Two isolates of nucleopolyhedroviruses (NPVs) from Kenya and South Africa were compared to Gemstar® (a commercial NPV) for their pathogenicity against the first four larval instars of Helicoverpa armigera (Hübner). The larvae were fed on droplets with the three virus products in concentrations of 0 (control), 6×102, 6×103, 6×104 and 6×105 occlusion bodies/μl. The bioassays showed that the median lethal dose (LD50) values of 23 and 631 occlusion bodies for the first and second instars, respectively, were comparable to those of Gemstar®. The LD50 values for the third and fourth instars were 3981 and 39,810 for the Kenyan isolate and 1288 and 25,119 for the South African isolate. There was a linear relationship between the log LD50, the larval age and the lethal time (LT50), which appeared to be dose dependent. This correlation constitutes a useful index for estimating susceptibility of larval populations. The LT50 increased from 2.8 to 11.9 days and 2.8 to 6.8 days, respectively, for the Kenyan and South African isolates, suggesting a slight increase of resistance with age within infected larvae.

Insect-free tubers of four potato varieties, namely Kenya Baraka, Anett, Kerrs Pink and Roslin Gucha were exposed to adult Phlhorimaea operculella for 14 days in uncontrolled conditions in storages. On examination of the tubers 16 days after exposure, the percentage of infested tubers was determined: Kenya Baraka—62.50, Anett—77.50, Kerrs Pink—85.00 and Roslin Gucha—86.25%. The larvae made the following mean tunnel lengths: 44.65, 95.33, 88.33 and 104.23 cm in Kenya Baraka, Anett, Kerrs Pink and Roslin Gucha varieties, respectively. Although there were no statistically significant differences in the number of tubers infested (per cent), there were significant differences in the mean length of tunnels made by the larvae in Kenya Baraka and the other three varieties at P < 0.05. The mean number of larvae which survived in 10 tubers were 6.75, 11.25, 15.75 and 18.00 for Kenya Baraka, Anett, Kerrs Pink and Roslin Gucha varieties, respectively. There were statistically significant differences between Kenya Baraka and Kerrs Pink; Kenya Baraka and Roslin Gucha; and Roslin Gucha and Anett varieties (P < 0.05). Thus Roslin Gucha was the least resistant of the four varieties tested, whereas Kenya Baraka emerged as the most resistant variety. The mechanism of resistance in this case was most probably antibiosis.

Phenolic tsetse attractants in host urine were shown to form gradually from proattractants identified as a mixture of glucuronates and sulphates. The breakdown of proattractants is predominantly due to microbial activity. Of the eight bacteria isolated from buffalo urine three have demonstrated varying ability to give rise to free phenols the formation of which was monitored by observing the build-up of 4-cresol by means of gas chromatography. These observations may provide a useful biotechnological model for controlled release of these semiochemicals in the field.

Vegetable and grain amaranths represent a vital source of micronutrients and protein in Asia and Africa. However, various foliar lepidopteran pests and stem-mining weevils hinder amaranth production. Insect-resistant cultivars can enhance the productivity of this crop. Here, we report on the performances of amaranth varieties screened for their resistance to insect pests under the field conditions at The World Vegetable Center stations in Asia and sub-Saharan Africa. We conducted two preliminary screening trials with a total of 263 entries from around the world in Taiwan and a third preliminary screening trial with 49 African-indigenous entries in Tanzania. Promising entries from these preliminary trials were collectively evaluated in an advanced screening trial in Tanzania, to identify lines resistant to foliar and stem-boring pests in East Africa. Four entries exhibited moderate resistance to foliar pests: TZ51 and TZ53 (Amaranthus cruentus), TZ34 (A. dubius) and TZ39 (Amaranthus sp.). Five entries showed moderate resistance to stem weevils: TZ06 and TZ27 (A. cruentus), TZ52 (A. graecizans), TZ59 (A. palmeri) and TZ07 (Amaranthus sp.). Lepidopteran pests affecting leaves were reared to adulthood and identified as Spoladea recurvalis (Crambidae), Spodoptera exigua (Noctuidae) and Spodoptera littoralis (Noctuidae). Stem weevil larvae were also reared and identified as: Neocleonus sannio Herbst, Gasteroclisus pr. rhomboidalis Boheman, Hypolixus pr. haerens Boheman and Baradine sp. (Curculionidae). These results highlight key amaranth pests in East Africa and identify insect-resistant entries that will be useful in breeding programmes and resistance studies.

