The developmental, oviposition, and mortality rates for the polyphagous earwig Diaperasticus eryihrocephala Olivier feeding on pollen and Ephestia kuehniella Zeller eggs were measured at constant temperatures of 18, 25 and 32 °C. The developmental period for D. erythrocephala required 533 degree-days (DD) above a threshold of 6.7 °C. Egg and larval development rates increased with increasing temperature, with the shortest developmental period being recorded at 32 °C. However, egg and larval mortality and larval malformation rates were significantly higher at 32 than at 25 and 18 °C. Over a period of 60 days, females laid an average of 26.5 eggs at 25 °C and none at 18 °C. Based on the results obtained, it is concluded that of the three temperatures, 25 °C is the most suitable for the laboratory mass rearing of D. erythrocephala.

The ability of three anti-juvenile hormone agents (AJHAs) to prevent the juvenile hormone dependent phase of larval-pupal transformation has been investigated. Neck-ligated post-feeding last instar larvae of Spodoptera mauritia were treated topically with different doses of a juvenile hormone analog (JHA) or the AJHAs, tetra-hydro-4-fluoromethyl-4-hydroxy-2H-pyran-2-one (FMev), ethyl-4-[2-(tert-butyl carbonyloxy)butoxy] benzoate (ETB) and ethyl-[E]-3-methyl-2-dodecanoate (EMD). Untreated ligated larvae or those treated with acetone survived for 12 ± 1 days without showing any sign of pupal cuticle secretion. On the other hand treatments of ligated larvae with different doses of JHA induced pupation. Among the three AJHAs tested treatments of ETB promoted pupation. Treatments of ligated larvae with lower doses of EMD induced the formation of larval-pupal intermediates whereas those treated with higher dose moulted into either pupae or larval-pupal intermediates. FMev-treated larvae exhibited a complete inhibition of moulting and metamorphosis. In order to study whether AJHAs would prevent the JHA induced pupation, neck-ligated larvae were treated simultaneously with different doses of AJHAs and 1 μg JHA. Co-application of JHA with different doses of EMD induced pupation in majority of the ligated larvae and thus appears to a certain extent to counteract the effects of treatments of same doses of EMD alone. Co-application of JHA with different doses of ETB elicited pupation in all the surviving ligated larvae. To a large extent co-application of JHA with different doses of FMev failed to induce pupation. The significance of the findings is discussed in the context of the mode of action of these AJHAs.

Damage to the antennae was equally common in kings and queens, and was randomly distributed. Damage to the legs was commoner in queens than in kings, and was not randomly distributed. Damage to many or all the legs of one individual may be symptomatic of degeneration due to age.

The biology of the sorghum shootfly, Atherigona soccata Rondani, was studied at the Corn and Sorghum Research Centre, Thailand. The preoviposition period is 3–5 days long. The females deposited a mean of 238 eggs with an average incubation period of 3 days. The larval development required an average of 7.8 days, and the pupal stage was 7.1 days long. The adults were reared with ordinary sugar, yeast and water. The females lived an average of 30 days and the males 20 days.

Carbofuran granular formulation is still the leading product for the control of the shootfly at the Research Centre. The application rate in the seed furrow is 0.45–0.60 kg a.i./ha with a row spacing of 75 cm. Furadan® 30ST, an emulsifiable formation of carbofuran, can also be used as a seed dressing at a rate of 20 cm3/kg of seeds. Counter®, another soil systematic insecticide, has been found effective in controlling the sorghum shootfly.

A modification of the ICRISAT trap for the sorghum shootfly is described. The trap may be effective in reducing the fly population.

The development, life table and intrinsic rate of natural increase of the reduviid predator Rhynocoris fuscipes (Fabricius) on Spodoptera litura Fab., Earias vittella Fab. and Corcyra cephalonica Stainton under laboratory conditions were constructed. Fecundity, longevity and minimum developmental period of the predator were dependent on the prey diet and decreased in the order: S. litura, E. vittella and C. cephalonica. The mean number of female progeny produced over the entire period (the gross reproductive rate) was 43.0, 37.5 and 32.5 on S. litura, E. vittella and C. cephalonica respectively. The net reproductive rate (Ro), intrinsic rate of increase (rc) and weekly multiplication rate were also highest on S. litura followed by E. vittella and C. cephalonica.

