Organosoluble extracts from 55 Turkish medicinal plants were tested under standardised conditions for biological activity against third-instar larvae of mosquitoes Aedes aegypti and Anopheles gambiae. Eight extracts demonstrated significant larvicidal activity, with An. gambiae being more susceptible than Ae. aegypti in all cases. The possibility of using indigenous plants for mosquito control is discussed.

The efficiency and profitability of an integrated pest management system consisting of a phytosanitary survey and threshold interventions (based on levels of insect damage) was tested at the Vallée du Kou irrigated rice scheme in Burkina Faso, for two consecutive crop seasons in 1987. There was a considerable advantage in cost, number of insecticidal applications and yield of a threshold intervention-based system over arbitrary or routine insecticidal application methods. The proposed method is considered to be environmentally friendly.

Survey questionnaires were administered to 50 farmers in three chiefdoms in the Moyamba District of southern Sierra Leone. The study was undertaken to gain insight into the indigenous farming practices for cowpea with emphasis on pest management. This is to serve as a guide in drawing up a research agenda and identifying appropriate measures for the control of cowpea pests. Farm sizes were generally small, usually less than 2 ha of intercropped cowpea. This suggests that the farmers were mostly subsistent and would require low cost inputs to boost production. Vertebrate and insect pests were identified by the farmers as limiting cowpea grain production. Insect pests were considered more serious than vertebrates. Pest control was mostly traditional and involved cultural measures such as weeding of plots, fencing, trapping and scaring of birds. These may be inefficient and labour intensive. Varieties planted by the farmers were mostly land races that have low yield potential and lack some other desirable agronomic character like semi-erectness and bold seeds. Selection criteria in breeding programmes should incorporate farmers' preferences which include high yields, sweet taste, resistance to pests and diseases, compatibility with the farming systems and acceptable seed appearance that would enhance marketing. The study further revealed that at present cowpea is grown mostly as a secondary crop. Therefore, introduced pest control efforts would have to be cheap, easy to adopt and integrative. These would include:

(a) education on control options hitherto unknown to the farmers;

(b) identifying and developing effective strategies that are low cost, labour insensitive, environmentally friendly and compatible with the socioculturel background of the farming community; and

(c) creating awareness on the necessity for the inputs to be readily available and affordable at the local government level.

Crystals of a local isolate of Bacillus thuringiensis variety israelensis were isolated by centrifugation on a continuous sucrose gradient (40–70%). Analysis of the crystals by SDS-PAGE revealed three major protein subunits of Mr˜25,000, ˜66,000 and Mr˜140,000. The crystals were solubilised using high pH and reducing conditions. Analysis of the soluble (protoxin) and insoluble fractions by SDS-PAGE showed the presence of proteins of Mr˜21,000 and ˜61,000, respectively. Proteolytic treatment of these fractions resulted in no apparent change in the molecular weights of the proteins. The crystals contained carbohydrate moieties as determined by periodic acid Schiff (PAS) and fluorescein isothiocyanate (FITC) Concanavalin A staining. In double radial immunodiffusion experiments, antisera raised against the Mr˜21,000 and ˜66,000 subunits did not react with other B. thuringiensis protoxins known to be active against the tsetse fly, Glossina morsitans morsitans, and the stemborer, Chile partellus.

The electrophoretic variation of four enzymes of wild Anopheles pharoensis in Mwea Irrigation Scheme, Kenya, was studied between 1987 and 1988. The enzyme loci examined were aldehyde oxidase, a-glycerophosphate dehydrogenase, β-hydroxyacid dehydrogenase and lactate dehydrogenase. All the loci examined were dimorphic. A mean heterozygosity (H) of 0.341 was obtained, which is comparable to values for other mosquito species. The allelic frequencies were in genetic disequilibrium compared to Hardy-Weinberg predictions. It is proposed that there may be more than one species in the taxon Anopheles pharoensis.

The agar gel double diffusion test was evaluated for detection of nuclear polyhedrosis virus infecting the silkworm, Bombyx mori L. (BmNPV). The test was successful using alkali-dissolved BmNPV as antigen. The antiserum raised against dissolved BmNPV gave positive results with a wider range of antigenic concentrations compared to antiserum raised against undissolved BmNPV. Gel plates prepared using phosphate buffered-saline as dissolving medium for agarose gave sharper and clearer precipitation bands compared to those made with sodium carbonate-saline as diluent. Sharp bands were obtained when the experiment was carried out at 25°C, whereas at higher temperature (35°C), the bands were diffused. The test was able to detect antigen concentration as low as 2 × 106 OBs/ml (18.9 μg/ml of antigen protein).

Studies were carried out to compare the efficacy of insecticide schedules based on calendar intervals with those based on plant growth stages for the control of cowpea insect pests. Spray schedules based on calendar intervals and plant growth stage gave reasonable control of the pest complex and increased grain yields significantly. However, spray schedules based on plant growth stages alone were more efficient for two of the three cowpea varieties tested. This was attributed to differences in maturity periods which made spraying by regular calendar intervals slightly out of phase with attack by key insect pests. Thus, spray schedules based on plant growth stages are recommended for the control of insect pests of cowpea.

