The oriental fruit fly Bactrocera dorsalis (Hendel) is a very serious pest of fruit trees, causing enormous economic losses globally. The present study examines the capability of an artificial neural network (ANN) with a Quasi-Newton (QN) algorithm to predict a fruit fly trap catch and compare the results with those of a traditional regression model. MATLAB 7.0 was used to develop ANN programming and the fortnightly measurement of 14 input variables (abiotic along with biotic variables) provided the database for analysing the ANN model. An input model using a total of 14 identified input nodes with a selected QN-ANN structure (14-25-20-1) gave an optimum result. In general, the present study showed that an ANN could be used to estimate fruit fly trap catch with enhanced accuracy (R2 = 0.92; root mean square error (RMSE) = 23.75; Nash–Sutcliffe efficiencies = 0.99) over traditional regression models (R2 = 0.76; RMSE = 30.28; Nash–Sutcliffe efficiencies = 0.76). This finding helps the region-specific fruit fly monitoring and management programmes that lack long-term historic data.

Deployment of cowpea with Bacillus thuringiensis (Bt-cowpea), to control Maruca vitrata Fab., must be preceded by the development of an insect resistance management (IRM) plan to ensure a sustainable use of the in-plant protection offered by the transgenic variety. One of the components of a resistance management plan involves the use of wild or cultivated host plants as refugia. In West Africa, wild refugia have the potential to be a major component of such an IRM strategy. In the current study, we examined the occurrence of M. vitrata on three cultivated cowpea varieties and one wild alternative host, Sesbania pachycarpa D.C. Our results indicate that M. vitrata population overlapped on the wild host and cowpea. The overall insect population on S. pachycarpa represents 9–13% of the population on cultivated cowpea. Based on these findings, we suggest that S. pachycarpa may contribute as a refuge for M. vitrata population in case of deployment of Bt-cowpea.

Adparaproba gabrieli Carvalho is a phytophagous neotropical bug with a restricted distribution to southeast Brazil. The histology of the digestive system and that of the male and female reproductive tracts of A. gabrieli was studied. We found that the male had a pair of testes with two follicles per testis, two short vasa defentia that joined in a muscular ejaculatory duct with two pairs of well-developed accessory glands. The female has a meroistic telotrophic ovary with three ovarioles per ovary. There is a pair of sac-like salivary glands. The digestive tract, after the pharynx, has a long, thin oesophagus ending in a muscular proventriculus. The transition fore-midgut is marked by a stomodeal valve, and the midgut is the main organ with an anterior portion with columnar cells and an posterior one with flattened cells. The hindgut is short and differentiated in the ileum and rectum. The Malpighian tubules are also described and the phytophagous feeding habit of A. gabrieli is discussed.

Botanical insecticides are among the most promising alternatives to synthetic insecticides for stored product protection. Calneem oil from Ghana and local neem oils from two localities in northern Cameroon (Garoua and Maroua) were tested at 0 (untreated control), 2, 4, 6, 8 and 12 ml/kg, on the adult and immature stages of the maize weevil Sitophilus zeamais (Motschulsky), for mortality and reproduction inhibition. The neem oils from Cameroon were extracted using the traditional kneading method and a hydraulic press in the laboratory (refined). Maize grains were coated with the five neem seed oils (Calneem, Garoua traditional and refined, and Maroua traditional and refined, respectively) and adult mortality was recorded at 1, 3, 7 and 14 days after exposure. Within 1 day of exposure, the highest tested concentration (12 ml/kg) of Calneem, Garoua traditional, Garoua refined, Maroua traditional and Maroua refined oils caused similar weevil mortality of 86.3, 93.8, 93.8, 97.5 and 97.5%, respectively. The 24-h LC50values for the oils in the same order were 7.0, 6.0, 5.0, 5.0 and 4.8 ml/kg, respectively. The lowest (2 ml/kg) and highest (12 ml/kg) concentrations of the oils suppressed progeny production by over 80 and 98%, respectively. The oils arrested the development of the hidden eggs and immature stages in the maize grains. The results suggested that neem seed oils from different localities of northern Cameroon, irrespective of the method of extraction, were effective for the protection of stored maize against S. zeamais. The promotion of natural neem seed oils as stored grain protectants in Cameroon would boost food security, alleviate poverty and reduce environmental degradation.

Biology, morphometrics and analyses of non-specific esterases were carried out for populations of Bemisia tabaci (Gennadius) collected from leucaena [Leucaena leucocephala (Lam.) de Wit] in New Delhi, India and compared with those for cotton populations. The developmental periods of the egg, and the first to fourth instars of the leucaena populations were 6.7 ± 0.18, 4.2 ± 0.18, 3.8 ± 0.14, 3.0 ± 0.0 and 5.2 ± 0.18 days, respectively, with a total life-cycle duration of 22.9 ± 0.58 days; fecundity (62.60 ± 61.53 eggs per female) and longevity (male: 13.50 ± 0.12 days, female: 16.50 ± 0.12 days) were higher than those recorded for the cotton population, with a sex ratio (male:female) of 1:3.7 in cotton and 1:4 in leucaena. Morphometrics revealed significant differences in the length of egg, second, third and fourth instars (P < 0.05). Of the 62 measurements of the puparia analysed, 70% of those of the head, 44% of those of the thorax and 51% of those of the abdomen showed significant differences between the cotton and leucaena populations. Mapping of the host association of samples onto principal component ordination showed their significant separation according to host plants, with the first three principal components accounting for 66% of the total variation. The analysis of non-specific esterases showed two bands at Rm E0.18 and E0.23 in the cotton populations but not in the leucaena populations. So far, B. tabaci is known on leucaena only from Taiwan. The present study reports it as a new host record from India in addition to documenting the biology, morphometrics and esterases of this and a cotton population.