Tick populations were monitored between October 1991 and September 1992 at monthly intervals on 10 Boran (Bos indicus) heifers at Didtuyura ranch, Yabelo district, Ethiopia. Twelve different tick species in four genera were identified from a total of 16 026 specimens collected. Of all the ticks collected, Rhipicephalus spp. constituted 84.7%, Amblyomma spp. 9.9%, Boophilus spp. 4.8% and Hyalomma spp. 0.24%. The ventral parts of cattle were found to be the most favoured feeding sites for most of the ticks collected. The size ranges of the standard ticks collected were 4–8 mm; 9–16 mm; 4–8 mm and 8–13 mm for R. pulchellus, A. variegatum, B. decoloratus and A. gemma, respectively, while their respective male to female sex ratios were 2:1; 3.2:1; 1:5.4 and 2.6:1. Packed cell volume (PCV) values of blood samples taken from 600 cattle were monitored monthly during the study period. There was a reduction in PCV during the dry season of the year but generally the values were within the normal range of 32–40%. The parasites causing anaplasmosis, babesiosis and theileriosis (T. mutans) were detected by microscopic examination of blood smears and serologically (ELISA) at seroprevalence rates of 94.68%, 77.19% and 30.9% respectively.

Sorghum is one of the most important cereal crops in the semi-arid tropics. Several insect pests damage it. The possibility of identifying genotypes with multiple resistance to these pests and transferring the relevant genes into high-yielding varieties and hybrids has been considered as an attractive approach to reducing yield losses. A set of 12 cytoplasmic male-sterile and maintainer lines, 12 restorer lines and their F1 hybrids were evaluated for resistance to sorghum shoot fly Atherigona soccata Rondani, spotted stemborer Chilo partellus (Swinhoe) and sugarcane aphid Melanaphis sacchari (Zehntner) under field conditions. There were significant differences among the genotypes tested. A total of 50% of male-sterile lines, 41.7% maintainers, 58.3% restorers and 35.4% of the hybrids tested showed moderate to high level of resistance to the three pests. The male-sterile and restorer lines showing resistance to different insects can be exploited for developing hybrids with multiple insect resistance for cultivation by the resource-poor farmers in the semi-arid tropics.

Morphology of haemocytes of healthy and Beauveria bassiana (Bals.) Vuill.-infected Dicladispa armigera (Olivier) adults was examined in a phase contrast microscope to characterize them into different types. The total haemocyte count (THC) and the differential haemocyte count (DHC) were also estimated. Four types of haemocytes were identified: prohaemocyte, plasmatocyte, granulocyte and spherulocyte. In the healthy adults, the THC varied between 5055 and 5950/mm3, out of which 85% were composed of granulocytes and plasmatocytes. As B. bassiana infection time increased, THC decreased and was associated with a significant concomitant increase in granulocytes and a decrease in prohaemocytes. Granulocytes reacted in various ways, including disintegration of the plasma membrane, formation of fine pseudopod-like cytoplasmic extensions and finally, clumping of cells. Granulocytes and plasmatocytes were the predominant haemocytes involved in all the cell-mediated defence reactions.

The effect of vegetation cover (millet) on the efficacy and conidial persistence of Metarhizium acridum (Driver & Milner) J.F. Bisch., Rehner & Humber was evaluated in semi-field conditions using breeding cages (2 × 2 × 1 m). A mixed population of third- and fourth-instar desert locust larvae, Schistocerca gregaria Forsskål, was used as a target. The insects were exposed in two different vegetation cover types classified as low (about 10%) and high (about 90%). Metarhizium acridum was used at a dose of 2.5 × 1012 conidia/ha in two different application volumes: 1 and 2 l/ha. Untreated insects kept in contact with treated vegetation were monitored to evaluate the persistence of conidia. The results showed that vegetation cover did not significantly (F= 1.320; P= 0.334) affect the efficacy of M. acridum. Under the high vegetation cover, the increase in the applied volume rate to 2 l/ha significantly improved the speed of mortality. Conidia persisted 6 days after treatment with a remarkable effect on untreated larvae exposed to the treated vegetation. In addition, the results of this study showed the efficacy of M. acridum in the low vegetation cover. With an important mass of vegetation, M. acridum conidia could persist even under high temperature conditions.

