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.

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.

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 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.

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.

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 aim of this study was to document what water types were most stimulatory to oviposition by the malaria mosquito, Anopheles gambiae Giles s.s. In laboratory choice tests, dishes of black cotton and red laterite soils from around Kisumu, Kenya, equally stimulated An. gambiae oviposition when saturated with water. When infused into either soil type, water from Lake Victoria was significantly more stimulatory than any other type of water or infusion tested. Water from natural An. gambiae puddle habitats, borehole water, cow dung infusion, Bermuda grass infusion and distilled water followed in declining rank order. Relative to An. gambiae puddle-habitat water and distilled water, Lake Victoria water appears to provide the strongest chemical cues for An. gambiae oviposition recorded to date. This work suggests that this important vector of human malaria may oviposit in and around Lake Victoria, as well as in its usual puddle habitats. Lake Victoria should be explored for its possible contribution to malaria mosquito populations.

Parasitism rates of Bemisia tabaci (Gennadius) and searching and oviposition behaviours of its parasitoid Eretmocerus mundus Mercet were compared on two cassava varieties: a glabrous variety, Nase 4 and a hirsute variety, MM97/0245 with c. 88 leaf hairs/cm2. Parasitism was assessed after potted plants of both varieties were exposed in open fields to natural infestation by B. tabaci and its natural enemy. For the behavioural studies, naive, less than 24-h-old females were individually observed on infested cassava leaflets under a microscope for a maximum of 1 h each. The different foraging behaviours were recorded using the computer software ‘The Observer 5.0’ (Noldus Ltd, Wageningen, The Netherlands). Total per cent parasitism and parasitism by E. mundus did not differ significantly between varieties. Upon encounter with leaf hairs, the parasitoids stopped and groomed before resuming the host search. The frequency of repeat probing, host feeding and antennation after probing and host feeding were higher on the glabrous than on the hirsute variety, while the converse was observed when feeding on liquids on the leaf. The duration of host assessment, initial probing, grooming and resting on the leaf was higher on the glabrous than on the hirsute variety. Leaf hairiness at the density investigated caused some changes in the behaviour of the parasitoids, but did not have an overall effect on field parasitism. Since cassava is generally considered to have glabrous leaves and the variety MM97/0245 is one of the most hirsute varieties, we discount leaf hairiness as a factor in determining levels of parasitoid activity.

Bemisia tabaci Gennadius is a major pest on cotton and vegetable plants in Africa. It is considered as a cryptic species complex. Identification of the most damaging species such as the Middle East–Asia Minor 1 (B biotype) and Mediterranean (MED) (which contains the Q and Africa silverleaf (ASL) biotypes) species represents an important step towards the management of B. tabaci. Some data on the geographical distribution of the B. tabaci species complex exist in Burkina Faso, Benin and Togo, but data on the pest's invasion and displacement dynamics, in relation to time, are lacking. Here, molecular markers (mitochondrial cytochrome oxidase, mtCO1) were used to determine the identity of B. tabaci. Our results illustrate population dynamics on cotton and vegetable plants between 2007, 2009 and 2010. On cotton in southern Togo, ASL was predominant and found in sympatry with Q1. Its frequency decreased slightly over time, i.e. from 92% in 2009 to 90% in 2010. In Burkina Faso, Q1, Q3 and ASL biotypes showed different temporal and spatial distribution patterns. There, Q1 dominated on cotton plants throughout the study. This work provides relevant information about the population dynamics of B. tabaci MED species in two West African countries, Burkina Faso and Togo, in connection with pest management programmes.

Dung beetles (Coleoptera: Scarabaeinae) mediate many ecological functions that are important to maintain the ecosystem functioning of terrestrial environments. Although a large amount of literature explores the dung beetle-mediated ecological processes, little is known about the individual contribution from distinct species. Here, we aimed to examine the intra and interspecific variations in dung burial rates performed by two roller dung beetle species (Canthon smaragdulus Fabricius, 1781 and Canthon sulcatus Castelnau, 1840). Furthermore, we evaluated the relationship between dung beetle biomass and dung burial rates. We set up a laboratorial experiment with three treatments (two males, two females, and a couple) and 10 replicates per treatment for each dung beetle species, and dung burial rates were measured after exposing 100 g of mixed pig and human excrement for 48 hours. Our results demonstrate that dung burial rates of males, females, and couples within each species do not differ. However, C. smaragdulus individuals performed a larger dung burial than C. sulcatus individuals did. In addition, we found no effect of individual biomass on the amount of dung burial on intra and interspecific levels. These findings highlight the need for further research considering that distinct species, even from the same genus, may perform different rates of ecological processes, as well as about the importance for considering the beetle biomass when measuring their ecological functions. We call for studies to fill in the knowledge gap about the individual species’ contribution to the maintenance of different dung beetle-mediated ecological processes.

