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.

Allelochemicals from essential oil-bearing plants have been categorized as green pesticides because they are biodegradable and predominantly non-toxic to vertebrates. With an aim to reduce the use of synthetic insecticides, they represent one of the most promising approaches for eco-chemical control of insects. Eight compounds were evaluated via topical application against third instar Chilo partellus Swinhoe larvae. Thymol was the most active (lethal dose (LD)50 = 189.7 μg/larva) and methyl eugenol the least (LD50 = 1069.4 μg/larva). The compounds were also tested at sublethal levels, i.e. LD10 and LD30, and there was approximately 15–43% of reduction in growth, which was transitory, and some recovery was observed 6 days post-treatment. Compounds were also used as binary mixtures and tested for synergy, using toxicity and feeding inhibition parameters. The data showed that thymol and α-terpineol synergized the effects of both linalool and 1,8-cineole, but linalool with 1,8-cineole exhibited only an additive effect against C. partellus. Although there is no specific generalization that could be drawn relating to efficacy of binary mixtures, the present findings resulted in several complex mixtures that could be developed and tested as leads for effective control of C. partellus.

Insect pests cause major damage to stored grain and foodstuffs, reducing the products' weight, quality and market value. Eight spices commonly used to add flavour and colour to food were evaluated, singly and in combination, for their contact and fumigant toxicity, repellency and effects on progeny development against the cowpea weevil Callosobruchus maculatus F. and rust red flour beetle Tribolium castaneum Herbst. The powders of large cardamom, turmeric and ginger showed contact toxicity against the two test insects. Green cardamom powder was found to have fumigant toxicity against adults of both insects. Clove powder at 1.5 g/50 g dose showed 100% repellency against adults of T. castaneum. The powders of large cardamom, cinnamon and clove caused complete inhibition of progeny production in C. maculatus and T. castaneum at a dose of 5 g/100 g. A 1:1 mixture of green cardamom and turmeric showed both contact and fumigant toxicity against C. maculatus, while a mixture of clove and large cardamom showed repellency and inhibited progeny development in T. castaneum.

Maize pests feeding on grains can transmit with their movement fungi harmful to human and animal health. The aim of the present work was to study the immigration and the dynamics of storage pests in traditional African maize granaries and the fungal spectrum associated with these insects. Treatments were (i) maize cobs protected just after pollination with gauze and stored thereafter, and (ii) unprotected maize cobs as controls. Eight different species of insects were identified in stores. No Prostephanus truncatus (Horn) was found in ‘protected’ maize during the 6 months of storage, but their mean number reached 239 individuals per kilogram after just 3 months of storage in the ‘unprotected’ stores. Similarly, significantly more Sitophiluszeamais (Motschulsky) were recovered from the unprotected than the protected maize treatment. Nine fungal species were found to be associated with the storage insects. On ‘non-protected’ cobs the genus Fusarium (36.05%) was the most frequently identified, followed by Penicillium (23.50%), Rhizoctonia (5.65%) and Aspergillus (3.95%). On protected cobs, Rhizoctonia sp. was most frequent (16.76%), followed by Fusarium spp. (16.62%), Penicillium spp. (8.24%) and Aspergillus spp. (2.33%). The toxigenic species encountered were Aspergillus flavus Link, Aspergillus parasiticus Speare and Fusarium verticillioïdes (Sacc.). Cathartus quadricollis (Guérin) appeared to carry more fungi towards the store, mainly Penicillium spp. (51.47%), Aspergillus spp. (46.56%) and Fusarium spp. (32.01%). Storage pests, in particular C. quadricollis and S. zeamais, play an important role in the contamination of maize with fungi, especially those that produce toxins.

A study was carried out to develop a diet for mass rearing of the pink bollworm Pectinophora gossypiella (Saund.) and optimize bioassays for testing the bollworm's sensitivity to two insecticidal proteins from Bacillus thuringiensis (Bt). A P. gossypiella colony was established in the laboratory from field collections and its developmental biology was compared on various test diets. Larvae reared on a diet of cottonseed and chickpea flours for the first 10 days and subsequently on pieces of okra attained rapid growth and development. This two-phase diet has been used for successful laboratory rearing of 51 generations of the bollworm. Neonates were found to be sensitive to both the Bt proteins Cry1Ac and Cry2Ab2, which are produced by the transgenic Bt cotton products Bollgard™ and Bollgard II™.

Participatory rural appraisal was undertaken in 70 villages in India and Nepal, covering 1185 farmers to generate baseline information on the current plant protection practices. The study revealed that 93% of the farmers in India and 90% in Nepal had adopted chemical control for the management of various insect pests in different crops; however, less than 20% of the farmers expressed confidence on their efficacy. In India, 52% of farmers get their plant protection advice from pesticide dealers, while in Nepal, the majority of the farmers (69%) make their plant protection decisions through agricultural officers. A majority of the farmers (73% in India and 86% in Nepal) initiate the plant protection based on the first appearance of the pest, irrespective of their population, crop stage and their damage relationships. About 50% of the farmers in India and 20% in Nepal were not using any protective clothing while spraying. Health problems associated with the application of plant protection chemicals were reported by farmers. The cost of plant protection on various crops ranged from 7 to 40% of the total crop production cost. Though integrated pest management (IPM) has been advocated for the past two decades, only 32% in India and 20% in Nepal were aware of IPM practices. IPM implementation in selected villages brought a 20–65% reduction in pesticide use in different crops. The vegetable samples analysed for pesticide residues revealed the presence of residues.

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.

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.

The effect of different constant temperatures on several reproductive attributes of the Mexican beetle, Zygogramma bicolorata Pallister, was studied. Fecundity and egg viability, pre- and post-oviposition period, and age-specific fecundity were assessed at 20, 25, 27, 30 and 35 °C. Maximum fecundity and per cent egg viability were recorded at 27 °C (928 eggs and 75.6%, respectively). Pre-oviposition and post-oviposition period declined with increasing temperature up to 27 °C, then increased at temperatures beyond that. Oviposition period decreased from 92.9 to 27.5 days with temperature increment. Age-specific fecundity was also temperature dependent. Z. bicolorata is a biological control agent of the parthenium weed Parthenium hysterophorus Linnaeus, and these findings may be useful in mass rearing programmes for the natural enemy.

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.

This is the first report of the weevil Naupactus curtus Boheman favouring Ascochyta disease on coffee plants in Brazil. From August to October 2008 (the period of N. curtus occurrence), six coffee crops were monitored with the evaluation of 565 coffee plants. Leaves showing injuries caused by N. curtus and Ascochyta coffeae strains were found in Ponte Nova and Jaboticatubas, Minas Gerais, Brazil. A positive and significant correlation between the number of lesions caused by the weevil and those resulting from an infection by the Ascochyta disease was observed. These results suggest that insect control may be an alternative in order to reduce disease proliferation.

The measurements of the hind femur and activities of five enzymes (α-glucosidase, amylase, cellulase, proteinase and lipase) were determined in the femoral muscles of all post-embryonic developmental stages of Zonocerus variegatus (Linnaeus). The length, width and weight of the hind femur increased during the post-embryonic developmental stages. The enzymatic activities in the femoral muscles of the adult stage were significantly (P < 0.05) higher than the lower instar stages. Proteinase and lipase activities were higher than the carbohydrases (α-glucosidase, amylase and cellulase), reflecting the nature and composition of the food plants consumed.