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.

The effect of diet on the biology of the predatory mite Amblyseius denmarki Zaher & El-Borolosy (Acari: Phytoseiidae) was studied in the laboratory. Predatory mites fed on the eriophyid mites eriophyes dioscoridis, E. olivi and Cisaberoptus kenyae had a faster development, higher fecundity and a more female-biased sex ratio than those fed on the other diets tested, namely pollen of the palm Phoenix dactylifera, the scale insect Parlatoria ziziphus and the whitefly Bemisia tabaci.

Laboratory studies were conducted to assess the infestation potential of Callosobruchus maculalus (Fab.) on 12 elite and one local cowpea cultivars which were stored under subtropical conditions. Index of susceptibility, loss in grain quality and the number of adult progeny that emerged from previously infested grain were the criteria used to assess the vulnerability of the cowpeas to post-harvest infestation. Cultivars TV × 309–1C and TV × 1193–10F showed some degree of resistance to post-harvest infestation by C. maculalus and could therefore be stored safely for a relatively long time. TV × 1192–01D and TV × 1999-1D were the most susceptible cultivars to post-harvest attack by C. maculatus. Length of storage adversely affected the ability of the cultivars to resist the insect attack. Crop resistance, adequately supplemented with good sanitation, can be profitably applied to control insect infestations in grains during storage.

Western flower thrips (WFT) (Frankliniella occidentalis) is an introduced pest that harms French bean production in Kenya and other countries. Since new WFT management approaches are being developed, a closer look at the genetic makeup of WFT populations can give new insights into source habitats, crop colonization patterns or host plant preferences, which are prerequisites for integrated pest management (IPM) strategies. For this purpose, we used six microsatellite loci to analyse the genetic structure, diversity and gene flow of WFT sampled on French beans, intercrops and weeds in Kenyan French bean production areas. The results of this preliminary study indicate that the available microsatellites are sufficiently polymorphic for more detailed analyses on local dispersal patterns of WFT in Kenya. Even with the limited data set, the results reveal that F. occidentalis populations show considerable genetic differentiation between host plant species but not between regions, which suggests reduced gene flow and a possible development of biotypes. Possible consequences of the results on IPM are discussed.

The lobate lac scale, Paratachardina pseudolobata Kondo & Gullan, is a recent insect invader to Hawaii that was first found in October 2012 on Oahu, Hawaii. It infests young branches of woody plants (usually less than 2 cm in diameter), forming a mass that appears as a dark crust, resulting in an unhealthy appearance, defoliation of leaves, and death of some plant species. This insect has infested many native and non-native plant species on Oahu, and the number of infested plant species is increasing. Our recent survey results, reported in this article, revealed 28 new host plant species in addition to 83 host species that we had reported previously, making 111 host plant species in Oahu's urban landscape. Efficacy and longevity of preventive treatment using the systemic insecticides imidacloprid and emamectin benzoate, delivered through trunk injection, against lobate lac scale on Chinese banyan, Ficus microcarpa, and curative treatment using imidacloprid on weeping banyan, Ficus benjamina, were evaluated. Forty-five Chinese banyans and 10 weeping banyans were included in this study. Our findings suggest that imidacloprid delivered via trunk injection is effective in preventing lobate lac scale infestation for at least 22 months post-treatment, and also in reducing lobate lac scale infestation curatively for at least 20 months post-treatment. This study provides an update on lobate lac scale's host species in Hawaii's urban landscape, and an effective preventive and curative management strategy against this pest.

We studied the food and habitat preferences of beetles of the subfamily Scarabaeinae in a protected tropical monsoon forest, the Wasgomuwa National Park in Sri Lanka. While gaining an insight into the capacity of different resources to support dung beetles, we tested the hypothesis that, in a landscape with a mosaic of habitat types and a diversity of large mammals, specialization facilitates coexistence of the scarabs. Pitfall traps were laid in five distinct habitat types (forest, riverine, sandy banks, scrub and grassland), and baited with five dung types (leopard, cervid, elephant, bear and buffalo). Four hundred and fifty seven beetles of 22 species in seven genera were recorded. Significant differences were seen in the species richness and abundance of dung beetles between different habitats and dung types, indicating habitat and food preferences. The highest richness of scarabs was in the riverine habitat and in leopard dung. Niche breath values of the individual species indicated differences in the degrees of specialization, while niche overlap values indicated a greater sharing of dung beetle species between similar habitats and dung types than between dissimilar ones. These findings provide evidence that selectivity of habitat, and dung, may be important in promoting coexistence among the scarabs in a tropical environment.

