Seedlings of 462 sorghum lines were screened to identify resistance to the sugarcane aphid, Melanaphis sacchari (Zehntner). About 7% of the lines exhibited resistance in the seedling stage in greenhouse trials. In an advanced screening experiment, 12 sorghum lines had resistance ratings of 1.0–3.0 (highly resistant or resistant). In a similar test, older and larger plants of the same lines were as resistant as in the seedling stage. Lines IS12664C, IS12609C, IS12158C, and IS12661C were highly resistant in preliminary and advanced screening trials. Antixenosis was shown to be a mechanism of resistance. Sorghum lines IS12664C, IS1144C, IS1598C, and IS12661C were less preferred than ‘Mtode’, a susceptible sorghum. Based on greenhouse and field trials, antibiosis adversely affected aphid longevity, days reproducing, and progeny production. On the least antibiotic sorghums, longevity, days reproducing, and number of nymphs produced were as high as 13.7, 6.0, and 26.6, respectively. On the most antibiotic sorghums, these values were 4.5, 0.0, and 0.0. Resistance appeared to be controlled by a dominant gene, but there were indications of modifiers linked to major genes.

The noctuids Busseola fusca and Sesamia calamistis and the pyraloids Chilo partellus, Chilo orichalcociliellus and Eldana saccharina are the most important stemborers of maize in East Africa. A wide range of egg, larval and pupal parasitoids of stemborers have been identified, but information on predators, nematodes and microbial pathogens is less extensive. The most abundant and widespread parasitoids in the East African region are the egg parasitoids Telenomus spp. and Trichogramma spp., the larval parasitoids Cotesia sesamiae and Sturmiopsis parasitica and the pupal parasitoids Pediobius furvus and Dentichasmias busseolae. Predators, such as ants, spiders and earwigs can cause high mortality of eggs and young larvae in some areas. Nematodes and microbial pathogens have been reported to infect all life stages, but their impact is low under natural conditions. The abundance of natural enemies can vary considerably between locations and seasons. In general, indigenous natural enemies are not able to keep stemborer populations below economic injury levels. This paper summarises what is currently known of the natural enemies of cereal stemborers in East Africa.

Deployment of cowpea with Bacillus thuringiensis (Bt-cowpea), to control Maruca vitrata Fab., must be preceded by the development of an insect resistance management (IRM) plan to ensure a sustainable use of the in-plant protection offered by the transgenic variety. One of the components of a resistance management plan involves the use of wild or cultivated host plants as refugia. In West Africa, wild refugia have the potential to be a major component of such an IRM strategy. In the current study, we examined the occurrence of M. vitrata on three cultivated cowpea varieties and one wild alternative host, Sesbania pachycarpa D.C. Our results indicate that M. vitrata population overlapped on the wild host and cowpea. The overall insect population on S. pachycarpa represents 9–13% of the population on cultivated cowpea. Based on these findings, we suggest that S. pachycarpa may contribute as a refuge for M. vitrata population in case of deployment of Bt-cowpea.

Bactrocera invadens Drew, Tsuruta & White and Ceratitis fasciventris (Bezzi) are the major fruit fly pests of fruits and vegetables in Africa. The effects of two types of larval diet, liquid and solid (carrot based), on various quality control parameters (pupal recovery, pupal weight, adult emergence, flight ability, fecundity and fertility) of the two fruit fly species were investigated for five generations. The potential to replace two imported ingredients (yeast and wheat germ oil) with inexpensive and locally available alternatives was also explored. Most of the quality control parameters evaluated (pupal recovery, pupal weight, adult emergence and fecundity) for B. invadens reared on a liquid diet outperformed those reared on the carrot-based solid diet. In contrast, even though C. fasciventris was able to develop successfully on the liquid diet, three of the quality control parameters evaluated (pupal recovery, pupal weight and fecundity) were significantly lower over the generations when compared with those from insects reared on a solid diet. Except for flight ability, the parameters of B. invadens reared on the diets subsituted with the local yeast were of lower quality compared with those reared on the liquid diet containing the imported yeast. Corn (maize) and soybean oils were promising substitutes for wheat germ oil in the liquid larval diet of B. invadens without compromising any of the quality control parameters.