Silkworm larvae infected transovarially with Nosema bombycis were fed with an aqueous suspension of Bavistin (50% carbendazim w/w) at 2 and 3% concentrations. The treatments increased the survival of worms and reduced the pebrine infection in the lot significantly, although complete elimination of infection was not observed. Significant beneficial effects of the treatments at 2 and 3% were also observed with respect to larval, cocoon and cocoon shell weights and cocoon to shell ratio. However, treatments with Bavistin at 4% concentration produced an adverse effect on cocoon characters.

The juvenoids fenoxycarb and methoprene were evaluated for morphogenetic activity on last-instar nymphs of the American bird grasshopper, Schistocerca americana (Drury) (Orthoptera: Acrididae). Topical application of fenoxycarb induced supernumerary nymphs, adultoids and adults with curled wings. Methoprene yielded similar morphogenetic effects although at reduced levels of activity. Of particular interest, however, is the discovery that, in addition to its morphogenetic activity, fenoxycarb causes significant mortality in developing fourth-, fifth- and sixth-instar nymphs.

Permethrin, deltamethrin, fenvalerate and cypermethrin were evaluated for their termiticidal efficacy in a graveyard test. Semul wood, Salmalia malabaricum veneers (size 15.00 × 6.00 × 0.06 cm) were impregnated with concentrations of 0.25, 0.50 and 0.75% aqueous solution of these chemicals. Fenvalerate provided 100% protection for 44 months at all three concentrations. Cypermethrin provided 100% protection at 0.50 and 0.75% concentrations, while permethrin and deltamethrin provided 100% protection at 0.75% concentration for 7 and 10 months, respectively.

Mature fruits from 21 mango, Mangifera indica L., cultivare grown in the Miami National Clonal Germplasm Repository were examined for resistance under laboratory conditions to identify those resistant (antibiotic or antixenotic) to the eggs and larvae of the Caribbean fruit fly, Anastrepha suspensa (Leow). The bioassay consisted of artificially infesting a slice of fruit with eggs obtained from a laboratory colony and counting the adults that emerged. Emergence ranged from 26.6% (on Tobago Small Red) to 119.0% (on Sabre) of controls (on artifical diet). Tobago Small Red, Becky, Saigon Seedling, Zilate, Sandersha, 13–1, Keitt, Turpentine, Rumani, Tommy Atkins, Irwin and Peach had the highest level of resistance observed with less than 80% emergence. The most resistant cultivars are promoted to breeders and growers for production in areas under quarantine for Caribbean fruit fly.

The effect on the larval development of Helicoverpa armigera of caffeoylquinic acids and their structural units, caffeic acid and quinic acid, was evaluated. 5-Caffeoylquinic acid (5CQA) (syn. chlorogenic acid) significantly retarded larval development and increased the number of days to pupation at a concentration of 9 mM in an artificial diet, although final pupal weights were not severely affected. Caffeic acid and quinic acid also inhibited larval development although their effect was less marked. In all cases the effect of the compounds was dose-dependent. A mixture containing 5CQA, 3-caffeoylquinic acid (3CQA) and the novel compound, 1-caffeoyl-4-deosyquinic acid (ICdQA), which were extracted from the wild groundnut species, Arachis paraguariensis (Chod et Hassl.) was also evaluated at a concentration equivalent to that found in the plant (9 mM). This mixture was a potent inhibitor of larval development and more potent than 5CQA alone at the same concentration. The potential role of these substances in host plant resistance of groundnuts and their interaction with other components of pest management strategies are discussed.

Genetic differentiations in natural populations of the tsetse fly, Glossina pallidipes Austen (Diptera: Giossinidae) collected from three ecologically distinct regions of Kenya, namely Lambwe Valley, Shimba Hills and Nguruman were analysed based on two enzymes, phosphoglucomutase (PGM) and phosphoglucose isomerase (GPI). The PGM gene frequencies of allele (a) of male and female flies from Lambwe Valley showed significant differences. A dendrogram of populations collected from different localities showed two clusters: one comprising Shimba Hills, Majimboni and Muhaka Forest and the other comprising Gendo, Homa Hills and Nguruman. This suggests mat different subpopulations of G. pallidipes have adapted to different habitats.

Two phenylpropanoid glucosides, namely acetylmartynoside A and 4”-O-acetylmartynoside, isolated from Aegiphila obducta (Verbenaceae) were studied for insect antifeedant activity against fourth-instar larvae of Chilo partellus (Lepidoptera: Pyralidae). Acetylmartynoside A showed weak antifeedant activity at all the concentrations tested while 4”-O-acetylmartynoside showed strong antifeedant activity, particularly at the higher concentrations of 400 and 500 μg/disk.