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.

Surveys for natural enemies of Mexican stemborers and the major biocontrol attempts using indigenous and exotic parasites in Mexico are reviewed. Although biological control of stemborers in Mexico was initiated in the 1920s, parasite explorations were intensified during the 1980s and have continued to date in response to the invasion of Diatraea grandiosella Dyar, D. lineolata (Walker) and Eoreuma loftini (Dyar) into the United States from Mexico. Recent surveys for stemborer parasites in Mexico has led to the discovery and laboratory culturing of the braconids Allorhogas pyralophagus Marsh, Digonogastra solitaria Wharton & Quicke and Macrocentrus prolificus Wharton; the ichneumonid Mallochia pyralidis Wharton and the tachinid Lydella jalisco Woodley. The Asian braconid Cotesia flavipes Cameron was introduced and established in the states of Tamaulipas and Sinaloa against Diatraea spp. Unsuccessful attempts to establish other exotic parasites are also discussed. Stemborer predators and diseases have been poorly studied in Mexico, and their potential as biocontrol agents is unknown. The current biological control programmes of stemborers in Mexico and the potential of indigenous and exotic parasites as biocontrol agents are discussed. National and international collaboration is stressed for optimisation of resources and efficient exchange of natural enemies and their mass rearing technology.

Seasonal activity and environmental and hormonal regulation of development and diapause were studied in three different orders of tropical insects at Barro Colorado Island (9°N), Panama.

The seed bug, Jadera aeola, reproduces in the late dry season coincident with mass production of its food, seeds of Sapindaceae. Newly emerged adults enter diapause. Population density and food, but not photoperiod, appear to be involved in diapause regulation. Juvenile hormone analogue (JHA) stimulates sexual maturation in both sexes.

The fungus beetle, Stenotarsus rotundus, aggregates at the base of a palm tree where it remains in imaginal diapause for up to 10 months. In addition to daylength (Tanaka et al., 1987), humidity plays an important role in regulating diapause termination. Gonad and flight muscle development occur more rapidly at high humidity than at low humidity. Beetles treated with JHA initiate oocyte and flight muscle development but not testis development. 20-hydroxyecdysone has no effect on diapause termination.

Flesh flies (Sarcophagidae), when monitored with a meat-baited trap, show striking seasonal fluctuations in abundance. Yet, we found no evidence for diapause in three fly species reared in the laboratory under a range of photoperiod and temperature conditions.

Papers on tolerance of alfalfa, barley, sorghum, corn, rice, wheat, cotton, vegetables and tea to insects are reviewed. Research methods used in identifying tolerant cultivars and the role of tolerance, as one of the three mechanisms of resistance, are discussed.

The effects of cowpea, Vigna unguiculata (L.) Walp. canopy structure and pod position in relation to infestation and damage by the legume pod borer, Maruca testulalis Geyer were investigated. Defoliated cultivars sustained significantly less infestation and damage (P < 0.05) than those undefoliated. Relative humidity measured under the canopy was lower in defoliated cultivars, while soil and ambient temperatures were higher. Percentage pod damage and larval infestation by M. testulalis in flowers were positively correlated with relative humidity, and negatively correlated with temperature. Both correlations were significant (P < 0.01).

Cultivars with pods held within the canopy suffered significantly more damage (P < 0.05) than cultivars whose pods were held in the normal position. Canopy structure and pod position acting together or independently, exerted profound effects on cowpea resistance to M. testulalis. Selection and breeding cowpea cultivars with less dense foliage (= open canopies) and long peduncles holding the reproductive structures above the canopy, should increase cowpea resistance to M. testulalis.

A tick assembly pheromone present in the excretory waste product of the soft tick, Ornithodoros porcinus porcinus (Walton), has been separated by high performance liquid chromatography (HPLC). It has been identified as guanine on the basis of absorption and mass spectral data, and bioassays using nymphs of Argas persicus (Oken). Guanine was active at a low concentration of 8 × 10 −12 M/cm2 of filter paper. Guanine was shown to induce assembly in Amblyomma cohaerens Donitz larvae and Rhipicephalus appendiculatus Neumann adults.

