The pathology of the nuclear polyhedrosis virus from Spodoptera littoralis against Kalotermes flavicollis was confirmed under light microscope. Sections of infected termites showed a comprehensive viral infection. Nuclei of cells of the foregut, cardiac valve, pyloric valve, hindgut, gut musculature, fat body, nerve tissue, muscle, oviduct, pedicel of he ovariole, calyx, accessory glands, wing buds in termite reproductive nymphs, and to a lesser degree, the tracheal matrix, malpighian tubules and hypodermis, were susceptible to the virus. Infection to midgut was generally limited. However, when the termites were heavily infected, the midgut epithelial cells sloughed off into the lumen, and became hypertrophied and granular.

Two species of rice leaffolders, Cnaphalocrocis medinalis (Guenée) and Marasmia patnalis Bradley are usually found in association on rice plants in South and Southeast Asia. Larvae of the two species are similar in morphology, as is their feeding behaviour. Spinning, the process of stitching leaf margins together to form a leaf roll before the initiation of feeding process, is an important behaviour of leaffolder larvae. The spinning behaviour of two species of rice leaffolders was compared to find out if accurate differentiation between larvae of the two species is possible. The manner of spinning, average number of stitch bands made, average time spent to complete one band, order of spinning, number of turns taken by the larvae per band made, and feeding behaviour, while spinning a leaf roll were compared. The results revealed that the two leaffolder species have similar spinning behaviour.

Factors stimulating host seeking behaviour of Eocanthecona furcellata (Wolff), a pentatomid predator, were investigated by using Spodoptera litura (Lepidoptera: Noctuidae) as prey. Faeces of S. litura larvae elicited a host seeking response by the predators. The active material is present in the prey mandibular gland secretions, digestive tract and body surface, which when placed on a filter paper evoked feeding attempts. Predators responded intensely towards the prey artificial diet too. Prey body washings with hexane and acetone also stimulated feeding behaviour.

Physical stimuli such as host shape or movement had no influence on acceptability of the prey to the predator. Larval size correlated with aggressive behaviour which limited predation rather than releasing stimulus for the host acceptance behaviour. Pharate instar stage of the prey was never accepted by E. furcellata. But pupal, egg and adult stages of S. litura stimulated predators to certain extent.

Neither extirpation of antennae nor blinding the vision prevented the bugs from locating the prey. However, excision of rostral tip decreased the prey capture efficiency. It is suggested that the rostral tip contains chemotactile sensillae which are responsible for the prey detection.

This short communication describes the morphological features of three specimens of Hyalomma truncatum which dropped off artificially infested rabbits in the laboratory.

Thirty-eight Leishmania isolates from different host species (humans, mammals, reptiles and sandflies) from various parts of Kenya were compared with six World Health Organization Leishmania reference strains. Isoenzyme variations were assessed on the basis of their electrophoretic profiles on cellulose acetate membranes. Out of 18 enzymes studied, Five were selected for differentiating the Leishmania isolates. These were glucose-6-phosphate dehydrogenase (G6PD, E. C. 1. 1. 1. 49), glucose phosphate isomerase (GPI, E. C. 5. 3. 1. 9), malate dehydrogenase (MDH, E. C. 1. 1. 1. 37), mannose phosphate isomerase (MPI, E. C. 5. 3. 1. 8) and phosphoglucomutase (PGM, E. C. 2. 7. 5. 1).

Twenty-one isolates showed enzymatic patterns identical to the Leishmania reference strain Leishmania major IC-236, five isolates were similar to the Leishmania reference strain L. donovani IC-245 and three isolates were identical to the Leishmania reference strain L. aethiopica IC-228.

However, nine Leishmania isolates could not be identified by this method. They are either leishmanial species for which more Leishmania reference strains are needed for comparison or unidentified flagellates species.

The banding patterns revealed by L. major IC-235, isolated from Israel, were different from those of L. major IC-236, isolated from Kenya, with respect to G6PD; GPI; MDH; MPI and PGM.

Feeding deterrency tests by leaf disc dipping method revealed AZT-VR/K extract of azadirachtin as the most potent antifeedant against cabbage butterfly, Pieris brassicae L. larvae. The leaf damage on treatment with the extract (at 3, 2 and 1%) was minimum and ranged between 4.9 and 16.3 % as compared to 98 % in untreated check. High level of feeding deterrency was exhibited at all the concentrations of AZT-VR/K, while in neemark (at 1%) and neem oil (at 2 and 1%), the deterrent effects declined considerably on their decreased concentrations.