The South American fruit fly Anastrepha fraterculus (Wiedemann) is an important pest in many countries. The sterile insect technique is an effective method of controlling Ceratitis capitata (Wiedemann) in Argentina and has been proposed for use against A. fraterculus. Because this technique relies on sterile mass-reared males mating with wild females, it is essential to verify that artificial rearing does not reduce male mating competitiveness. Several morphometric characters were evaluated to detect differences between a wild population and a laboratory strain that was derived from it and reared artificially since 1997. Eight morphometric traits were analysed as indicators of body size, head shape and potential mobility: Thorax Length, Head Width, Face Width, Eye Length, Wing Length, Wing Width, Third Tibia Length and Femur Length. The results were analysed using multivariate analysis of variance, linear multiple regression and logistic multiple regression. In general, laboratory flies were larger than wild ones (possibly because the larval diet was supplied ad libitum). Laboratory males had significantly larger Head Width and Eye Length and a smaller Wing Width than wild males. Laboratory females differed from wild ones only by having narrower wings. These results could be due to environmental and genetic factors, or as a consequence of genetic drift (for the latter) during colony establishment plus gradual adaptation to laboratory conditions, where flight ability is most likely less important (resources are found easily at close distances). Also, short-distance interactions among individuals are more frequent in a colony, possibly favouring increased facial trait sizes by sexual selection. Because long-term morphological changes could represent the beginning of intraspecific differentiation, they should probably be worthy of some consideration if a large mass-rearing colony is established.

The objective of the present study was to evaluate the larvicidal potential of the α-amylase inhibitor from the seeds of Macrotyloma uniflorum (Lam.) Verdc. against Aedes aegypti (L.) larvae. Macrotyloma uniflorum α-amylase inhibitor (MUAI) was partially purified using ion exchange chromatography on a carboxymethyl cellulose column. MUAI at concentrations of 20, 60, 100 and 200 ppm was tested against different instar larvae, pupae and adults of A. aegypti to establish its bioefficacy. MUAI showed a strong larvicidal and a moderate adulticidal effect at a concentration of 200 ppm but did not exhibit pupicidal and ovicidal activities. MUAI-treated larvae showed lower α-amylase activity. MUAI also exhibited ovipositional deterrence activity. Dose-dependent mortality was observed, being highest in the first and second instar larvae. The results thus obtained provide a safe and eco-friendly means in the biological control of A. aegypti larvae.

Volatile oils of Citrus sinensis, Ageratum conyzoides, Cymbopogon citratus, Callistemon rigidus and Ocimum gratissimum were tested as repellents against blackfly, Simulium damnosum s.l., the vector of human onchocerciaisis. Topical applications of 10 and 20% v/v concentrations of the oils with liquid paraffin as the carrier, were made on the forearms and legs of four volunteers, with ordinary paraffin oil used as the control. At 10% v/v concentration the protection time was between 30min and 1h with the Citrus, Ageratum, Cymbopogon and Callistemon oils. At 20% Citrus, Ageratum and Cymbopogon oils repelled the blackflies for up to 2h while Callistemon and Ocimum oils were effective for 3h. Application of these volatile oils, especially at the peak biting periods, would serve to reduce human–vector contact and thereby limit disease transmission.

