The crude n-hexane and methanol extracts of the aerial parts of plant, Pimpinella monoica Dalz. (Umbelliferae) showed significant feeding deterrency to Spodoptera litura F. larvae. Phytochemical investigation of these extracts has resulted into the isolation of one furanocoumarin and five biogenetically related furanochromones. Furanocoumarin, isopimpinellin was found to be most active. Furochromones, visnagin and khellin exhibited significant activity while their hydroxymethyl analogues, khellol and ammiol showed moderate activity. α-Hydroxyisopropyldihydrofurochromone, visamminol was found to be least active.

Behavioural and electrophysiological (EAG) studies were undertaken to determine the olfactory selectivity of the antennae of Glossina morsitans morsitans Westwood and Glossina pallidipes Austen to phenolic kairomones. Responses of both species to 3-alkylphenols increased as the alkyl chain increased from one carbon atom to three, while the opposite trend was observed with 4-alkylphenols. These results indicated that 4-cresol and 3-n-propylphenol are the most stimulatory of the two respective groups of phenols. However, comparison of the responses indicated differences in the sensitivities of the chemoreceptor systems of the two species. Hence different compositions of the phenols may be required to best attract these species. Probable interactions of the phenols with the binding sites on the receptor surface are discussed.

Immature stages of Amblyomma lepidum were fed on rabbit ears and the adult ones on calf ear. There was a three-host type of development during an average period of 160.5 days. The mean larval feeding period was 5 days, 7 days for nymphs and 14.5 for females. At 27 ± 1°C and 100% r.h. the engorged larvae required 21 days for moulting and nymphs took 22 days to develop to adults. The pre-oviposition period was 14.2 days and the oviposition period was 21.4 days during which a mean number of 7564.6 eggs were laid. Hyalomma anatolicum anatolicum and Rhipicephalus evertsi evertsi were fed on rabbit ears. The larvae, nymphs and adults of Hyalomma ticks fed for 4.6 and 8.5 days, respectively. The larvae and nymphs of R. e. evertsi fed sequentially on the same host for 14 days while the females took 7.5 days to engorge. At 27 ± 1°C and 75–80% r.h. the engorged larvae and nymphs H. a. anatolicum moulted after a further 8.5 and 13 days respectively. The engorged nymphs of R. e. evertsi at 27 ± 1°C and 75–80% r.h. moulted 14.5 days after dropping off the host. At 27 ± 1°C and 75–80% r.h. the preoviposition and oviposition periods of H. a. anatolicum were 4.6 and 20.8 days, while those of R. e. evertsi were 5.4 and 14 days. The average number of eggs laid per female under the same conditions (27 ± 1°C and 75–80% r.h.), was 4684.6 for H. a. anatolicum and 3392 for R. e. evertsi.

Larvae, nymphs and adults of Amblyomma variegatum, and nymphs and adults of Hyalomma rufipes were infected with Dugbe virus by intracoelomic inoculation. Each developmental stage of tick was divided into three groups A, B and C and the three groups were infected respectively with a Dugbe, virus concentration of 4.5 LD50 (log10), 1.5 LD50 (log10) and 0.5 LD50 (log10). The virus multiplied to a high titre in groups A and B and reached a peak which was over 5 (log10) the infective doses of some of the larvae and nymphs.

With the exception of group B adult H. rufipes (with an infection rate of 65%), all other ticks in groups A and B have an infection rate of between 97 to 100%. The infection rate of group C ticks was below 40%.

The 1–5% infection threshold occurred with a dose higher than 0.5 log10 in larvae of A. variegatum and adults of H. rufipes, but with a dose lower than 0.5 (log10) in all other stages of the two tick species. The 50% infection threshold occurred with a dose less than 1.5 (log10) in all the developmental stages of the two tick species.

All the developmental stages of ticks transmitted Dugbe virus to rabbits during feeding.

Stability of resistance to corn planthopper, Peregrinus maid is (Ashmead), was studied over three plant growth stages in 56 sorghum germplasm accessions. Genotype x stage interactions were significant. Plant age exerted a profound influence on the rate of oviposition, establishment of nymph, macropterous and brachypterous adult populations and plant damage. Resistance to corn planthopper was stable over three growth stages in IS 18557, IS 18677 and PJ 8K(R), which also supported low colonization of nymph and adult populations; IS 12308 was unstable due to high deviation. Significantly low rate of oviposition on resistant as compared to susceptible genotypes and the positive and significant correlation between oviposition and plant damage illustrated that antixenosis for oviposition is the primary mechanism of resistance. As a consequence the genotypes preferred for oviposition showed susceptibility due to higher plant damage. Establishment of nymphs was affected on the genotypes, IS 1054, IS 1082, IS 2194, IS 3992, IS 12308, IS 18676 and IS 19349 which may be due to the factors involved either in reduced hatchability of eggs and/or deterrence or poor feeding preference of nymphs.