Lipophorin was isolated from the stalk borer, Busseolafusca, larvae by ultracentrifugation in a KBr density-gradient. The lipophorin (M, ˜ 700,000) is a high density lipoprotein (density = 1.13 g/ml) composed of 46% lipids and 4% carbohydrates. It consists of two apoproteins, apolipophorin-I (apo Lp-I, Mr ˜210,000) and apolipophorin-II (apo Lp-II, Mr ˜78,000). Both apoproteins are glycosylated as shown by periodate Schiff reagent staining and binding to the lectin, concanavalin A. Amino acid composition analysis of lipophorin showed predominance of aspartate (13%), glutamate (9%) and glycine (9%).

In an immunoblotting experiment, both apoproteins showed immunoreactivity with antiserum to B, fusca lipophorin and no cross-reactivity occurred with any other haemolvmph proteins. Immunodiffusion studies with the same antibodies showed cross-reactivity with haemolymph derived from other Lepidoptera and not from Orthoptera, Dictyoptera or Diptera.

The leaf surface treatment given to nymphal instars of Lipaphis erysimi with methoprene (1–10,000 ppm) prolonged the developmental period only in the second instar. The percentage emergence decreased significantly in the treatments of first and second instar and the alate production increased in the treatment of the latter instar only. In addition, dose-dependent morphological abnormalities were also observed. The longevity and fecundity were affected adversely when adults were given both topical and leaf surface treatments. However, these effects were not transmitted to the F1 generation.

Four maize varieties, 8321–21-W, DMR-LSR-W, ACR-83TZUT-W and TZB were simultaneously fed to Sitophilus zeamais in a completely randomized design. Susceptibility was assessed on such parameters as weight loss of grains caused by the weevil infestation, number of progenies at 42 days after infestation and the percentage of damaged kernels. The least susceptible in terms of loss of weight of grains was TZB. Losses in the other three were not significantly different at 5% level (P ≻ 0.05).

The least percentage mortality of adult weevils and the highest number of punctured kernels were observed in var. 8321–21-W (48%), 27 kernels respectively while var. DMR-LSR-W had the highest mortality score (80%) and ranked second in the total number of kernels punctured (13). Details of the description of maize varieties used and the analysis of damage caused by the weevil are discussed in the paper.

Studies on developmental biology and feeding and ovipositional preferences of the pea leaf miner, Chromatomyia horticola (Goureau), were carried out on 11 varieties of field peas, Pisum sativum L. Two varieties, P-200 and P-402, offered maximum resistance to the development of pea leaf miner by inhibiting growth as both larval and puparial development were prolonged, and adult longevity, survival and fecundity reduced. These varieties were also least preferred for feeding and oviposition. Differences between the moderately resistant HFP-4 and highly susceptible varieties HFP-5, HFP-6, HFP-12, PG-3, RAU-21, RAU-25, RAU-37and T-163 were not well marked, as most of these had a relatively high value for the developmental success index, based on indices for larval-puparial development, adult longevity, survival and fecundity, and were also highly preferred by the ovipositing females. Variety PG-3, though offering some resistance to development, was highly preferred for oviposition. The local variety T-163, was the most susceptible variety, as it had the maximum value for the developmental success index, and was highly preferred by ovipositing females. The physiological basis of resistance in the two pea varieties is suggested to be mainly non-preference and antibiosis.

Five insecticides and three mixtures were tested on the cotton flea beetle (CFB), Podagricapuncticotis (Weise), the spiny bollworm (SBW), Earias insulana (Boisd.), and the cotton aphids (CA), Aphis gossypii (Glov.). The relative potency (in terms of LD50 and or LC50) for CFB followed this order: endosulfan + dimethoate > endosulfan + chlorpyrifos > dimethoate > fenvalerate > endosulfan > endosulfan + amitraz > amitraz. The LCS0 values ranged from 12. 0–1150 ppm. For SBW, the following order was obtained: fenvalerate > endosulfan + dimethoate, endosulfan + chlorpyrifos > endosulfan > dimethoate > chlorpyrifos > endosulfan + amitraz > amitraz. LC50 ranged between 0.35 and 3388 ppm. With regard to CA endosulfan + chlorpyrifos > endosulfan + dimethoate > endosulfan + amitraz > chlorpyrifos > endosulfan > fenvalerate > dimethoate > amitraz.

