In a comparative situation, the moths Plodia interpunctella (Hubn.) and Ephestia cautella (Wlk.) caused more damage in groundnuts (41.85% for P. interpunctella; 29.21% for E. cautella) than in maize, when these commodities were stored for 1 month in plastic jars. For maize stored for 3 months in plastic and traditional storage gourds, the weight losses caused by the moths were: P. interpunctella—15.48% in jars; 4.53% in gourds; E. cautella—20.68% in jars; 4.12% in gourds. Orange peel suppressed two-thirds of the populations of P. interpunctella and E. cautella at a dosage of 20.0g/100g maize. Neem leaves caused 100% mortality of P. interpunctella at 15.0g/100g groundnut and suppressed more than half the population of E. cautella at 5g/100g groundnut. The results show that the plant materials utilised have some insecticidal properties against P. interpunctella and E. cautella over a short period.

Newly-deposited pupae Glossina pallidipes were incubated until emergence at constant temperature (20.5, 22.5, 25.0, 27.5, and 29.5°C) and compared with pupae held at ambient conditions (19 to 31°C). Egg follicles and enclosed oocytes of newly-emerged females were dissected and their lengths measured together with the lengths of the cutting blade of the hatchet cell of the right and left wings. Linear discriminant functions analysis showed that the mean length of egg follicle A accounted for 80% of the temperature-related variability. We therefore used a simple predictive equation for temperature experience based on mean follicle length in small batches of newly-emerged females. The equation predicted with reasonable accuracy the temperature experience of 19 monthly samples of newly-emerged G. pallidipes reared in an insectary under ambient conditions. Mean sizes of egg follicle A of the newly-emerged tsetse may therefore be of utility in estimating temperature experience of pupae.

Animal burrows are major habitats for both P. martini and P. duboscqi, vectors of visceral and cutaneous leishmaniases in Kenya. In burrows, both species were collected throughout the year. The highest relative abundance of P. martini and P. duboscqi was recorded in August and in April, respectively. The lowest relative abundance was observed in july for P. martini and in October for P. duboscqi. In termite mounds, P. martini was present all the year round, but P. duboscqi was absent for the greater part of the year. The highest relative abundance of P. martini was observed in November and April, while that of P. duboscqi was seen in March and April. The lowest relative abundance of P. martini was recorded in July. In termite mounds, P. duboscqi showed a significant positive correlation with rainfall, contrary to P. martini which did not afford any significant correlation with any environmental factor. Rainfall, relative humidity and ambient temperature did not correlate with relative sandfly abundance in animal burrows.

Glossina tachinoides and G. morsitans submorsitans in Niger and G. morsitans morsitans in Mozambique conform to the general pattern of Glossina resting behaviour in that they rest on the woody parts of the vegetation during the day and on the foliage at night. G. m. submorsitans and G. m. morsitans both prefer low horizontal branches as their main day-resting sites, while G. tachinoides rests mainly on the bases of trunks. G. m. morsitans was found to exhibit a 3-phase pattern of resting behaviour: on foliage at night; low down on trunks for a short period after dawn; and on branches higher up for the remainder of the day. No relationship between temperature or relative humidity on the choice and vertical distribution of night resting sites could be found. For G. tachinoides, the microclimatic conditions of its resting sites were more favourable than ambient conditions during the middle of the day.

Bruchidius atrolineatus Pic is a Coleopteran Bruchid developing in cowpea (Vigna unguiculata Leguminosae) seeds. This insect causes important damage in tropical countries during storage of cowpea seeds. The influence of some volatile sulfur compounds is studied on adults and larvae of B. atrolineatus. Dimethyl trisulfide and diethyl trisulfide produce the highest mortality to adults, eggs and larvae. The toxicity of the sulfur compounds is higher than that of carbon tetrachloride but is less than that of Dichlorvos at a dosage of 500 g/l. It is suggested that the sulfur compounds produced by the leaves of some tropical plants (Alliaceae, Bignonlaceae, Mimosaceae) could be used for control of Bruchid populations in the stored products.