Cotesia vestalis was introduced into Kenya from South Africa in March 2003 for biological control of Plutella xylostella with initial release in 2004. To confirm establishment, the rate of spread beyond the release sites and parasitism rates by C. vestalis were assessed between October 2011 and April 2012 in eastern and southeastern Kenya (Kitui, Mwingi/Yatta and Loitokitok areas). Monthly observations on kale infestation by diamondback moth, damage scores, parasitism and parasitoid guild were undertaken on 20 randomly selected plants in farmer-managed kale farms. Sampled larval and pupal stages were placed in containers and taken to the laboratory for parasitoid emergence. The infestation levels ranged from 0.4 to 2.5 DBM per plant, while damage scores ranged from 1.2 to 1.6, which correlated with the infestation levels. Cotesia vestalis was not only the most abundant parasitoid, but it had also spread to new areas from the release sites. In December, the three sites recorded an average of 50% from C. vestalis. Excluding the exotic parasitoids C. vestalis and D. semiclausum, indigenous parasitoids accounted for less than 5% total parasitism. The parasitoid guild of the diamondback moth varied between months and study sites with January recording the highest species diversity and evenness of 1.15 and 0.63, 1.28 and 0.80, 1.08 and 0.47 in Loitokitok, Kitui and Mwingi/Matuu, respectively. Therefore, C. vestalis had an impact on the management of the DBM with parasitism rate of 35% to 88% and had spread beyond the release sites.

Seven species of stored grain pests were found infesting underground storage pits “bakars” in the Bay Region of Somalia. These species and their relative abundance (%) in “bakars” are as follows: Alphitobius laevigatus (Fabricius) (Coleoptera, Tenebrionidae) (3.7%), Palorus subdepressus (Wollaston) (6.1%), Tribolium castaneum (Herbst) (29.2%); Rhizopertha dominica (Fabricius) (Bostrichidae) (23.9%); Sitophilus oryzae (Linneaeus) (Curculionidae) (4.7%); Cryptolestes ferrugineus (Stephens) (Cucujidae) (32.4%); Sitotroga cerealella Oliver (Lepidoptera, Gelechiidae) (unsampled). The mean percentage damage by insects for the region was 10.4 and by rats was 8.4 for sorghum grain stored as heads in 100 “bakars”. Actellic, K-Othrine and Malathion, applied as a 2% dust to threshed durra sorghum grain stored in sacks above ground, provided 99.2, 99.5 and 94.5% control, respectively.

Genetic and biological implications from interbreeding the Ghanaian okra and cassava biotypes of Bemisia tabaci (Gennadius), reared on eggplant, were studied in reciprocal crossing plans and crosses compared with parental generations using RAPD–PCR. Interbreeding did not affect fecundity of mated females and survival of F1 progeny. However, the sex ratio of the hybrid progeny was significantly male dominated (by 70% males) compared to purebred progeny of each biotype (>60% females) (P<0.01). Each biotype was characterized by its own RAPD profiles. Hybrid females had one locus identical to that of both parents, while the males resembled the mother biotype at two loci. The F1 females were oviposited normally and there was a possible restricted gene flow between insects from the two biotypes, sharing the same host plant. However, the biological isolation seems to buttress ecological isolation in nature, hence maintaining the genetic and biological identity of sympatric populations in both biotypes.

Aqueous extracts of Tephrosia vogelii and Hyptis suaveolens, and of oils of Azadirachta indica and Jatropha curcas, as well as the pesticide Furadan 5G were evaluated for their insecticidal activity against the maize cob borer Mussidia nigrivenella Ragonot in laboratory and field experiments. In general, treated plants had a strong deterrent effect on ovipositing M. nigrivenella. The oviposition deterrence index was highest with neem oil at both concentrations, J. curcas at 5% and H. suaveolens at 20%. In addition, neem and Jatropha oils adversely affected egg hatch; it decreased with an increase in concentrations of oil emulsions and varied between 3 and 25.5% for neem and 6 and 16% for J. curcas. The lethal concentration 50 values calculated were 1.3 and 0.8%, respectively, for neem and J. curcas. By contrast, larval survival was not affected by the oil treatments. In the field, Furadan, neem and J. curcas oils significantly reduced the number of M. nigrivenella larvae by 16–49.2%, while aqueous extracts of T. vogelii and H. suaveolens were similar to the emulsified water control. The treatments did not significantly influence cob weight, and only neem oil at both concentrations and Furadan significantly reduced cob damage and consequently grain losses. These results showed that oil emulsions of A. indica and J. curcas oils act not only as an oviposition deterrent but also as ovicides. The prospects for possible inclusion of botanicals into integrated M. nigrivenella control in maize cropping systems are discussed.