In general, C A was relatively tolerant to most tested insecticides when compared with the other two pests. The SBW was the most susceptible.

The effects of plant growth habit (erect versus spreading and flowering pattern) on the resistance of cowpea Vigna unguiculata (L.) Walp., to the legume pod borer, Maruca testulalis Geyer, were studied in Nigeria. Five cowpea cultivars of known agronomic and architectural characteristics were selected for the study: TVu 946, IT82D-716, VITA-3, Oloka local and Kamboinse local. Seed and pod damage assessment values were better in profuse flowering than in non-profuse flowering cultivars and in erect cultivars than in spreading cultivars. Best performances were obtained from TVu 946 (profuse flowering and erect resistant), and worst results from Oloka local (spreading susceptible) and VITA-3 (susceptible non-profuse) respectively. Erect and profuse flowering cowpea cultivars are proposed as having good architectural components for reducing M. testulalis damage to cowpea. The implications of architectural variations in cowpea are discussed.

The biophysical characters of the mosquito, Culex quinquefasciatus, a dreaded vector of bancroftian filariasis was investigated. The data represents the “system” in bioaerodynamics which comprises the adult mosquito and induced air, and constitutes “action-reaction pair” for the hovering flight. Hence the static and dynamic parameters of this species are determined. An expression for moment of inertia of the flight surface (wing) is deduced considering wing design and geometry. Further aerodynamic requirements in relation to flight performance of the insect are elaborated. It is concluded that this study provides useful information on the hovering flight behaviour of the mosquito C. quinquefasciatus.

Species of Culicoides feeding on horses were investigated in Ibadan and Ilorin in the southwestern part of Nigeria using light, sticky and emergence traps. A totalof 2949 Culicoides consisting of 22 species were caught over a period of 22 months. Culicoides quinquelineatus was the most numerous, followed by C. imicola. The greatest proportion of Culicoides was caught with the sticky traps followed by the emergence traps during the period of moderate to heavy rains. Males were scarceand the proportion of fed females was generally low.

A significantly greater number of Culicoides was caught during the rains than during the dry season. The results are discussed within the context of previous investigations on Culicoides in Nigeria. The possibility of some species, especially C. imicola and C. quinquelineatus being vectors of African horse sickness is also discussed.

Plastic dishes 30 cm dia. and 15 cm depth filled with water as traps for Tropinota squalida Scop, adults and painted blue, green, red, white and yellow were exposed in infested peach areas at Abo-Sultan during 1987–1988. Traps painted blue showed high degrees of attractancy to the pest. White, yellow and green attracted the least number of beetles while red was found to have no attraction. Trapping is considerably influenced by microecological conditions, trap placement and trap diameter. Blue traps (25) were sufficient to suppress the pest population in an infested peach area. Blue trap could be considered as a new forecasting method and for studying the swarming dynamics of T. squalida adults.

Eggs of Heliocheilus albipunctella de Joannis were picked up during ear formation of millet at Bambey in 1988 and were followed up in the laboratory at temperatures 25–30°C and 60–70% r.h. Trichogrammatoïdea sp. probably T. armigera parasitized 60.3% of them. During the period in which eggs were collected, percentage of parasitism increased, which certainly means a build-up of parasite populations.

A tsetse survey was conducted around the Lambwe Valley in South West Kenya in order to establish the extent of Glossina pallidipes distribution outside the Valley. Between October 1988 and March 1989 flies were found far outside the Lambwe Valley. A proportion of these flies was infected with three species of trypanosomes. The capture of teneral flies suggested that breeding was occurring and that viable populations of G. pallidipes therefore exist away from the core breeding areas in the valley.

