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.

Along with plant sources, arthropods (such as millipedes) are also known for their antioxidant activities that can help combat human ailments. Therefore, methanolic extracts of males and females of two endemic giant pill-millipedes of the Western Ghats (Arthrosphaera fumosa Pocock and Arthrosphaera magna Attems) were evaluated for antioxidant potential. The bioactive principles and activities assessed were total phenolics, total antioxidant activity, 2,2-diphenyl-1-picrylhydrazyl or DPPH radical scavenging, ferrous ion chelation, reducing power and hydrogen peroxidase scavenging. Significant differences were shown between the two species, the sexes and the sexes within millipede species in total antioxidant activity, DPPH radical scavenging and ferrous ion chelation. Total phenolics and EC50 of DPPH radical scavenging activity differed significantly only between species and the sexes. This study clearly demonstrated that the antioxidant capacity of the methanolic extract of Arthrosphaera spp. is comparable to the ascorbic acid standard and possesses potential scavenging ability against reactive oxygen species generated during oxidative stress.

Experiments were conducted in the laboratory to screen the leaf extract of Dracaena arborea (Willd.) Link for the presence of chemical groups with insecticidal activity against Sitophilus zeamais (Motsch.) and Callosobruchus maculatus (Fab.). The plant materials were collected, dried, ground to fine powder and extracted with 90% ethanol. Phytochemical screening involved the use of thin layer chromatography analysis for chemical compounds such as alkaloids, tannins, saponins, anthraquinones, flavonoids and terpenes. Partitioning of the extract was carried out by dissolving the extract in water to obtain the aqueous phase, which was partitioned between equal volumes of chloroform, n-hexane, n-butanol and ethyl acetate. The different fractions were screened for insecticidal activity against S. zeamais and C. maculatus. Some fractions of the leaf extract such as ethyl acetate and aqueous fractions demonstrated 100% mortality, offered protection to grains, reduced progeny development and repelled the insects compared with the control. Based on the activity of some fractions, the leaf extract of D.arborea has the potential for development as a botanical insecticide against S. zeamais and C. maculatus.

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.

The pest complex of sunflower and its relative abundance and economic importance are discussed. A total of 80 insect species were collected—five of these were recorded on roots, 51 on stems and leaves and 29 on floral parts and developing seed. The major pests of sunflower commonly encountered in all the localities studied were Agrotis segetum Schiff, Agrotis ypsilon Hfn, Plusia orichalcea F., Nezara viridula L. and Heliothis armigera HB.

Six cowpea cultivars, TVu 1890, TVu 1, TVx 3343-03E, IT82E-9, VITA-3 and Ife Brown, with different responses to infestation and damage by pod-sucking bugs (PSBs) were studied for the biophysical and biochemical characteristics of pod that may be involved in this differential response to feeding by PSBs. Tough pod wall, requiring a force of 25 newtons/mm2 to penetrate at pod maturity, is considered to be an important factor contributing to the lesser PSB feeding damage observed in the cultivar TVu 1890. The phenolic content of the pods of the studied cowpea cultivars was not correlated with their tannin content. Furthermore, no correlation could be established between the tannin content in the pod and the level of susceptibility of the cowpea cultivars to infestation and damage by PSBs. While tannins are considered to be important in conferring certain types of anti-herbivory properties to a number of plants and crop varieties, our findings suggest that in the cowpea cultivars studied, phenols in addition to the tough pod wall may be more important in conferring resistance to PSBs.

The effect on the larval development of Helicoverpa armigera of caffeoylquinic acids and their structural units, caffeic acid and quinic acid, was evaluated. 5-Caffeoylquinic acid (5CQA) (syn. chlorogenic acid) significantly retarded larval development and increased the number of days to pupation at a concentration of 9 mM in an artificial diet, although final pupal weights were not severely affected. Caffeic acid and quinic acid also inhibited larval development although their effect was less marked. In all cases the effect of the compounds was dose-dependent. A mixture containing 5CQA, 3-caffeoylquinic acid (3CQA) and the novel compound, 1-caffeoyl-4-deosyquinic acid (ICdQA), which were extracted from the wild groundnut species, Arachis paraguariensis (Chod et Hassl.) was also evaluated at a concentration equivalent to that found in the plant (9 mM). This mixture was a potent inhibitor of larval development and more potent than 5CQA alone at the same concentration. The potential role of these substances in host plant resistance of groundnuts and their interaction with other components of pest management strategies are discussed.

