Four cultivars of maize, Zea mays L. viz., CM 600, Basilocal, CM 500 and Kisan were examined for their relative resistance to the maize stem borer, chilo partellus (Swinhoe) in relation to nutrition. Freshly hatched larvae of C. partellus were allowed to grow on the leaf whorls of the cultivars in the laboratory at 27 ±.2°C and 70–90% r.h. The rate of growth, food consumption and its utilization, egg laying and egg hatchability were studied. The insects showed better growth when fed CM 600 or Basilocal maize; this was shown by a higher percentage pupation (56.8 and 54.8, respectively on CM 600 and Basilocal) as compared to (24.4 and 5.6 respectively) on CM 500 and Kisan. Pupal weights were higher (40.2, 45.2, 34.4 and 32.8 mg for male pupae and 57.6, 63.7, 51.8 and 35.8 mg for female pupae), when larvae were reared on CM 600, Basilocal, CM 500 and Kisan, respectively. The growth index decreased from 1.65 on CM 600 and 1.49 on Basilocal to 0.40 on CM 500 and 0.09 on Kisan. A better consumption and utilization of the cultivars CM 600 and Basilocal was shown as also expressed by the higher weights attained by larvae grown on these two than on CM 500 and Kisan. Growth rate slowed down to 0.068 on CM 500 from 0.161 on CM 600 maize. A similar trend was observed in egg-laying and hatchability of eggs. Number of eggs laid per female decreased from 290 on CM 600 reared C. partellus to 157 on Kisan reared insects and none of the eggs laid by the latter could hatch. The degree of resistance of the cultivars to C. partellus on the basis of nutritional factors in a decreasing order is: Kisan > CM 500 > Basilocal > CM 600.

Published information was used to compile a summary of natural enemies (parasitoids, predators and diseases) reported attacking Spodoptera litura (F) under field conditions. Species (71) of insect parasitoids in seven families of Hymenoptera and two families of Diptera were listed as parasitoids of different stages of S. litura. Predatory insects (36) belonging to 14 families and 12 species of spiders from six families have been reported to feed on this species. Four protozoan, four fungal, seven bacterial, four each of viral and nematode species were also reported to be the pathogens of this species. Published information suggested that periodic releases of large number of egg parasites could help in suppressing populations of this pest. There is a considerable scope for increased attention to the role of natural enemies as component of integrated pest management programmes of S. litura.

Competition between larvae of Sitophilus oryzae (L.) and Sitotroga cerealella (Oliv.) within sorghum grains was studied at 30°C and 70% r.h. Newly hatched S. cerealella larvae (0 - 24 hr) were allowed to infest single sorghum grain having one S. oryzae egg deposited either on the endosperm half or the germ half. S. cerealella larvae were obtained from eggs of the same age as those of the weevil. The moth larvae entered the grain through the germ half. When S. oryzae egg was deposited in the germ half, S. cerealella survival probability was 0.78. However, when S. oryzae egg was deposited in the endosperm half, S. cerealella survival probability was 0.47. When the data for the two sites were combined the probability that the moth larvae will survive competition (P = 0.58) was not significantly different from that of the weevil. Hence, both larvae have similar chances of surviving competition within the sorghum grain.

The Insect Rearing Management (IRM) system was used to rear the black lyre leafroller, Cnephasia jactatana (Walker) (Lepidoptera: Tortricidae). The results obtained include life cycle development at various temperatures, application of “day-degrees” in manipulating the life cycle, and use of low temperature for storage of life stages. IRM is a valuable system for regulating production of different life stages as it produces insects of specified quality as required. IRM can be adapted for rearing facilities which handle multiple-species rearing.