Surveys of the cereal stemborers and their natural enemies in Zambia were initiated in 1997. The surveys verified the presence of three stemborer species on maize, sorghum and pearl millet. These were the maize stalk borer, Busseola fusca Fuller (Lepidoptera: Noctuidae), the spotted stemborer, Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) and the African pink borer, Sesamia calamistis Hampson (Lepidoptera: Noctuidae). Occasionally, the sugarcane borer, Eldana saccharina Walker (Lepidoptera: Pyralidae) was also recovered especially around areas near the sugarcane plantation at Mazabuka, Southern province. Chilo partellus was the predominant stemborer in region I (areas with less than 600 mm of rainfall per annum). Three ‘hot spot’ areas, namely Luangwa, Buleya Malima and Kalobolelwa, were identified based on the abundance of Ch. partellus. The exotic parasitoid, Cotesia flavipes Cameron (Hymenoptera: Braconidae) was released in the three areas for the control of Ch. partellus. However, post-release surveys in these areas have not revealed any recoveries of Co. flavipes. Three indigenous natural enemies, namely Cotesia sp., Dentichasmias sp. and Dolichogenidea sp. emerged from the field-collected larvae.

A binary mixture of (Z)-ll-hexadecenal and (Z)-13-octadecenal was first identified as the sex pheromone components of female Chilo suppressalis. Later, an additional component was identified as (Z)-9-hexadecenal, which markedly enhanced the attractiveness to males when it was mixed to the binary mixture. Rubber septa containing ca. 0.3–1.0 mg of a mixture of the above three components in the natural ratio have been shown to keep up significantly higher attractiveness than virgin females for at least one month. It has also been shown that the pheromone trap is much more effective than a light trap, where both traps usually showed similar trap catch patterns. Several factors affecting trap catch, such as trap type, trap placement, etc., have been examined. Feasibility of the population monitoring with the synthetic pheromone was discussed.

The density responsiveness of larvae and adults of Cheilomenes lunata (Fabricius) preying on Aphis craccivora Koch was investigated under laboratory conditions where temperature and relative humidity were uncontrolled and fluctuated between 24–30°C and 43–90% respectively. The feeding rates of C. lunata were positively correlated with the population density of prey. The number of prey consumed daily by each predator stage tested, increased more steeply at lower, than at higher prey densities, exhibiting thus the Type II functional response. Fecundity of C. lunata females also increased to a plateau with increasing prey density.

Three new species of braconid wasps from Costa Rica are described here: Allorhogas crinitus reared from leaf galls on Protium panamense (Burseraceae), Allorhogas lacuna reared from galls on Melastomataceae and Allorhogas triopsis reared from fruit galls on Psychotria (Rubiaceae). These new species are diagnosed and compared with other species in the genus. These are the first records of an Allorhogas species associated with the plant families Burseraceae and Rubiaceae. It is the third association of Allorhogas with the family Melastomaceae.

An experiment was undertaken at two locations in Nigeria to identify the major insect pests of cowpea, assess the yield losses caused by them and recommend profitable control packages. Various combinations of insecticidal applications were tested at four crop growth stages, in conjunction with varieties possessing moderate levels of resistance to one or two insect pests. Flower thrips were the most important pests, followed by pod sucking bugs and foliage pests. The resistance levels of the varieties did not contribute much to reducing yield losses. Yield losses of upto 75% were caused by insects attacking cowpea during the flower bud and flowering stages, and of 23% by insects attacking during pod development. Insects attacking during the foliage growth stage had little effect on yields. Profitable spray schedules which increased yields by about 50–200% were: three sprays at flower budding, flowering and podding (the optimum), the sprays at either flower budding and flowering or flower budding and podding depending on the location, and one spray at either flower budding or flowering stage. Other spray combinations were also viable, but less profitable. Appropriate recommendations for various categories of farmers are given.