Ovlposition and development of the ichneumonid Trathala flavoorbitalis (Cam.) a parasitoid of the brinjal shoot and fruit borer, Leucinodes orbonalis Guen., was investigated. The parasitoid responded to a host larva by inserting its ovipositor (stinging) into the larva, whichever instar (first to fifth) it was. All the first and about 50% of the second instars that were stung and oviposited in, were mutilated and died as a result. Successful parasitization and parasitoid development up to adult emergence occurred in 53% of the third, 57% of the fourth and 41% of the fifth instar host larvae. When given a choice of instars for oviposition, the parasitoid avoided all first instar and most second instar larvae, while third to fifth instars were equally accepted. The total developmental time of the parasitoid was much the same (about 20–24 days) whichever larval instar (second to fifth) was parasitized. The parasitized host at pupation contained different developmental stages of the parasitoid, differing in this respect from most other species of larval-pupal parasitoids.

Restriction endonuclease digestion of genomic DNAs from WHO Leishmania reference strains generates prominent kinetoplast DNA (kDNA) fragments ranging from 0.5–2.0 kb. Following fractionation by agarose gel electrophoresis, these DNA fragments were visualized as distinct bands in gels. Using as parameters the presence or absence of the prominent bands and their size and number, the Leishmania reference strains fell into three distinct genomic groups. These genomic groupings were applied to new Leishmania isolates. DNA analysis, involving restriction endonuclease digestion and Southern blot hybridization with probes generated from the prominent DNA bands of reference strains L. major IC-236 and L. major IC-235, cloned in plasmids, showed significant genetic variation within Leishmania and allowed some distinct isolates to be identified.

A number of natural and man-made habitats in Marigat area of Kenya were surveyed for sandflies in 1985/86. Of the 98,573 adult sandflies collected, 2.7 % belonged to the genus Phlebotomus and 97.3% to Sergentomyia. Relative abundance of sandflies of the genus Phlebotomus was four times higher in burrows than in termite hills, while sandflies of the genus Sergentomyia collected from termite hills were twice as numerous as those from burrows. Termite hills had the highest sandfly population compared to other sites, followed by tree holes and animal burrows. Fifteen species were identified, of which five belonged to Phlebotomus and 10 to Sergentomyia. The most abundant and widespread species were Sergentomyia antennatus, S. bedfordi, S. ingrami, Phlebotomus martini, S. schwetzi, S. africanus and P. duboscqi. Sandflies of both genera were present for the greater part of the year. Most species of sandflies decreased in numbers during the dry season. High population densities of sandflies were recorded during the wet period. Correlations between relative abundance of sandfly vectors of leishmaniases and rainfall were positive. However, none of the correlation coefficients was statistically significant.

Sorghum head bug, Calocoris angustatus Leth. (Hemiptera: Miridae) is an important insect pest of sorghum in the semi-arid tropics. A technique to screen for resistance to head bugs under field conditions was tested. Planting infester rows of susceptible cultivars (CSH 1 or CSH 5), 20 days before the test material or planting early (40–45 days) flowering lines (IS 802, IS 13429 and IS 24439) along with the test material, split planting of test material at 15-day intervals, grouping test material according to maturity, and use of sprinkler irrigation to maintain high humidity, were found effective in increasing the efficiency of screening and selecting for resistance to head bugs.

A headcage technique to screen for resistance under no-choice conditions has also been developed. Panicles infested with 10 pairs of bugs at pre- and half-anthesis, result in maximum population build-up and grain damage under headcage. This technique is useful for confirming the resistance observed under field conditions.

Under natural infestation, five genotypes harboured relatively lower head bug numbers than the susceptible checks, but only three (IS 17610, IS 17618 and IS 17645) maintained their level of resistance under the headcage. Seed germination was > 70% in these genotypes compared to < 10% in CSH 1 and CSH 5.

