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 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.

Frankliniella schultzei Trybom is a polyphagous pest and vector of tospoviruses worldwide. It occurs in dark and pale colour forms that are morphologically similar but differ in vector competency and geographic spread. In Kenya and other tropical regions, mixed populations of both colour forms are observed in similar habitats, so are considered as one species. To ascertain the taxonomic status of the two colour forms, they were characterized using morphological, molecular, biological and ecological approaches. Morphological characterization revealed differences between the colour forms on eight features and they separated into distinct clusters through principal component analysis. Restriction fragment length polymorphism of the internal transcribed spacer region (ITS-RFLP) analysis revealed differences between the two colour forms and was confirmed by differences in ITS2 sequences. Virgin pale females had female offspring (thelytoky), while virgin dark females had male offspring (arrhenotoky). Interbreeding of dark males with pale females resulted in pale females, indicating absence of interbreeding between the two colour forms. Laboratory colonies of pale forms lacked males and further analysis of F. schultzei males from Ipomoea setosa flowers in the field indicated the presence of dark males and the absence of pale males. Field surveys in Kenya indicated differences in distribution and host plant preferences among the colour forms. Lack of interbreeding, distinct host preferences and distribution, and morphological and molecular differences indicate that the two colour forms of F. schultzei could be different species. The results highlight the need for combining morphological, biological, molecular and ecological characteristics for resolving taxonomic status of closely related insects.

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.

Baiting studies performed in large, medium and small hospitals in Brazil revealed the presence of 14 ant species, with up to nine recorded in one hospital. Dominant species were exotic ants, and in the large hospital, Tapinoma melanocephalum was the most prevalent. Ants were not uniformly spread through the hospitals, but tended to be found in the more critical areas, particularly in nursery, intensive care, obstetrics, neurology and dermatology units. Bacteriological studies using specific media for bacteria associated with intra-hospital infections indicated the potential for the mechanical vectoring of species of Staphylococcus, Serratia, Klebsiella, Acinetobacter, Enterobacter, Candida and Enterococcus by ants. Although T. melanocephalum did not have the highest rate of association with these bacteria, its ubiquitous occurrences resulted in the highest overall potential as a vector of these bacteria. Because of a largenumber of ant species occurring in Brazilian hospitals, ants pose a potential problem to the spread of diseases in hospitals. Because of the number of associated ant species in hospitals, the control of this potential problem is much more difficult than in registered temperate areas.

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.

Urine from the buffalo, Syncerus caffer, a natural host of the tsetse, has been shown previously to be a potent olfactory attractant for tsetse in the field. The attractant compounds have been found to be extractable into dichloromethane. Fractionation of the extracts by liquid flash chromatography yielded four fractions one of which gave a seven-fold increase in trap catches in the field compared to the control traps. Gas Chromatographie and gas chromatography–mass spectrometric analysis of this fraction revealed the presence of seven simple phenols including phenol itself.

In Reunion Island, insect and mite pests are significant limiting factors to the development of market crops. Several studies have been carried out on some families of pests during the last 40 years, but no comprehensive survey has been undertaken on the arthropods of vegetable crops on this island. During 1997/1998, we studied the arthropod complex on eight main families of crops, namely Solanaceae, Cucurbitaceae, Brassicaceae, Fabaceae, Liliaceae, Asteraceae, Apiaceae and Rosaceae. During a complete year of collection, we gathered 123 species of pests, including 114 species of insects and 9 of mites. We also identified a total of 128 species of beneficials, including 51 species of parasitoïds and 77 species of predators and consisting of 101 species of insects, 14 of mites and 13 of arachnids. Our data constitute the first step for the implementation of strategies for pest monitoring and integrated pest management in an important sector for the island's insular economy.

The behavioural responses of adult female western flower thrips, Frankliniella occidentalis (Pergande) to volatiles from meadow-sweet (Filipendula ulmaria), bay laurel (Laurus nobilis) and sage (Salvia officinalis) were investigated in laboratory bioassays. Volatiles collected by entrainment of a solvent extract of F. ulmaria were more attractive than was the original extract. Frankliniella occidentalis was also significantly attracted to volatiles from L. nobilis and S. officinalis. Analysis by gas chromatography and mass spectrometry identified 1,8-cineole (eucalyptol) as one of the main volatile components of all three plant species. In coupled gas chromatography-electroantennography studies with F. ulmaria, both 1,8-cineole and methyl salicylate elicited responses from F. occidentalis. Eucarvone was identified as the major component of F. ulmaria volatiles, but showed no electrophysiological activity. Behavioural responses of thrips to a range of concentrations of 1,8-cineole and methyl salicylate were tested using a modified Pettersson ‘star’ olfactometer. 1,8-Cineole showed some attractant activity for the thrips at 0.01 mg, but methyl salicylate was repellent at all the concentrations tested.