Tropical African ticks are found on their hosts throughout the year, but at varying infestation levels. These population changes, for most of the time, have been associated with climatic changes. Their development is inversely related to temperature. Several workers reported that development failed for a number of tick species at temperatures below 15°C, suggesting a possible lower temperature threshold for tick development. The upper development limit for most of the tropical rhipicephalids appear to be 37°C.

Ticks are particularly susceptible to attack during lethargic pre-moulting and the weak post-moulting period. Many biological features enable them, however, to survive especially well. They lay numerous eggs and withstand a comparatively wide temperature and humidity range with greater ease. They survive for months or years without food.

Their degree of host specificity varies from genus to genus or within subgroups of various genera. The requirement of two or more kinds of hosts often with divergent habits, limits their distribution to certain faunal areas.

This paper reviews our current knowledge on development and survival of ixodid ticks under tropical field conditions including some laboratory studies.

Phenology of Arboreum varieties: G 27, LD 133 and LD 230 differed from Hirsutum, F 414 under unsprayed conditions in Ludhiana. Protection to Arboreum varieties at seedling stage against grasshopper and to bolls formed between 1 August to 15 September against bollworm damage was found necessary. In Hirsutum variety, F 414 bolls formed between 16 August to 15 September needed maximum protection from bollworm damage.

At vegetative phase, jassid population was positively correlated with the leaf size and negatively with number of gossypol glands and leaf thickness, and that of whitefly was positively correlated with number of leaves per plant. Six plant morphological characters: number of leaves, squares, bolls, vegetative and reproductive branches and shoot pubescence-affected bollworm infestation significantly and the effect was related to and varied with the age of the plant. Anthocyanin pigment was not detected in any plant part in the four cotton varieties. At vegetative and reproductive phases, gossypol, total phenols, condensed tannins, leuco-anthocyanins and flavenols in leaf, shoot and boll per se did not influence insect pest infestations under field conditions. The parasite population was not related to pest infestations throughout the plant growth. Prédation rates, however, on pest populations seemed to be considerable. Sclereids and lignified cells affected penetration of first instar Earias vittella larvae into bolls.

Trials using deltamethrin impregnated odour-baited targets for control of tsetse, have been running in Galana Ranch on the coastal hitherland since 1986. In July 1988, a similar trial was started in Lambwe Valley, Western Kenya. Glossina pallidipes is the sole vector in the valley and is present in very high densities.

In Galana Ranch trial, octenol and acetone are used as odours while in Lambwe Valley, natural cow urine is used in addition to acetone and octenol. Tsetse population densities were assessed weekly for 3 weeks, before deployment of targets and thereafter at monthly intervals. A herd of cattle is used to monitor the effect of the control measures on disease incidence.

On Galana Ranch, the block where the initial trial began has remained free of G. pallidipes for a period of 3 years. In a period of 9 months in the second year of the trial, the berenil index in a herd of cattle was 0.07 in the controlled area compared to 2.5 in the uncontrolled area.

In Lambwe Valley a 99.9% reduction in trap catches has been observed in most parts of the park at the end of the first year. The berenil index in the cattle has dropped from 6.3 to 0 and there is a general improvementin the health of the animals. Observations are continuing at both sites.

Since the introduction of irrigation in the early 1950s major changes in the crop regime have taken place in Israel. These changes had greatly influenced the populations of the four species of corn borers found in Israel. Chilo agamemnon, which was the main pest during the 1960s decreased and the numbers of Sesamia nonagrioides increased. The reduction in the sorghum acreage, caused a decrease in the numbers of Sesamia cretica. In 1981 an increase in the numbers of the European corn borer, Ostrinia nubilalis, was observed. At present S. nonagrioides and O. nubilalis are the main corn pests in Israel.

Chilo agamemnon was first recorded in Israel in 1959 near the Gaza strip. In the course of 2–3 years it became a very serious pest in the southern parts of the country. Later, the spread of the pest continued throughout the country. Since 1973 a drastic decrease in the populations of C. agamemnon was recorded. The probable reasons for the decrease in the populations of this pest in Israel are:

(1) The relative increase of the areas of sweet corn, which is not its preferable host plant.

(2) Rice and sugar-cane, which are very important host plants in Egypt, are not grown in Israel.