Farmers in the groundnut belts of Mali, Burkina Faso, Niger, Nigeria and Benin in West Africa were interviewed for their ability to identify economically importanct soil pests infesting their groundnut (Arachis hypogaea L.) crops, and to obtain information on farm histories and cultural practices which may influence soil pest infestation and spread in a field. Termites, whitegrubs and millipedes were recognised by the farmers as being the most important soil pests, with termites being the most damaging group. A negative correlation (P < 0.05) was found between the number of years a farm was cultivated and the frequency of termite occurrence in it. Information on cultural practices obtained from interviews and field visits indicated that practices such as late harvesting and the leaving behind of residues of previous sorghum, millet and maize crops increased termite infestation. The cutting down and burning of the vegetation in a farm before planting significantly (P < 0.05) reduced the percentage of plants attacked by termites. The cultivation of short-duration (< 100 days) varieties to escape drought at the end of the cropping season did not significantly reduce termite damage, due to late harvest. Other farmers' practices which are likely to have contributed to soil pest damage are also discussed.

Five barley varieties, viz. Proctor, Kenya Research, Tumaini, MPYT 169-2Y and Can B35/2, were tested in the field to evaluate their resistance traits to D. flavibasis. Can B35/2 was identified as a moderately resistant variety useful for reference in further work. The varieties were observed to recover their growth after the infestation. Visual growth recovery scores in the field experiments suggested the tolerance type of resistance.

Spatial pattern of distribution of populations of three insect species, namely, Amrasca biguttula biguttula (Ishida), Bemisia tabaci (Genn.) and Aphis gossypii Glov. was studied in Upland cotton (Gossypium hirsutum L.) at an interval of 13–15 days during July, August and September in Punjab. The populations were found to be aggregated from the beginning of season upto 25 August in jassid nymphs, 12 August in whitefly adults and the end of season in apterous aphids. Environmental heterogeneity at low population in July and innate behaviour at high population were responsible for the aggregated dispersion in each of the three homopterans. Based on these observations the appropriate number of samples required to be drawn for population studies were determined which varied with change in pest density in each case.

The anatomy of damaged and undamaged young stem, peduncle and young pods were examined from transverse sections in three varieties of cowpea in order to evaluate the anatomical basis of resistance to the pod borer Maruca testulalis.

While tissue development in the stem, peduncle and pods of the three varieties of cowpea were similar, the relative thickness of the various tissues were different in the order Vita-1>ICV-2>TVu 946. The smaller diameter and the relative abundance of strengthening tissues in the stem and peduncle of TVu 946, by limiting total ingestible biomass, might be restricting the damage to these organs by the pod borer.

Pod damage, on the other hand, was concentrated on the parenchymatous tissue of the pod wall lining and inter-seed spaces and the sizes of this tissue were also different among the varieties in the order Vita-1>ICV-2>TVu 946, the same order of susceptibility to attack by M. testulalis.

Three consecutive generations of Hypsipyla robusta Moore (Lepidoptera: Pyralidae) were reared on the McMorran–Grisdale Diet (MGD) medium. Mortality rates among the older larvae were consistently low (less than 1.0%) but high (up to 50%) in the first instar stage which was due primarily to escapism and non-feeding. Developmental period from egg to adult was not adversely affected by the artificial diet and ranged between 29 and 41 days. However, a comparison of numbers of larval instars and pupal sizes indicated that the nutritional quality of the MGD and natural food sources differed appreciably. A longterm study to evaluate the usefulness of the MGD for planned mass rearing programmes of H. robusta is recommended.

A method of marking tsetse flies is described based on the transfer of fluorescent pigment from marked males to females during copulation. Powder applied between the coxae of the male lodges in the scutellar groove of the female during mating. Powder persists well on males before mating and on females afterwards. Individual males can mark several females, and the marks of different males can be detected on females after multiple mating. Aspects of behaviour which may possibly be investigated using this method are described.

In intertropical Africa, various haematophagous Diptera are considered responsible for the maintenance and spread of cases of cattle trypanosomiasis in regions where tsetse flies are absent. In comparing early observations with the results of two recent tsetse control campaigns, this paper raises the question of whether the role of machanical vectors is as important as that normally attributed to them, and stresses the insufficiency and impressive nature of available information on this important epidemiological problem, which requires much more intensive research.