Per cent survival, larval period and weight, pupal duration and weight, emergence, adult longevity and fecundity of Heliothis armigera (Hubner) were affected by the pulse species on which it was reared. The pulses could be classified into two groups i.e. pigeon pea and chick pea which were suitable for growth, development and fecundity and black gram, sweet pea, green gram, broad bean and lentil which were unsuitable.

Samples of ground beetles (Carabidae) were collected throughout the year-long 1985 Joint Indonesian–Royal Entomological Society expedition, Project Wallace, in an area of rain forest in N. Sulawesi. The beetles were collected by a range of collecting techniques including insecticide fogging, malaise, flight interception, pitfall and light trapping as well as hand collecting. The state of ovary maturation was determined by dissecting the females. A high number of species of Carabidae show a distinct seasonal reproductive rhythm in the form of gonad dormancy, avoiding reproduction in the slightly cooler months in the middle of the year. In contrast, most species of tiger beetles (subfamily Cicindelinae) are reproductively active at this time of year. The study area appears to have an unusually variable monthly rainfall for this region, and we suggest that the seasonality in the ground and tiger beetles is a response to the strict annual rainfall patterns of the coastal areas 10–20 km to the north and south.

Larval instars of Chilo partellus Swinhoe reared on sorghum plants were determined. The larvae were separable into five non-overlapping instars by analysis of variance and Duncan's multiple range test, frequency distribution and scatter diagram of the head capsule widths. Head capsule increment from one instar to the next conformed to Dyar's rule, while at the same time agreeing with Richards' hypothesis. The stadial periods for the five instars were 6, 4, 5, 3 and 7 days, respectively.

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.

The relationships between estimates of tsetse challenge and trypanosome prevalence in trypanotolerant and susceptible cattle were examined at sites of the African Trypanotolerant Livestock Network. Estimates of tsetse challenge were determined as the product of tsetse relative densities, their trypanosome infectionrates and the proportions of feeds taken by them from cattle. Trypanosome prevalence in both trypanotolerant and susceptible breeds of cattle was estimated from monthly examination of groups of ear-tagged cattle. Regression equations between estimates of trypanosome prevalence and tsetse challenge were fitted using an arcsin transformation of trypanosome prevalence and a log10 transformation of tsetse challenge. Highly significant relationships between estimates of tsetse challenge and trypanosome prevalence were found for sites with trypanotolerant cattle (P < 0.0001) and sites with susceptible cattle (P < 0.01). Mean trypanosome prevalence at a given level of tsetse challenge was at least twice as high in susceptible as in trypanotolerant cattle. The slopes of the regression lines for the two groups of cattle were significantly different (P < 0.05). The results confirm the superior ability of trypanotolerant cattle to withstand tsetse challenge in the field. The curves obtained for the two groups of cattle illustrate the necessity in tsetse control campaigns for a major reduction of tsetse populations to take place before significant decreases in trypanosome incidence in livestock can be achieved.

Late third stage (7-day-old) larvae and 1-day-old pupae of Anastrepha suspensa Loew (Diptera: Tephritidae) were dipped for 5 min in suspensions of 25% WP Dimilin® (diflubenzuron) at six dosages ranging from 0.003–0.1% a.i. Diflubenzuron caused significant (P < 0.05) mortality during the pupal stages of both groups treated. Consequently, the resulting adult populations were drastically reduced. The incidence of crumpled wings, deformed abdomens and ovipositors in these adults was 2–7 times and 4–9 times higher than the respective controls of treated larvae and pupae. The morphological abnormalities altered mating competitiveness of males and successful copulation and oviposition by females. Fecundity of females was reduced and diflubenzuron effects persisted into the first generation and caused decreased egg viability.

