Introduction. Shea tree (V.paradoxa C.F. Gaertn.), a species endemic to the Sudaniansavanna woodlands, is dominant in the parklands of West Africa whereit is of great socioeconomic importance. However, shea tree hasbeen reported in recent decades to be threatened by plant parasites,Loranthaceae. Our study aimed to assess possible variation of theimpact of these parasites on shea tree fruit yield in two contrastinghabitats. Materials and methods. We selected 41 weaklyand 41 heavily infected shea tree individuals, of similar size,in a protected area as well as in its adjacent parklands. Shea treetraits such as diameter at breast height, canopy diameter, treeheight, canopy height, number of fruit yielded, number of parasite stumpsper tree and an impact index ratio were assessed on each shea treeindividual. Two-way ANOVA was performed to compare parasite impacton shea tree fruit yield in relation to habitat. Hierarchical cluster, canonicaldiscriminant and one-way ANOVA analyses were used to show quantitativetraits that characterize shea tree groups from habitats. Results.Loranthaceae did not reduce fruit yield significantly either inthe parklands or in the protected area. Quantitative traits tendedto discriminate all pooled shea trees in relation to habitats. Sheatree individuals in parklands were characterized mostly by the highestvalue of number of infected stumps per tree and of the impact index ratio,suggesting that many shea tree individuals in parklands were sensitiveto Loranthaceae impact on their fruit yield. Conclusion.These findings were helpful for implementing some shea tree conservationplans.

Introduction. Various whitefly species attack sweet oranges in Nigeria. The economic importance of these whiteflies varies from one area to another depending on prevailing environmental conditions. Trials were established to assess the relative susceptibility of sweet orange varieties to woolly whitefly Aleurothrixus floccosus (Maskell) attack, its population dynamics and the impact of its entomopathogenic fungi Aschersonia spp.in population management. Materials and methods. Four sweet orange varieties were used for the trials: Agege, Bende, Pineapple and Valencia. The population dynamics of A. floccosus and its fungi-colonised nymphs were monitored in 2006 and 2007 by sampling 24 leaves per tree at 14-day intervals. Average monthly precipitation, relative humidity and temperature were collated for the period of our study. Results and discussion. No significant difference was observed among the populations of A. floccosus nymphs or the level of nymphal infection by Aschersonia spp. in the sweet orange varieties. Higher numbers of woolly whitefly eggs and adults were observed on the Agege and Bende varieties in 2006 and 2007, but the results were only significantly different in 2007. In both years, the populations of eggs, nymphs and adults of A. floccosus and its entomopathogenic fungi Aschersonia spp. were relatively high in the dry season months of January to March, dropped during the rainy seasons and rose again from October. Evaluation of Aschersonia spp impact showed active colonisation of whiteflies. Generally, our results showed that weather factors such as rainfall and relative humidity negatively influenced the woolly whitefly population. Conclusion. The association between the woolly whitefly population and fungi was beneficial and suggests that Aschersonia spp. could be considered as a potential biological control agent for A. floccosus

Introduction. In Cameroon, plantain plays a major role in food security. An increase in production is necessary to satisfy the demand. Since April 2002, CARBAP has supported a monitory centre of plantain production. The main objective is to prioritise studies of production constraints and characterise commercialisation strategies, in order to improve profitability for small-scale farmers. Materials and methods. Eighteen plots were identified within farms that represent the agro-ecological and socio-economic diversity of the region. Plots were considered as the sampling unit for agronomic and pathogenic constraints analysis. Farms were considered as the sampling unit used in the socio-economic constraint analysis. For each plot, a regular survey of 50 banana plants and agronomic practices was carried out. A survey of each farm was also set for the observation of production conditions thanks to the participation of smallholders. Results. It is possible to distinguish smallholders with different levels of diversification towards plantain production. Agronomic results in the plots surveyed were judged thanks to parameters of growth, yield and pest infestation. Good/bad results on young/older plots were basically distinguished. These divisions of individuals are influenced by initial factors (varieties available for planting, former crops in the plot), means available (inputs) and technical skills in plantain cultivation. Conclusion. This method allows the detection of indicators of diversification towards plantain cultivation and allows one to check the sustainability of such strategies. It is possible to propose improved technical practices. They will be used for further local studies aimed at improving the plantain production.