With the advent of transgenic Bacillus thuringiensis (Bt)-cowpea, there is a need to identify the feeding preferences of Maruca vitrata Fab. to determine in which component of the plant the expression of the toxin needs to be the highest to ensure the greatest efficacy of insecticidal Bt proteins. In the current study, we examined the feeding preferences of M. vitrata larvae in a naturally infested cowpea field. We also tested, in the laboratory, the suitability of different flower components for the larval development of M. vitrata. Our results indicate that in the field, all types of flowers, regardless of their age, were infested with M. vitrata larvae. The reproductive organs, in the flowers, were the preferred feeding diet for the larvae. Laboratory bioassays confirmed that the reproductive organs were the optimal tissues for M. vitrata larval development. The implications of these findings for transgenic Bt-cowpea are discussed.

—Infochemicals play an important role in the biology of many insect species. An understanding of their role in plant-herbivore-carnivore interactions can be used in the development of tools for the enhancement of environmentally benign alternatives to synthetic pesticides. This review discusses how chemical information mediates ecological interactions between organisms and the role of infochemicals in integrated pest management. Infochemicals can be used in pest monitoring and in pest control, through mating disruption, mass trapping and to aggregate herbivores at delivery sites for biological control agents. Particular emphasis is placed on the potential of using pheromones and kairomones in the management of the banana weevil, Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae), a pest in plantations of East African highland banana and plantain in most banana-growing regions of the world. Cosmopolites sordidus produces an aggregation pheromone that attracts both males and females. This pheromone has been identified and synthesised and is being recommended as an effective agent in the trapping and control of the weevil. The synergism between banana plant extracts (kairomones) and the synthetic pheromone in attracting C. sordidus should be better exploited. Future research areas that can provide information for the development of an infochemical-based trapping system for the management of C. sordidus are discussed.

In the first section of this review, the stimuli involved in orienting biting flies to their hosts from a distance are discussed under the following headings: (1) Appetitive search—driven by endogenous rhythms and hunger. (2) Activation—the switchover from search behaviour to active host-location brought about in the insect by host-originating stimuli including, depending on species, carbon dioxide, visual contact, and specific host odours. (3) Attraction—the process of active host-location through which the insect comes into the immediate vicinity of the host. This relies on host-originating stimuli including visual contact and olfactory stimuli such as carbon dioxide, volatiles such as acetone, and specific, usually very potent host-related odours.

The second part of this review discusses the properties of the odour plumes biting flies rely on to locate the host. Possible methods of host-location using air-borne odour plumes are presented and the “positive anemotaxis” model based on moth pheromone work is stressed.

Conidial suspensions of four isolates each of Beauveria bassiana and Metarhizium anisopliae were evaluated in the laboratory for their virulence to adult Ootheca mutabilis. All the isolates tested were pathogenic to the beetle, but to varying degrees. Three of them, B. bassiana CPD 3 and CPD 10 and M. anisopliae CPD 6 were superior to all other isolates in terms of mortality induced on adult beetle, LT50 and LC50, with B. bassiana CPD 3 having the lowest LC50 value. In feeding assays; consumption by beetles treated with B. bassiana CPD 3 was significantly reduced within 2 days treatment (DAT) and the trend continued until 7 DAT, when all the beetles died. The antifeedant effects of the pathogen on O. mutabilis could partly offset its slow speed of kill, and might play an important role in field control.

