Dosage–mortality responses of F1 progeny of treated rice weevils, Sitophilus oryzae, indicated that the weevil is highly tolerant to R-20458. However, the ability of the insect growth regulator (IGR) to suppress F2 progeny production, demonstrated that R-20458 could be used as a protectant for grains.

The study revealed that there was quantitative recruitment in colonies of Amitermes evuncifer, whenever food was discovered by the scouting foragers. Discovered food stimulated the termites to accelerate their running speed, to and from the food source. Increased trail-laying activity, accelerated movement and carrying of food by the returning workers facilitated recruitment of other confederates from their nest. These activities equally directed the recruited termites to the food source.

Amitermes evuncifer was observed to regulate traffic in relation to newly discovered food source. The results showed that there was rapid communication between the termites of food source within 3–4 min. It was further observed that the trail to newly found food source did not become dominant over the trail to the already existing food source. The results showed clearly the effect of food on vital activities of termites.

Calmodulin is a ubiquitous endogenous calcium receptor in eukaryotic cells and is involved in many different physiological functions. The presence of calmodulins in protozoa has been reported for Tetrahymena and Paramecium. Calmodulin purified from T. pyriformis is composed of 147 amino acids and the amino-terminal is acetylated.Compared to bovine brain calmodulin, there are 11 substitutions and 1 deletion of amino acid residue(s). Besides such structural specificity, Tetrahymena calmodulin (T-CaM) is highly unique in that it has a potential ability to activate the pellicle-bound guanylate cyclase in a calcium-dependent manner. This stimulatory effect is also observed in Paramecium calmodulin (P-CaM). Bovine brain calmodulin represses the T-CaM-dependent activation of guanylate cyclase, indicating that bovine brain CaM exerts its inhibitory influence by interfering with the calmodulin-binding site of this enzyme. The 14S and 30S dyneins extracted from demembranated cilia with EDTA contai ATPase activities which are potentiated by addition of calmodulin. Taken together with its location in cilia, T-CaM appears to regulate the ciliary movement. Moreover, evidence has been provided that calmodulin may be implicated in the glycoprotein biosynthesis. The phosphorylated derivatives of the long chain polyisoprenoid alcohols (dolichol phosphates) are known to act as coenzymes, and the microsomal enzyme involving dolichol phosphorylation is calcium-requiring CTP-dependent and activated by calmodulin. A role for calmodulin in the control of cell growth is postulated by the concerted fluctuations of calmodulin contentand guanylate cyclase activity during the cell cycle in synchronized Tetrahymena cells. In addition, some other possible functions for calmodulin can be considered in protozoa.

Adult ticks of Rhipicephalus appendiculatus were fed on rabbits immunized with antigen–antibody complexes derived from the immunodiffusion reaction in agarose of tick extracts with antisera from rabbits immunized previously with tick extracts. Ticks feeding on the precipitin complex immunized rabbits displayed delayed attachment, prolonged engorgement and extended periods to drop off the host. While final engorgement weight was not affected, the immunization was observed to produce an adverse effect on egg hatchability. Fewer than 10% eggs from ticks fed on immunized animals hatched live larvae compared to greater than 90% live hatchings from ticks fed on controls. The tick antigens responded to by the immunized rabbits were characterized by crossed immunoelectrophoresis. Antisera from precipitin complex immunized animals precipitated four to five separate antigens from immunizing extracts. One (or more) of these antigens may be the target for the observed deleterious effect on tick reproduction.

Field trials were conducted to assess the effectiveness of a parasitic nematode, the DD136 strain of Neoaplectana carpocapsae Weiser in controlling Heliothis zea (Boddie) on naturally infested sweetcorn.

Nematode suspensions at concentrations of 0, 4 × 103, 4 × 104, 4 × 103 (applied twice) and 4 × 104 (applied twice), nematodes/ml respectively, were sprayed on the ears at early silking stage.

Treatments with 4 × 104 nematodes/ml sprayed twice at 3 days interval gave significantly better control (55%) than the rest. The mean number of surviving H. zea larvae was also significantly reduced with increasing concentrations of nematodes. Economic damage was not prevented but damage to treated ears was significantly lower than that of the untreated plots.

Diaeretiella rapae (M'cintosh) was the only parasitoid of the cabbage aphid, Brevicoryne brassicae L., during studies reported here.

Percentage parasitism of B. brassicae ranged from 27.1 to 76.1% in studies carried out around Nairobi area during 1978/79. It was highest during the month of September, when the aphid population density had reached maximum, and lowest in May when aphid numbers were low. High parasitism coincided with a decline in aphid population.

Because of these high levels of parasitism and other attributes of the parasitoid, it was concluded that D. rapae played a significant role in suppressing populations of B. brassicae and should be taken into consideration in any control programme aimed at protecting brassica crops against aphid pests in Kenya.

