Biconical traps were studied for their efficiency in sampling for Glossina morsitans morsitans Westw., G. pallidipes Aust., G. austeni Newst. and G. brevipalpis Newst. in three localities in Mozambique where these species occur sympatrically or singly. Studies were also carried out to determine whether acetone vapour was effective in enhancing the efficiency of the biconical trap. Various comparisons were also made between biconical traps and Langridge traps, and with fly-round patrols, with and without bait oxen.

It was demonstrated initially that the blue biconical trap (BBT) was more efficient for G. morsitans and G. pallidipes than red or white models or Langridge traps. In all subsequent studies, therefore, the BBT was used. It was concluded that: the BBT was ineffective for sampling G. morsitans, with or without acetone; the BBT was markedly more effective than fly rounds for sampling G. pallidipes, and its efficiency was significantly enhanced by acetone; and G. austeni was attracted to the BBT, but not all flies would enter the non-return cage—G. brevipalpis was readily caught in the BBT. Acetone with the BBT gave inconclusive results for these species.

This paper briefly discusses insect pest responses in mixed crop stands, their peculiarities and possible crop protection advantages. Results on the effects of a bean–oat diculture on the movements and feeding activity of the adult pea leaf weevil, Sitona lineatus L. are presented and discussed. Mixtures of these crops were found to significantly reduce the amount of notching of the bean leaflets by the weevil and weevil relative populations are compared to the sole bean crops, and to increase emigration from the more diverse plots.

Full-grown pupae Agrotis ipsilon were irradiated with 5 or 10 krad and crossed with unirradiated female. The F1 progeny were more sterile than parents. Percentage of mated female of F1 was greatly reduced while the mating frequency was increased. Less inseminated females were among the F1, particularly when the female inherited the sterility. The mortality among larvae of the F1 was high and dose-dependent, and that among F2 larvae was even higher. The sex ratio of the F1 progeny was altered in favour of male, while that of the F2 was normal. 10 krad for P1 male was sufficient to inhibit hatching of the eggs produced by F1 adults.

Two questionnaire-based surveys were carried out amongst the small vegetable planting community in order to evaluate the effectiveness with which pesticides are being used and the ensuing health and environmental hazards. Good practice was assessed by a certain number of indicators based on various parameters. Data on health hazards were obtained from cases of poisoning and from surveys on blood cholinesterase levels.

The results give pertinent indications on pesticide flow, usage and perception. Generally, aged planters tend to adopt good practice, especially if they have had at least primary education, in which case they would seek advice. Many planters however do not get advice from the right source with regards choice of pesticides and dosage, although a significant proportion of planters do not follow recommended dosages. About three-fourths of the planters frequently resort to cocktails of two or more pesticides. Safety intervals are simply not observed by a good majority of growers. Measuring and protective devices, washing of spraying equipment, disposal of empty containers, and the types of pesticides stores leave much to be desired. The practice of mixed cropping leads to the use of a wide range of pesticides for the control of a single pest on various crops. There has recently been a general shift in pesticide usage with the introduction of synthetic pyrethroids. The misuse and/or abuse of pesticides has serious repercussions on the health of those exposed to such toxic chemicals, and cases of poisoning too are increasing. Remedial measures are suggested.

Although biconical traps are now widely used for the sampling of tsetse populations, they provide only relative population estimates determined by the fly density, activity and trap response. Studies were therefore undertaken to convert such biconical trap indices into unbiased absolute population density estimates. The first step was to determine the range of attraction of such traps for the main trypanosome vector in Kenya, Glossina pallidipes, although some data were also obtained for G. brevipalpis. Two different techniques were used. Firstly traps were placed at varying distances apart, resulting in competition and consequent reduction of catch sizes per trap when ranges of attraction overlapped. Secondly, the catches in grassland at varying distances from a forest edge were compared with two predicted functions relating catch size to distance. Results from the competition experiments showed a marked decline in catch per trap when the intertrap distance was less than 30–40 m. The resultant estimate of maximum range of attraction of 15–20 m for G. pallidipes was compatible with the observed pattern of decline of catches at increasing distances from the forest edge. The range for G. brevipalpis was tentatively estimated as up to 10–15 m.

The body weight of the host was considerably reduced on attack by the parasitoid, Apanteles glomeratus Linnaeus. It varied from 466.65 ± 87.78 mg to 177.94 ± 52.01 mg. Average weight of the parasitoids per host was 268.54 ± 80.86 mg and individual parasitoid weighed 3.12mg. There was a reduction in the total body lipid: from 8.85 ± 1.27% (wet wt) in the normal caterpillar to 1.93 ± 0.42% in one batch and to 5.16 ± 0.80 in another batch of infected caterpillars. The haemolymph protein content of the host also showed a reduction from 9.89 ± 1.29 to 3.59 ± 0.76%.

