer, Liriomyza trifolii (Burgess) (Diptera: Agromyzidae) was studied in cotton-growing tracts of Tamil Nadu State, India. The incidence was higher on summer than on winter cotton and the cropping pattern was found to have an impact on the incidence of the leafminer on cotton. Biological studies on L. trifolii conducted on cotton, Gossypium hirsutum L., tomato, Lycopersicon esculentum Mill., and cowpea, Vigna sinensis (L.) Walp., revealed that its life cycle varied with different hosts. The duration of the pupal stage of L. trifolii was the longest in the leafminer's life cycle. Lycopersicon esculentum was the preferred host—females of L. trifolii survived the longest and had the highest fecundity on this host. Sex discrimination was possible at the pupal stage, on the basis of size; female adults were found to emerge from larger-sized pupae and males from smaller ones.

A questionnaire survey of 100 smallscale cotton growers was conducted in two cotton-growing provinces of Mozambique to assess the constraints faced by the farmers in relation to the timing of insecticide application. The results showed that majority of the farmers started spraying too early (four weeks after germination) and were unaware that such sprays reduced the population of natural enemies of insect pests and might not lead to increased yields. The farmers applied an average of three sprays in the cotton growing season, about half of them according to pest observance and 41 % by following instructions of extension officers, but were constrained by the unavailability of insecticides and sprayers. Another constraint was lack of information on the timing of insecticide application. More than half of the farmers had suffered mild insecticide poisoning and needed more effective training on the judicious and safer use of insecticides, integrated with non-chemical pest management practices.

The response of two cotton varieties (TCH 1002 and 77/10) and two hybrids (TCHB 213 and DCH 32) to damage caused by the American bollworm, Helicoverpa armigera was evaluated under two spacings and three fertiliser levels each. Variety TCH 1002 was less damaged than 77/10, whereas between hybrids, DCH 32 was less preferred than TCHB 213. Damage was higher when the varieties were grown at a spacing of 50 × 20 cm and the hybrids at a spacing of 120 × 45 cm compared to 75 × 30 and 120 × 60 cm, respectively. Increasing the amount of fertiliser applied did not have any significant effect on damage caused by the pest. Tannin and gossypol contents were found to influence levels of damage caused by H. armigera. A combination of high tannin and gossypol resulted in reduced damage. The highest tannin content in varieties was recorded in leaves of TCH 1002 grown at a spacing of 75 × 30 cm, with a fertiliser level of 120:60:60 NPK kg/ha. The highest gossypol content was recorded in flowers of TCH 1002 under similar spacing and management levels. In the hybrids, the highest tannin and gossypol contents were recorded when DCH 32 was grown at 120 × 60 cm spacing with a fertiliser regime of 120:60:60 NPK kg/ha. Cotton was damaged to a greater extent when grown at a closer spacing. Increasing levels of nitrogen resulted in higher damage levels.

The development of Helicoverpa (= Heliothis) armigera (Hb.) (Lepidoptera: Noctuidae) on foliage, squares and bolls of four cotton cultivare [G 27, HD 167 (Gossypium arboreum), H 777 and H 974 (G. hirsutum)] and one hybrid (HHH 81) was studied under controlled conditions. The results indicated that some biological parameters were influenced only by plant parts and not by cultivar/hybrid. The larvae died as first instars when reared on the foliage of cv. G 27 and HD 167. Irrespective of cultivar, the larvae and pupae weighed more when the larvae were reared on cotton bolls than on squares and foliage. The larval and pupal periods were shortest for larvae reared on bolls, followed by squares and foliage. The fecundity of the female was highest when the insect was reared on bolls, followed by foliage and squares. The longevity of the female moth was highest in insects reared on bolls, followed by insects reared on squares, and on foliage. The longevity of the male moth was not influenced by rearing on the different plant parts. The duration of the life cycle was shortest for insects reared on bolls, followed by squares and foliage.

A questionnaire survey was conducted to find out the information and knowledge of extension workers on thresholds of cotton bollworms, (Helicoverpa armigera and Diparopsis castanea). A sample of 30 extension officers was interviewed in Southern and Central provinces of Zambia. The results showed crucial deficiencies in extension worker's knowledge on thresholds of key pests and their implementation in cotton IPM. More than 60% extension officers were not aware of the basic information and knowledge such as thresholds of cotton bollworms, the recommended time to start scouting (weeks after germination of cotton) and the number of cotton plants to be examined for pest observance in each field. All extension officers indicated a desperate need for more field oriented practical training on thresholds. The recent increase in the incidence of aphids, Aphis gossypii as reported by 50% extension workers is obviously due to calendar sprays of synthetic pyrethroids and the lack of a suitable aphicide in current spray programme. Demonstrations on the practical aspects of thresholds deserve much more attention at college level and also during the in-service training. More co-operation in cotton IPM training for extension officers within Central and Southern Africa is suggested.

The charged and partially discharged Electrodyn was evaluated at various swath rows of cotton. The results of field trials suggest that under a low pest pressure, a wider swath up to two or even more rows is possible, with the current version of Electrodyn sprayer, without any significant effect on the yield of seed cotton. Similar yields of seed cotton were also obtained with both charged and partially discharged Electrodyn.

The insecticide application techniques on cotton were compared in a series of trials. The new techniques compared well with knapsack sprayers and can play an important role in the control of Heliothis and other insect pests of cotton in Zambia. The ‘Electrodyn’ knapsack and ULV sprayers gave similar yields and pest control with cypermethrin at 30 g a.i./ha. A new pyrethroid lambda cyhalothrin (12 g a.i./ha) gave similar yields to cypermethrin (30 g a.i./ha) irrespective of the spraying techniques (Electrodyn, knapsack and ULV). The new application techniques have more potential for small-scale cotton farmers in developing countries as they receive limited training on the dilution of insecticides with water and calibration of knapsack sprayers.

Spatial pattern of distribution of populations of three insect species, namely, Amrasca biguttula biguttula (Ishida), Bemisia tabaci (Genn.) and Aphis gossypii Glov. was studied in Upland cotton (Gossypium hirsutum L.) at an interval of 13–15 days during July, August and September in Punjab. The populations were found to be aggregated from the beginning of season upto 25 August in jassid nymphs, 12 August in whitefly adults and the end of season in apterous aphids. Environmental heterogeneity at low population in July and innate behaviour at high population were responsible for the aggregated dispersion in each of the three homopterans. Based on these observations the appropriate number of samples required to be drawn for population studies were determined which varied with change in pest density in each case.