Stem and cob borers cause substantial damage to maize and affect the quality and economic value of maize in West Africa. Manipulation of planting dates is considered a possible mechanism for averting the overall impact of borers and their damage to the crop. Experiments were carried out in southern Benin to evaluate the effect of various planting dates on the incidence and damage to maize by Sesamia calamistis (Hampson). The trials were conducted at the Benin station of the International Institute of Tropical Agriculture (IITA) at Abomey-Calavi and at Sèhouè, located 70 km north of the IITA, Benin station. The planting dates were: early planting (the day following the first rains), intermediate planting (2–3 weeks after the early planting) and late planting (4–5 weeks after the early planting). The experiments were carried out in the main and minor cropping seasons, respectively, during two successive years in 2003 and 2004. The variables measured included population density of S. calamistis, percentage of infested plants and cob damage. In the main cropping season, incidence of stemborers and percentage of infested plants were higher in the late planting than in the early planting and intermediate planting treatments. The manipulation of planting dates for the control of S. calamistis during the minor maize growing season is not recommended.

Laboratory trials were conducted in Uganda at the Kawanda Agricultural Research Institute to determine attraction, eclosion success and larval survivorship of the banana weevil Cosmopolites sordidus (Germar) on crop residues of different ages. In the first experiment, studies focused on different types and ages of residues of one susceptible highland banana clone ‘Nabusa’ (genome group AAA-EA). Corms attracted 65% of the test weevils, pseudostems 30%, while 5% were non-respondents. Oviposition levels and the number of eggs per female were higher on young than old corms. Eclosion rates of < 1-day-old eggs inserted into corm pieces of residues (cultivar ‘Kisansa’, genome group AAA-EA) declined from 66% in residues collected < 2 days after harvest (DAH) to 58% in residues collected >30 DAH. To assess immature survival, < 1-day-old 1st instar larvae were put on banana corms of suckers and crop residues of the cultivar Kisansa in single rearing chambers. The number of surviving individuals was recorded at 3-day intervals until adults emerged. Survivorship was 12% on sword suckers, 10% on maiden suckers and 7% on flowered plants; and 12% on residues collected < 2 DAH and 5% on residues collected >30 DAH. Larval duration and mean days taken for adult emergence increased with plant and crop residue age. Females emerging from the different plant and residues treatments were similar in weight. The data suggest that all aged residues are suitable hosts for C. sordidus, suggesting that sanitation practices should be implemented soon after harvest.

Hexane and acetone extracts of Trichilia connaroides leaves were evaluated for their biological activity against the Bihar hairy caterpillar Spilosoma obliqua Walker, a destructive pest of crop, medicinal and ornamental plants. Fresh caster (Ricinus communis) leaves treated with a range of concentrations (1–10%) of the extracts were offered to 2nd instars for 120 h, followed by untreated leaves until pupation. Acetone extracts exerted better growth-regulatory properties than hexane extracts, shown by morphogenic malformation and adverse effects on the insect's larval duration, pupal duration, adult emergence and fecundity.

Aqueous extracts of Tephrosia vogelii and Hyptis suaveolens, and of oils of Azadirachta indica and Jatropha curcas, as well as the pesticide Furadan 5G were evaluated for their insecticidal activity against the maize cob borer Mussidia nigrivenella Ragonot in laboratory and field experiments. In general, treated plants had a strong deterrent effect on ovipositing M. nigrivenella. The oviposition deterrence index was highest with neem oil at both concentrations, J. curcas at 5% and H. suaveolens at 20%. In addition, neem and Jatropha oils adversely affected egg hatch; it decreased with an increase in concentrations of oil emulsions and varied between 3 and 25.5% for neem and 6 and 16% for J. curcas. The lethal concentration 50 values calculated were 1.3 and 0.8%, respectively, for neem and J. curcas. By contrast, larval survival was not affected by the oil treatments. In the field, Furadan, neem and J. curcas oils significantly reduced the number of M. nigrivenella larvae by 16–49.2%, while aqueous extracts of T. vogelii and H. suaveolens were similar to the emulsified water control. The treatments did not significantly influence cob weight, and only neem oil at both concentrations and Furadan significantly reduced cob damage and consequently grain losses. These results showed that oil emulsions of A. indica and J. curcas oils act not only as an oviposition deterrent but also as ovicides. The prospects for possible inclusion of botanicals into integrated M. nigrivenella control in maize cropping systems are discussed.