Preliminary electrophysiological tests on certain tarsal and ovipositor sensilla of stem-borers, Chilo partellus and Eldana saccharina, show that the sensilla are innervated by mechano- and contact chemoreceptor cells. Tarsal receptors are sensitive to sucrose, whereas the ovipositor sensilla are not and responses of the ovipositor mechanoreceptor units can be related to the oviposition behaviour of the moths.

Taxonomy is the starting point of any basic or applied biological research. In biological control work, the pest species, its probable area of origin, and, consequently, the location where promising natural enemies may be found, are identified. The close co-operation of taxonomists during pre- and post-release surveys of natural enemies in target areas helps to indicate the indigenous fauna present and the progress of a biological control programme. Biological control programmes should budget for appropriate taxonomie studies in areas where the local fauna is poorly known. Instructing local researchers on the correct collection, preservation, and identification of relevant indigenous and exotic species should be emphasized.

Lepidopteran stemborers (Chilo zacconius Bleszynski, Chilo diffusilineus de Joannis and Maliarpha separatella Ragonot) and diopsid flies (Diopsis spp.) are economically significant insect pests of rice in Burkina Faso. The objective of this study was to monitor damage trends and the pre-imaginal populations of these insects on two host plants, cultivated (Oryza sativa L.) and wild rice (Oryza longistaminata Chev and Roehr). The study was conducted over four consecutive rice crop seasons from 1999 to 2001 in three irrigated rice-growing locations in western Burkina Faso. Sampling of cultivated rice was conducted monthly in 1 m2 quadrates in 100 randomly selected farmers' fields. Data on wild rice were collected monthly from each of the three locations using 500 tillers that were plucked at random and dissected. Results showed that in the absence of a rice crop lepidopteran stemborers and diopsid flies are able to survive on O. longistaminata, which can host the pre-imaginal populations of these insects throughout the year. Damage caused on cultivated rice varied across farmers' fields, seasons and phenological stages of the plants. With 8% the highest average extent of ‘whiteheads’ was recorded during the dry season. These results are important elements in the design of a sustainable management strategy for these insect pests.

Three species of fruit fly parasitoids, Psyttalia concolor (Szépligeti), Psyttalia cosyrae (Wilkinson) and Psyttalia lounsburyi (Silvestri) (Hymenoptera: Braconidae) were reared on different host larvae to determine the effects of host species, size and colour on parasitoid development. Ovipositor, ovipositor sheath and hind tibia lengths were found to be different for progenies from preferred and non-preferred host larvae. Ratios of ovipositor–tibia and ovipositor sheath–tibia showed no difference when P. concolor was reared on a bigger host (Ceratitis cosyra) (Walker) (Diptera: Tephritidae), whereas rearing P. cosyrae on a smaller host (C. capitata) (Wiedemann) showed significant differences. Comparison of the linear measurements, ratios and number of flagellomeres of parasitoids reared on preferred hosts, separated the species into their natural groupings. When reared on a different-coloured host, P. lounsburyi lost its dark markings but other characters remained unchanged. Morphometric analysis also indicated differences between parasitoids reared on preferred host larvae and those reared on non-preferred host larvae. Rearing parasitoids on larvae other than their preferred hosts resulted in colour and size changes, and thus, these characters alone were not reliable for the identification of parasitoids. This is especially important in post-release sampling surveys to ascertain establishment of the parasitoids in new environments where they may adapt to new host species.

This study evaluated the potential use of commercial mycoinsecticide formulations against red-gum lerp psyllid Glycaspis brimblecombei Moore in semi-field conditions. Eucalypt seedlings infested with psyllid nymphs were sprayed with different formulations and two concentrations of each product. Conidial deposits were evaluated after spraying for control efficiency. The conidial deposit was affected by the pathogen species and by formulation types. Higher conidial deposits were associated with mycoinsecticide formulation concentrates of lower granulometry and oil dispersion. However, some products with low deposits of conidia were highly efficient against psyllid nymphs. The results showed that the use of entomopathogenic fungi is a promising alternative method for controlling the red-gum lerp psyllid.