Successful mass production of biocontrol agents is a prerequisite to their effective use in the field. Thus in the present study the suitability of ten aphid species of a ladybird beetle Anegleis cardoni (Weise) in terms of growth, development, survival and mortality life table attributes was assessed for the purpose of mass production. The study revealed that the developmental duration of the immature stages of A. cardoni was shortest when fed on Uroleucon compositae (Theobald), Rhopalosiphum maidis (Fitch), Hyadaphis coriandri (Das) and Myzus persicae (Sulzer) in comparison with other aphid species. Immature survival, development rate, adult weight and growth index were also highest when A. cardoni larvae were fed on these aphids, while lowest when fed on Hysteroneura setariae (Thomas) and Ceratovacuna silvestri (Takahashi). Any larva of A. cardoni did not reach adult stage when fed on Aphis nerii Boyer de Fonscolombe; therefore it may be considered as a toxic prey. Life table data revealed that the overall mortality prior to adult stage was lowest in U. compositae and highest in C. silvestri. The first instars suffered the highest mortality in comparison with other instars on all the aphid species tested. However, the life expectancy for each aphid species as prey revealed a continuous decline with the advancement of age. Thus among all the ten aphid species tested, U. compositae, R. maidis, H. coriandri and M. persicae were found equally suitable for mass production of A. cardoni.

The use pattern of alternative host plants by Maruca vitrata was investigated in southern and central Benin. Among the wild host plants, Pterocarpus santalinoides, Pueraria phaseoloides and Centrosema pubescens were found to be key relay hosts during the long dry season, Lonchocarpus sericeus and L. cyanescens were the most important hosts during the main rainy season, while Tephrosia platycarpa was an essential relay host during the short wet season in between. Cowpea was the major cultivated host plant and can sustain M. vitrata all year round, if available. However, this pest was able to maintain high population levels exclusively on wild hosts without needing to switch to cultivated crops. The relevance of these findings and their implications for the control of M. vitrata are discussed.

The effects of larval crowding on growth, development and reproductive output of the Parthenium beetle Zygogramma bicolorata Pallister were investigated. Experimental manipulations of larval densities indicated that crowding creates intraspecific competition among the larvae, which negatively affected their growth and development. Larvae at high densities grew more slowly and exhibited longer larval periods compared with those at lower densities. Best-fit curves of developmental rates against larval densities were drawn, which revealed maximum theoretical density for 95% (6 or 15 larvae/63.6 cm2) and 50% developmental rate (1.75 larvae/63.6 cm2), respectively. The reproductive potential of the beetle reared at different larval densities was also observed, but no effect of increased larval densities was observed.

Experiments were conducted to assess the effect of four plant growth regulators (PGRs), namely coumarin, kinetin, gibberellic acid (GA3) and indole-3-acetic acid (IAA), on the development of the melon fruit fly, Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae). All four compounds exerted growth-and development-inhibitory effects on the fly. Coumarin was most potent, followed by kinetin, GA3 and IAA. The first and second instars of the fly were more sensitive than the third instar. Treatment with the PGRs also prolonged the fly's developmental period, reduced percentage emergence and increased percentage of abnormal flies emerging. At the higher concentrations tested (125, 625 and 3125 µg/ml) coumarin, kinetin and GA3 caused 100% mortality in first instars.

Crude ethanol extracts (CE) of leaves of 60 plant species belonging to 32 families and 52 genera were bioassayed for toxicity to adult Tribolium confusum by spraying a 10% (w/v) concentrate under a Potter's tower. CE of eight plants had none and three had some bioactivity; 36 CE killed from 13 to 40% of the beetles. Thirteen plant extracts inflicted between 53 and 100% mortality in the following order: Azadirachta indica (53%) < Eupatorium odorantum = Gliricida sepium = Mimosa pudica (60%) < Annona reticulata = Hibiscus rosa sinensis (67%) < Cycloptis semicordata < Artocarpus altilis < Capsicum annum (90–97%) < Bontia daphnoides = Cuscuta americana = Dioscorea polygonoides = Nkotina tabacum (100%).

Essential oils of three genotypes of Tagetes minuta, six of Tagetes patula and 15 of Tagetes erecta were screened for potential fumigant and contact toxicity against three stored product beetle species, Callosobruchus maculatus (Fabricius), Sitophilus oryzae (Linnaeus) and Tribolium castaneum (Herbst). Genotype 1 of T. minuta (TM-1), genotype 2 of T. patula (TP-2) and genotype 13 of T. erecta (TE-13) were the most toxic. These three genotypes were then evaluated for adult toxicity, oviposition deterrence, and ovicidal and population reduction activities. Essential oils of genotypes TM-1 and TP-2 induced 100% adult mortality for all three insect species at dosages of 50,000 ppm and 500 μg/insect in fumigant and contact toxicity bioassays, respectively. Adults of C. maculatus and S. oryzae were highly susceptible to the essential oils of the three genotypes in both fumigant and contact toxicity bioassays. The essential oil of genotype TM-1 deterred oviposition in T. castaneum by 81% and suppressed its egg hatchability by 91% when applied at a dosage of 70,000 ppm on filter paper.

