Paltothyreus tarsatus F. extracts showed anticonvulsant effects in laboratory mice. Chemical examination of Paltothyreus tarsatus revealed the presence of alkyl sulphides (8.5%), ketones (9%), fatty acids (50%), small amounts of alkanes, alkenes and sterol. Constituents were analysed by gas chromatography. Tentative identification of the unknown was confirmed by comparison of its mass spectrometry and its gas chromatography retention time with those of an authentic sample and by co-injection.

The spatial distribution of the eggs and larvae of Anaphe venata Butler within canopies of its host, Triplochiton scleroxylon K. Schum situated at Araromi Village northeast of Ibadan was determined. Sampling branches of T. scleroxylon once in a spiral from base of canopy upwards was sufficient in determining the distribution of eggs and larvae of A. venata. Although the differences in the mean count of egg masses and larval groups in the lower, middle and upper canopy levels were not significant, the highest percentage of egg masses and larvae occurred on the tips of branches in the lower canopy. Sampling studies on the developmental stages of A. venata may therefore be done at the lower canopy level for best precision. Eggs and larvae are aggregated while the larval dispersion on the host suggest photo-positivity. The use of mounted, motorised elevators is proposed in order to enhance efficiency of sampling and avoid destructive sampling.

Urticating spicules of Hylesia moth of Guyana (H. metabus Cramer = H. urticans Floch et Abonnenc) are produced by trichogen and tormogen cells which form a monolayer hypoderm similar to that which produces scales. Urticating spicules are interpreted as modified scales.

Field screening of Lablab niger germplasm for 3 years revealed that two cultivars, PLS-24 and PLS-16-1 consistently displayed resistance to pod borer, Adisura atkinsoni Moore larval boring and egg laying. Observations at different intervals of plant growth permitted a comprehensive evaluation of cultivar response to the pod borer complex.

Preliminary tests indicated pod colour, pubescence and fragrance to be associated with the borer resistance in L. niger. However, none of the characters per se imparted resistance or susceptibility, partly or fully. Cumulative effect of the aforesaid characters appeared to impart borer resistance to Adisura. Pod wall did not form a physical barrier to Adisura larval entry. Positive relationship existed with amount of chloroplast and susceptibility, and starch grains and resistance in four cultivars studied for anatomical details. Anthocyanin pigment in the pod wall was associated with resistance in L. niger to Adisura.

Based on field and laboratory evaluations of Lablab niger cultivars to the bean aphid, Aphis craccivora damage, the “local” and H-2, rated as highly susceptible to borers, reacted as resistant and PLS-24 and PLS-16-1 rated as resistant to borers reacted as highly susceptible to the aphid attack. It is therefore imperative that promising Lablab niger cultivars be evaluated for resistance to both the sucking and chewing insect pests.

Under artificial infestation conditions the resistant cultivars exhibited susceptibility to larval boring by Adisura, but confirmed resistance to ovipositional response. Non-preference for oviposition was the most important factor in imparting resistance to the borer damage in L. niger. Factors inducing host preference for larva and for adult were different and independent. PLS-24 and PLS-16-1 contained significant degrees of antibiosis as demonstrated by reduced larval survival, larval and pupal weights, prolonged larval duration and altered sex ratio.

Cultivars that sustained low levels of seed yield loss at high infestation levels were identified as tolerant. MS-9579 and IC-661-1 exhibited low degree of tolerance. Resistant cultivars proved non-tolerant even to slight infestations (ca 10%) received under field conditions.

Studies were carried out in 1983 to determine the relative abundance and species composition of three lepidopterous stem borers in upland and irrigated rice at Ibadan, southwestern Nigeria. The relationship between irrigated rice crop phenology and the population of the borers and stalk-eyed fly was also studied.

White stem borer, Maliarpha separatella was the predominant species in upland and irrigated rice, followed in upland rice by pink stem borer, Sesamia calamistis, and striped stem borer, Chilo zacconius and in irrigated rice by C. zacconius and S. calamistis. The proportion of M. separatella was higher in irrigated rice than upland. Three population peaks were observed annually in both upland and irrigated rice.

Studies on the relationship between irrigated rice phenology and field population of lepidopterous borers and a dipteran borer showed that the stalk-eyed fly, Diopsis spp., occurred before 20 days after transplanting (DAT) in ITA 212 and continued up to 90 DAT: the peak was observed at 40 DAT. The lepidopterous borers did not appear until 40 DAT and populations peaked at 80 DAT.