The cotton boll worm, Heliothis armigera Hbn, was grown under standard conditions. Parameters are given for identification of larval instars on the basis of head capsule width. Intrastadial weight of larvae in terms of fresh weight is presented for a regular time interval of 12 hr. The maximum larval growth in all the stadia was observed in the first 24 hr after the preceding moult. Weight of larvae was almost constant in the last quarter of the stadium, till they moulted into the next. Although the last instar larvae gained maximum weight amongst all the stadia, their actual growth was minimum. First instar larvae recorded a 13 times increase in body weight in comparison to the last instar larvae with 3.9 times. Fifth instar larvae entered into the prepupal stage after they had completed an age of 60 hr. Temperature had a profound influence on the incubation period of eggs; the higher the temperature, the shorter it was. Between 28 and 36°C the incubation period was almost the same. The maximum tolerance level of constant temperature for the eggs of Heliothis armigera was 37°C.

Based on a semi-synthetic diet, a standard rearing method for the cotton bollworm, Hetiothis armigera Hübner, is described. The diet is composed of chickpea (Cicer arietinum) flour, yeast powder, sucrose, ascorbic acid, cholesterol, choiine chloride, wheat germ oil, vitamin mixture and a combination of preservatives. A plastic container for individual rearing of the cannibalistic larvae and a cage for mating of adult moths are described. After inoculation with the neonate larvae, development of the different stages was synchronouson this diet. The larval and pupal development period was 14.3 ± 1.2 and 11.7 ± 0.82 days, respectively. Females reared on this diet produced an average of 2000 eggs. Adult longevity was 22 days. The female moths retained their oviposition rhythm even after 3 years of laboratory rearing. A method for introduction of wild populations into the laboratory culture is discussed. The reliability of the technique was checked by monitoring the insects' performance for at least 25 generations.

The effect of pod angle on the resistance of cowpea, Vigna unguiculata (L.) Walp. to the legume pod borer, Maruca testulalis Geyer, was investigated under field conditions at the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria, using two cowpea cultivars: IT82D-716 (susceptible to borer damage) and TVu 946 (resistant to borer damage). Three different pod angles were used In the study — a normal angle, a decreased angle and an increased angle. Negative and highly significant (P < 0.01) relationships were found between pod angle and per cent pod damage, as well as the seed damage Index In the two cowpea cultivars. Pods with wide angles (≥ 89°) were damaged on only one and rarely on both pods. Apart from biochemical and other bio-physical factors, selection and breeding for wide pod angle is suggested as a strategy for reducing M. testulalis damage to cowpea pods.

The possibility of the involvement of pod wall toughness in the resistance of cowpea, Vigna unguiculata (L.) Walp., to the legume pod borer, Maruca testulalis was studied. The toughness of non-intact and intact pod wall increased with age, but the rate varied at different growth stages of the pod as well as between cultivars. There was a positive and significant correlation (r = 0.82**) between pod age and pressure required to penetrate pod wall. No significant differences (P > 0.05) were observed in non-intact pod wall toughness between TVu 946 (resistant) and IT82D-716 (susceptible) at all the growth stages tested. However, significant differences (P < 0.05) were observed between these two cultivars for only 6-day-old intact pods where IT82D-716 recorded a higher value than TVu 946. Correlation between pod damage severity by M. testulalis and toughness of non-intact and intact pod wall of these cultivars at different growth stages were not significant.

While pod wall toughness would be a desirable trait, it is concluded from this study that pod walls of the cultivars studied did not play any appreciable role on cowpea resistance to the larvae of M. testulalis.

There were significant differences in the level of susceptibility among the 12 varieties which were screened for resistance to A. lycopersici Pronounced tolerance to leaf damage was recorded on varieties Early Stone Improved and Beauty. Oxheart and Bonny Best both of which had comparatively lower mite densities were highly susceptible. Flower bud formation was not significantly affected by the mite damage. However, the number of dead flowers and flower buds on infested plants was significantly more than on protected ones.

Russetting of young fruits due to mite damage differed significantly among the varieties tested, and was positively correlated with moisture content of young fruits. The least and most affected varieties were Beauty and Red Cloud respectively. The percentage yield loss was highest on Hybrid Beefmaster and Oxheart and lowest on Roma and Money Maker.

The mosquito C. p. pipiens L. never colonize sewerage water covered with duck weed. The Lemna minor vegetations affected the identification of the oviposition site by the females. The amputation of sensilla made the mosquito incapable of choosing the oviposition site. The immature stages of the mosquito are susceptible to the water borne synomones of the duck weed; the first instar larvae are most susceptible and have high mortality.