From August 1988 to January 1997, natural enemies were reared from 335 colonies of Plnnococcus citri Risso (Homoptera: Pseudococcidae) sampled for 87 months from 225 randomly selected cocoa farms in the six cocoa-growing regions in Ghana. A total of 20,408 P. citri individuals was recorded, comprising adult females, third instar nymphs and mummified individuals harbouring parasitoids. Observed predators were larvae of Coccodiplosis coffeae Barnes (Diptera: Cecidomyiidae), nymphs and adults of Hyperaspis egregia Mader and Scymnus (Pullus) sp. (Coleoptera: Coccinellidae), as well as an unidentified lepidopteran. Twelve parasitic Hymenoptera were also reared, including Aenasius abengouroui (Risbec), Leptomastix dactylopii Howard, Anagyrus beneficions Compere, Tropidophryne melvillei Compere, Anagyrus amoenus Compere and Chryptochetum (Lestophonus) spp. Also recorded were a hyperparasitoid, Cheiloneurus carinatus Compere, parasitising Coc. coffeae, Xyplugaster pseudococci Risbec and six rare, undetermined parasitoids. Coccodiplosis coffeae was the commonest parasitoid, occurring throughout the year and infesting 72.8% of the P. citri colonies. Parasitism levels were generally low, the highest mean being 4.6 ± 2.6% for Aen. abengouroui. Simultaneous parasitism by more than one species was common and this gave rise to mean monthly parasitism levels ranging from 0.8 to 4.5%. Aenasius abengouroui, Ana. amoenus and H. egregia are being reported for the first time in P. citri on cocoa in Ghana, and the recovery of L. dactylopii suggests its establishment in the country, where it was introduced in 1949.

Introduction. Le plantain est une culture importante pour la sécurité alimentaire en Afrique sub-saharienne. Pour mieux hiérarchiser les priorités de recherche en fonction des contraintes des producteurs, une cellule d'observation permanente a été mise en place dans le cadre d'une démarche interdisciplinaire. Matériel et méthodes. Un échantillonnage en bananeraies a couvert les zones de contextes agroécologiques distincts qui approvisionnent Douala. Les données ont été obtenues par un suivi de parcelles et d'exploitations. À l'échelle des parcelles, les observations ont porté sur les pratiques culturales, les populations de nématodes et de charançons, et les rendements. À l'échelle des exploitations, les suivis ont porté sur les fonctions économiques du plantain. Résultats et discussions. La gamme de situations culturales étudiées correspond à une diversité de contextes et d'objectifs des exploitations agricoles. Les observations effectuées sur bananiers (rythme d'émission foliaire, circonférence du pseudotronc, nombre de doigts et de feuilles vivantes, poids et longueur des doigts, poids du régime) ont permis d'expliquer comment se déterminait le rendement. Celui-ci est surtout affecté par les pertes avant récolte, en relation avec l'état sanitaire des racines et la présence de nématodes et de charançons. Ces pertes ont été maximales à la fin de la saison sèche. Le rendement est également lié au poids du régime déterminé par le nombre de doigts essentiellement lié à la croissance et à leur remplissage. Pour ce dernier caractère, les résultats obtenus ne mettent pas clairement en évidence l'incidence de la maladie des raies noires. Des améliorations du protocole de suivi sont proposées.

Introduction. Au Cameroun, les tentatives de lutte chimique contre Trioza erytreae, psylle des agrumes, ne permettent pas de maîtriser le niveau élevé des pullulations de ce ravageur dans les vergers. La lutte biologique serait la voie la plus prometteuse pour limiter ses populations dans le pays. Matériel et méthodes. Le parasitisme du psylle a été étudié sur des bourgeons d'agrumes parasités. Les larves momifiées du psylle ont été collectées, dans un verger de la région de Yaoundé, sur des agrumes isolés et sur une rutacée endémique, Clausena anisata. Ces momies ont été suivies au laboratoire et les hyménoptères qui en sont sortis ont été identifiés. Résultats. Le parasitisme global a été de 15 % environ. L'inventaire des espèces d'hyménoptères parasitoïdes de T. erytreae a montré la présence de parasitoïdes primaires : Psyllaephagus pulvinatus (36,3 %), Tamarixia dryi (3,5 %), P. secus (3,3 %), Psyllaephagus sp. (0,6 %), P. chiangamus (0,6 %), Bethylidae (genre et espèce non connus) (0,4 %) et Coccophagus pulvinariae (0,03 %) et des hyperparasitoïdes : Aphidencyrtus (Syrphophagus) cassatus (45,3 %), Tamarixia sp. (6,8 %), Tetrastichus sp. (1,5 %), Marrieta javensis (0,2 %), Physcus sp. (0,2 %), Aphanogmus sp. (0,2 %) et Cheiloneurus cyanonotus (0,1 %). Discussion. La faune des parasitoïdes de T. erytreae est aussi riche au Cameroun qu'en Afrique du Sud. Certaines espèces sont signalées sur ce psylle pour la première fois : Aphanogmus sp., Tamarixia sp., Psyllaephagus chiangamus, Psyllaephagus sp., Psyllaephagus secus et l'espèce non décrite de Bethylidae. Conclusion. La présence naturelle de parasitoïdes primaires de T. erytreae au Cameroun est un atout intéressant pour démarrer, dans ce pays, une lutte biologique contre cet important ravageur des agrumes.

