The attraction of the melon fly, Bactrocera cucurbitae (Coq.) (Diptera: Tephritidae) to soybean hydrolysate, fishmeal, beef extract, banana/grapes, bread and dog biscuit was evaluated in snakegourd (Trichosanthes anguina L.) gardens during 2000–2001. Vinegar and beer were added as the ‘bait components’ to the above ‘base baits’ to enhance their attractiveness. Edible oils, glycerine and petroleum jelly were tested as the ‘controlled releasers’ to sustain the attractiveness. The results indicated that banana and soybean hydrolysate were 85–95% more attractive to adult B. cucurbitae than fishmeal, beef extract, bread and dog biscuit. Among the fruit pulps, grapes and banana appeared to be more attractive than pineapple. The attractiveness of baits with palm oil lasted longer (up to 5 days) than that of baits without any controlled releaser (2–3 days). Grapes + beer + palm oil was found to be 37% more attractive than the other admixtures. The fruit flies were attracted towards the baits more intensively between 0600 and 0800 h and between 1600 and 1800 h.

Rearing temperature has an important influence on the efficiency of food utilization by larvae of the silkworm Bombyx mori L. To assess food intake and utilization efficiency in B. mori reared at different temperature combinations, larvae of Pure Mysore race were fed ad libitum on M5 mulberry leaves and reared at four different constant temperatures, viz. 26, 28, 30 and 32°C during instars I to III and combinations of these temperatures during later instars (IV and V). The larvae reared at 28°C (T2) when young and combinations of temperatures 26–26, 28–26, 30–26 and 32–26°C later were taken as controls. The amount of dry food consumed was significantly higher, but a significant decrease in conversion efficiencies (K1 and K2) was noticed in silkworms reared young at 28°C than at the other temperatures. However, the dry food consumed, food converted, assimilation rate and assimilation efficiency increased with the increasing temperature, and larval duration and conversion efficiency decreased significantly with the rise in temperature during both young- and late-instar rearing. Comparisons between these two ages with regard to food utilization parameters were carried out and the factors responsible for these changes are discussed.

Grass pea Lathyrus sativus L. plays a major role in the nutrition of many poor people in Ethiopia. However, the crop suffers heavy damage by pea aphids Acyrthosiphon pisum (Hemiptera: Aphididae). To test potentially more sustainable and harmless alternatives to the commonly used insecticides, some botanicals (neem, garlic and hot pepper), soap, kerosene and the aphicide pirimicarb, were tested for their efficacy against A. pisum at Wondata village, close to the town of Bahir Dar, in northwestern Ethiopia, from 1999 to 2002. After pirimicarb, hot pepper was consistently the most effective botanical in controlling the pea aphid in terms of both pea aphid population as well as grain yield. Compared to the untreated control, there was up to 83 and 55% lower aphid population on pirimicarb- and hot pepper-treated plots in the 2000/2001 cropping season, respectively. There was also up to 93 and 54% higher grain yield on plots treated with pirimicarb and hot pepper extract, respectively. Soap was less effective, while kerosene caused phytotoxicity. Infestation levels increased with advancing maturity of the crop, rising exceptionally suddenly and dramatically near crop maturity. Combined ANOVA over years and crop growth stages indicated that aphid populations varied with years and growth stages. In 2001/2002, aphid populations were higher and grain yields were lower compared with the other years. Percentage parasitism of aphids was significantly higher on pirimicarb-treated plots (∼40%) than other treatments (<20%). Parasitism was essentially a late-season occurrence. Predator population, especially of ladybird beetles (Adonia spp.), was especially higher on hot pepper- and garlic-treated plots, and lowest on pirimicarb treated plots. Grain yield was positively correlated with level of aphid parasitism, ladybird beetle population and number of pods per plant, and strongly negatively correlated with aphid population. In conclusion, a fresh extract of hot pepper sprayed at the rate of 70 ml/4 m2 was selected for further research on rate, frequency and cost of application.

Toxicity and antifeedant activity of crude seed extracts of Annona squamosa (Magnoliales: Annonaceae) from Maluku, Indonesia, against the diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae) and the cabbage looper, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae) were determined using different bioassays. Aqueous seed extracts and an aqueous emulsion of ethanolic seed extracts were toxic to both species. Crude aqueous extract also deterred feeding of fourth-instar P. xylostella in a leaf disc choice bioassay. Toxicities of crude aqueous extracts to natural enemies, Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) and Orius insidiosus (Say) (Hemiptera: Anthocoridae) were investigated using direct spray and residual contact tests. Chrysoperla carnea larvae were less susceptible to the extracts than were O. insidiosus adults.

The leaf miner Coelaenomenodera lameensis Berti & Mariau (Coleoptera: Chrysomelidae: Hispinae) is the most serious pest of oil palm in West Africa. A study of mortality factors was carried out at 19 sites located in seven plantations of 3000–7000 ha, over a 2–4-year period in the early 1980s throughout the forest zone of Côte d'Ivoire, West Africa. All life history stages of C. lameensis were found to be attacked by natural enemies. Fluctuations in numbers of egg parasitoids were related to climatic factors and host population dynamics and parasitism rates varied substantially among sites. High egg mortality in C. lameensis, related to parasitism, was directly linked to climatic factors, mainly relative humidity. Fluctuations in egg mortality not linked to parasitism were similar among plantations. There was also a negative correlation between beetle fecundity and egg mortality; climatic conditions favourable to an increase in fecundity also disfavoured egg mortality. This can be a major cause of population increase of larval C. lameensis. Different species of larval and pupal parasitoids and predators were observed. In addition, viruses, isolated from dead larvae in galleries, killed 55–60% of the larvae, probably playing an important role in limiting populations. The destruction of mines by several species of ants also eliminated about 25% of beetle larvae. Parasitoids played a smaller role (less than 10% of larval mortality is due to parasitoids). Mortality in larvae and pupae can exceed 90%, but varied widely from one plantation to another. Examples of mortality tables are given for clearly characterized situations and they help to explain the stability of populations and the occurrence of outbreaks on a plantation or sites scale. Mortality rates lower than 98.6% can lead to population instability and an outbreak in an area.