The spatial distribution of Bactrocera fruit flies in the Goa region (west coast of India) was studied using several dispersion parameters between April 2006 and March 2008 in three ecological zones, viz. coastal, midland and upland. These zones are 10, 25 and 50 km to the east from the coastline of the Arabian Sea at an elevation of 15, 70 and 100 m above mean sea level, respectively. The dispersion parameters revealed that the population of all the fruit fly species attracted to methyl eugenol-baited traps, viz. Bactrocera dorsalis, Bactrocera caryeae, Bactrocera zonata, Bactrocera affinis and Bactrocera correcta, followed the negative binomial distribution pattern and was highly aggregated or clumped.

Infectivity of the entomopathogenic fungus Metarhizium anisopliae against workers of the arboreal termite Odontotermes sp. was assayed under laboratory conditions. Test isolates were collected from different sources, including soil from varied locations and insect hosts from the orders Lepidoptera, Coleoptera, Hemiptera and Orthoptera. All the 23 isolates tested and the standard (ARSEF 7413) were pathogenic to the workers of Odontotermes sp. at a concentration of 107 conidia/ml, with mean mortality ranging from 57.5 to 100%. Two of the isolates (Ma2, Ma13) and the standard caused 100% mortality in the termite species. A detailed bioassay was subsequently conducted with the five most promising isolates, namely Ma1, Ma2, Ma13, Ma16 and Ma17, at concentrations ranging from 104 to 107 conidia/ml. The lethal concentrations (LC50) of these isolates ranged from 0.01 to 0.46 × 105 conidia/ml. The average survival time (AST) for the termites treated with the most virulent isolate (Ma2) varied from 4.2 to 5.7 days across the four spore loads, while AST with the standard isolate ranged from 5.3 to 6.3 days. Two of the isolates, Ma2 and Ma13, were found to be significantly more pathogenic to Odontotermes sp. workers than all the others, including the standard.

We evaluated the contact toxicity, fumigant toxicity and repellency of the essential oil of Hyptis suaveolens (L.) leaves against adults of four stored-product coleopteran pests, namely Callosobruchus maculatus (Bruchidae), Rhyzopertha dominica (Bostrychidae), Sitophilus oryzae (Curculionidae) and Tribolium castaneum (Tenebrionidae). Four major compounds were identified in the oil by gas chromatography: sabinene (41.0%), terpinen-4-ol (12.31%), β-pinene (10.0%) and β-caryophyllene (8.0%). Oil concentrations of 0.05–2.0% were tested on adult coleopterans for contact toxicity by topical application. Repellency was evaluated at 0.4–18.3 mg/cm2 concentrations using an area preference test, whereas fumigant toxicity of the oil was tested both in air and admixed with grain at 1–50 μl/l air and 25–100 μl/l, respectively. Persistence of the oil admixed with grain was tested at 0.1–2.5% concentrations for a period of 40 days. Percentage repellence ranged from 20.0 to 94.7% at 5 h against the test insects at the highest dose tested (18.3 mg/cm2). Adults of C. maculatus were the most susceptible in both contact and fumigant toxicity assays, with an LD50 value of 57.0 μg/mg weight of insect and an LC50 value of 4.7 mg/l air, respectively. The oil had low persistence. H. suaveolens leaf essential oil may have potential as an alternative to the synthetic pesticides used in the treatment of grain in storage.

Microbial isolates from the gut region of larvae and adults of the variegated grasshopper Zonocerus variegatus (Linnaeus) were screened for extracellular production of the enzymes lipase, amylase, esterase, protease, linamarase and cellulase. Using the pour-plate culture technique, 15 bacterial, 4 yeast and 5 mould isolates were tested. None of the bacterial isolates showed lipase activity, but virtually all showed esterase and protease activities. Many bacterial isolates demonstrated linamarase and cellulase activities, and a few of them amylase activity. Of the yeast isolates, a few had amylase activity. None of the mould isolates showed enzyme activity, except Aspergillus sp., which showed lipase activity. Evidently, the gut of Z. variegatus contains micro-organisms that are able to produce digestive enzymes. Of significance is the biosynthesis of linamarase (β-d-glucosidase) by the grasshopper's gut bacteria, which probably contributes to the insect's neutralization of the toxic effects of cyanogenic glycosides present in cassava (Manihot esculenta), one of its major food plants.