Major workers are the dominant caste in foraging parties of Macrotermes michaelseni; they also have the largest sternal gland, with the highest potential trail-laying activity. The termite utilizes pheromonal trails along open-air foraging routes, surface galleries and in the subterranean gallery network. Thus, surface galleries appear to serve primarily as protective structures to foraging traffic, while trails lead foragers to food sites. Well-established trails on paper lost activity within 2–3 hr under open-air field conditions. In a choice situation, a trail leading to food source was 30–40 times stronger than that directed to an empty food chamber, suggesting that food influences trail-laying and recruitment behaviour of the termite.

Bruchidius atrolineatus appears at the end of the rainy season when pods of its host plant Vigna unguiculata begin to mature. The eggs are deposited along the ventral suture of pods in the vicinity of the seeds. When the eggs are not attacked by Trichogrammatidae their larvae penetrate the seeds and mortality is low during the post-embryonic development. Most of the adults emerging at pod maturity have functional reproductive organs. In that case the females laid on the same mature pods and larvae develop inside the seeds during the first part of the drying season characterised by high diurnal temperature and low relative humity. If the first emerged adults have functional reproductive organs, the following (60% of the population) are in reproductive diapause. Such diapausing insects have been found during the dry season in shelters near the cultivated fields of Vigna unguiculata. Induction or termination of this reproductive diapause are not yet studied. This diapause probably allows the maintenance of populations during the dry season in absence of host plant.

The ability of peasant farmers in the third world to monitor environmental occurrences around them has often been ignored. This study looks at Nigerian fanners' perception of pests and pesticides and determines the relevance of such knowledge as an input to efforts to devise effective integrated pest management strategies.

Farmers in Kabba area of Kwara State, Nigeria were extensively interviewed and the following findings were highlighted: they had a deep knowledge of all insect, animal and fungi pests; could identify each pest, know their breeding cycles and their general behaviour characteristics; were able to make a relatively accurate assessment of damage caused by pests; and developed an indigenous integrated pest management strategy.

Due to massive pest damage in the last few years, and strenuous advertisement by the Ministry of Agriculture, many farmers are now turning to chemical pesticides for solution to the pest problem. Prognosis of future trends in pesticide usage among farmers reveal the likely danger of farmers becoming pesticide-dependent with the consequent possibilities of human poisoning and eventually aggravating the pest problem.

The relationship between seasonal numbers of outbreaks of African armyworm (Spodoptera exempta) in Kenya and Tanzania, and early season rainfall in source areas has been examined using records for 21 seasons. Significant inverse relationships were found between numbers of Kenya outbreaks and early season rains in the Kisumu area, and between numbers of Tanzania outbreaks and early season rains in the Morogoro and Mtwara areas. Total Kenya and Tanzania outbreak numbers were significantly inversely related to early season rainfall for 8 areas combined. These results suggest that early season rainfall totals, either from specific likely source areas or countrywide, could be used in January to give a seasonal forecast of likely numbers of armyworm outbreaks during the rest of the season. Seasons with more than average numbers of outbreaks often follow poor early season rains and visa versa. Further work is needed to establish biological causes of this apparent relationship.

Fleas are vectors of bubonic plague, murine typhus and several other rodent borne diseases. As with other vectors of medical importance there is widespread insecticide resistance among the flea population. In our efforts to find alternative insecticides 20 plants were screened for their pulicidal properties by obtaining extracts from these plants. It was observed that extracts of plants Acorus calamus, Allium sativum, Anona Squamosa, Brassica nigra, Croton tiglium, Ocimum sanctum, Piper nigrum possessed pulicidal activity.

A high level of resistance to chlorpyrifos has been detected in Culex quinquefasciatus larvae from Dar es Salaam. To study the impact of this resistance on the routine anti-larval spraying programme with this chemical, pit latrines, cess pits and soakage pits were examined regularly after spraying. Larvae were eliminated immediately after spraying, but in most cases they re-appeared about 2 weeks later. Bio-assays with susceptible and resistant larvae in water samples from the pits showed that in most cases there would have been sufficient insecticide residue for at least 10 weeks to kill a susceptible population, but resistant larvae could survive in the water from about 2 weeks after spraying. Chemical analysis showed that the water was toxic to resistant larvae so long as it contained about 0.02 mg/l chlorpyrifos. These observations might have suggested that the routine spraying programme every 10 weeks would be having very little impact on the population now that resistance has evolved. However, in fact, adult densities in houses in a year with spraying on schedule were much less than in years when many sprayings were missed owing to shortage of supplies. Thus the regular spraying programme still apppears to have a beneficial effect.