Occurrence of protozoa in the digestive tract of herbivores is dependent upon the occurrence of an environmentally compatible section of the tract and a retention time for gut contents in that section which exceeds the protozoan generation time. In general, herbivores can be classified as pre-gastric (foregut) or post-gastric (hindgut) fermentors. Fermentation in the foregut has evolved through enlargement of the stomach in some way to slow down ingesta passage rate and provide physical separation of the ingesta from the acid-secreting regions, as well as an adequate production of buffered saliva. Hindgut fermentations occur in the caecum-proximal colon area. Most of the protozoa in the digestive tract of herbivorous mammals belong to the class Kinetofragminophorea in the orders Prostomatida, Trichostomatida and Entodiniomorphida. They are anaerobic, live in conjunction with a large bacterial population and can ferment the structural polysaccharides of plants. End products of protozoal fermentation are similar to those of the bacterial population, i.e. volatile fatty acids, lactic acid, carbon dioxide and hydrogen. Additional products of the fermentation are vitamins and microbial protein which are subsequently utilized by foregut fermentors, whereas these products are essentially lost in hindgut fermentors unless they practice coprophagy. Only limited information is available on digestive and metabolic pathways of the gut protozoa, primarily because of our inability to grow them in axenic culture. Specific faunas appear to be associated with site of fermentation, animal species and diet. Diet in turn can affect pH and contents turnover time, both of which are very important in the establishment and growth of a protozoan population in the digestive tract.

Immune resistance to infestation by an ixodid tick, Rhipicephalus appendiculatus, the vector of the African cattle disease, East Coast Fever, was induced in rabbits by either repeated tick feeding or immunization with tick extracts. In addition to resistance to tick infestation, tick extract immunization led to a reduction in the viability of eggs laid by ticks feeding on the immunized host. Resistance to infestation by ixodid ticks has previously been reported by others to have a humoral immune component. Therefore, antibodies from resistant host animals were used to detect the tick antigens they recognized as an approach to identification of the target antigen(s) for the observed immune responses on feeding ticks. In crossed immune electrophoresis two antigens were detected using sera from animals made resistant by multiple tick infestations. Sera from extract immunized animals detected these antigens and nine others. The tick antigens detected by both sets of sera in crossed immune electrophoresis were radiolabelled with [35S]amino acids. No labelled antigens were detected by Staphylococcus aureus mediated immune precipitation with sera from hosts made resistant by multiple infestations. Antibodies from extract-immunized animals identified nine protein antigens by S. aureus immunoprecipitation. The molecular weights of these antigens as assessed by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis were 180,000; 140,000; 130,000; 98,000; 92,000; 88,000; 85,000 and 82,000. The rate of synthesis of these antigens appeared to vary in relation to the tick feeding cycle.

Life history components, especially those of the adult stage, were investigated in Aedes aegypti and Culex quinquefasciatus in the laboratory. Males of Cx. quinquefasciatus had a greater expectation of life at adult eclosion than males of Ae. aegypti. There was no statistically significant difference in the means of life expectancy for females of Ae. aegypti versus those of Cx. quinquefasciatus. In both species, males had a shorter life than females. The two species exhibited considerable heterogeneity for reproductive characters. Females reproducing for the first time were younger in Cx. quinquefasciatus than in Ae. aegypti. Net reproductive rate and the per capita rate of increase were greater in the former than in the latter species. Cx. quinquefasciatus had a shorter generation time than Ae. aegypti. The data reported here are inconsistent to varying degrees when compared with data gathered by other workers from the same species. The results are discussed with reference to the theoretical constructs of the life history theory.

Heterosis in Antheraea assama Westwood in respect of oviposition is observed over mid-parental value only in respect of four crosses viz. N × W1, N × W2, Y × W1, and Y × W2 and there is no inbreeding depression in oviposition rate until F3 generation. The cocoon weight and silk content in all the six crosses exhibit significant heterosis over both mid-parental and better parental values. In the F3 generation significant inbreeding depression is noted for both the characters and the values are at par to the mid-parental value. Commercial exploitation of hybrid vigour therefore should be limited up to F2 generation.

Nearly 8 years of intermittent treatments with temephos on the lower Volta River at Senchi Rapids, Ghana, produced no change in the susceptibility of larvae of the S. damnosum complex to temephos [Abate (R)]. In contrast, 14 months of temephos treatment in southern Ivory Coast produced resistance.

This difference can be explained by the relatively weak selection pressure exerted by the intermittent treatments on the Volta River and the frequent changes in the composition of the population as shown by cytotaxonomic identification of the larvae.

The effects of various exposure to irradiation from cesium 137 in nitrogen and air on survival and fecundity of Glossina palpalis palpalis were compared. With doses from 3 to 21 krad in nitrogen atmosphere, male fertility was inversely correlated with dose, above 15 krad male survival was inversely correlated with dose. All males subjected to either 21 krad in nitrogen or 15 krad in air were sterilized. Females appeared to be more sensitive to gamma-irradiation than males; a dose of 6 krad in nitrogen resulted in 100% sterility and arrested further development of the ovaries after the ovulation of follicles A1 and C1. In males, this dose caused 70.3% sterility. Approximately 97 and 98% sterility were obtained when males were treated with 15 krad in nitrogen and 12 krad in air respectively. No fly emerged from irradiated puparia younger than 15 days. Irradiation of 15 or 20 days old puparia killed the insect either before or shortly after eclosion, whereas the normal patterns of emergence, survival and reproduction were observed from puparia that were irradiated when 25 days old or older.