Various purines and ammonium salts tested in the assembly bioassay, and with exception of adenine, were shown to be active for A. persicus.

Light and pheromone trap networks were used to monitor and compare moth catches ofHelicoverpa (= Heliothis) armigera (Hubner) in both types of traps at many locations across India. There were obvious changes with latitude in flight patterns and in the correlation between light and pheromone trap catches. At northern locations, the correlation between light and pheromone trap catches were higher as compared to southern locations. The traps located in the central part of India showed correlations, intermediate between those of northern and southern locations. Pheromone traps were thus found suitable for monitoring at northern and central locations. At southern locations, where light and pheromone trap catches differ considerably at different times of the year, both types of traps should be operated simultaneously for better monitoring of this insect. Good correlations were found between larval population and light and pheromone trap catches of H. armigera at Patancheru, one of the southern locations in India.

The predacious mite, Hypoaspis vacua (Michael) successfully developed from larva to adult stage when fed on eggs of housefly, Musca domestica (L.) and nymphs of acarid mite, Rhizoglyphus echinopus (Fum. & Rob.) in the laboratory. The duration of the immature stages and of the adult stage were determined. Food type greatly affected female fecundity and feeding capacity. Immature stages of H. vacua consumed in total an average of 13.6 eggs of M. domestica and 33.0 nymphs of R. echinopus, whereas each day throughout her life, the adult female consumed an average of 4.1 eggs of M. domestica and 13.23 nymphs of R. echinopus. Eggs of housefly were the most suitable diet, as it prolonged adult longevity (76.8 days) and increased female fecundity (1.3 eggs/female/day).

In many countries in eastern, central and southern Africa, twice-weekly to two-weekly acaricide applications are practised to prevent mortality of exotic cattle from tick-borne diseases. This practice has been extended to areas where only local cattle are present. These measures are very costly, inefficient in controlling diseases and ecologically undesirable.

In view of the many difficulties with the present method of tick control, exploitation of tick-resistant cattle breeds in enzootically stable situations would appear to be a pragmatic, alternative approach to the intensive use of acaricides. This paper reviews studies on host-tick relationships in Africa with a view to understand the role of naturally acquired resistance in limiting tick populations and hence its use in integrated pest management strategies. The levels of information required are outlined such as identification and quantification of resistance, effect of cattle breeds and productivity and economics in relation to host-resistance.

We surveyed three locations in West Africa, two in northern Nigeria and one in southern Niger, for the presence of wild alternative hosts of the legume pod borer (LPB) Maruca vitrata Fabricius, which could serve as natural unstructured refugia for transgenic Bacillusthuringiensis (Bt)-cowpea. We surveyed a total of 67 sites in proximity to cowpea fields in the Sudan Savannah (Kano, Nigeria), the Northern Guinea Savannah (Zaria, Nigeria) and the Sahel Savannah (Maradi, Niger) ecological zones. The results indicate that alternative host plants for LPB are scarce or absent during the cowpea-growing season in these areas.

Combinations of Bacillus thuringiensis subsp. kurstaki (Btk) and some plant extracts, namely Acacia arabica (Lam.) Willd., Annona squamosa L., Datura stramonium L., Eucalyptus globulus (Labille), Ipomoea carnea Jacq., Lantana camara L., Nicotiana tabacum L. and Pongamia pinnata (L.) Pierre, were studied for their efficacy and synergistic activity against Spodoptera litura (Fab.) larvae. D.stramonium seed extract fortified with Btk recorded highest mean larval mortality of 74.7%, followed by 61% with A. arabica seed extract, 54.4% with N. tabacum leaf extract and 53% with A. squamosa seed extract. Combination of A. arabica seed extract at 25% concentration and Btk resulted in considerable mortality within 24 h. All Btk fortified extracts caused higher larval mortality than with Btk alone, indicating synergistic action except for the A. arabica leaf extract and Btk combination, which showed antagonistic effect.