Adults fed a 0.1% a.i. diflubenzuron-treated diet for 27 days had no significant mortality, but had decreased fecundity. However, their pattern of oviposition did not differ from the control. Fecundity levels similar to the control's were achieved 6 days after the treated diet was replaced by normal diet. Diflubenzuron treatment of adults also drastically decreased the survivorship of first-generation individuals between egg-hatch and pupation. However, almost all individuals that pupated emerged as adults. No abnormalities were observed in first-generation adults or in the survivorship of their offspring.

Surveys for population densities of the maize borer Sesamia eretica Led. (Lepidoptera: Noctuidae) were conducted for three consecutive years (1997–1999) in several localities of the Nile delta in Egypt, in order to get a better insight into the population dynamics of the pest and to propose rational basis for its biocontrol using a recently isolated granulovirus. High population densities (more than one borer per plant) were observed only in the first plantings after winter (first fortnight of April). After this peak, populations almost vanished until the end of the crop season (September-October) when a slight increase was observed (0.1 borer per plant). The drastic decrease in population densities in plantings from the end of April occurs because most final instars of the borer leave the plant to pupate in the soil. This behaviour, uncommon in maize borers, results in a very high mortality rate due mainly to pupal parasitism. Only the few larvae pupating in the stem, which are much less parasitised, give rise to adults. Spatial distribution was studied using Taylor's power laws which enabled the elaboration of enumerative sampling plans for eggs, small larvae (1st and 2nd instars) and older ones. Fixed optimal sample size and sequential sampling plans for different precision levels were developed. The precision of the estimated sample size was checked using resampling of some of the data that were not used to build the models. The validation study showed that the plans were suitable for the entire Nile delta region.

As a background to an IPM project, this paper describes pesticide treatment of cotton in Sudan Gezira, starting in 1945/46. Until the end of the 1950's, one treatment per season was sufficient to control the only important pest, the jassid, Empoasca lybica, but the number of treatments increased during the 1960's (from 3 to 5) and has since the early 1970's been 6–9.

The continuous use of pesticides has resulted in changes of the pest complex, ultimately creating “hyper” pests such as the whitefly (Bemisia tabaci), cotton bollworm (Heliothis armigera) and aphids (Aphis gossypii). The increase in number of applications of pesticide is coupled with the rising costs of pest control and a stagnant yield. The stickiness problem created by the honey dew of whitefly and aphids increased with the rising number of sprays. The exclusive use of chemical control not only failed to improve the quality or quantity of the yield, but put a great strain on the national economy as well.

The Sudan therefore requested the FAO to initiate an IPM project starting in 1979, with financial support from the Netherlands. During the past 2 years support has also been given by the World Bank. The IPM approach has given very valuable results during the last two seasons when large (more than 100 acres) plots in the Gezira and Rahad Schemes were left unsprayed with the objective of investigating the potential of the natural enemies in the absence of pesticides, and to compare findings with population trends of pest and beneficial organisms in the fields subjected to conventional chemical control.

The first significant finding was that Bemisia tabaci and Aphis gossypii can be managed at desirable levels by their indigenous natural enemies, and that their outbreaks are attributed to the decimation of these natural enemies by chemical treatment. Populations of beneficial arthropods were consistently much lower in the fields which received regular pesticide applications.

The result of the large-scale experiments indicate that Empoasca lybica is the only really damaging pest (“key pest”) in the Gezira because of the absence of natural enemies to regulate its population. Control of E. lybica in the 1940's and 1950's resulted in the creation of Heliothis armigera as a major pest. This situation necessitated early season applications of pesticides to suppress H. armigera, which further reduced the role of the natural enemies of B. tabaci and A. gossypii. Both have developed into major pests of regular occurrence.

Cotton farmers in Gezira are now faced with a complex of very serious pests. In order to solve this problem, we will have to make drastic changes in pest control strategies and to adopt an IPM approach as soon as possible. The biological control H. armigera is considered as first priority in order to avoid the early season application of pesticides. Trichogramma pretiosum was introduced from the USA and released in the Rahad Scheme in 1988/89. The preliminary results are very promising.