Field experiments against C. agamemnon, carried out when populations were high, showed that dust applications were more effective than sprays.

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 stage-specific and age-specific survivorship of the immature stages of Anopheles gambiae Giles s. l. were studied in Baringo District Kenya, using vertical life-table methods.

Survivorship from first instar to adult emergence was 0.085, giving a mortality of 91.5% during the rainy season. However, survivorship dropped to zero (100% mortality) in the dry season.

Mortality was most severe in the first and second instars in all cases. Mean life expectancy increased significantly for larvae that survived beyond the first 3 days of life. Suspected predators of mosquito pre-imagines in the breeding sites were collected and counted. From their large numbers and diversity it was inferred that predation was probablyan important mortality factor.

Juvenile hormone analogues (JHAs), JHA I (6,7′-epoxy-3′,7′-dimethyl-dec-2′-enyl 6-ethyl-3-pyridyl ether), JHA II (3′,7′-dimethyl-undec-2,6′-dinyl 6-ethyl-3-pyridyl ether), MV-678 (2-methoxy-9-[4-isopropyl phenyl]-2, 6-dimethylnonane), and R-20458 (4-ethylphenyl-6, 7′-epoxy-geranyl ether) in acetone solution were applied to insect diets at 10ppm (v/v), and their effects on four species of stored products beetles observed. The larvae of the flour beetles, Tribolium confusum Jacquelin duVal, and Tribolium castaneum (Herbst), reared in media treated with JHAs I and II failed to pupate. At the end of the 6-week observation period, these larvae had not yet pupated. MV-678 and R-20458 produced ecdysial failures, lethal morphological abnormalities and larval/pupal and pupal/adult intermediates. Only a few apparently normal adult flour beetles emerged from these treatments. The lesser borer grain beetle, Rhizopertha dominica (Fabricus), completely failed to reproduce in a medium treated with JHA I. JHA II, MV-678 and R-20458 affected the reproduction of the two grain beetles, R. dominica and Sitophilus oryzae (L.), to varying extent, with MV-678 being the least potent JHA.

Three severe outbreaks of cassava mealybug (CM), Phenacoccus manihoti, have occurred in Zaire. Two were associated with droughts. The third occurred in the driest part of the country and ended only when nearly all cassava plants had been killed. Native coccinellid predators sometimes greatly reduced CM populations, but only after the cassava crop had been heavily damaged. The exotic coccinellid Diomus sp. may be an effective biological control agent in Kinshasa, where CM on a hybrid form of cassava remained common during the rainy season. CM populations in Kinshasa declined greatly in the second year after the release of the exotic parasitoid Epidinocarsis lopezi. In one study the number of mummies with E. lopezi increased with host densities up to 20 CM per shoot tip. Since CM populations remained low after the releases of E. lopezi it is tentatively concluded that E. lopezi, despite considerable rates of hyperparasitism, prevents CM outbreaks over the whole area of its distribution (130,000 km2) in western Zaire.

Seedlings of apple variety, Yarlington mill, were sprayed with different sprays containing 0.1% cypermethrin, and were subjected for 15 min to 65.3 mm artificial rainfall. The effectiveness of deposits after rainfall were tested in the laboratory with neonate codling moth larvae.

Cypermethrin formulations sprayed with each nozzle were more persistent after artificial rain, when small droplets of volume median diameter (VMD = 30–70 μm) were applied by spinning discs (charged or uncharged) compared with larger droplets (VMD* = 90–160 μm) produced by air shear nozzle. No significant difference in effects was obtained between droplets by either charged or uncharged disc.

In experiments to select a character for identifying larval instars in Sesamia calamistis and Eldana saccharina, body length, body width and head capsule width were measured in populations reared on artificial diet. Seven instars were found in S. calamistis and 5 in E. saccharina. For both species, body length was determined to be the best characteristic to distinguish instars because it was easy to measure and had the smallest error.