Field studies to investigate the effect of intercropping on the relative resistance and susceptibility of cowpea cultivars to Maruca testulalis impure stands and intercropped with maize, were conducted at the International Centre of Insect Physiology and Ecology (ICIPE). It was clearly indicated that intercropping affected the relative resistance and susceptibility of cowpea cultivars. The resistance of TVU 946 to Maruca was reduced when the cultivar was under maize. This was attributed to the phenological changes observed, i.e. when planted with maize there was a significant (P = 0.05) increase in length of the pods and peduncles and significant (P = 0.05) reduction in the number of branches. Weekly mean temperatures and relative humidities indicated that there were significant differences between cropping patterns. Similarly there was a significant reduction in the photosynthetic active radiation incident on cowpea canopy in all the intercropped plots. This suggested that both intercropping and microenvironmental differences observed, reduced resistance in cultivar TVU 946 by probably acting directly on the crop, thus rendering it more susceptible.

The anatomical and biochemical basis of resistance of Vigna vexillata (Benth) (Ace. TVNu 72) to Monica testulalis were investigated. An uncharacteristic network of fibrous structures was observed on the petal surface of TVNu 72 but not on those of the susceptible control, IT82D-716. Stems of TVNu 72 and IT82D-716 have thick and closely packed collenchyma cells. Both varieties have been identified as possessing resistance to stem feeding; however, IT82D-716 is susceptible to flower and pod damage. The distance between pod wall epicarp and mesocarp was significantly (P ≺ 0.05) smaller in IT82D-716, but cell and tissue arrangement were similar for both varieties.

Total sugar content in the pod wall and seed of TVNu 72 was higher (P ≺ 0.05) than in IT82D-716. Phenol content was lower (P ≺ 0.05) in the pod wall of TVNu 72 but the reverse was true for fresh and dry seeds. This suggests that neither phenol nor total sugar are involved in the resistance of TVNu 72 to M. testulalis. However, it seems that thick and compact collenchyma cells in the stems and Fibrous tissues on the petal surface contribute to the resistance in TVNu 72. The results are discussed in line with previous reports which indicate that trichomes are the principal factors in the resistance of TVNu 72 to M. testulalis.

In the majority of insects, migration occurs exclusively or predominantly during the pre-reproductive period (PRP) and therefore, the duration of the PRP provides a useful index of migratory potential. The present study describes a novel method for estimating the PRP of Spodoptera exempta (Walker) (Lepidoptera: Noctuidae). It relies on the fact that as the female approaches sexual maturity, there is a substantial change in the shape of her gonopore-patch (an area of black scales at the posterior of the abdomen). Gonopore-patch shape (GPS) is strongly correlated with PRP (as determined by “calling” behaviour) and may prove to be the best method for estimating migratory potential in some circumstances. A number of other species of moths also have gonopore-patches which may aid the study of their migration.

Accessions of Vigna vexillata, Vigna oblongifolia, and Vigna unguiculata (subspecies unguiculata, dekindtiana, and pubescens) were evaluated under laboratory conditions to identify sources of seed and/or pod resistance to the cowpea weevil Callosobruchus maculates. TVnu 37 and TVnu 88 (V. oblongifolia) and TVnu 72 (V. vexillata) possessed high levels of seed resistance. On mature, dry pods, seventeen-fold differences in mean eggs laid/cm2 were observed, suggesting that ovipositional nonpreference could be a practical form of resistance to C. maculatus. In infested pods, pre-establishment larval mortality (mortality before larvae become established in seeds) varied among accessions, ranging from 19.3% in N1 778 (cv-gr. Biflora) to 91.3% in NI 816 (cv-gr. Textilis). The total percentage larval mortality in infested pods ranged from 34.6% in TN 88–63 (V. unguiculata) to 100% in TVnu 72 (V. vexillata) and NI 816 (cv-gr. Textilis) with the majority of accessions producing over 80% mortality. Higher levels and more durable forms of bruchid resistance might be achieved by combining seed and pod resistance.