This study was conducted in the Knuckles Forest Region in central Sri Lanka, and investigated how termite species richness, abundance and functional group diversity vary in different montane forest types and identified the likely causes of this pattern. Termite diversity declined with increased elevation, with upper montane forests recording a single endemic species, Postelectrotermes militaris Desneux. Transect sampling in lower montane forests yielded 26 species, with a higher number from dry forests (22 species) than from wet forests (15 species). Species specificity also was high in dry forests (11 species) compared with wet forests (four species). Termite abundance did not show a distinct trend in dry and wet forests. Live-wood termites were present only in upper montane and high-altitude lower montane dry forests. Wet forests had a higher relative abundance (78%) but not species richness (40%) of soil and soil–wood interface feeders. In dry forests, both species richness (82%) and abundance (88%) of fungus-growing wood feeders were higher. The study suggests that key drivers of the species distribution pattern are low temperature and differing forest floor conditions. In the upper montane forest floor where earthworms dominate, wet soil and damp, woody litter riddled with beetles are not favourable for termites. In lower montane wet forests, moist, thick decomposing leaf litter and in dry forests, drier, relatively undecomposed leaf litter with many dry sticks and branches support species with specific food habits.

The possibility that Sitophilus zeamais Motschulsky prefers a particular grain side and a grain side area for feeding, and the implications and value in maize programmes' breeding for resistance were investigated in the laboratory at ambient temperature (32.7 °C) and relative humidity (70.4%) using standard techniques. A total of 20 elite maize varieties were used: TZBRCOMP.2C1F1, TZBRELD3C5, PVASYN-3F2, PVASYN-6F2, DTSYN-11-W, BR9943DMRSR, IWDC3SNY-W, WHITEDTSTRSYN, 2008DTMA-YSTR and 2000SYNEE-WSTR, obtained from the Maize Breeding Unit of International Institute for Tropical Agriculture (IITA), Ibadan, Nigeria, and ILE-1-OB, IFEMAIZEHYBRID-1, IFEMAIZEHYBRID-2, IFEMAIZEHYBRID-5, IFEMAIZEHYBRID-6, ARTCOMPOSITE-A-Y, ARTCOMPOSITE-B-Y, ART/98/SW1-OB, ART/98/SW4-OB and ART/98/SW5-OB, obtained from the Institute of Agricultural Research and Training (IAR&T), Moor Plantation, Ibadan, Nigeria. The flat side of a maize grain at the point of penetration was significantly preferred (P≤ 0.05), possibly because it provided much needed space for anchorage and feeding. The South locus of the flattened side of a maize grain was also significantly preferred (P≤ 0.05), possibly because of its soft nature and proximity to the nutrient-rich embryo. The findings of the study have implications for seed viability and can be considered in breeding for resistance to infestation by S. zeamais in stored maize.

Six companion crops, i.e. Tagetes erecta, Daucus carota L., Coriandrum sativum L., Brassica oleraceae L. var. acephala, Capsicum annuum L. and Zea mays L., were evaluated for their efficacy in suppressing field populations of Frankliniella occidentalis (Pergande) and Megalurothrips sjostedti Trybom on French bean Phaseolus vulgaris L. Each companion crop was interplanted with French beans in a 3×10 m plot and replicated three times in a completely randomized block design. The thrips populations on French bean flowers in experimental plots were compared with those on beans treated with two insecticides: L-cyhalothrin (Karate 1.75% EC) and methiocarb (Mesurol 500 SC) or untreated (control). Coriandrum sativum, Z. mays and T. erecta are recommended as companion crops for intercropping with French beans to reduce populations of thrips and hence minimize the use of chemical insecticides on this crop.

We studied the abundance and diversity of flower-visiting insects on Bt and non-Bt cotton plants in the Makhathini Flats region of South Africa during the 2003/2004 and 2004/2005 crop seasons to detect any impact of the Bt toxin (Cry1Ac). Bt cotton cultivars produced more flowers than non-Bt cultivars regardless of the cropping conditions (farmers' fields or research station), probably due to the fact that Bt cotton is not susceptible to flower bud pests. The results obtained in both crop seasons highlighted the prevalence of honeybees (Apis mellifera L.), various Nitidulidae and a unique Meloidae species (Mylabris oculata Thunberg) as flower visiting insects in this area. No impact of the Bt phenotype on insect abundance and diversity could be drawn on the basis of our comparative results on Bt and non-Bt cotton plants, and no direct effect of these transgenic plants was actually noted. The potential role of some of the inventoried insects, especially M. oculata, in the dispersal of transgenic pollen is discussed.

