Maize (Zea mays L.) is Kenya's most important staple crop with annual production fluctuating between 2.6 and 3.1 million tons in 2012 and 2011, respectively. However, frequent food shortages are still experienced in the country. These have been attributed to pests and diseases and post-harvest constraints. The dominant post-harvest pest of maize is Sitophilus zeamais (Motsch.), which causes losses between 10 and 20% of harvested grain. The objective of this study was to establish the repellent activity of essential oils extracted from selected eucalyptus species against S. zeamais. Essential oils were extracted from the fresh leaves of Eucalyptus saligna Sm., Eucalyptus globulus Labill., Eucalyptus camaldulensis Schlecht and Eucalyptus citriodora Hook by steam distillation using a Clevenger-type apparatus. A repellency bioassay, with varying concentrations (0.002, 0.02, 0.2 and 2 μl/μl) of the oils, was carried out against the maize weevils using a Y-shaped olfactometer. Repeated measures of analysis of variance were applied to test the different doses and repellents, and their interactions against S. zeamais. The essential oils of E. camaldulensis and E. citriodora presented better repellent activity at the 2 μl/μl concentration (74.35 and 69.15%, respectively) followed by those of E. globulus (53.68%) and E. saligna (40.5%). Gas chromatography (GC)–mass spectrometry and GC co-injections with authentic samples showed the presence of the following major constituents in: (i) E. camaldulensis oil: 1,8-cineole (18.9%), α-cardinol (6.4%) and β-phellandrene (2.6%); (ii) E. citriodora oil: 1,8-cineole (11.2%), β-pinene (3.2%) and 4-terpineol (3.1%); and (iii) E. globulus oil: 1,8-cineol (17.2%), α-pinene (7.1%) and spathulenol (6.5%). The results provide a scientific rationale for the use of eucalyptus oils in the protection of maize against weevils.

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.

The fall armyworm (FAW) Spodoptera frugiperda J. E. Smith is the most noxious insect to maize and sorghum in the state of Colima, Mexico. In this work, two maize landraces (‘blanco’ and ‘aperlado’), native to Colima, were grown in Tecomán, Colima, to determine the FAW population behaviour under natural conditions. The spatial distribution of the FAW larvae was random, and natural infestations were strongly associated with the maize phenological stages. The relationship between FAW and plant phenology was explained by non-linear regression models.

Investigations into the potential impacts of selectively managing Apis mellifera on pollination ecology were carried out in several sites in Tsavo National Park of southern Kenya, a typical arid African environment. Temperature alone contributed significantly to the foraging patterns of both managed honeybees and wild bee species within the acacia–commiphora community. Honeybees, vulnerable to heat stress, foraged earlier in the day than wild bee species. Foraging patterns of the latter ranged from oligolectic to broadly non-specialized. Floral biology and adaptations were also considered in the analysis of divergent foraging trends. Observations suggest that honeybees potentially out-compete highly specialized wild bee species for scarce seasonal floral resources. No evidence was found of direct interaction on abundant seasonal floral resources such as the mass synchronous flowering of Acacia spp. at current managed honeybee densities. Investigation of visitors revealed a high diversity of potential insect pollinators, particularly high in wild bee species (Apoidea) diversity. Suggestions for the improved management of honeybees in arid African environments include shading of hives, providing access to water with protection from predators, and cultivation of indigenous, nectariferous plants close to hive colonies.

A method for steady production of Chilo partellus has been established. An efficient simple and easy method of collection of first instar larvae from incubation chambers has been developed. It has been established that pupae of Chilo partellus can be held at a chilling temperature between 5 and 15°C without any adverse effect on the emergence of adults. This finding has been used in synchronizing the emergence of males and females for mating or longer storage of the pupae.

Studies on the effect of high and low humidities on egg development have shown that low humidities affect the hatchability of Chilo partellus egg but did not effect the actual development of the embryo adversely. It has also been shown that Chilo partellus oviposits best under high humidity.