Citrus orchards in the Nile Delta and middle Egypt were surveyed for predacious soil mites and parasitic nematodes. There were 16 species of predacious mites and the citrus parasitic nematode, Tylenchulus semipenetrans Cobb. was recorded everywhere. In the medium-heavy soil of the Nile Delta orchards, the general predators or decomposer mites like uropodids were most common. In the light-medium soil of El-Fayoum in middle Egypt, the specialized predator mites like gamasids were most common. In localities where gamasids were common, negligible infestations of citrus parasitic nematodes were reported. Regarding Egypt as a whole, the uropodid mites Uroobovella krantzi (Zaher & Afifi) and Nenteria hypotrichus (El-Borolossy & El-Banhawy) represented about 50% of the sampled mites. The remaining mites were represented by 14 mesostigmatid species, the most common being Gamasiphis pulchellus (Berlese). At least 6% of orchards suffered injurious nematode infestations, 13% critical infestations and 22% moderate infestations, and the remaining 59% were free or with negligible infestations.

The purification and characterization of rhodanese, an enzyme that catalyses the detoxification of cyanide, from the gut of the variegated grasshopper (Zonocerus variegatus L.) were carried out to understand the biochemical basis of the survival of this grasshopper living on cyanogenic plants such as cassava. All experiments, including enzyme assay, were carried out at room temperature and all buffers contained 10 mm sodium thiosulphate to stabilize the enzyme. Grasshoppers were caught alive from a cassava farm within the locality and kept frozen until analysis. Each grasshopper was dissected and the gut was removed quickly. Approximately 102 g of the gut were homogenized in three volumes of 0.1 m acetate glycine buffer (pH 7.8) containing ɛ-amino-n-caproic acid. The supernatant was collected by centrifugation at 12,000 rpm, for 30 min at 40 °C. The enzyme was purified to homogeneity by a combination of procedures such as ammonium sulphate precipitation, ion-exchange chromatography (CM-Sephadex and DEAE-Sephadex), gel filtration (Sephadex G-75) and Agarose-Blue affinity chromatography. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS–PAGE) and non-SDS–PAGE were used to ascertain the purity of the enzyme. The native and subunit molecular weights of the enzyme were determined by gel filtration on a Bio-Gel P-200 column and SDS–PAGE, respectively. Kinetic parameters were determined by using varying concentrations of one of the substrates at a fixed concentration of the other, and vice versa. Furthermore, the effects of temperature, pH and cations on the activity of the enzyme were investigated. The purified enzyme had a specific activity of 51.7 μmol thiocyanate formed/ml/min/mg protein (U/mg protein) with a yield of about 29%. The apparent molecular weight of the enzyme estimated by Sephadex G-75 gel filtration was 35,400 ± 482 Da and its subunit molecular weight determined by SDS–PAGE was 33,000 ± 212 Da. The Km values of KCN and Na2S2O3 were found to be 29.63 ± 02.87 and 26 ± 03.04 mm, respectively. An optimum pH and temperature of 7.0 and 35 °C, respectively, were obtained for the enzyme. The results of enzyme inhibition showed that the activity of the enzyme was not affected by NH4Cl, MgCl2, CoCl2, CaCl2, MnCl2, NiCl2 and SnCl2, but inhibited by ZnCl2 and BaCl2. In conclusion, these results suggest that the survival of Z. variegatus depends on the presence of the enzyme rhodanese, which shows high activity and has suitable kinetic properties in the gut of the grasshopper that feeds mainly on cassava leaves which are cyanogenic.

A study on the spatial distribution of the silkmoth Anaphe panda (Boisduval) cocoon nests, egg clusters and the host plant Bridelia micrantha (Hochst) Baill. was conducted in two different habitats of the Kakamega Forest of western Kenya: Ikuywa (indigenous forest) and Isecheno (mixed indigenous forest). The mean densities of cocoon nests, egg clusters and B. micrantha were significantly different in the two blocks and were not semi-randomly distributed in the two habitats. The host plants were underdispersed in the indigenous forest, whereas they were overdispersed in the mixed indigenous forest. The cocoon nests were overdispersed and the silkmoth egg clusters were underdispersed in the two blocks of forest. This study reveals that A. panda tends to distribute its egg clusters uniformly over the lower and middle crown of B. micrantha with a preference to eastern localization and confirms the insufficient presence of populations of this silkmoth in a mixed indigenous forest compared with an indigenous forest. Consequently, indigenous forests should be managed in a sustainable way and more indigenous tree species should be used in reforestation campaigns.