The suitability of the East African goat and various types of hybrid goats to serve as hosts for tsetse was compared over an extended period. Although there was no significant difference between indigenous and hybrid goats when feeding up to 350 flies per host, about 94% more indigenous goats than hybrid goats became unsuitable as hosts and required a prolonged period of rest when the fly burden was increased to 450 flies per host. Of the hybrid types assessed, Toggenburg crosses were best suited as hosts even though they required more frequent rest periods than the other hybrid types.

A method is suggested for estimating sampling biases for male tsetse, based on the assumptions of the classical feeding cycle “model”. Sampling intensity for any particular method is denned as the catch of flies in different segments of the non-feeding phase of their current cycles, expressed as a percentage of the catch of flies that are just entering the feeding phase. Two examples are given, of Glossina palpalis in Nigeria and G. morsitans in Zambia. In both cases, sampling intensity is low just after feeding and increases slowly at first, and then rapidly as flies enter the feeding phase.

Flies in their feeding phase can apparently find and feed on hosts within one day. Feeding rates are inversely related to the fat content of flies entering the feeding phase of their current cycle, whilst rates of fat usage increase with this variable. These results suggest that it is important to distinguish between tsetse flight activity in general, and feeding behaviour in particular. Finally, it is emphasised that the analytical technique proposed depends on our still inadequate understanding of the field behaviour of flies.

The main pest control tactic employed by the farmers in Tanjong Karang is the application of pesticides. The fanners seem more aware of the need to spray their crops. No fixed spray schedule is being adhered to. Most farmers spray when pest damages are observed. Three to four applications per season are usually used and most farmers spend less than M$100 (US $43) on chemicals in a season. Chemicals are usually bought with cash from chemical sales representatives.

More than half of the farmers rank rats as their most important pest (56.5%) and more than a quarter (27.2%) rank stem-borers as their most important pest. It is felt that farmers tend to mention these two pests, especially stem-borers, when they are being asked, as these are the “traditional” pests and their damages are usually visible.

In the main season 1980/81, 43.5% of the farmers reported serious pest damages in their fields. All these farmers attempted to control the pests using chemicals. However, only 27.5% of them felt that they had succeeded. This clearly suggests the need for better pest control practices to be implemented in Tanjong Karang.

A one-year survey was carried out in two brackish water pools to study the incidence of Amblyospora sp. in field populations of Culex sitiens larvae at the Kenya coast. Salinity of the pools, water temperature, and rainfall patterns were also recorded to check their possible effects on the infection rates. Levels of infection in both pools were low, and ranged between 2 and 15%. Infections occurred in a wide range of salinity. Statistical analysis (t-test) showed no significant correlation between infection rates and neither salinity, temperature nor rainfall in the field.

A test with 100 nymphs of Hyalomma anatolicum anatolicum for evaluation of resistance of cattle to ticks was found to have a good potential for assessing the resistance status of cattle. Thus, 7% of nymphs engorged and moulted on a resistant host with average engorgement weight of 7.6 mg compared to 19 and 45% of engorged nymphs on two susceptible hosts with 15.8 and 13.6 mg average engorgement weights. Similarly, the number of detached fully engorged Rhipicephalus evertsi nymphs dropped from the resistant cows ranged between 14 and 57 compared with 118–124 from the two susceptible animals. The correlations between the three parameters; ranking cattle for resistance (natural tick burdens), the number of detached fully engorged R. evertsi nymphs, and the percentage survival of H. a. anatolicum nymphs after artificial infestation are discussed and found to be significant (r = +0.778; r = +0.886; r = +0.936). It is, therefore possible to assess the overall resistance status of hosts and cull the susceptible, if necessary.

Decrease in trehalose (40–60%) and total sugar (58–68%) content was observed in both sexes of ageing Callosobruchus maculatus. The variations in the level of trehalose and total sugar with age, suggest that these serve as energy sources responsible for the maintenance of metabolism in the process of ageing in bruchids.

A study of Glossina pallidipes (Austen) was done using various trapping devices. It was observed that groups of females of the same physiological age, the same pregnancy stage, and all replete, entered traps simultaneously. Swarms of teneral females of the same physiological age were also captured simultaneously. These observations led to the conclusion that female tsetse swarm together according to pregnancy stage and/or age groups for the purpose of both looking for hosts and larviposition sites. Laboratory studies on the feeding pattern and behaviour of heavily pregnant female G. pallidipes indicated that only about 5% of such females fed 2 days before larviposition; that is when the breathing lobes of the larva had turned black and it was ready to be larviposited. The rest did not take a meal once they were in the last stage of pregnancy. Field observations of fed females in similar pregnancy stage generally agreed with this, indicating 4.6% as the portion that fed when in that last pregnancy stage. The abortion rate in the field population was estimated to be about 0.1%. The weakness of the method of determining abortion rates in the field is discussed.