Iris yellow spot virus (IYSV) vectored by Thrips tabaci threatens profitable onion production in eastern Africa. Host plant resistance is considered to be the first line of defence against insect-transmitted virus diseases. Hence, information on resistance to IYSV and T. tabaci among common onion cultivars in Kenya is crucial for the development of integrated pest management strategies. This study evaluated the resistance to thrips and IYSV among widely grown onion cultivars in Kenya, viz. Red Pinoy, Red Creole, Bombay Red, Green Bunching and Texas Grano, over two growing seasons. Straw-coloured, diamond-shaped necrotic lesions typical of IYSV infection were observed 2 weeks after transplantation. Observations on thrips numbers per plant, IYSV disease incidence and severity, and virus intensity were undertaken to assess the resistance. Varieties differed significantly with respect to both IYSV disease incidence and thrips numbers per plant from fourth week to physiological maturity. Red Pinoy, Green Bunching and Red Creole were highly susceptible to the virus and thrips, while Texas Grano and Bombay Red were moderately resistant. There were significant differences among the varieties with regard to IYSV intensity, with the highest and the least virus intensity positively correlated with disease severity being recorded in Red Pinoy and Texas Grano, respectively. Among the varieties, Texas Grano produced the highest yield in both seasons, while Red Pinoy produced the least. Hence, Texas Grano and Bombay Red could be recommended as moderately resistant cultivars to thrips and IYSV to be grown in Kenya for markets where pungency is not preferred and preferred, respectively. Regions with high levels of thrips population and IYSV infestation are not suitable for the cultivation of Red Pinoy.

Maruca vitrata Fabricius (legume pod borer, LPB), the most serious economic pest of legume crops in the tropics, is primarily controlled by chemical pesticide application with serious consequences for the ecosystem and human health. In this study, various concentrations of three commercial biopesticides, NeemBaan®, Bactospeine® (Bacillusthuringiensis (Bt) subsp. kurstaki) and Florbac® (Btaizawai), were tested either in the field or laboratory or in both conditions. In the laboratory experiments, different concentrations of NeemBaan® exhibited significant effects on the mortality of all the tested larval instars and a mortality rate of over 80% was recorded at a dose of 3000 ppm. Bactospeine® was found to be more effective against M. vitrata than Florbac®. Bactospeine® applied at a lower dose of 500 ppm caused 100% mortality in the first-instar and second-instar larvae; however, at the same dose, Florbac® caused mortality of only 26.67% (first instar) and 20% (second instar). In the field experiments, a higher dose of NeemBaan® (6000 ppm) significantly reduced pod damage to approximately 20% in both the first and second cropping seasons. In conclusion, neem- and Bt-based biopesticide products have insecticidal potential to be used in an integrated pest management strategy for controlling M. vitrata in Thailand.

Vegetable legumes are important crops in tropical agriculture, but they are susceptible to a substantial number of arthropod pests and diseases. Using farm-level survey data for 240 farm households growing yard-long bean (Vigna unguiculata subsp. sesquipedalis) in Thailand and Vietnam, this study shows that the farmers' main problem is the legume pod borer (Maruca vitrata). Farmers rely exclusively on the use of synthetic pesticides to manage this pest, and no other control methods are generally applied. Small cultivated areas for growing yard-long bean (particularly in Vietnam), a high level of satisfaction with the use of pesticides and a lack of market demand for pesticide-free produce are formidable challenges to the introduction of integrated pest management (IPM). It is important to ensure that IPM methods, if adopted, do not reduce profits and that farmers are allowed to experiment with these methods while raising awareness in the general population about the risk resulting from pesticide exposure.

In this study, the effect of exposing entomopathogenic bacteria isolated from macerated termite cadavers to varying intensities of a magnetic field for different periods of time on their pathogenic potential was examined; pathogenicity tests were carried out for each of the bacterial species. Two of the bacteria, Bacillus subtilis (Ehrenberg) Cohn and Serratia marcescens Bizio, were able to induce morbid effects on termites and both were re-isolated from the resulting cadavers. Reinfection using different concentrations of both bacteria was carried out on termites to determine the minimum lethal concentration required for pathogenicity. Bacillus subtilis was able to degenerate the termites at concentration values of 108 colony-forming units (cfu)/ml and S. marcescens at 107cfu/ml. Both bacteria were then exposed to magnetic fields of different intensities for different periods of time, after which they were used for reinfection of healthy termites. Post-infection study after the exposure of termites to magnetic field-treated bacterial cells revealed no reduction in the entomopathogenic potency of S. marcescens. As the extensive use of chemicals to control insect pests has been found to have detrimental effects on people and the environment, there is a pressing need to discover and develop new entomopathogens to control these insects biologically. Therefore, bacteria discovered in this study to have entomopathogenic potency against termites may be further studied and formulated into either powdery forms or suspensions to be applied to infested wood or wood products.

The effect of vegetation cover (millet) on the efficacy and conidial persistence of Metarhizium acridum (Driver & Milner) J.F. Bisch., Rehner & Humber was evaluated in semi-field conditions using breeding cages (2 × 2 × 1 m). A mixed population of third- and fourth-instar desert locust larvae, Schistocerca gregaria Forsskål, was used as a target. The insects were exposed in two different vegetation cover types classified as low (about 10%) and high (about 90%). Metarhizium acridum was used at a dose of 2.5 × 1012 conidia/ha in two different application volumes: 1 and 2 l/ha. Untreated insects kept in contact with treated vegetation were monitored to evaluate the persistence of conidia. The results showed that vegetation cover did not significantly (F= 1.320; P= 0.334) affect the efficacy of M. acridum. Under the high vegetation cover, the increase in the applied volume rate to 2 l/ha significantly improved the speed of mortality. Conidia persisted 6 days after treatment with a remarkable effect on untreated larvae exposed to the treated vegetation. In addition, the results of this study showed the efficacy of M. acridum in the low vegetation cover. With an important mass of vegetation, M. acridum conidia could persist even under high temperature conditions.