Hypoaspis solimani n. sp. was collected from compost from the farm of the Faculty of Agriculture, Cairo University, Giza, Egypt. Morphological characters of the different stages are described, illustrated and a key to the Egyptian species of Hypoaspis presented. H. solimani sp. n. was successfully reared on larvae of house fly, Musca domestica L. and vinegar fly, Drosophila melanogaster Morgan, and the two soil fungi, Macrophomina phaseoli and Fusarium oxysporum. The two kinds of prey proved to be the favoured diet, accelerating development and increasing female longevity and fecundity.

Four synthetic juvenile hormone analogues (JHAs) with high morphogenetic activity on a variety of insects prevented embryonic development of Tribolium confusum to varying degrees when applied to freshly laid eggs. At 1 ppm (v/v) of the JHAs a few eggs hatched; however, some of the larvae died within a day of hatching. Older eggs were totally insensitive to JHA treatment even at higher concentrations. Larvae that hatched from these eggs appeared to be perfectly normal and continued to develop into apparently normal larvae.

Acanthoplus speiseri Brancsik, a pest of grain crops in Zambia, was reared in the laboratory at different temperatures. Mean development times of the eggs, nymphs and adults were determined at the different temperatures and used to develop a thermal unit model for use by farmers to predict the appearance dates of the different nymphal instars and the adults in the field in a given season. The predictions generated by the developed model for the 1990/1991 season, were compared to the actual dates on which the first specimen of each developmental stage was collected in the field during the season. The predicted dates of appearance all fell within 1 week of the observed dates of collection. Reasons for the slight deviations between the predicted and observed dates and the significance of the developed thermal unit model to the future control of A. speiseri in Zambia, are discussed.

Rates of virus-induced mortality and values of the LC50 and LT50 showed that, in general, parasitism by Microptitis rufiventris Kok. increased the susceptibility of the Egyptian cotton leafworm, Spodoptera littoralis second-instar larvae to its nuclear polyhedrosis virus (SLNPV). By comparing the LC50 values, data revealed that virus-infected parasitized larvae were ca. 3.5 and 4.8 times more susceptible to SLNPV than virus-infected unparasitized ones at 8 and 12 days post-infection, respectively. Also, in virus-infected unparasitized larvae, the time required to attain a 50% mortality was significantly longer than that in virus-infected parasitized ones.

Baiting studies performed in large, medium and small hospitals in Brazil revealed the presence of 14 ant species, with up to nine recorded in one hospital. Dominant species were exotic ants, and in the large hospital, Tapinoma melanocephalum was the most prevalent. Ants were not uniformly spread through the hospitals, but tended to be found in the more critical areas, particularly in nursery, intensive care, obstetrics, neurology and dermatology units. Bacteriological studies using specific media for bacteria associated with intra-hospital infections indicated the potential for the mechanical vectoring of species of Staphylococcus, Serratia, Klebsiella, Acinetobacter, Enterobacter, Candida and Enterococcus by ants. Although T. melanocephalum did not have the highest rate of association with these bacteria, its ubiquitous occurrences resulted in the highest overall potential as a vector of these bacteria. Because of a largenumber of ant species occurring in Brazilian hospitals, ants pose a potential problem to the spread of diseases in hospitals. Because of the number of associated ant species in hospitals, the control of this potential problem is much more difficult than in registered temperate areas.

Mating and oviposition of Earias vittella was studied in the absence or presence of the host (okra fruit) or the host odour. When the host was accessible, there was a significant increase in the frequency of copulation, the number of spermatophores transferred and the number of eggs oviposited. Availability of host odour, instead of the host, gave similar results. Further, in general, the number of eggs oviposited by a female was significantly correlated with its mating frequency.

The 130 kDa polypeptide appears to be the most susceptible of the polypeptides constituting the Bacillus thuringiensis ssp. israelensis δ-endotoxin to the proteases associated with sporulation. Stabilization of this polypeptide in the recently described K-S sporulation medium has been achieved through limiting its cleavage by removing contaminating proteases from the culture by washing. In this way, the complete δ-endotoxin profile is retained for studies on all of the constituent polypeptide fractions.