A study was conducted at Katumani, Kiboko and Ithookwe, in the semi-arid Eastern Province of Kenya for four seasons (short rains 1996-long rains 1998), to confirm the major stemborers of maize, and to introduce and monitor the colonisation of Cotesia flavipes Cameron (Hymenoptera: Braconidae) in these stemborers. About 6750 adults of Cotesia flavipes were released at each site, from ‘release stations’, starting one week after plant emergence and repeated fortnightly up to harvest. Pre-release parasitism of the stemborers was determined, for two seasons prior to release of Co. flavipes, during the season of release and one season after the release of this parasitoid. Parasitism was assessed from developmental stages of the stemborers recovered through destructive sampling of 100 plants, starting one week after plant emergence. This was repeated weekly at Katumani, and fortnightly at Kiboko and Ithookwe until harvest. The stemborers recovered from maize were Chilo partellus, Sesamia calamistis, Cryptophlebia leucotreta and Busseola fusca in descending order of abundance, with Ch. partellus being the most widespread stemborer. Cotesia flavipes parasitised and successfully colonised Ch. partellus and S. calamistis in the three sites during the season of release and one season post-release of the parasitoid. Parasitism by Co. flavipes ranged from 7.14–25.80 %. The colonisation rate of Co. flavipes in the two major stemborers in the semi-arid Eastern Province of Kenya suggests the high potential of this parasitoid in regulating populations of stemborers that attack maize in this region.

A survey was conducted in the four regions of Tanga, Morogoro, Coast and Dar es Salaam in eastern Tanzania to determine the distribution and species composition of cereal stemborers and their natural enemies. A total of 22 fields were sampled in Tanga, 28 in Morogoro, 17 in Coast and one in Dar es Salaam. Chilo partellus was found to be the predominant species, accounting for 80 % of all stemborers collected. Busseola fusca, Sesamia calamistis and Chilo orichalcociliellus made up 15,4 and less than 1 % of the stemborers collected respectively. Infestation levels varied with the age of the plants, whereby younger plants were more severely infested (infestation ranging from 20–40 %) than mature plants (infestation ranging from 5–15 %). Two larval parasitoids, Cotesia sesamiae and Cotesia flavipes, were the main natural enemies collected. However, the levels of parasitism of the stemborers were very low. The exotic natural enemy Co. flavipes may have spread from the Kenya coast (where it is established) into eastern Tanzania.

Patterns of parasite infestation by plerocercoid forms of the tapeworm Ligula intestinalis (Cestoda, Pseudophyllidea) in the second intermediate host, the roach Rutilus rutilus, were analysed in three fish populations of South-Western France during 1998. In all three studied sites, i.e. Pareloup Lake, Lavernose-Lacasse and Muret gravel pits, roach were commonly parasitized with plerocercoids. A strong increase in prevalence, mean number of parasites and parasitic load was observed in the youngest hosts with a maximum peak reached in the medium-age (2+, 3+)roach classes. Such trends as a function of host fish age would indicate the occurrence of parasite-induced host mortality, with the most heavily infected fish specimens being removed from the three roach populations. The three roach populations infected by L. intestinalis exhibit different patterns of parasite-induced mortality which could correspond to different possible ecological and evolutionary responses associated with local variation in host-parasite interactions. The parasite-induced host mortality observed, i.e. direct mortality caused by pathogenic effects and /or enhanced fish predation by piscivorous birds to increase parasitic transmission is discussed within the context of the adaptative parasite-induced manipulation hypothesis.

