The efficacy of the powder and volatile oil of Piper guineense Schum & Thonn at protecting cowpea against seed beetle, Callosobruchus maculatus (F.) was tested in the laboratory. At low concentrations the powder significantly reduced oviposition and adult emergence while oviposition was completely suppressed at a higher concentration of 42%. The same concentration provided adequate protection for the same amount of cowpea placed in containers of different volumes. The powder, however, did not show any fumigant effect. Volatile oil at 0.002 and 0.005% significantly reduced oviposition and adult emergence, while oviposition was completely suppressed at 0.02% and above. Weight loss of seeds at 90 days after treatment with volatile oil decreased as concentration of the oil increased. The practical significance of the results in small scale storage of cowpea is 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.

Results of research on biology of Thinophilus guineensis Coul. et Neg. (Diptera, Dolichopodidae) confirm the importance of predaceous feeding behaviour of some other species of Dolichopodidae such as Medetera fisch, Hydrophorus fallen, Sciapus fatten, Diaphorus meigen, etc. Larval mortality of some pests (mosquitoes, blackflies, scolytes, etc.) reach 83 to 99%.

These species, because of their extraodinary ubiquity and their biocoenotical importance, could well be used in biological control programmes of vectors of pathogens affecting man and other animals or pests in agroforestry.

Females of Bruchidius atrolineatus (Pic) lay their eggs in the fields on maturing or dry pods of their host plant, Vigna unguiculata. Under experimental conditions in the presence of maturing and dry pods connected with the plant, 80% of eggs are laid on maturing pods. The preference for maturing pods is observed in two generations of B. atrolineatus and varies with the age of females. In the presence of pods separated from the plant, 69% of eggs are laid on dry pods. These results show the importance of methodology during insect behavioural studies. In the absence of choice, reproduction of B. atrolineatus females is more stimulated with dry pods than with maturing ones. These experiments show that factors which influence the choice of the pods are probably different from those stimulating oviposition.

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.

The pathology of the nuclear polyhedrosis virus from Spodoptera littoralis against Kalotermes flavicollis was confirmed under light microscope. Sections of infected termites showed a comprehensive viral infection. Nuclei of cells of the foregut, cardiac valve, pyloric valve, hindgut, gut musculature, fat body, nerve tissue, muscle, oviduct, pedicel of he ovariole, calyx, accessory glands, wing buds in termite reproductive nymphs, and to a lesser degree, the tracheal matrix, malpighian tubules and hypodermis, were susceptible to the virus. Infection to midgut was generally limited. However, when the termites were heavily infected, the midgut epithelial cells sloughed off into the lumen, and became hypertrophied and granular.

Results of 7 years' experiments conducted in South China indicated that root-zone application of systemic insecticides effectively controlled nearly all the potential insect pests of rice—the yellow stem-borer, the striped stem-borer, the pink borer, the rice leaf folder, the rice gall midge, the brown planthopper, the greem leafhopper, the rice thrip and the rice weevil. Altogether, 16 compounds have been evaluated for the control of various species. Applications of carbofuran mixed with derivatives of nereistoxin (padan, thiocyclam or dimehypo) in the root-zone were found to be most effective against the major insect pests. The merits and demerits of root-zone applications has been discussed in this paper.

Seasonal incidence of the sorghum earhead bug, Calocoris angustatus Lethierry, was studied by sowing the crop once in 10 days, throughout the year during 1978 and 1979, as well as by sowing it at fortnightly intervals from early “kharif” to late “rabi” during 1979. The bug was found throughout the year except for a few weeks during March, April and May. The milky stage of the earhead was the most preferred stage compared to pre-flowering, a third flowering, flowering and ripening stages. The adults dominated during pre-flowering and a third flowering stages whereas nymphs dominated during milky and ripening stages. The computed seasonal indices were higher during August (230), September (222), October (224) and January (215) which coincided with blooming and milky stage of sorghum in general fields. Correlation studies between the bug population at the milky stage and maximum temperature indicated negative and significant (r = -0.2967) relationship, and positive and significant (r = +0.2727) relationship with relative humidity. Low incidence of bugs was observed on the crop sown during June.

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.

The dwarf variety of coconut, Cocos nucifera L. (Palmae), was found to be eaten by the larvae of the African armyworm, Spodoptera exempta (Wlk.). The comparison of the armyworm infestation on the leaves of the coconut seedlings and the adjacent grass species revealed lower larval density and growth rate on coconut seedlings. This observation suggests that a small population of the African armyworm can survive and develop on the leaves of the dwarf variety of coconut.

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.

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.