Newly deposited Glossina morsitans morsitans larvae were chilled over ice and inoculated with 1 μ1 of either virus suspension derived from Glossina pallidipes salivary gland homogenate or sterile tsetse physiological saline. They were allowed to pupariate and then maintained at 25°C, 70% r.h. until soon after emergence when their salivary glands were examined for enlargement and presence of virus particles. Teneral G. m. morsitans which received the virus inoculum (n = 135) as larvae all became infected as revealed by gross hypertrophy of their salivary glands and ultrastructural manifestation of virus particles within the glandular epithelial cells and lumina. In the control group, which received the tsetse physiological saline (n = 91), only 1.1% of the flies showed the salivary gland enlargement, a level equivalent to the prevalence of virus infection normally detectable in the G. morsitans colony. This technique opens the way for testing the biocontrol potential of this virus. The DNA virus from G. pallidipes is clearly infective to G. morsitans morsitans, suggesting that the hypertrophied, chalky-white salivary glands, reported in various Glossina spp., are a manifestation of infection by one and the same virus.

The present study revealed that the ratio of antennal to body length in Lipaphis erysimi (Kalt.) increased from 0.55: 1.00 in the first instar to 0.75: 1.00 in the adult alatae as compared to apterae, where the ratio stayed almost the same. The antenna showed specific growth regions i.e. first and fourth annuli, where the increase in size was more compared to other parts. Five morphologically distinct types of sensilla were recorded i.e. sensilla companiform. sensilla trichodea with enlarged spatulate tips, sensilla trichodea with tapering uniporous tips, plate organs and coeloconic pegs. The distribution pattern of these sensilla showed that the number of sensilla trichodea increased during the development, the increase was more in alatae compared to apterae. The secondary sensoria were restricted to adult alatae only, but could be seen under the cuticle in fourth instar alatae. In addition, the variation in the surface sculpturing in the form of scale-like projections were also observed on the antenna.

The lowest weight at which a final instar larva of the leafroller, Cnephasia jactalana (Walker) (Lepidoptera: Tortricidae) can initiate pupation, the larval critical weight, was unaffected by diet quality. Use of a non-nutritive artificial diet showed that the larval-pupal metamorphosis was possibly triggered by stretch receptors, and was not related to nutrition per se. However, a final-instar larva was not able to moult until it had ingested and assimilated the quantity of food required to attain the larval critical weight. The period between attaining the larval critical weight and the larval maximum weight is the latent feeding period which was found to be longer on higher-quality diets. The decrease from larval maximum weight to pupal weight depended on diet quality: optimum-quality diets gave the smallest decreases. The decrease from pupal to adult weight was not affected by diet. Reproductive performance was strongly affected by the quality of the diet during the latent feeding period.

The biology of Maruca lestulatis Geyer was studied on different parts of 18 cowpea cultivars to determine the role of antibiosis in their levels of resistance. M. testulalis larvae were successfully reared from first instar to adult stage on floral buds, flowers and sliced pods, but not on stems, terminal shoots and intact (unsliced) pods, where there was complete larval mortality. The mean pupal weight ranged from 43.5–54.5 mg on floral buds, 38.5–58.6 mg on flowers and 42.7–58.6 mg on sliced pods, with highly significant differences between (P ≺ 0.01) resistant and susceptible cultivars on each part. Growth indices showed that sliced pods were the most suitable for larval growth and development, followed by flowers and floral buds.

The levels of resistance found were inadequate for solving the M. testulalis problem in cowpea. Selection and breeding for cowpea ideotypes (architypes), to combine such resistance with morphological, biochemical and biophysical traits, could enhance the low levels of resistance in the cowpea crop and ultimately lead to the effective management of this pest. The correlations between growth and development parameters showed that larval period had the most influence on M, testulalis survival and population build-up in the succeeding generations.