This study used the theory-based impact evaluation approach to understand as to how promotion of beekeeping by the Commercial Insects Programme (CIP) of the International Centre of Insect Physiology and Ecology (icipe) has had an impact on honey production in the former Mwingi District of Kenya (now merged into Kitui County). We examined the adoption of modern hives promoted by icipe and applied data envelopment analysis (DEA) to assess the technical efficiency (TE) of participants in CIP. CIP participants had an average TE of 0.56, which was significantly higher than that of non-participants in the former Kitui District (average TE of 0.26). Those who adopted modern hives achieved the highest average levels of TE (0.59). The study fits a Probit model to identify the drivers of adoption and a Tobit model to assess the intensity of adoption of modern hives. The propensity score matching approach was used to evaluate the impact of modern hives on honey production. Results indicate that perceptions about the yield and quality of honey obtained from modern hives significantly increased beekeepers' adoption decisions. The intensity of adoption expressed as the proportion of modern hives owned by beekeepers was significantly high among farmers who participated in CIP. A positive and significant relationship was observed between the adoption of modern hives and the quantity of honey produced. The present study indicates, through the average TE, that considerable room still exists for the improvement of beekeeping and provides strong evidence for scaling up the dissemination of modern hives in areas of Kenya with high potential.

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 stored grain weevil, Sitophilus oryzae (Linnaeus), causes significant losses to maize grains in tropical countries. Despite the nutritional superiority of the quality protein maize (QPM), an important concern is the possible vulnerability of QPM genotypes to stored grain weevil infestation. In the present study, the responses of 24 QPM inbred lines, along with several non-QPM inbred lines and hybrids, were evaluated against S. oryzae under laboratory conditions. Two attributes, namely (i) % weight loss in the grains after a fixed period of incubation with the insect and (ii) the number of progeny insects (insect multiplication) generated from six pairs of adult insects, were considered. A cumulative resistance index was computed for each genotype giving equal weight to both attributes. The study revealed DMRQPM-60 and CML167 as the most resistant entries. Shaktiman-1, the released QPM hybrid in India, showed moderate resistance against the grain weevil. However, most of the elite QPM inbred lines as well as some non-QPM inbred lines and hybrids were found to be highly susceptible to the weevil infestation. To explore the possible relationship between enhanced protein quality and varying degree of kernel vitreousness and vulnerability to the grain weevil infestation, both the QPM and the non-QPM genotypes were analysed. The correlations between kernel quality traits and kernel texture with % kernel weight loss due to weevil infestation and insect multiplication were found to be non-significant, indicating possible influence of other factors, including pericarp thickness and endosperm composition, in determining the susceptibility of the QPM genotypes to S. oryzae. The study indicates that QPM genotypes are not necessarily susceptible to the stored grain weevil and identifies promising QPM genotypes with resistance to S. oryzae.

The bioefficacy of various plant extracts, namely Azadirachta indica A. Juss, Khaya senegalensis Desrousseaux (A. Jussieu) and Hyptis suavuolens (L.) Poit, either alone or in combination with half the recommended dose of synthetic pesticides, was studied with farmers to find a more sustainable strategy for the management of bollworms in cotton. A number of treatments were farmer innovations. The treatments were compared six times during the season to the application of the fully recommended dose of synthetic pesticides and to a control with no pesticide application. Applications of either the fully recommended dose of the synthetic pesticides or the combinations with a neem seed extract (6 kg/ha) were most effective in reducing bollworm incidence and damage. Both the treatments gave the highest yields of cottonseed, the latter being the most cost-effective. All the pesticides used, except neem alone, had a toxic effect on bollworm predators. This study has increased farmers' confidence in endogenous technology. The researcher's interaction among the local learning group members, who conducted the experiments, facilitated the introduction of a cost-effective alternative to the standard full-dose synthetic pesticide recommendation.