Surveys were conducted to determine the species composition of stemborers and their natural enemies in maize and sorghum in 1999 and 2000 in eastern, northern, southern and western Ethiopia. The six species of stemborers found attacking maize and sorghum were Chilo partellus (Swinhoe) (Lepidoptera: Crambidae), Busseola fusca Fuller, Sesamia calamistis Hampson (Lepidoptera: Noctuidae), S. nonagrioides botanephaga Tarns & Bowden (Lepidoptera: Noctuidae), Rhynchaenus niger (Horn) (Coleoptera: Rhynchophoridae) and Pissodes dubious (Ström) (Coleoptera: Rhynchophoridae). Twenty species of primary parasitoids of eggs, larvae and pupae of Ch. partellus, B. fusca and S. calamistis were recorded. Other natural enemies, including predators, fungi and nematodes, were also found. Cotesia flavipes Cameron (Hymenoptera: Braconidae) was the dominant and the most widely distributed parasitoid of stemborers in Ethiopia, and was reared from field-collected Ch. partellus, B. fusca and S. calamistis.

The traditional values of caterpillars to the Bisa people of northern Zambia were assessed through a questionnaire survey involving 104 households from 24 villages. Information validation was by Participatory Rural Appraisal, Focus Group Discussions, caterpillar collection and identification. Caterpillars of eight Saturniidae moth species are valued very highly by the Bisa. Six of these were collected and identified from the miombo woodlands of the study area. The harvesting of Gynanisa maja (Klug), Gonimbrasia belina (Westwood), Cirina forda (Westwood), Imbrasia epimethea (Drury), I. rubra (Bouvier) and Imbrasia sp.3 caterpillars by local people, provides an alternative source of dietary animal protein and is associated with several cultural and spiritual processes and beliefs which bind the people together as one tribe. Edible caterpillars are bartered and sold at markets, enabling the local people to gain access to goods and services that normally are out of their reach. An individual collector processed 11.5 kg of sun-dried edible caterpillars worth Zambian Kwacha (ZK) 172,600 (US$ 52) during the caterpillar-harvesting period in 1999, while a household averaging six members processed 69.1 kg caterpillars worth ZK 1,036,098 (US$ 309). The income generated from sales of edible caterpillars far outstripped that generated from the sale of agricultural produce. Estimates of household incomes for 1999, an edible-caterpillar bumper harvest year, and the Bisa traditional edible-caterpillar management system are discussed.

The oviposition-deterrent and toxic effects of seven plant species with known biological effects were tested against the Adzuki bean beetle, Callosobruchus chinensis L. (Goleoptera: Bruchidae) on stored faba bean seeds for two years at Holetta Research Centre, Ethiopia. Oils of Azadirachta indica, Milletiaie ferrnginea and Chrysanthemum cineraraefolium were the most effective in partially or completely preventing egg laying, and no bruchids emerged from the few eggs laid. The Phytolacca dodecandra, Hagenia abyssinica and Schinus molle treatments had no significant effect on the bruchids and most of the eggs laid developed into adults. Eucalyptus globulus seed powder treatment caused the death of only emerging adult beetles.

The citrus swallowtail Papilio demoleus L. is a serious pest of citrus in many regions of the world. We evaluated the effects of pyriproxyfen, a juvenile hormone agonist, on late-stage larval and pupal development of the pest. Fourth and fifth instars, as well as freshly formed prepupae were treated topically with concentrations of 7.5–60 μg/μl of the juvenile hormone analogue. Effects included prolongation of larval duration, delay in larval–larval and larval–pupal ecdysis, mortality, formation of mosaics with larval, pupal and adult characteristics, decreased and imperfect pupation, and complete inhibition of emergence. These results demonstrate that pyriproxyfen has an adverse effect on the development and metamorphosis of the citrus swallowtail, and further work is recommended, including laboratory and field studies.