Coptotermes heimi (Wasmann) is a termite widely present throughout Pakistan and causes detrimental effects in standing trees. In this study, the feeding preferences of C. heimi for 18 different wood species were determined through choice and no-choice trials under laboratory and field conditions. In no-choice laboratory trials, different combinations of wood blocks were used to determine wood consumption by C. heimi. Weight loss, consumption/individual and survival rate were evaluated. Populus euramericana was found to be the most susceptible wood species and Syzygium cumini the most resistant one. Nine different wood combinations were used under choice laboratory conditions; maximum feeding was recorded in P. euramericana and Pinus roxburghii (50.8–24.5 mg). However, minimum feeding was recorded in S. cumini (2 mg) and Tectona grandis (14.9 mg). Under no-choice field conditions, minimum feeding was recorded in S. cumini (9.5 mg) and maximum feeding in P. euramericana (60.5 mg). Under choice field conditions, maximum (58 mg) feeding was recorded in P. euramericana and minimum feeding in S. cumini. Feeding preferences in descending order based on wood consumption as a quantitative parameter documented were as follows: P. euramericana>Ailanthus excelsa>Azadirachta indica>P. roxburghii>Butea monosperma>Morus alba>Bauhinia variegata>Albizia lebbeck>Dalbergia sissoo>Heterophragma adenophyllum>Erythrina suberosa>Cassia fistula>T. grandis>Mangifera indica>Eucalyptus camaldulensis>Jacaranda mimosifolia>Bambusa bamboo>S. cumini.

To evaluate the effect of the carpenter bee, Xylocopa olivacea Lepeletier 1841, on the pod and seed yields of Phaseolus coccineus L., in this study, its foraging and pollination activities were examined in Ngaoundéré during the June–July 2010 and July–August 2011 cropping seasons. Treatments included open floral access to all visitors, bagging of flowers to avoid all visits and floral access to limited visits of X. olivacea. Observations were made on 120 flowers per treatment. In addition, all flower visitors were recorded. The seasonal rhythm of the activity of the carpenter bee, its foraging behaviour on flowers and its pollination efficiency (fruiting rate, number of seeds/pod and percentage of normal or well-developed seeds) were recorded. Phaseolus coccineus flowers were visited by 13 insect species in 2010 and by 14 insect species in 2011. Xylocopa olivacea was the most frequent visitor and intensely and exclusively foraged the flowers for nectar. The mean foraging speed was 9.28 flowers/min. In 2010, the foraging activity of X. olivacea resulted in a significant increase in the fruiting rate (27.49%), number of seeds/pod (45.43%) and percentage of normal seeds (89.38%). In 2011, the corresponding values were 56.14% (fruiting rate), 74.44% (number of seeds/pod) and 66.44% (percentage of normal seeds). These results reveal that this crop experiences a pollination deficit, considering that flowers visited by X. olivacea had higher yields than those under unlimited access to all visitors. Hence, the conservation of X. olivacea nests close to P. coccineus crop fields is recommended for improving pod and seed production.

To assess the impact of the carpenter bee, Xylocopa olivacea Fabricius 1787, on the pod and seed yields of Cajanus cajan (L.) Millsp. 1900, in this study, its foraging and pollinating activities were examined in Nkolbisson during two seasons (July 2008–January 2009 and June–December 2009). Observations were made on 180 inflorescences per treatment. The treatments included unlimited floral access to all visitors, bagging of flowers to prevent access to all visitors, and floral access to limited visits by X. olivacea only. In addition, information on all floral visitors was recorded. The carpenter bee's seasonal rhythm of activity, its foraging behaviour on flowers, its pollination efficiency, the fruiting rate (Fr) and the number of seeds per pod were recorded. Nineteen species of insects were recorded visiting the flowers of C. cajan.Chalicodoma cincta cincta was the most prominent one, followed by X. olivacea, Apismellifera adansonii, Megachile bituberculata and Xylocopa albiceps, and the bees were the most frequent floral visitors. Xylocopa olivacea mainly foraged for nectar and pollen and its foraging speed was 11.75 flowers/min. The Fr, the number of seeds/pod and the percentage of normal seeds of unprotected inflorescences were significantly higher than those of inflorescences protected from insects. The foraging activity of X. olivacea resulted in a significant increase in the Fr by 22.26%, as well as the number of seeds/pod by 34.98% and the percentage of normal seeds by 12.09% in the two study years. Placing X. olivacea nests close to C. cajan fields is recommended to increase pod and seed production in Cameroon.

Kerria lacca (Kerr) is commercially harnessed for lac resin, which is principally an ester complex of aleuritic acid (9,10,16-trihydroxyhexadecanoic acid) and jalaric acid. The present study is an attempt made to identify the possible pathways involved in the biosynthesis of lac resin. It is proposed that acetyl-CoA is the common precursor for the biosynthesis of aleuritic acid and sesquiterpenic acids (jalaric acid). Prenyltransferases are involved in the biosynthesis of sesquiterpenes; hydroxylation of hexadecanoic acid, after chain elongation, appears to occur through the action of cytochrome P450 enzymes. Two related genes as proposed above were identified and sequenced. The diurnal rhythm of resin secretion and protein concentrations were also studied and correlated for ascertaining the active secretory phase.