A study was carried out for four years in the forest area of Daloa in Côte d'Ivoire to assess the rate of trypanosome infection in tsetse, and thereby the trypanosomiasis infection risk. In different Glossina biotopes, 18,908 Glossina palpalis palpalis were caught with Vavoua traps and were dissected. The most widespread species of trypanosomes infecting the Glossina was Trypanosoma congolense (7.63%) followed by T. vivax (4.50%). Trypanosoma brucei, the trypanosome responsible for animal and human African trypanosomiasis (HAT), was found only in 34 of the tsetse flies collected, and it had a very low infection rate (0.18%). Although infected tsetse flies were captured in all habitats examined, the infection rate was relatively higher along footpaths (0.44%), in farms (0.20%) and around forested water springs (0.27%) compared to the edge of villages (0.06%) and forest borders (0.05%). Among the 34 tsetse flies infected with T. brucei, only 0.05% had parasites exclusively in their salivary glands. Our results suggest that footpaths, plantations of coffee and cocoa and forested water springs are potential biotopes where the risk of infection by T. brucei is most important. The anthropophily of Glossina associated with the high number of parasites in these sites could be the reason for the disease is endemic in Daloa today. In our study, female Glossina were infected more frequently with trypanosomes (0.14%) than males (0.04%) and generally, females lived longer than males. It is likely that the longevity of females, which carry parasites, is the major cause for the endemicity of HAT in this locality.

The African rice gall midge Orseolia oryzivora is a major pest of rice in Burkina Faso. The present study was carried out during four consecutive crop seasons from 1999 to 2001, in three rice-irrigated schemes, near Bobo Dioulasso town in south Burkina Faso. The fluctuation of immature stages of the pest and their damage, with regard to host plants was monitored. These included the cultivated rice Oryza sativa and its ratoons, and wild rice Oryza longistaminata. Sampling on growing rice was carried out monthly in 1m2 quadrats, in each of 100 randomly selected farmers fields. Sampling on rice ratoons was carried out after rice harvest and 500 tillers were randomly selected in the same fields and taken to the laboratory for dissection. Data on wild rice were collected every month by sampling and dissecting 500 tillers per site. This study revealed that in the absence of rice, the pest survived on rice ratoons and wild rice. However, cultivated rice was the preferred host plant as the crop recorded over 15% galling during wet seasons while damage was very low in dry seasons. Results from this study represent an important step towards the development of an IPM programme to control the rice gall midge, with regard to its host plant relationships.

Powders from dry leaves of four plant species: Ficus carica (Moraceae), Eucalyptus globulus (Myrtaceae), Olea europaea (Oleacea) and Citrus limon (Rutaceae), were evaluated under controlled conditions (30±1°C and 70±5% RH), for their biological activity against Callosobruchus maculatus (Coleoptera: Bruchidae), and were compared to a powder from cloves of myrtle Syzygium aromaticum (Myrtaceae) and to eugenol (the essential oil from cloves). Once mixed with seeds of chickpea Cicer arietinum at doses of 1 to 5% (w/w), all the five powders significantly reduced adult longevity. Among these tested botanicals, clove powder was the most toxic as adult survival in treated seeds was less than 24h, even at the lowest dosage of 1%. The powders from dry leaves also reduced fecundity while that from cloves completely inhibited oviposition in C. maculatus. Indeed, the mean number of eggs laid in chickpea seeds treated with powders from dry leaves of the four plant species above varied from 273.2±30.3 to 373.8±58.2 against 401.8±37.9 in the control (untreated seeds). At the highest dose of 5%, all powders significantly reduced the number of emerging adults: 149.3±46.7 in treatment with O. europaea, 139.8±25.1 with E. globulus, 82.8±48.1 with C. limon, 31.5±20.5 in treatment with F. carica and 0.0±0.0 with S. aromaticum. Tests with lower doses (0,1–0,5%) of clove powder revealed that from the dose of 0.2% and above, C. maculatus adults died before laying eggs. Treatments with eugenol at 5μl/50g seeds (v/w), significantly reduced adult longevity (1±0.0 day), the number of eggs laid (0.0±0.0 egg) and adult emergence rate (0.0±0.0 adult), compared to the control used in this test where these parameters are respectively 7.00±0.8 days, 1134.4±204.2 eggs and 745.6±144.9 adults of the first generation.

The effect of diet on the biology of the predatory mite Amblyseius denmarki Zaher & El-Borolosy (Acari: Phytoseiidae) was studied in the laboratory. Predatory mites fed on the eriophyid mites eriophyes dioscoridis, E. olivi and Cisaberoptus kenyae had a faster development, higher fecundity and a more female-biased sex ratio than those fed on the other diets tested, namely pollen of the palm Phoenix dactylifera, the scale insect Parlatoria ziziphus and the whitefly Bemisia tabaci.

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.