Various alkaloids from Adhatoda vasica (Acanthaceae) were found to be responsible for the antifertility and antifeedant activity of the extracts of the plant against insects. Among the major alkaloids vasicine, vasicinol and vasicinone severe antifertility effects were exhibited by vasicinol against Dysdercus skoenigii and Tribolium castaneum due to blocking of oocytes in the oviduct. Feeding deterrence was observed against Aulacophora foveicollis and Epilachna vijintioctopunctata at 0.05 and 0.1% levels of these compounds. These allelochemics appear to show a dual activity vis-à-vis a species specificity.

Studies conducted on the spatial pattern of Leucinodes orbonalis Guen. larvae at the Experimental Farm, Barapani of ICAR Research Complex for NEH Region, Shillong revealed that they follow positive binomial distribution within plant, shoot and fruit. The larvae were distributed as negative binomial (contagious) within plot (2 × 2 m) at all stages of sampling except during initial and last stages of crop where they follow positive binomial distribution. The possible reason for this change in distribution may be due to comparatively lower larval densities at initial and last stages of crop.

Studies on breeding sites of Phlebotomus duboscqi, a vector of Leishmania major, were intensified in Marigat, Baringo District, Kenya using the soil incubation technique, following the previously successful attempt to look for sandfly breeding sites. Soil samples obtained from nest areas of the animal burrows yielded Phlebotomus duboscqi and Sergentomyia ingrami. These two species had been shown to harbour L. major parasites inside animal burrows. Other phlebotomine sandflies recovered from these same breeding sites included P. martini, P. rhodhaini, S. bedfordi, S. africanus, S. antennatus and S. graingeri

When parasitic disease, whether of protozoan or other origin, gets out of control, it is mostly due to increasing, rarely decreasing, human population pressure and/or to changes of human behaviour. By his various activities man changes his environment; it thus appears logical to try to control disease by environmental management. The goal thereof is not to eradicate disease but rather to establish a new, tolerable equilibrium.

Environmental management has been shown to alleviate the situation. It ought not, however, be seen as a unique measure; it must rather be an integral part of a comprehensiveplan which includes various other approaches simultaneously, such as medical treatment, vector and intermediate host control, improvement of water supply and nutrition, improvement of housing and sanitary conditions.

Environmental management is thus closely interlinked with traditional occupations, customs and beliefs. In addition, environmental management, in the long run, can be undertaken only by local populations. These, therefore, need information and motivation, information through acceptable health education, motivation through long-lasting government support, from all levels and with all departments concerned co-operating, and possibly through appropriate, unobtrusive expatriate assistance.

Over the last decade, public authorities from all parts of the world have expressed their growing concern about leishmaniasis being a serious threat to health. This increased awareness occurred partly as a result of serious outbreaks which were reported, such as for instance, the one in Bihar, India and earlier in Kenya. Several health services in South America have indicated increases in both the mucocutaneous and cutaneous disease. It is difficult to say to what extent these observations reflect true increases or perhaps indicate more successful efforts in detecting new patients.

Limonin, deoxylimonin, citrolin, obacunone, harrisonin and acetoxyharrisonin were assayed as potential antifeedanfe against the African crop pests, Spodoptera exempta, Eldana saccharina and Manica testulalis. Even at the highest applied concentration, limonin, deoxylimonin, citrolin and acetoxyharrison were not active against S. exempta. At high concentrations, obacunone and harrisonin were mildly active in S. exempta assays. Harrisonin and obacunone displayed potent activity against E. saccharina and M. testulalis.

J. O. Corliss explained that the original title given to the Workshop (namely, the phylogeny and evolution of the protozoa) seemed out of date, since today we clearly cannot persist in separating various protozoa from many of the algae and from certain zoosporic fungi by erection of formidable taxonomic barriers at the phylum (division) or kingdom level. All such forms, the species of which are being discovered to be inextricably comingled at various levels (for the latest extensive review, see Corliss, 1984), are perhaps better assigned to a single kingdom Protista or to several kingdoms predominantly containing these ‘lower’ eukaryotes (see subsequent sections of this report, below).

Five (Sergentomyia antennatus, S. garnhami, S. schwetzi, S. ingrami and S. adleri) of the six species of sandflies fed on mammalian blood containing cultured Leishmania donovani promastigotes on day 0, were able to feed through cockerel skin membranes at 5.5, 10, 34.3, 45.7 and 95% feeding rates, respectively. Sergentomyia bedfordi was able to feed on mammalian blood only through a lizard skin membrane at 100% feeding rate. Promastigotes were found in 9.3, 25 and 37.5% of S. schwetzi, S. adleri and S. ingrami respectively, dissected on days 3–9.

The results open way for artificial feeding of Kenyan sandflies on mammalian blood through membranes, and indicate that it is necessary to select the type of membrane depending on sandfly species. The ability of L. donovani to develop in Kenyan sandflies is being investigated to experimentally establish and confirm the importance of various genera and species in the epidemiology of leishmaniasis.