Insects have evolved a potpourri of mechanisms for manipulating the allelochemicals that fortify their preferred host plants. A concatenation of physiological and biochemical events frequently follows the ingestion of a toxic natural product and can eventuate in a variety of fates for the compound. A particular allelochemical may be absorbed, metabolized, and sequestered, whereas the fates of concomitant natural products may be very different. Some compounds may be directly excreted in the faeces and their concentration will thus mirror that in the plant. In other cases, selective absorption and sequestration combine to biomagnify minor constituents so that the concentration of these sequestered compounds in insect tissues diners drastically from their concentrations in the host plants.

The acridid Romalea guttata is utilized in this paper as a paradigmatic insect which eclectically processes ingested allelochemicals from a wide range of host plants. This generalist herbivore is eminently suitable as a model because it feeds on plants containing a veritable pharmacopoeia of toxic compounds. The proven sequestrative potential of its defensive glands further qualifies R. guttata as an excellent candidate for determining the fates of toxic phytochemicals. An analysis of this insect's processing strategies for the compounds ingested after feeding on catnip (Nepeta cataria) reveals that for R. guttata variety is the spice of herbivorous life. The results of this investigation persuasively demonstrate that each insect species—and the phytochemical mixture that it ingests—must be regarded as a unique evolutionary case that constitutes a distinctively idiosyncratic phenomenon.

Maliarpha separatella (Rag) was found to infest the rice crop for the greater part of the crop's growth cycle. There was an extended peak of larval activity, and the build up of the larval population was correlated with stand establishment and stem development. The intensity of both tiller infestation and internode tunnelling was found to increase with the crop maturity. Some aspects of control measures of the pest as related to the insect-pest/host-plant relationship are discussed.

Laboratory and field methodologies for screening for resistance against Chilo partellus on sorghum and maize are reviewed in relation to the insect biology, plant phenology and insect-plant interaction. The value of field and laboratory techniques in achieving the goal to produce resistance varieties and hybrids is discussed. Recommendations for future work are made.

Studies on seasonal patterns of okra leafhopper, Amrasca biguttula biguttula Ishida were conducted for two years. Time series analyses were adopted for working out weekly seasonal index of okra leafhopper. Low incidence of leafhopper was recorded from June to mid-January. Results further revealed that incidence of leafhopper was highly correlated with minimum temperature. There was no discernible time lag for population increase of leafhoppers. Prediction of leafhoppers at different crop growth stages for various months of sowing was done using dummy variable technique.

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.

The spatial distribution of the eggs and larvae of Anaphe venata Butler within canopies of its host, Triplochiton scleroxylon K. Schum situated at Araromi Village northeast of Ibadan was determined. Sampling branches of T. scleroxylon once in a spiral from base of canopy upwards was sufficient in determining the distribution of eggs and larvae of A. venata. Although the differences in the mean count of egg masses and larval groups in the lower, middle and upper canopy levels were not significant, the highest percentage of egg masses and larvae occurred on the tips of branches in the lower canopy. Sampling studies on the developmental stages of A. venata may therefore be done at the lower canopy level for best precision. Eggs and larvae are aggregated while the larval dispersion on the host suggest photo-positivity. The use of mounted, motorised elevators is proposed in order to enhance efficiency of sampling and avoid destructive sampling.

The pupal parasitoid Xanthopimpla stemmator Thunberg oviposits in the pupae of the spotted stalk borer (or sorghum stem borer) Chilo partellus (Swin). The adult parasitoid emerges from the pupal case, killing it in the process. Ten mated females of the parasitoid had an average longevity of 30 days (maximum 37 days and minimum 22 days). The number of progeny produced ranged from 71 to 115, with an average of 84.5. The male:female sex-ratio of their progeny averaged 1.14:1. The maximum mean progeny production per day (mx) was 1.9. The innate capacity for increase was 0.131 per female per day; and the population multiplied 43.43 times in the generation time of 28.78 days.

Mating and oviposition of Earias vittella was studied in the absence or presence of the host (okra fruit) or the host odour. When the host was accessible, there was a significant increase in the frequency of copulation, the number of spermatophores transferred and the number of eggs oviposited. Availability of host odour, instead of the host, gave similar results. Further, in general, the number of eggs oviposited by a female was significantly correlated with its mating frequency.