Hyposidra talaca (Walk.) is a major pest of tea (Camellia sinensis L.) in Northeastern (NE) India. The present study examined (1) the likely causes of expansion of H. talaca to tea from its ancestral home of sal forests, and (2) the anti-predatory mechanisms that helped it to build up in tea plantations. Studies were made on the role of the regulating agents of the eggs and caterpillars of the pest and responses of caterpillars to different predator-like stimuli (predatory wasps, ants and birds) and mechanical vibrations. Eggs collected from the fields were reared in the laboratory to study egg parasitization and monitored in the field to study the role of natural predators. Prolonged drought and inconsistent rainfall influenced the range expansion of H. talaca. In tea plantations, female moths preferred to conceal the eggs in the scaly bark of shade trees. Excluding woodpeckers, H. talaca eggs were scarcely attacked by other natural enemies. The caterpillars dropped off the plant in response to potential predators and assumed a deimatic ‘U’ or ‘S’ shape, and remained motionless when stimulated by mechanical vibration. This study suggests that the lack of specialized natural enemies helped H. talaca to build up in the tea plantations of NE India in a short period of time.

Continuous breeding efforts in Ethiopia resulted in the release of 15 improved chickpea (Cicer arietinum L.) varieties with improved yield, seed quality, disease resistance and better adaptation to different production zones within Ethiopia. This study was conducted to examine whether breeding for increased yield and other important agronomic traits without direct selection for resistance to the adzuki bean beetle (Callosobruchus chinensis L.) has inadvertently resulted in a significant level of susceptibility to this seed pest within the new cultivars. Field and laboratory studies were conducted to see whether breeding for better seed quality has increased susceptibility to infestation by the adzuki bean beetle. Seeds of 130 accessions/genotypes were infested with the beetle in 2009 under ambient temperature and relative humidity at Holetta, Ambo and Debre Zeit, Ethiopia. Data were recorded on attributes of infestation level and seed damage. Data on seed size, proportion of seed coat and grain yield were collected from a replicated field trial conducted with the same accessions/genotypes grown under the same conditions in 2009/10 at Ginchi and Ambo, Ethiopia. Differences among the genotypes were significant for most traits with the exception of the number of uninfested seeds. Accessions with partial resistance include 41320, 41289, 41291, 41134, 41315, 207658, 41103, 41168, 41142, 41174, 41029, 41207, 209087, 231327, 41161 and 41008. The improved varieties were more susceptible than germplasm accessions. The results indicate that genetic progress was achieved both in grain yield and seed size, but breeding efforts for these traits had also inadvertently increased seed susceptibility to C. chinensis. Improvements in seed size resulted in higher infestation levels and seed damage. Future breeding to improve seed quality should simultaneously consider corrective measures to incorporate resistance to the adzuki bean beetle.

A cotton field was used to set up an arena trial for investigating the dose transfer of oil-based ultra-low-volume sprays of Metarhizium anisopliae (Metchnikoff) Sorokin to the cotton bollworm Helicoverpa armigera (Hübner). Two doses of conidia (75 and 50 g/ha, being 3.75 × 1012 and 2.5 × 1012 conidia/ha, respectively) formulated in 2 litres (70:30, kerosene–peanut oil) were applied using a Berthoud ‘Micro Ulva’ to three groups of larvae of cotton bollworms positioned in three rows downwind of a single spray line. Both the distribution of the droplets and the effect of direct contact with spray droplets were quantified. The mean number of droplets decreased from 416 ( ± 60) droplets per cm2 (line 1; 0.4 m) to 45 ( ± 36) droplets per cm2 (line 3; 5 m). To achieve 50% mortality, >10 and >13 days were necessary for 75 and 50 g/ha, respectively. From day 15, the difference in mortality rates was significant between the two treatments. At line 3 (5 m), at 12 days after application, the mortality rate reached 52% for 75 g/ha and 47% for 50 g/ha. The results are discussed in view of optimizing the application of the biopesticides.

The tomato red spider mite Tetranychus evansi Baker & Pritchard is a serious pest of solanaceous plants worldwide. Management of this oligophagous pest in African nightshades has been a challenge to smallholder African farmers due to its high reproductive rate and rapid development of resistance to synthetic pesticides. The aim of the present study was to determine the influence of leaf trichomes on T. evansi by comparing its fecundity and movement on the leaf surfaces of five African nightshade species, namely Solanum sarrachoides Sendter, S. villosum Miller, S. tarderemotum Bitter, S. americanum Miller and S. scabrum Miller. Data were recorded in the laboratory at 23 ± 1°C, 50–70% relative humidity and a 12 h light:12 h dark photoperiod for the effect of trichome type and density of the abaxial leaf surface on mite fecundity. Distances travelled by mites on the leaf surface from the edge of a thumbtack pin inserted on the leaf were also recorded. Different trichomes, glandular and non-glandular types, were identified. There was a significant negative correlation of fecundity and distance walked by mites with the density of glandular trichomes. Significantly fewer eggs were laid on S. sarrachoides in comparison with the other Solanum species. The distance walked by mites was also significantly shorter in this species, indicating that higher densities of glandular trichomes interfere with mite movements. These results suggest that African nightshade genotypes differ in their levels of resistance to T. evansi, which is partially associated with differences in trichome types and their densities.