A study was undertaken to test the hypothesis that the quality of host plant parts determines the nutritional quality of herbivorous insects feeding on it to their parasitoids. A Gossypium hirsutum-Helicoverpa armigera-Campoletis chlorideae tritrophic system was evaluated. The superior nutritional quality of bolls and young leaves of Gossypium hirsutum (MCU-5 variety) contributes to more efficient feeding, growth and reproduction of the bollworm, Helicoverpa armigera (Hübner) and better survival of its larval parasitoid, Campoletis chlorideae Uchida. Longer total developmental duration and decrease in adult longevity were observed in H. armigera reared on senescent leaves than in those reared on bolls. Consumption, growth rate and efficiency measures were significantly lower in parasitised H. armigera larvae than in unparasitised larvae. Percentage parasitism was highest (84.1%) in H. armigera fed on bolls. The parasitoid C. chlorideae displayed shorter developmental duration and improved survival on H. armigera fed on bolls.

Populations of larvae and pupae of the African rice gall midge, Orseolia oryzivora Harris & Gagne (Diptera: Cecidomyiidae), and two parasitoids, Platygaster diplosisae Risbec and Aprostocetus procerae (Risbec)[= Tetrastichus pachy diplosisae Risbec], were recorded in replicated experiments on farmers' fields at Karfiguéla, Burkina Faso in the 1992 wet season and the 1993 dry season. In each season, four plantings were made at 14-day intervals and samples taken at weekly intervals for 10 weeks. Gall midge populations in the wet season developed through three distinct phases: an initial slow increase, followed by a period of rapid increase coinciding with maximum tillering, and then a final decline. On average, the highest midge populations and highest levels of parasitism developed in the later plantings. During the dry season midge infestations were low and no parasites were detected.

The effect of maternal crowding on the offspring sex ratio of a cereal aphid parasitoid Lysiphlebus delhiensis (Subba Rao & Sharma) (Hymenoptera: Braconidae) was examined. Increasing the number of mothers per host-patch always increased the proportion of males in the population (p). The extent of variations in p at different levels of maternal crowding was compared with the prediction of the Hamiltonian LMC model, i.e. p = (n-1)/2n, where n = number of mothers/host-patch. The perception of trace odours of conspecific females induced haploid oviposition. Differential mortality of the larvae by sex in superparasitised hosts, shifting the p towards sons has been discussed. The inversely parasitoid-density-dependent p indicates that for obtaining maximum number of female progeny, the ratio of female parasitoid to the host in mass breeding should not be less than 1:100 at a time.

Larval parasitism of the sorghum shoot fly, Atherigona soccata Rondani (Diptera: Muscidae), by Neotrichoporoides nyemitawus Rohwer (Hymenoptera: Eulophidae) was studied in the laboratory. Ten shoot fly larvae of each instar (3) and two periods of exposure (24, 48 h) were used in a factorial design with four replicates. Significant differences of parasitism were observed with respect to instars, periods of exposure, and the interaction instar-period of exposure. The second larval instar was most parasitized (68.75 and 85% of parasitism after 24 and 48 h, respectively), followed by the first instar (46.25% of parasitism) exposed for 48 h to adult parasitoids. N. nyemitawus was an effective shoot fly endo-larval parasitoid. Observations on N. nyemitawus searching sorghum seedlings for shoot fly larvae are summarized.

Studies were conducted in Niger in 1986 and 1987 on the population dynamics and parasitism of the millet stem borer, Coniesta (= Haimbachia) ignefusalis (Hampson) (Lepidoptera:Pyralidae), Sesamia calamistis Hampson, and the millet head caterpillar, Heliocheilus albipunctella de Joannis (Lepidoptera: Noctuidae). Planting dates were assessed for effects on population densities of C. ignefusalis and H. albipunctella. Population densities of C. ignefusalis were not reduced by adjusting millet planting dates, but were affected by millet growth stage. Platytelenomus sp. (Hymenoptera: Scelionidae) was the most common parasite of C. ignefusalis on millet. Parasitism of C. ignefusalis larvae and pupae was rare. Sesamia calamistis was a minor pest of millet in Niger, and was rarely parasitized. Population densities of H. albipunctella were reduced by delaying millet planting dates. Bracon hebetor (Hymenoptera: Braconidae) was the most common parasite of H. albipunctella.

Eggs of Heliocheilus albipunctella de Joannis were picked up during ear formation of millet at Bambey in 1988 and were followed up in the laboratory at temperatures 25–30°C and 60–70% r.h. Trichogrammatoïdea sp. probably T. armigera parasitized 60.3% of them. During the period in which eggs were collected, percentage of parasitism increased, which certainly means a build-up of parasite populations.