Occurrence, abundance and seasonal fluctuations of Culicoides peliliouensis in the mud and sand flats of Hooghly estuary were studied in relation to some important environmental parameters (air temperature, soil temperature, soil moisture, rainfall, salinity, dissolved oxygen and pH of interstitial water, organic carbon, available phosphorus, percentage of sand, silt and clay of soil) at three stations in and around Sagar Island during July 1982 to June 1984. They were more or less found throughout the year, withmaximum abundance during postmonsoon and minimum during premonsoon. Several statistical analyses have been computed to study the relation between population of C. peliliouensis and all ecological parameters. Results of ANOVA indicate that almost all ecological parameters varied significantly over months, stations and years, whereas the population of C. peliliouensis varied significantly only over months and stations. Soil temperature, rainfall, organic carbon and available phosphorus appear to be the major factors controlling their distribution in the intertidal habitat as evident from correlation coefficient analysis. Multiple regression analysis shows that the combined effect of all parameters is positively significant at all the stations.

The effects of climate on the diurnal biting pattern of Simulium damnosum s.s. were measured at Jos Plateau, Nigeria. Rain in the hours prior to the catch inhibited morning activity by lowering the temperature and light intensity, and raising the humidity. Under shade there were no remarkable fluctuations in the light intensity, and no obvious peaks in activity; in sunny places, activity was bimodal, with a small morning peak and a pronounced afternoon one. The fastest changing climatic factor relative to an increase in the biting activity of flies was light intensity; followed by temperature.

In the present study, we investigated the development of Leishmania donovani promastigotes in Aedes aegypti. Infection rate in the mosquito averaged 53%. Promastigotes were limited to the hindgut where they appeared on day 4 post-infection. Massive multiplication of promastigotes occurred between 6 and 17 days post-infection. The mosquito pylorus and rectum had the highest concentration of promastigotes. A maximum life span of 20 days was observed for L. donovani promastigotes in the mosquito. Morphologically intact L. donovani promastigotes were ejected with A. aegypti faeces, following a blood meal. Implications of the development of Leishmania spp. in the mosquito host are discussed.

Maize is the single most important food cereal in eastern and southern Africa. Yield levels, however, are among the lowest in the world. Among the major constraints limiting production are the insect pests. Objective assessment of damage and losses caused by these pests are lacking in several countries within the region. This paper discusses some of the methodologies available, and how they can be used to estimate the losses caused by insect pests under different situations. It emphasizes the need for standardization of the methodologies, so that information generated from different countries can be compared. This will promote collective action to combat the pest menace and increase food security.

A study of several populations of the cassava green mites from eleven African countries representing wide ranging ecological zones were studied using a Principal Component Analysis. This study revealed that there is only one species of the Mononychellus present on cassava in Africa and is here designated M. tanajoa.

The effect of light on the development of the angoumois grain moth, Sitotroga cerealella, was studied. Three different light conditions, i.e. continuous light (LL), continuous darkness (DD) and antural illumination (LD), were used.

Eggs bred under LL system showed the shortest mean incubation period, 3.27 and 4.66 days after one and four generations, respectively. The light had no effect on egg hatchability. The number of larvae that reached the adult stage under LL was less (33–36%) than under LD (37–40%) or DD (38%). The fertile females begin egg laying within 0.9 to 2.3 days after mating under all light systems. The shortest period (0.9) was shown under continuous light. The least oviposition period 4.4 and 4.5 was obtained under LL, while the longest period (6.4 and 5.7 days) was obtained under LD, after one and four generations, respectively. The light has no effect on the post-oviposition period. The longest life span of adults was recorded under LD and the shortest under LL. The females bred under LL, laid the least number of eggs (85–87 eggs), while those bred under LD and DD laid the highest number (128–130 for LD and 113–146 for DD, respectively).

Field trials of various neem formulations were conducted to determine their effectiveness for the control of some major pests of eggplant, Solanum melogena (L), okra, Hibiscus esculentus (L) and cowpea, Vigna unguiculata (L), Walp. Various concentrations of neem emulsion reduced incidence of Selepa docilis (Butler), Urentius sp. and Zonocerus variegatus (L), on eggplant. Damage caused by Sylepta derogata (F), defoliator of okra, was less in plots treated with 5, 10 and 20% aqueous-methanol extracts of defatted neem cake. Moreover, neem seed cake applied as dust enhanced cowpea yield.

Vertical distribution of different larval instars and pupae of Culicoides oxystoma in different depths in the mud and sandflats of Hooghly estuary were studied in relation to soil temperature and moisture at three stations in and around Sagar Island during March 1983 to February 1984. Temperature recorded higher in 0–3 cm depth and gradually decreased in subsequent depths. During the last part of the pre-monsoon (May and June) season, moisture was recorded minimum in 0–3 cm depth and gradually increased in greater depths, but in other seasons (monsoon and post-monsoon) the results were just opposite. Larval and pupal population showed a peak during post-monsoon then gradually declined in pre-monsoon and early monsoon. They were mostly encountered throughout the year from 0–3 cm depth except during summer months (May, June and July). First and second instar larvae were only recorded from 0–3 cm depth. Third and fourth instar larvae were distributed in all the depths, maximum in 0–3 cm. Pupae were never encountered from deeper depth (6–9 cm). Temperature and moisture act as important factors to control the vertical distribution of larvae and pupae of this species.