Laboratory experiments were carried out to study the effect of irradiating T. confusum pupae on the susceptibility of their adults to four insecticides. Results indicate that gamma irradiation significantly decreased the tolerance of adults from pupae irradiated 1 and 2 days before eclosion to Duradin. On the contrary, malathion and formothion, belonging to the same chemical group, i.e. organophosphate, were similar in their toxicity to adults, showing that irradiation of pupae afforded some protection to adults from death. However, s. fenvalerate exhibited the same trend noticed for malathion and formothion where irradiation of pupae reduced its effectiveness to adults. In general, adults from pupae irradiated 1 and 2 days before eclosion were less tolerant to tested insecticides than those from pupae irradiated 3 days before eclosion. Studying of tolerance ratio of various insecticides revealed that at 24 hr post-treatment, the most obvious trend is that adults from irradiated pupae, 3 days before eclosion, showed a moderate level of tolerance to formothion (3.29-fold) and s. fenvalerate (3.62-fold), and high level of tolerance to malathion (16.30-fold). While all adults from irradiated pupae elucidated different levels of tolerance to malathion, formothion and s. fenvalerate, the effectiveness of Duradin on those adults was significantly enhanced. This means that the application of Duradin in combination with gamma radiation is more effective than their separate applications. The dissimilarity of adult responses to the insecticides may be attributed to the enzyme alterations, either quantitative or qualitative and are the key to these irradiation effects on toxicity of insecticides to insects.

A comprehensive review of the major investigations on the biology of African ixodid ticks is made with a view to identifying weaknesses in the life systems which may be employed as control components in an integrated package. The possibility of breeding ticks with low oviposition capacities needs to be confirmed and further studied with respect to the economically important ticks in Africa. Studies on the membrane or artificial feeding of ixodid ticks must be conclusive and more importantly the disease transmission abilities of these membrane fed ticks is worthy of being looked into. Additionally, the hybrid status of both Genus Rhipicephalus and Genus Amblyomma ticks should be studied. Efforts must also be made to intensify research on selecting resistant host breeds to multihost ticks, R. appendiculatus and A. variegatum, among the very many cattle breeds present in Africa.

Field investigations were carried out in northern Nigeria to determine the prominent natural habitats of phlebotomine sandflies. Two biotopes, termite hills and rock crevices, were identified as the major habitats with the termite hills being the most significant. All the 12 species (Phlebotomus duboscqi, P. rodhaini, Sergentomyia antennula, S. bedfordi, S. africana, S. schwetzi, S. ingrami, S. adleri, S. clydei, S. buxtoni, S. affinis and S. christophersi) identified in this study came from this source. Only a small number of samples representing a few species were collected from the three other habitats (tree holes, animal burrows and a cave) investigated. The distribution of the sandflies was found to be influenced by the availability of suitable biotopes and physico-chemical composition of the soil.

Argasid ticks have been induced to feed successfully through different types of artificial membranes but this technique has not been easily applicable on ixodid ticks. In order to get hard ticks to feed artificially, two major approaches have been employed: Feeding on a diet through artificial membranes; and feeding from diet-filled capillary tubes placed over the tick's mouthparts. In both cases the ixodid ticks could not be fed to repletion. This paper gives a brief account about artificial feeding of ticks in general and the techniques used to obtain successful feeding of an ixodid tick Rhipicephalus appendiculatus through a modified Baudruche membrane.

The fine structure of the trifoliate process of three species of Atherigona were studied. The outer surface of the lateral lobe of the process for the three species, A. bedfordi, A. hyalinipennis and A. secrecauda is covered with a dense mat of hairs. There are spine-like outgrowths on their inner surface referred to as “commasets” as well as some unusual sensilla on the rim of the lateral lobe and the section connecting the lobes to the stem. These structures showed inter-specific variation. The stem of the process is glabrous and granulate in A. bedfordi and A. secrecauda, but sparsely pilose in A. hyalinipennis.

Techniques for assessing infestation trends of Latoia viridissima are presented in this report. A plot of the head capsule widths of larvae indicated six larval instars with instars one and two being more abundant. It also illustrated the composition of larval instars in the population and hence would serve as a standard against which future samples of the species could be compared. Larval survivorship data indicated heavy mortality (>60%) during instars one and two. Major mortality factors were an aggregate of natural enemies, particularly predators (causing 40–50% of the death during the age interval), parasitoids and pathogens responsible for 60–80% mortality throughout the entire larval life. The residual cocoon populations were further reduced by about 20–30% by parasitoids (Brachymeria sp., Chrysis spina, Cocygodes coccyx, Palexorista sp and Systropus pelopoeus) and a pathogenic fungus. Data from cocoon samples showed that the sexes of the moth could be separated on the basis of cocoon size. Cocoon weights were therefore, a better criterion than cocoon diameter values for separating the sexes; since overlap between the sexes was less than 5 % for cocoon weight as against 20% In the case of cocoon diameters. The separation point tended to lie between cocoons weighing 350–399 mg. Fecundity of the females was highly correlated with female weights (r = 0.901) and wing length (r = 0.89), The calculated fecundity of 143 eggs/female (using wing length) was not statistically different (P ≤ 0.05) from the observed value of 149 eggs/female. The significance of the findings as regards forecast of outbreaks and assessment of outbreak situations are discussed.