Mature (5- to 6-day-old) male and female pupae of C. partellus were irradiated at 5 to 20 kilo-Roentgen (kR) and 5 to 10 kR respectively. Emergence of normal appearing moths, pupal periods and adult longevities remained statistically unaffected. Fecundity of normal (nonirradiated) females mated with males irradiated as pupae was nonsignificantly different from control, but fecundity of females irradiated as pupae at 10 kR was significantly reduced when they were mated with normal mates. Dominant lethals of varying intensities were induced at 5–20 kR. However, induction of dominant lethality was sex- as well as dose-dependent. Radiation doses inducing 100% dominant lethals in sperm (20 kR) and ova (5 kR) did not mitigate the mating ability of males and receptivity of females. However, receptivity of females was reduced significantly when they were irradiated as pupae at 10 kR. Rates of embryonation in F1 eggs were significantly reduced when normal females were crossed with males irradiated as pupae at 20 kR, but similar effect was observed at 10 kR in reversed crosses. Embryonic development was delayed in eggs obtained from crosses, where male or female parent was irradiated in pupal stage, but in both cases most of the dominant lethals acted late in embryonic development.

One of the critical factors in assessing maize lines for resistance to Sesamia calamistis is the number of larvae/plant used for infestation. Artificial infestation of maize plants with two and five larvae/plant resulted in 29.1 and 39.5% stand loss (dead hearts and stalk breakage), while 10 and 15 larvae/plant resulted in 52 and 72.9% stand loss, respectively. For a satisfactory artificial infestation in maize screening trials against the maize stem borer in Nigeria, a population level of 10–15 larvae/plant is recommended.

Biochemical analysis of lakefly (chironomid/chaoborid mixtures and Povilla adusta samples) were conducted to determine their nutrient value and their potential as source of high quality nutrients in animal feeds. The results showed lakefly as rich in protein (62–67 g/100 g), fat (10 g/100 g) and ash (4–6 g/100 g). Moisture was low as was crude fibre. Povilla were richer in crude protein (67.4 g/100 g) and calcium (152 mg/100 g). The chironomid chaoborid mixture was however extremely rich in phosphorus (1.2 × 103 mg/100 g) and potassium (1.2 × 103 mg/100 g). Other trace elements were present in significant quantities as were niacine, thiamine and riboflavin. It is therefore deemed feasible to produce high quality nutrient concentrates from lakefly material for use in animal feeds. Further work Is however essential to determine lakefly digestibility and palatability and to ascertain suitable lakewide harvest techniques for the lakefly.

Investigations on temporal distribution of Bemisia tabaci (Gennadius) was carried out on 14 weeks old cotton genotype, RAS 299–1, during 1987–1988 at Raichur (Karnataka). Oviposition was restricted mainly on the leaves of the youngest branches. Highest egg load of 89.16 per sq cm was recorded on youngest leaf of terminal host branch. Nymphal and pupal population was more on the middle leaves than on extreme leaves and followed a normal curve in their distribution. Adults exhibited similar trend in distribution to that of the egg stage.

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.

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 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.

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.

A headcage technique to screen for resistance to sorghum head bug, Eurystylus immaculatus Odh. (Hemiptera: Miridae) was standardized for use in West Africa. Panicles infested at the half-anthesis to complete-anthesis stage had greater population build-up and suffered maximum grain damage, loss in grain mass, grain hardness and seed germination. Panicles with higher grain damage also showed greater severity of grain mould incidence. Maximum population build-up and grain damage was recorded in panicles infested with 20 pairs of adults. Panicles infested with 30–40 pairs of bugs generally showed a decrease in population build-up, possibly because of crowding. Head bug numbers decreased with a decrease in panicle size, while the extent of grain damage increased. To screen for resistance to head bugs, data should be recorded both on head bug numbers and grain damage. Fifty nymphs (third to fourth instar) or 40 bugs collected at random can also be used in the headcage to screen for resistance to head bugs.

Feeding on Ricinus communis leaf treated with different concentrations (0.1, 0.3 and 0.5%) of ether extracts of Erithrina indica seed and Delonix regia flower against Ergolis merione, Porthesia scintillans and Spodoptera exigua resulted in high larval and pupal mortality. Food consumption, assimilation, conversion and fecundity decrease with increasing concentration. Larval mortality was 20 to 91 % and damage was decreased by 65% through the application of the highest concentration of each chemical.