Sixty artificially infested grain sorghum genotypes were evaluated for resistance against Busseola fusca. Evaluation of leaf feeding damage indicated levels of resistance ranging from intermediate to susceptible. Genotypes were categorized according to the presence or absence of both antibiotic and tolerant characteristics. Genotypes (17%) exhibited both antibiosis against leaf feeding and tolerance for borer damage. Borer damage resulted in a 4% increase in grain yield of one genotype and a 50% increase in the number of heads of a second genotype. Tolerance and recovery resistance were the most important factors limiting yield loss in grain sorghum genotypes. In this study, the ability of sorghum for tillering (recovery resistance) was separated from the ability to produce heads on infested stems (tolerance). The importance of distinguishing between tolerance and recovery resistance in the evaluation of sorghum germplasm for borer resistance is emphasized.

Studies on larval movement, feeding and development of Chilo partellus Swinhoe were carried out at Mbita, Western Kenya. Larval movement away from the plant was observed during the first and third instars. Plants inoculated at the stems recorded greater larval migration compared to those inoculated at the leaf whorls. Larval feeding was greater on IS 18363 than on IS 2146, but growth rate, weight gain and efficiency of conversion into body substances were greater in IS 2146. Thus it seems that varietal susceptibility to damage by C. partellus is different from varietal suitability for growth of the larvae.

Microscopic examination of stem tissues damaged during larval feeding revealed that feeding was mainly restricted to the pith and that the vascular bundles were hardly affected.

A comparison was made of the EAG responses of repleted males and females of Glossina palpalis gambiensis Vanderplank, G. tachinoides Westwood, G. fuscipes fuscipes Newstead, G. morsitans morsitans Westwood and G. austeni Newstead to the odour of various concentrations of acetone, 4-heptanone, 3-nonanone and l-octen-3-ol. The stimulatory effectiveness of these substances increased in the order: acetone < 4-heptanone < 3-nonanone < l-octen-3-ol. Amounts of acetone 103–104 times greater and of 4-heptanone and 3-nonanone 10–100 times greater than those of l-octen-3-ol were required to obtain similar EAG responses. These results are discussed in relation to the behavioural effects of the odours of these substances on tsetse in wind tunnel experiments in the laboratory and catching experiments in the field. In G. m. morsitans and G. tachinoides, the EAG responses of males were somewhat higher than those of females. In G. austeni, G. f. fuscipes and G. palpalis gambiensis, however, the reverse occurred. All species were equally tuned to the four odour substances, which indicates that these odours do not determine host specificity.

Non-parametric statistics were used to describe the spatial distribution of eggs laid by Zabrotes subfasciatus Boh. (Coleoptera, Bruchidae) inside pods of wild Phaseolus lunatus and cultivated P. vulgaris. Eggs tended to be uniformly distributed among seeds inside the pods of P. lunatus whereas egg distribution patterns were random or aggregative inside P. vulgaris pods. These differences were explained in terms of the internal pod morphology of the two host plants. It was concluded that this bruchid normally oviposits uniformly among accessible seeds inside the pods of its host plants in the wild.

Studies were conducted on components of resistance to sorghum midge on four resistant (DJ 6514, AF 28, TAM 2566 and IS 15107) and two susceptible (CSH 1 and Swarna) cultivars. Short floral parts, faster rate of grain development and high tannin content of grain were apparently associated with resistance to sorghum midge, Contarinia sorghicola Coq. Genotypic and phenotypic correlations between the factors associated with resistance to sorghum midge were in the same direction (positive or negative) as their association with resistance to this insect. Glume g2, lemma 12, anther and lodicule length, rate of grain development based on dry weight (except oviposition), and tannin content of mature grain showed correlation and path coefficients (direct effects) in the same direction. These characters can serve as a useful criteria to select for resistance to sorghum midge.

Using D2 and canonical cluster analysis, AF 28 was found to be distinct from other sources of midge resistance. However, based on larvae/100 florets, DJ 6514 was also placed distantly from TAM 2566 and IS 15107. Based on egg numbers, adults emerged and grain damage, DJ 6514 was grouped with TAM 2566 and IS 15107. Susceptible hybrid check, CSH 1 was generally placed distantly from the self pollinated susceptible variety, Swarna. These results indicate that the sources of resistance to sorghum midge are diverse, and there is a distinct possibility of increasing the levels and diversity of resistance to this insect.