Exploratory field surveys of the natural enemies associated with balloon vine Cardiospermum grandiflorum Swartz, an environmental weed in South Africa, Australia and other countries, were conducted in northern Argentina from 2005 to 2009. The surveys included other plant species in the genus Cardiospermum and other native Sapindaceae, permitting an assessment of the distribution and host range of the natural enemies. Seventeen phytophagous insects in five orders and ten families, and two fungal pathogens were found. The nature of the potential agents' damage, their field distribution and abundance, and the results of preliminary host-specificity testing indicated that the seed-feeding weevil Cissoanthonomus tuberculipennis (Coleoptera: Curculionidae) and the fruit-galling midge Contarinia sp. (Diptera: Cecidomyiidae) were the most promising biological control agents for C. grandiflorum outside of its native range.

The larvicidal activity of 13 essential oils, 14 major monoterpenoids and 9 N-methyl carbamates based on these monoterpenoids was tested according to the recommendations of the WHO against fourth instar larvae of Culex pipiens L. The results of the larvicidal assays after 24 hr revealed a high potential for the essential oils, such as cinnamon, chenopodium and eucalyptus. Of the monoterpenoids, chlorothymol was found to be the most effective followed by thymol, carvacrol and cinnamaldehyde. Conversion of the most active monoterpenoids into their N-methyl carbamate derivatives resulted in higher larvicidal activities than those of the corresponding monoterpenoids. The use of piperonyl butoxide (PBO) to improve the efficacy of the most active monoterpenoids resulted in higher larvicidal activity. Also, all N-methyl carbamate derivatives were synergized by PBO. Carvacrol derivative, which was strongly synergized by PBO, was comparable with the standard synthetic insecticide malathion.

The reproductive behaviour of a generalist aphidophagous ladybird beetle Cheilomenes sexmaculata (Fabricius) was studied in detail. The males first mated at an age of about 2 days, while females mated at 1 day after their emergence. Mate recognition was displayed in five steps, viz. approach, watch, examine, mount and copulatory attempt. Being provided with four dummy models, the male appeared to recognize the female through visual and other possible cues, maybe chemical. The duration of mating was maximum (mean ± SE; 133.0 ± 2.8 min) when an unmated male copulated with a virgin female and minimum (95.0 ± 4.2 min) when a mated male copulated with a mated female. Mating duration seems to be influenced more by the change in male sexual status, thus revealing it to be male dominated. The maximum oviposition period (46.0 ± 1.2 days), fecundity (861.0 ± 2.2) and hatching percentage (64.0 ± 0.6) in C. sexmaculata were noticed after multiple matings, while these parameters were minimum (15.0 ± 1.0, 70.0 ± 2.8 and 37.0 ± 1.0, respectively) after single mating. Thus, multiple matings enhanced the total egg output and percentage of hatchability.

Functional response of all instars, adult males and females of the ladybird Coccinella septempunctata L. was studied against two species of aphids, namely Lipaphis erysimi (Kalt.) and Brevicoryne brassicae L., infesting mustard and cabbage crops, respectively. The predatory stages of C. septempunctata exhibited a type II response on both the prey species. The attack rate was highest (0.0192) with the lowest handling time (7.9 min) when the adult female consumed L. erysimi. There was a significant difference in the predicted values of consumption of L. erysimi by fourth instars, adult males and females compared with those of B. brassicae, indicating that the former prey is preferred over the latter one. The adult females prey upon significantly more numbers of aphids than the adult males.

The population density of the diamondback moth (DBM), Plutella xylostella (L.), the species diversity of its predators, parasitism on eggs, larvae and pupae, and associated yield of canola were evaluated in experimental plots where spring canola was grown either as a monoculture or strip-intercropped with annual alfalfa in the ratio of 3C:3A, 6C:3A and 9C:3A over a 2-year period. The egg density was significantly higher in monoculture than in intercrops. The highest and lowest densities of larvae and pupae of DBM were recorded in monoculture (2.9–3.2 larvae per plant and 1.14–1.20 pupae per plant) and intercrop 3C:3A (0.7–0.6 larvae per plant and 0.34–0.29 pupae per plant), respectively. Shannon diversity index (H') for species composition of the predators of DBM immature stages was lower in monoculture than in intercrops, and was similar amongst the three intercrops. Moreover, the percent parasitism for eggs, larvae and pupae was higher in intercrops than in monoculture. The dry seed weight loss was higher in monocrop (37.6–40.1%) compared to 3C:3A (7.9–8.6%), 6C:3A (19.5–21.4%) and 9C:3A (21.6–25.4%). Our results indicate that intercropping canola with annual alfalfa, especially in the ratio 3C:3A, can increase the species diversity, parasitism rates of DBM immature stages, and enhance the yield of canola. The implications of these findings, in relation to integrated pest management (IPM) in canola cropping systems, are discussed.