Susceptibility studies keep farmers informed, and enhance breeding programmes' testing against infestation and damage by stored product pests. Therefore, the susceptibility of 20 elite maize varieties to Sitophilus zeamais infestation was investigated in the laboratory at 32.7 °C ambient temperature and 70.4% relative humidity. The varieties tested were obtained from the Maize Breeding Units of International Institute of Tropical Agriculture (IITA), and Institute of Agricultural Research and Training (IAR&T), both in Ibadan, Nigeria. Susceptibility was assessed, using as indices, weevil mortality and survival rates, percentage grain damage, percentage grain weight loss, weight of grain powder, weevil development time, and number of emerged adults. The susceptibility index was determined post-infestation at 56 days using Dobie's formula and at 90 days from a new formula derived from Dobie's formula. Susceptible varieties produced significantly (P≤ 0.05) high numbers of F1 and F2 progeny, and had significantly (P≤ 0.05) low weevil mortality and early first weevil emergence. Grain damage and loss increased with storage duration. There was no visible damage to varieties 2000SYNEE-WSTR and TZBRELD3C5 at 56 days post-infestation. At 90 days, the two varieties had the lowest percentage grain damage, percentage weight loss, and weight of grain powder. The index of susceptibility at F2 progeny showed that the resistant varieties decreased in number from 17 (85%) to 13 (65%) and the moderately resistant varieties increased from 2 (10%) to 6 (30%). This suggests the effect of prolonged storage duration on the inherent ability of varieties to resist weevil attack. Variety PVASYN3F2 was susceptible. The factors conferring high resistance to 2000SYNEE-WSTR and TZBRELD3C5 should be investigated. They should be promoted to control S. zeamais infestation and damage in stored maize.

The pearl millet, Pennisetum americanum L., a major food crop in the Sahel, is regularly attacked by a complex of spike worms, of which Raghuva albipunctella De Joannis (Noctuidae: Lepidoptera) is the most common and abundant species. The research on taxonomy, economic importance, biology and ecology of spike worm and control measures used to suppress its populations is reviewed from 1972 (period of its first outbreak) to 1984. Further studies are proposed to develop a viable pest management strategy which would be effective, practical, economical and easily adopted by the farmers. The present paper also discusses the difficulties and possibilities of such approach in relation to subsistence farming systems.

Dacus oleae (Gmelin) is a major pest of the olive tree Olea europea causing early fruit drop, ‘sting’ damage to table olives and substantial decreases in the quantity and quality of oil. This review describes the control strategies being developed and in current use—biological, trapping methods, sterile insect release, chemical insecticides, growth regulators and integrated control. Present problems and the implications of the controlling regimes on the disturbance of the agroecosystem are presented. Emphasis is given to newer methods which should be characterized by their specificity and effectivity.

The influence of young, mature and senescent leaves of bitter gourd Momordica charantia L. (Cucurbitaceae) on the feeding, growth and reproduction of Epilachna dodecastigma (Weid.) (Coleoptera: Coccinellidae) were studied under laboratory conditions (27 ± 0.5 °C, 12 h light: 12 h dark photoperiod, 65 ± 5% RH). Larval developmental time of E. dodecastigma was longest on senescent leaves followed by young and mature leaves, whereas the pupal period was shortest on young and mature leaves. The longevity of females was generally higher than males. Male and female longevity were highest on mature leaves and lowest on senescent leaves. Fecundity was highest on mature leaves followed by young and senescent leaves. The growth and development of E. dodecastigma were related with nutrient and phenol content of three types of bitter gourd leaves. Carbohydrate content was higher in young and mature leaves, whereas protein, nitrogen, amino acid and lipid content were in greater quantities in mature leaves followed by young and senescent leaves. Phenol content was greatest in senescent leaves and least in mature leaves. Higher level of carbohydrates, proteins, lipids, nitrogen and amino acids including water content and lower phenol content of mature leaves had influenced higher growth rate and fecundity of E. dodecastigma.