Pheromone traps were used for monitoring flight activity of peach twig borer, Anarsia lineatella (Zeller), during a 3 year period between 1983–1985 in Iraq at Tarmiya and Madain regions, and cumulative emergence was related to physiological time (degree-days, DDs). Data of moth catches indicated the presence of two generations per year and perhaps a partial third generation. Flight in both regions peaked from April to mid-May and from early June to mid-June. First capture of peach twig male ranged from 16 to 29 March and corresponded to a mean DD accumulation from 1 March of 138 in Tarmiya and 127 in Madain. Such results are very important for managing this pest.

The rice plant is an extremely versatile crop that is grown under both tropical and sub-tropical conditions in various ecological conditions. Several insect pest species attack the rice crop at all growth stages while in the field. The nature and magnitude of crop loss due to insect pest attack in tropical and sub-tropical Africa are highlighted. Reliable evaluation techniques for establishing relation between insect pest intensity/damage and crop loss are outlined. Natural insect pest infestation in the field, manipulation of pest infestation with chemicals, caging to confine or keep out insect pests and the use of resistant varieties as methods of estimating on-farm losses due to insects are discussed. In tropical Africa, the major constraint to the determination of crop loss due to insect pests of rice is research-related.

Preliminary investigations have shown the presence of pathogenic fungi in natural populations of the cassava green spider mites. Among others, Entomopthora sp. and Hirsutella sp. were isolated from dead mites sampled from the field. Laboratory bioassays have given mite mortality of up to 60%, indicating the possibility of utilizing some of these pathogens in mite control. Tests with Beauveria bassiana, isolated from lepidopteran pests, have also shown that the mite is susceptible to this fungus.

A low cost artificial diet was formulated from materials which are locally available in Africa. The diet utilized cowpea, sorghum and corn instead of pinto bean and wheat which are widely used in the USA. The new diet was as satisfactory as the pinto bean diet for all the biological criteria tested. On a pinto bean diet, pupation and eclosion required 14.3 ± 1 and 26.3 ± 1 days, respectively. On the cowpea diet, 14.6 ± 1 and 26.9 ± 1 days were required, respectively. Ninety-eight per cent of adults eclosing on each diet were viable. Females eclosing on the cowpea diet laid 739 ± 53 eggs of which 59 ± 2% hatched. On the pinto bean diet, 774 ± 62 eggs were laid per female with 61 ± 2% hatching. Pupal weights were 526 ± 22 and 537 ± 28 mg when larvae were reared on the pinto bean and cowpea diets, respectively. Food consumption and utilization by larvae reared on the new diet were comparable with those of larvae reared on the popular pinto bean diet.

Armyworm, Spodoptera exempta (Wlk.) feed on cereals and grassland in eastern and southern Africa. Data on the yield losses and economic effects of an attack on cereals is sparse. They can be an indirect cause of cattle deaths. The need to examine the situation at the farm level has been recognized. A national survey was conducted in 1987, and is currently being analysed. The work entails identifying representative areas and farmers, completing a questionnaire with each farmer, noting the frequency of outbreaks experienced, the farmers' response, the level of government support, the effectiveness of control measures and the costs incurred. Proposals are outlined for future work within the region to determine the reduction in cereal yields due to this insect and to set up action thresholds for control activities. A major difficulty with the survey approach is the disaggregation of various loss-causing factors. At a sub-sample of survey sites, where outbreaks are present, the damage to the crop and the subsequent yield of the damaged crop or the planting of a replacement crop would be recorded to build up data from which action thresholds might be determined.

Polyphenism is a common feature in the mustard aphid, Lipaphis erysimi (Kalt.) in tropical countries. The function related changes in basic biochemical pool are reported during development of polyphenic forms. A gradual decrease in the protein content in this aphid was recorded, as the nymphs advanced in their instar number and reached adult stage. However, the protein content was significantly lower in the apterous forms as compared to alate. The number, density and mobility of protein bands varied as the nymphs passed through different instars and the number of bands was more in alate forms. The glycogen and trehalose contents showed a decrease upto the third instar and showed an increase in the fourth instar, but again declined in the adults of both the phases.

Laboratory mice infected with a Trypanosoma congolense isolate of water-buffalo origin did not respond when treated with diminazene aceturate (Berenil, Hoechst, West Germany) at 3.5 mg/kg and 7 mg/kg body weight (b.wt.) and also isometamidium chloride (Samorin, May & Baker, Dagenham, England) at doses less than 3 mg/kg b.wt. Effective cure was achieved with isometamidium and diminazene at 3 mg/kg and 14 mg/kg b.wt. respectively; doses in excess of those recommended for use in the field to treat animal trypanosomiasis by the manufacturers. Irregular use of the two drugs on infected water-buffaloes while improperly restrained may be one of the factors responsible for the dual drug resistant T. congolense isolate emerging.