Field and laboratory observations were carried out to understand the significance of prolonged copulation and the male substance transferred from males to females in the white grub beetle Dasylepida ishigakiensis Niijima & Kinoshita. Adults emerged from the soil in the evening and formed mating pairs on sugarcane plants, where copulation lasted for 1–3 h. Mating pairs (30%) observed in the field were accompanied by one or two additional males. Some females mated with one such male after ending copulation with the first male, showing multiple mating. After mating, males dropped to the ground to burrow into the soil earlier than females. Females received a large amount of colloidal secretion from males during mating. The amount and rate of transfer of this secretion from males to females were investigated in this study. Transfer of the secretion from males to females was completed within 30 min, and females that had mated with two males in the laboratory stored a larger amount of male secretion in the bursa copulatrix than those that had mated once. The results of both field and laboratory observations might indicate a possibility that prolonged copulation serves as a post-insemination female guarding behaviour to prevent mating by other conspecific males.

Neem (Azadirachta indica A. Juss.) has been demonstrated to reduce insect populations in stored products through its toxic and growth-disrupting and other effects on the pests. Grain movement and percussion also help to kill pests in grain. The combination of neem and grain movement on population growth and development of four insect pests is reported in this study. Dried whole neem leaves, neem leaf powder and neem seed kernel oil were combined individually with dried beans and rice in separate experiments, and subjected to varying degrees of gentle grain tumbling. The results showed that the combined treatments were more effective in reducing populations and disturbing growth and development of Acanthoscelides obtectus (Say) (Bruchidae), Sitophilusoryzae (Linnaeus) (Curculionidae), Oryzaephilus surinamensis (Linnaeus) (Silvanidae) and Cryptolestes ferrugineus (Stephens) (Cucujidae) compared to the untreated control or the neem or tumbling treatments alone. This study demonstrates the potential of a simple, effective and cheap method of protecting stored seed or food grain in small-scale storage for resource-poor farmers who do not have access to sophisticated control methods, entoleters or other mechanical devices for grain protection.

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.

Nucleopolyhedrovirus (NPV) was isolated from infected Hyposidra talaca (Walker) caterpillars. This defoliating pest was sampled from the Terai and Dooars tea plantations along the foothills of Darjeeling, India. Phase contrast and transmission electron microscopy revealed polyhedral occlusion bodies (OBs) typical of NPVs. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis showed that the molecular weight of the major protein of the OBs is 32.17 kDa. Dose–mortality bioassays conducted for OBs on the second instar caterpillars of H. talaca resulted in a median lethal concentration (LC50) of 2.8 × 103 OBs/ml. The median lethal time (LT50) was 5.45 days for 1 × 104 OBs/ml, 4.15 days for 1 × 105 OBs/ml and 4.05 days for 1 × 106 OBs/ml concentrations. These results indicate the potential of using this NPV as a microbial pesticide against H. talaca.

Host-plant resistance is one of the major components of integrated pest management programmes against the noctuid pod borer Helicoverpa armigera (Hübner) in chickpea. Survival and development of H. armigera on nine chickpea genotypes were compared using two food substrates, namely fresh leaves and pods, and artificial diets containing lyophilized leaf or pod powder of the same genotypes. Among the genotypes used, six showed different levels of resistance to H. armigera, while three were used as susceptible checks. Using leaves and pods, five of the resistant genotypes yielded lower larval weights compared to one of the susceptible checks used. Significant differences between four of the resistant and two of the susceptible genotypes were also observed when using artificial diets containing leaf or pod powder, but the rankings were different from that on the fresh leaves and pods. On both substrates, four resistant genotypes resulted in lower larval survival, pupation, adult emergence and fecundity when compared to one of the susceptible checks. A similar trend was also observed for larval survival and development when using F1 hybrids based on four of the resistant genotypes. Survival and development of H. armigera on the two food substrates, fresh leaves and pods and artificial diets with lyophilized leaf or pod powder, were highly correlated, suggesting that incorporation of lyophilized leaves or pods into the artificial diet can be used to assess antibiosis to H. armigera in chickpea.