Cotton leaf curl disease, a viral infection vectored by the whitefly Bemisia tabaci (Gennadius), is a major threat to the cotton industry in India and Pakistan. We examined the settling preferences of B. tabaci adults on infected versus healthy cotton plants under choice conditions. For experiments with plants at 20 and 35 days post-inoculation (DPI), whiteflies preferentially settled on healthy cotton plants after 8 and 1 h of release, respectively. Whiteflies, however, were unable to discriminate between virus-infected and healthy cotton plants at 5 DPI. Our results suggest that whiteflies' preference for healthy plants compared with diseased plants can lead to rapid virus spread in the field, resulting in higher crop losses.

Pollinators are important natural agents for fruit and seed formation in most tree crops and the use of appropriate sampling methods is fundamental in studying their population. A study to develop surveying and monitoring protocols for cocoa pollinators was undertaken in Ghana. Yellow, white and blue UV-bright painted pan traps (UVPPT), McPhail traps and motorized aspirators were used to sample pollinators of cocoa for 13 successive months, after 6 days assessment of the effectiveness of the traps and diurnal active period of the pollinators. The peak pollinating period of cocoa by ceratopogonid midges was between 07.00 and 12.00 h, as previously reported. All three methods were effective in sampling ceratopogonid midges with the UVPPT being the most efficient in terms of sampling effort. The number of ceratopogonid midges caught by the yellow-UVPPT was significantly higher than that by blue- and white-UVPPT. The diversity of midges caught could not be determined due to taxonomic difficulties, and thus all the three colours of UVPPT should be used until efficiency in terms of diversity is determined. It is reported here that the meliponine bee Liotrigona parvula Darchen visits cocoa flowers and thus their effectiveness in cocoa pollination should be investigated.

Antheraea assamensis (Helfer, 1837) is a sericigenous insect with distinct coloration, namely green, blue, orange and yellow in their larval stages and these are multivoltine in culture. However, wild morphs with diapause are found in dense forests. In this study, the wing venation and its variation in A. assamensis were analysed using traditional as well as landmark-based morphometric methods. The venation patterns are reviewed and significant changes in veins recorded. The samples were analysed using geometric morphometric methods and other conventional statistical methods. Landmark-based data were measured among selected veins and the centroid sizes, procrustes to tangent distance of different veins were analysed. Results show significant differences in some of the veins among the intraspecies of A. assamensis. The results suggest that both visual comparison as well as a quantitative approach in A. assamensis may lead to unsound taxonomic conclusions at intraspecies level.

Agricultural research in the 21st century has become a collaborative effort. Research on crop pests like Spodoptera frugiperda (J.E. Smith), commonly known as the fall armyworm (FAW), can involve international collaboration because it is a pest not only in the southern United States, but also in Latin and South America. Our interest to study the genetic variation of 24 subpopulations of FAW from the southern United States, Mexico, Puerto Rico, Brazil and Argentina required insect collection procedures that preserve the integrity of DNA for molecular genetic analysis. The samples were collected primarily from maize (Zea mays L.), but also included outliers collected from pigweed (Amaranthus sp.), Royal Paulownia (Paulownia tomentosa (Thunb.) Sieb. and Zucc. ex Steud.), lemon tree (Citrus limon (L.) Burm) and Bermuda grass (Cynodon dactylon (L.) Pers.). A common insect preservation technique is to place individual insects in 95% ethanol (ETOH). However, various regulations for shipping and the size of this insect often prevent large sample sizes stored in ETOH from being imported. Genomic DNA from samples preserved in 95% ETOH, lyophilized and fresh insects was extracted and evaluated using DNA quantification and polymerase chain reaction–amplified fragment length polymorphism (PCR–AFLP). All three treatments yielded high-quality/high molecular weight (c. 70–150 μg) DNA. No differences in quality of genomic DNA for AFLP analysis were observed. Lyophilization is a reliable tool to preserve FAW samples, which yields high-quality DNA for use in AFLP genetic analysis.

The African rice gall midge (AfRGM) Orseolia oryzivora Harris and Gagné is an important insect pest of rice in Nigeria. Studies were conducted at Ogidiga (forest zone) and Edozhigi (southern Guinea savanna) in Nigeria, under rainfed lowland conditions during the 2006 and 2007 rainy seasons, on the population dynamics of AfRGM adults using light trap and random sampling of % tiller infestation (plant damage due to AfRGM) and % parasitism by Platygaster diplosisae Risbec and Aprostocetus procerae Risbec (parasitized larvae and pupae and parasitoid species present in dissected tillers). The results obtained showed that AfRGM populations were relatively low in June and July – the beginning of the 2006 and 2007 rainy seasons, respectively – and increased abruptly from September, reaching a peak in October at both locations. The increase was attributed to the rapid build-up of the pest populations at both locations. There were strong positive correlations between adult populations from light-trap catches and % tiller infestation, and between % tiller infestation and parasitism. The peak period of parasitism by P. diplosisae and A. procerae occurred towards the end of the rainy season in October, coinciding with high level of % tiller infestation. It is concluded that conservation of the parasitoids early in the cropping season (i.e. to improve their synchronization with the host) could become an effective management strategy against AfRGM.

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.

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™.