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.

Observations of the diurnal resting behaviour of Glossina longipalpis and Glossina fusca congolensis were carried out at Ele forest, Oke-Ako between September 1975 and May 1976 both inclusive. The two species of tsetse were observed resting most frequently on underside of stems and branches with diameter range 1–60 mm. Some G. fusca congolensis rested vertically. Whether resting vertically or obliquely, this species always rested with head pointing downwards. More than 95% of G. longipalpis and G. fusca congolensis rested between the heights of 20–240 cm. Preferred resting objects included shrubs, young saplings, climbers and, during high temperatures, bases of tree trunks.

For control purposes it is suggested from the above information that a discriminative and selective spraying of the area be planned for the late dry season and early rains when fly populations are more concentrated and individual flies tend to rest at lower heights. The spraying which should be directed to the undersurface of resting objects will help to reduce the risk of trypanosomiasis at the Oke-Ako cattle ranch.

Electrophoretic studies of Guatemalan blackflies, Simulium ochraceum, the main vector of Central American onchocerciasis, were performed using isozyme patterns. A total of six larval and adult populations originating from four localities (a non-endemic area, Finca La Ruda, a low-endemic area, Finca Rincon, and two high-endemic areas, Finca Brote and Finca Recreo) were analyzed. The enzymes examined were adenylate kinase (AK), alkaline phosphatase (ALP), glucose phosphate isomerase (GPI), hexokinase (HK), isocitrate dehydrogenase (IDH), leucine aminopeptidase (LAP), malic enzyme (ME), and phosphoglucomutase (PGM). Of these, six enzymes, AK, ALP, HK, IDH, LAP, and ME showed no variation either within or among populations. GPI and PGM were found to be highly polymorphic in all of the six populations. χ2-test for fit to Hardy-Weinberg equilibrium (HWE) revealed that the distribution of the phenotypes of the two polymorphic enzymes was not significantly out of the HWE. A verages of values of proportion of polymorphic loci (P) and heterozygosity per individual (H) of the six populations were 0.234 and 0.084, respectively, each of which was similar to the values reported for different groups of organisms (Nei, 1975). Genetic diversity among populations was measured by FST and GST and both parameters showed that the non-endemic population from the Finca La Ruda (Dl) was greatly differentiated genetically from the other five populations. Estimates of genetic distance (Nei, 1975) showed that the Dl population was furthest from the other populations.

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.

The diel activity patter n of Glossina austeni was studied on the south coast of Kenya, and in the laboratory. In the field, flies were sampled hourly by continuous catch from a standing vehicle, or by traps. In the laboratory, observations were made of the flies' take-off-responses to host odour at various times of the diel cycle, in a flight chamber. The results showed that G. austeni is day-active with some activity throughut the daylight hours, but with significant peaks occurring at 09.00–10.00h and between 14.00 and 17.00h, i.e. a roughly V-shaped pattern.

In laboratory assays, two Bacillus thuringiensis var. kurstaki preparations, HD-263a WP and HD-263c WP, were highly effective against larvae of the honeydew moth, Cryptoblabes gnidiella Millière (Lepidoptera: Pyralidae), especially against the first and second instars. Both preparations were more effective than DipelR WP at most concentrations tested. Two viral preparations, AcMNPV and Amorbia cuneana NPV, were ineffective.

A study of the noxiousness of the African white rice stem borer, Maliarpha separatella Rag carried out under controlled field conditions has revealed that the impact of this pest on the yield and its components is assessable. For mean infestation rates up to 68% during the period of highest sensitivity of a paddy rice culture (second half of tillering to panicle initiation), no significant decrease could be observed in the number of panicles, nor any significant increase in the number of white heads and the number of empty grains per hill. However, with increasing infestation rates, the number of immature panicles increased and the number and weight of filled grains per hill decreased. An explorative analysis of the infestation rate-yield loss relationship, showed that a sigmoid model describes this interdependence appropriately. The proposed economic injury level (EIL), is here considered more the result of an approach, which had as its goal the re-definition of the status of the pest than as an instrument of a chemical control programme with treatments based on an action threshold.

A pheromone trap network was used to study the temporal and spatial variations in the abundance of the pod borer, Helicoverpa (= Heliothis) armigera (Hubner) in India. The pattern of pheromone trap catches of Helicoverpa armigera was similar within any given agroclimatic zone but there were also obvious changes with latitude in patterns of trap catches. The catches were generally higher and had more sharply defined peaks, at northern locations than at southern locations. The catches at the eastern locations were lower than those elsewhere. The practical applications of this information for pest control are discussed.