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.

The effect of different constant temperatures (20, 25, 27, 30 and 35 °C) on life history stages of the Mexican chrysomelid beetle, Zygogramma bicolorata Pallister, fed on the weed Parthenium hysterophorus Linnaeus was investigated to analyse the development and survival of different life stages and the adult sex ratio. Fastest development and maximum survival were recorded at 27 °C. The first instar was the most vulnerable, while the pupa was least vulnerable. For complete development, the lower temperature threshold (t°C) was 18.5 °C and the thermal constant (K) was 480.8 day-degrees. A higher percentage of females was obtained at all temperatures; however, this was unaffected by the temperature regime. This study established that the percentage life span spent by immature stages was similar across all five temperatures, indicating developmental rate isomorphy. 27 °C was the most suitable temperature under controlled abiotic conditions for the propagation of Z. bicolorata, a bioagent for parthenium weed.

A survey on the occurrence of entomopathogenic nematodes (EPNs) was conducted in selected banana fields from three regions in Tanzania, namely Mbeya (Southern Highlands), Morogoro (Lowland) and Pwani (Coast). The main objective of this study was to isolate EPNs naturally occurring in banana fields in Tanzania and to test their effect on banana weevil (Cosmopolites sordidus Germar 1824). We report for the first time the presence of EPNs in Tanzania where four (4.4%) out of 90 samples contained nematodes in the genera Steinernema and Heterorhabditis. EPNs were only isolated in the coastal region in soils with a high sand content. The virulence of nine EPN isolates was tested against larvae and adults of C. sordidus. All isolates caused mortality of the larval stages, whereas the adults appeared resistant to nematode infection. Larval mortality was found to increase significantly with increasing nematode dose. It was also shown that nematodes were able to penetrate and establish in the banana weevil larvae in increasing numbers with increasing nematode dose. The study indicates the potential for including EPNs in management strategies of banana weevil.

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.

Plant essential oils possess diversified insecticidal properties. Under screening programme of survey of bioactive agents for insect control 31 essential oils from different botanicals (2% in acetone), were studied for repellency and direct toxicity (insecticidal) against laboratory bred houseflies, Musca domestica L. The essential oils obtained from Ocimum gratissimum L., Thymus serpyllum L., Illicium verum Hooks, f., Myristica fragrans Houtt., Curcuma amada Roxb. showed 100% repellent activity, and Acorus calamus L. and Thymus serpyllum L. showed about 40% insecticidal activity. Results were compared with N, N-diethyl-meta-toluamide, dimethyl phthalate, malathion, pyrethrum extract, thymol, mineral oil and piperonylbutoxide. Biochemical studies of these promising oils may emerge new leads in developing future pesticides.

Phytoplasmas are insect-vectored pathogens that cause characteristic and destructive diseases in carrots and other vegetables. A phytoplasma disease was first observed in Israeli carrot fields in 1995. Analysis of infected carrots showed the presence of aster yellows and western-X phytoplasmas. In this study, commercial and experimental fields in the western Negev region of Israel were monitored for three years using yellow sticky traps and vacuum sampling. Potential vectors of leafhoppers and planthoppers were analysed by PCR for the presence of phytoplasma DNA. Infected plants were also assayed for phytoplasma DNA. Extracted phytoplasma DNA was subjected to RFLP analysis to determine groups to which the phytoplasmas belonged. It was determined that carrots and leafhoppers from the experimental station were infected with a phytoplasma belonging to the Elm Yellows (EY) group; this is the first report of EY infecting carrots. Based on our findings, the two most probable insect vectors are Circulifer haematoceps complex (Mulsant & Rey) and Neoaliturus fenestratus (Herrich-Schäffer).