Ovlposition and development of the ichneumonid Trathala flavoorbitalis (Cam.) a parasitoid of the brinjal shoot and fruit borer, Leucinodes orbonalis Guen., was investigated. The parasitoid responded to a host larva by inserting its ovipositor (stinging) into the larva, whichever instar (first to fifth) it was. All the first and about 50% of the second instars that were stung and oviposited in, were mutilated and died as a result. Successful parasitization and parasitoid development up to adult emergence occurred in 53% of the third, 57% of the fourth and 41% of the fifth instar host larvae. When given a choice of instars for oviposition, the parasitoid avoided all first instar and most second instar larvae, while third to fifth instars were equally accepted. The total developmental time of the parasitoid was much the same (about 20–24 days) whichever larval instar (second to fifth) was parasitized. The parasitized host at pupation contained different developmental stages of the parasitoid, differing in this respect from most other species of larval-pupal parasitoids.

Experiments were conducted during two consecutive years (1983 and 1984) on irrigated rice, in the Southwest of Burkina Faso, in order to monitor the seasonal incidence of the rice gall midge, Orseolia oryzivora H. et G.

The damage incidence is the same whatever the date of planting within the rainy season. Attacks are low during the early growth phase of the rice plants (0 to 3% of “silver shoot”), and increase gradually to reach spectacular levels (20 to 55% of “silver shoot”) between 70 and 90 days after transplantation, after which there is decreased attack.

Parasitism is an important check on the larval population of the pest; up to 77% of parasitized larvae were observed. However, this parasitism due mainly to microhymenoptera, Platygaster diplosisae Risb. and Tetrastichus pachydiplosisae Risb., gets established late.

These results could contribute significantly in developing an IPM process on irrigated rice in Burkina Faso.

Larva of fifth instar silkworm, Bombyx mori L. (Lepidoptera: Bombycidae), parasitized by uji-fly, Exorista sorbillans (Weidemann) (Diptera: Tachinidae), consumed less food and egested less faecal matter than unparasitized one in the instar period. Uji-fly infested worm showed increased digestibility in the last 2 days while the unparasitized larva ingested excessive amounts of food than needed during these days. A reduction of 18.1% in the mean weight of parasitized worm at pupation was recorded. Further, parasitization resulted in 50.7% reduction in the mean cocoon weight and 51.12% reduction in the mean shell weight. Parasitized worms started spinning a day earlier than the healthy ones and the cocoon spun by the former was abnormal.

Oviposition and development of Evania appendigaster and Tetrastichus hagenowii in live P. americana oothecae ranging in age from 0–44 days was investigated. E. appendigaster oviposited in oothecae of all ages but developed only in 0–28 days old oothecae. T. hagenowii oviposited only in oothecae 0–34 days old, but developed only in 0–28 days old oothecae. Oothecae parasitized by E. appendigaster were superparasitized only during the first 4 days after the initial parasitization. A single parasite emerged from each such oothecae, indicating that only one of the two ovipositions was successful. Oothecae superparasitized by T. hagenowii during the first 8 days of the initial parasitization, resulted in ca. 90 parasites from both ovipositions. Oothecae parasitized by each species of parasite were subjected to multiple parasitism by the other species. Oviposition of E. appendigaster in 0–25 days old oothecae, parasitized by T. hagenowii was ineffective as it resulted in the emergence of T. hagenowii only. Reparasitization of 0–36 days old E. appendigaster-parasitized oothecae by T. hagenowii within 0–32 days resulted in the development of T. hagenowii, but reparasitization thereafter was ineffective as only E. appendigaster emerged. Even though T. hagenowii is more efficient than E. appendigaster, in parasitizing and developing in different types of P. americana oothecae, under field conditions the two species of parasites contribute equally towards the natural control of P. americana.

In the Chitwan valley, Nepal, Chilo partellus preferred maize and sorghum over rice, teosinte, finger millet and sugar-cane. Infestation on young maize plants produced “dead hearts” and on older plants reduced growth and sometimes prevented cob formation. The yield reduction in some maize cultivars reached 60% and stem infestation levels reached 98%. Borers produced “dead hearts” in young and “whiteheads” in older rice plants.

The egg, larval and pupal periods from April through September lasted 4–5, 16–41 and 4–8 days, respectively. A complete generation took 28–48 days under summer field conditions and 192–233 days from October to May. Of the one egg, four larval and two pupal parasitoids, all hymenopterans, which were reared from C. partellus, the two most important were Trichogramma chilonis (70% egg parasitism) and Apanteles flavipes (30% larval parasitism).