The predacious mites Amblyseius gossipi El-Badry and A. swirskii Athias-Henroit developed, survived and reproduced successfully on several artificial diets. The best diet consisted of 1 g yeast, 1 g milk, 30 mg cystine, 30 mg proline, 30 mg arginine, 20 mg sucrose, 50 mg glucose, 30 mg streptomycin sulphate and droplets of sorbic acid. Mean eggs/female/day by the two predators was 0.54 and 0.30 when reared on the best diet compared to 1.21 and 0.40 when fed on a natural diet, respectively. Female longevity of A. swirskii was 84.3 days, nearly twice as long as that on a natural diet Eggs showed no abnormalities; larvae fed on diets had normal development, and adults were comparable in size to individuals reared on a natural diet.

Seven phenolic compounds (phenol, 3- and 4-cresols, 3- and 4-ethylphenols, and 3- and 4-n-propylphenols) previously shown to be components of a fraction of an extract of buffalo urine which was active as a tsetse attractant, were evaluated in field experiments, individually at different concentrations, and in blends. The results indicate that 4-cresol and 3-n-propylphenol are the most important components for the of the attractancy phenolic mixture.

The brown cocoa mirid, Sahlbergella singularis is the most important insect pest of cocoa for field damage has been classified into three categories that include blast, stagheadedness and mirid pocket. The mirid attack predisposes the cocoa plant to secondary infection by opportunistic pathogenic fungi. This study evaluated the dieback conditions associated with mirid damage due to associated fungi from lesions on pods, twigs and pin punctures. The relationship between Phytophthora black pod infection and mirid infestation in the field was also established. The results indicated that dieback progression from the mirid lesions (8.5 mm) was significantly different (P< 0.05) from that of pin punctures (7.8 mm). Lasiodiplodia theobromae had the highest proportion of isolates from pods (33%), twigs (47%), and pin punctures (38%). Fusarium decemcellulare (Albonectria rigidiuscula) accounted for 27.8% and 31.6% from pods and twigs; however, it was not recovered from pin punctures. Other isolated pathogens were Aspergillus species and Rhizoctonia species. There was a significantly strong positive correlation coefficient of 0.74 between the mirid population and the black pod disease infection in the field. The major fruit-bearing season of cocoa witnessed an increase in mirid infestation and blackpod infection. The effect of mirid–pathogenic fungi-associated damage could be ameliorated through effective crop husbandry practices to ensure that cocoa plant tissues are not unduly exposed to biological and mechanical injuries.

Resistance mechanisms to the pod-sucking bug (PSB) Clavigralla tomentosicollis Stäl, in cowpea genotype IT86D-716, were studied in field and laboratory. Non-preference was evaluated on three cowpea varieties (IT86D-716, Moussa local and KVx396-4-5-2D) through measuring differences in population parameters and extent of damage under field and laboratory conditions. Antibiosis was evaluated based on development parameters of C. tomentosicollis when reared on pods of the aforementioned varieties. The variety IT86D-716 consistently exhibited both non-preference and antibiosis resistance mechanisms to C. tomentosicollis. A chemical analysis of the pods was conducted to identify compounds conferring antibiosis. Several compounds including cyanogenic heterosides, flavonoids, tannins and trypsin inhibitors were present in pods of IT86D-716. Evidence suggests that antibiosis due to these compounds may contribute to the resistance to PSB. In the case of antibiosis, 5-day long exposures were adequate to observe nymphal mortality. Based on this finding, a fast, reliable and low-cost screening of pods can be carried out in the laboratory for identification of lines that are C. tomentosicollis resistant.

The structure of two compounds extracted from the leaves of Vitex negundo L., their repellent activity and toxicity against three strains of Tribolium castaneum (Herbst) were elucidated. Two compounds were purified and a residual film bioassay was used to evaluate the toxicity to adult T. castaneum. Mortality was recorded 24, 48 and 72 h post-exposure to compounds. The repellency activity of methanol extract was tested by using nine concentrations. Each dose was applied on a half circle of the filter paper, keeping the other part untreated. Insects released on treated filter paper were assessed for repellency up to 5 h. Two bioactive compounds, 22,23-dihydro-α-spinasterol-β-d-glucoside and salicylic acid were isolated from the methanolic leaf extracts by column chromatography and thin-layer chromatography. Their structures were elucidated by various spectroscopic methods. Compound 22,23-dihydro-α-spinasterol-β-d-glucoside is the first report from this plant. Both compounds showed insecticidal activity and the leaf extracts caused 100% repellency in the three tested strains of T. castaneum. Both compounds showed toxicity to T. castaneum, but compound 22,23-dihydro-α-spinasterol-β-d-glucoside was more potent. Its potential future use as herbal insecticide against T. castaneum is discussed.