Cultural and biological control of E. lybica will be attempted in order to further reduce pesticide applications. The control of this pest by the use of “milder” pesticides is also included in the programme.

The presently used threshold levels for all major pests are very low, and are under revision through properly conducted large-scale experiments.

Studies of cocoa tree genetic resistance to attack by Scihlbergella singularis (Haglund.) (Hemiptera: Miridae), have so far been based on field observations of cultivar performance. Although this approach was useful in guiding breeding programmes, observations on tree crops are time-consuming (3–4 years) and labour-intensive. Thus a standard laboratory microassay method based on a study of the mirids’ dietary preferences was developed to quantify the attractiveness of cocoa trees to mirids under controlled conditions, with reproducible results.

A dual approach was taken to establish relations between laboratory data and field observations: preliminary cultivar sorting of both clones and hybrids in the laboratory, by microassays was combined with an eight-year observation programme in two different ecological zones in Ivory Coast: on the shores of a lagoon (Bingerville) and under thinned forest in Basse Côte (Divo). In Cameroun only clones from IRA field station at Nkoemvone were tested by microassays.

After three successive sets of field observations, a comparative analysis of the results revealed close correlations between cultivar responses in microassays and those observed in the field.

Cultivar responses to mirids revealed that there are two performance groups within the planting material selected, viz., in increasing order of attractiveness, Forasteros (upper and lower Amazon cultivars) and Trinitarios.

In Cameroon, microassays revealed behavioural polymorphism amongst the cultivars tested: plants of the same origin can react very differently to mirids as it was the case for the local trinitarios SNK group.

The microassay technique is quick and easy to use, and is effective for the early selection of mirid-tolerant plant material.

The red locust, Nomadacris septemfasciata (Serville) (Orthoptera: Acrididae), is a threat to agricultural productivity in Malawi. The country has a single known red locust outbreak area, the Lake Chilwa flood plains in southern Malawi, in addition to several other areas where the locust occasionally breeds. Activities of the red locust in Malawi during the period 1988 to 1998 are discussed. Four major outbreaks occurred during the period—in 1993, 1995, 1996 and 1997. Control of these outbreaks was conducted by air except for the 1995 outbreak in Mpatsanjoka River Valley which was controlled by spot treatment on the ground. The use of both a helicopter and a fixed-wing aircraft, where the helicopter locates locust swarms and their concentrations and guides the spray aircraft, appears to be the most efficient and effective strategy for controlling locust outbreaks in Malawi.

Limonoids such as deoxylimonin, obacunone and pedoniti are known to have antifeedant effects against some lepidopteran pests. However, there is no electrophysiological data showing the effect these compounds have on taste receptor cells. This information gap is due to the fact that limonoids are insoluble in water and this makes it difficult to apply the tip-recording technique in an electrophysiological bioassay of limonoids. This problem was solved by dissolving the limonoids in a mixture of 50 % tetrahydrof uran and 50 % aqueous NaCl. Limonoids and sucrose so dissolved were used to investigate responses of Eldana saccharina maxillary styloconic sensilla. The solvent mixture did not appear to damage the taste receptor cells and the taste receptor responses to solutes dissolved in that solvent were reproducible. Sucrose stimulated a cell in the medial as well as in the lateral styloconic sensilla. Deoxylimonin alone stimulated a cell in the medial sensillum but not in the lateral sensillum. When presented with sucrose, deoxylimonin inhibited the sugar receptor cell and this was also true for obacunone.

Dysdercus fasciatus and D. cardinalis were studied in the field to ascertain their occurrence and relative abundance on different host plants at Masongaleni near Kibwezi, Machakos District, Kenya. It was carried out using a complete randomized block with four replicates. It was shown that D. cardinalis occurred more commonly on its wild host plants than D. fasciatus. D. cardinalis was also commonly found feeding on Sterculia spp. on which D. fasciatus was not recorded during these studies. Neither species was recorded from baobab trees.