The effects of Decis® (deltamethrin) and Systoate® (dimethoate) were assessed by the number of Megalurothrips sjostedti (Trybom) (Thysanoptera, Thripidae) recorded per cowpea plant at 40, 50, 60 and 70 days after planting (DAP), evaluated by the drop-cloth sampling method. The trial was carried out under natural infestation conditions during the 1985 early cropping season (from April to July). Systoate® was better than Decis® in controlling the flower thrips and its effect was significantly different from the unsprayed control (P = 0.01). The Decis® effect on the flower thrips was also effective in comparison with the control (P = 0.01). The effectiveness of two insecticides used in relation to pest management and the adequacy of the drop-cloth sampling method in relation to other methods are discussed.

The purpose of this study is to elucidate the production dynamics, growth characteristics and trends of African trypanosomiasis research (ATREP) literature between 1900 and 1985 through graphical methods.

The data analysed comprised 5139 articles from Tropical Diseases Bulletin and Tsetse and Trypanosomiasis Information Quarterly. Counting technique was employed in sorting the articles according to yearly production and respective subject disciplines. The bibliometric ranks of the disciplines were determined based on (1) the total output and (2) the average decennial relative changes (Rc) in publications between 1936 and 1985 using 1936/45 as the base decade.

The results show that the growth is neither linear nor logistic but exponential with an average 39.5-year doubling time. A marked feature is the occurrence of high “epidemic” peaks between 1910–1914 and 1979–1985, a state in which publications were produced at relatively high level probably due to new discoveries or research orientation; and hence capable of quickly infecting a large number of scientists enhancing productivity. There was also a low level of activity from 1914 which lasted for about 22 years.

The foundation disciplines for African Trypanosomiasis Research Programme (ATREP) are entomology and parasitology. Entomology had the highest bibliometric rank followed by parasitology. However, the Refactors indicate that greater attention, as depicted by publication outburst, was given to physiology, immunology, biochemistry, and epidemiology between 1976–1985 than had been before.

In spite of its consistently higher output, entomology exhibited the greatest fluctuating growth trend than all the other components. A possible explanation for this behaviour was ventured.

Incorporated in this paper were the results of a study made on the quantitative variation of total carbohydrate, protein and lipid in whole body, fat body and integument of the larval and pupal developmental stages in rice moth, Corcyra cephalonica (St.) a storage grain pest. All three macromolecules referred to in case of whole body, exhibited a progressively decreasing trend from larva to pupa. In fat body total carbohydrate and protein contents were more in pupa than larva, while in integument the said nutrients were less in pupa than larva, showing the reverse results. The lowering down of the nutrients' level under stress caused by pyrethrum (a botanical insecticide) was also observed. The physiological and statistical significance of these findings was discussed.

Ticks have always been a major obstacle to livestock production due to the devastating diseases which they transmit especially in the tropics. The control of ticks which has relied heavily on the use of acaricides is now faced with serious problems e.g. increased resistance in ticks, high costs and toxicity to the environment. Over the last few decades, alternative tick control methods which utilize natural factors with little or no acaricides have been sought and those which have shown some promise are discussed in this paper. They include release or conservation of biological control agents e.g. parasitoids, predators and pathogens; anti-tick grasses and pasture spelling. The possibility of integrating some of these factors into low cost environmentally-safe tick control strategies affordable by resource limited farmers is also discussed.

The geographical distribution and host range in Nigeria of the mango mealy bug, Rastrococcus invadens Williams (Hemiptera: Pseudococcidae), a serious exotic insect pest of mango and many other crops is reported. The spread of R. invadens in Nigeria is at present limited to Lagos, Ogun and Oyo States of the humid south-west contiguous with the Republic of Benin, where the incidence of the pest has previously been reported.

Infestation has not been observed in any of the 11 states of the north nor in the Federal Capital Territory all of which have lower rainfall and relative humidity. R. invadens is highly polyphagous on over 20 species of host plants in 12 different plant families ranging from fruit crops which constituted 42.85% of the crops attacked, to food crops (14.28%), and to shade trees and ornamentals (42.85%). Severity of attack which was based on the number and area of foliage, Inflorescence and fruits attacked by R. invadens alone or together with sooty mould was highest in mango, citrus, breadfruit, guava and ornamentals including oleander, frangipani and roses. Hosts with mild infestation include maize, pawpaw and croton. The frequency with which infested plants are being felled, burnt or sprayed with synthetic chemicals suggests the panic which R. invadens attack has caused to growers.