Aqueous extracts (5%) of the seeds Parkia clappertoniana (Jacq), Azadirachta indica A. Juss, and Piper guineense Schum and Thonn caused 90% mortalityof the worker caste with P. guineense, and 86% mortality with A. indica and P. clappertoniana respectively within 3 hr of topical application. At 24 hr, mortality of Macrotermes nigeriensis (Sjostedti) workers was 100% with the same concentration of each extract. Oral toxicity at 3 hr to the worker caste using cuttings of cassava, Manihotesculenta Crantz impregnated with each extract gave 65% mortality with Piper, and 45 and 29% with Azadirachta and Parkia, respectively. Mortalityby oral toxicity reached 100% in 12 hr with Piper, 95 and 69%, respectively with Azadirachta and Parkia. Increasing the concentrations of each extract to 15% did not significantly (P > 0.05) increase the toxicities of the extracts to the worker caste even at prolonged exposure periods.

Rhipicephalus appendiculatus salivary glands extracts and saliva contain both biochemically active and pharmacological agents with various effector functions, including inhibition of host enzymes or inactivation of other host molecules that may be important in mounting tick rejection. The majority of these salivary biochemicals may interact with host antibodies at the feeding site or in the gut (or both), that interfere with proper tick attachment and feeding. The possible role of these biochemicals in tick feeding is discussed. Of particular interest is a salivary anticoagulant, which increased as feeding phase progressed and was present in all life cycle stages of the tick. Antibodies raised in rabbits against salivary gland extracts obtained from female if. appendiculatus fed on rabbits for various days, recognized several antigens on Western blots of salivary gland extracts, but failed to react with the purified tick salivary anticoagulant molecule. Thus, tick anticoagulant was poorly immunogenic compared to other salivary moieties. These results may help to explain the strategies adopted by the tick to circumvent biochemical detachment by the damaging host-protective immune responses, thereby enabling the vector to co-exist with its mammalian hosts.

Greenbug, Schizaphis graminum (Rondani), an important vector of barley yellow dwarf mosaic virus, is a major pest of cereals in many countries. A preliminary survey conducted in the Punjab and North Western Frontier Province of Pakistan revealed medium to heavy infestations at Charsadda (density 12 apterous greenbugs/25 plants), Sher Shah (Multan) (density 33) and Malkot (Murree) (density 114). However, it was found in small numbers at many other locations.

A culture of greenbugs collected from Charsadda, was established on susceptible wheat cultivar Faisalabad-83 at 27 ± 3°C, 60% r.h. and 16:8 hr day:night regime. A seedling bulk test using local and exotic host differentials indicated that DS-28A and Largo wheat were susceptible, whereas Amigo wheat, Post and Will barley were resistant. This indicates that the population of greenbug from Charsadda culture was different from greenbug biotypes occurring in the USA. Therefore, it was designated as biotype PK-I for future reference.

Of the 44 recommended wheat cultivars in Pakistan, Punjab-85 was found to be resistant (visual damage rating (DR) 3 at 0 to 9 damage scale; 0, healthy; 9, dead). Faisalabad-85 had a DR of 4, PARI-73, Sandal and Yecora had a DR of 5, and PAK-81, WL-711, Sutluj-86 and Nuri-70 had a DR of 6. All the remaining cultivars were highly susceptible to greenbug (DR ≻ 6).

Three tests, namely, antixenosis (non-preference), antibiosis and tolerance, were conducted to determine the nature of resistance in selected entries. In the antixenosis test, PARI-73, WL-711 and Yecora were found to be the least preferred. The lowest fecundity (antibiosis) of the greenbug was on Punjab-85. In the tolerance test, the lowest damage was recorded on PARI-73 (DR= 4.1), followed by Sandal (DR= 4.8) and Punjab-85 (DR= 4.8). These three tests indicated that resistance in Punjab-85 is mainly due to antibiosis and a low level of tolerance.

During this study 439 native wheat germplasm lines were also tested. Of these, 16 germplasm lines (PAK 15081, PAK 15115, PAK 15139, PAK 15242, PAK 15433, PAK 15479, PAK 15481, PAK 15519, PAK 15992, PAK 15994, PAK 15995, PAK 15997, PAK 16007, PAK 16008, PAK 16010 and PAK 16190) were found to have a high level of resistance (DR ≺ 3). Of the test entries, 114 were moderately resistant (DR= 4–6) and the remainder were susceptible (DR ≻ 6) to greenbug. The germplasm lines found resistant may have different genes for resistance which can be exploited in breeding programmes.