Plants express evolutionary adaptations in response to overall environmental stresses (selection pressures), of which insect infestation usually represents only a minor component. The majority of insect-host plant relationships involves adaptations of insect species to existing plants. Over time, plants have evolved a variety of physical and chemical defence mechanisms against environmental stresses. Only some of these are active against insects, and then not against all species. Plants rarely seem to evolve defences specifically against insects. Parameters of plant resistance to parasites are classified as constitutive or inducible. Soybean resistance to agromyzid stem-miners involves both constitutive and inducible components. Expression of such resistance parameters involves controls ranging from single genes (e.g. for trichome traits) to various combinations of genes (e.g. for the metabolic pathway for phenyl-propanoids). Environmental stresses (e.g. high illumination) especially affect the expression of resistance parameters which involve dynamic metabolic pathways. Soybean (Glycine soja) resistance to beanflies is an example of ‘horizontal’ resistance. Thus, the expected stability is long-term. Such stability is attributable to its major parameters being fundamental components of the soybean's primary and secondary growth and differentiation. These kinds of parameters are major products of the soybean's successful evolutionary experience at survival.

Pheromones have been successfully used on a large scale for control of pink bollworm, Pectinophora gossypiella, by mating disruption in Egypt and Pakistan using various slow release formulations. Similar formulations are being developed for control of other cotton bollworms, Earias insulana and E. vittella. Small-scale trials are in progress to evaluate pheromone formulations for control of sugar-cane borers, Chilo sacchariphagus and C. auricilius in Mauritius and India, and the tropical warehouse moth, Ephestia camelia, as a pest of stored cocoa in Brazil. Traps baited with the pheromone of the African armyworm, Spodoptera exempta, have been extensively used in Eastern and Southern Africa as the basis of a forecasting system of pest incidence.

Traps baited with the synthetic aggregation pheromone of the larger grain borer, Prostephanus truncatus, have been developed and are in use in E and W Africa for detection and monitoring of this pest of stored grain.

Tanzanian strains of Tribolium castaneum (Herbst), Gnatocerus maxillosus (F.), Sitophilus oryzae (L.) and Sitophilus zeamais Motschulsky were confined to maize grain treated with a dilute dust of permethrin at the rates of 1.5, 3.0 and 6.0 ppm active ingredient. The adult mortality and resulting F1 generation were recorded. G. maxillosus was very susceptible to the insecticide and even the lowest dose brought complete control. T. castaneum adults survived all treatments but few F1 were produced. Adult survival of s. oryzae and S. zeamais was progressively reduced by increasing dosage, although S. zeamais was much less susceptible to the treatment than S. oryzae.

The repellency of grain, treated with 3.0 ppm permethrin, to S. oryzae, S. zeamais and T. castaneum was tested in a simple choice chamber. Neither male nor female T. castaneum were repelled but significantly fewer eggs were laid on treated grain. For both Sitophilus spp there was no significant difference between the numbers of females or eggs observed on treated or untreated grain, but males were repelled from permethrin.

The importance of these results is discussed in relation to a recent recommendation that the treatment of shelled grain with 3.0 ppm permethrin should be adopted in Tanzania in order to control Prostephanus truncatus (Horn), a new and serious storage pest.

Occurrence, abundance and seasonal fluctuations of Culicoides peliliouensis in the mud and sand flats of Hooghly estuary were studied in relation to some important environmental parameters (air temperature, soil temperature, soil moisture, rainfall, salinity, dissolved oxygen and pH of interstitial water, organic carbon, available phosphorus, percentage of sand, silt and clay of soil) at three stations in and around Sagar Island during July 1982 to June 1984. They were more or less found throughout the year, withmaximum abundance during postmonsoon and minimum during premonsoon. Several statistical analyses have been computed to study the relation between population of C. peliliouensis and all ecological parameters. Results of ANOVA indicate that almost all ecological parameters varied significantly over months, stations and years, whereas the population of C. peliliouensis varied significantly only over months and stations. Soil temperature, rainfall, organic carbon and available phosphorus appear to be the major factors controlling their distribution in the intertidal habitat as evident from correlation coefficient analysis. Multiple regression analysis shows that the combined effect of all parameters is positively significant at all the stations.

Five-to six-day old male pupae of Ectomyelois ceratoniae Zeller were irradiated with 0, 20, 25 and 30 krad of gamma rays. When the radiated males were mated with normal females there were deleterious effects on fertility without extreme effects on mating or fecundity. Percentage of embryonated eggs and progeny per female decreased to two thirds of the control by 25 and 30 krad treatments. Productivity of the female mated with irradiated males was decreased and significant reductions in egg viability, egg hatch and larvae per female were observed in F1 generation. Similar pattern of sterility was observed in sibling crosses of F2 at the three doses.

Populations of larvae and pupae of the African rice gall midge, Orseolia oryzivora Harris & Gagne (Diptera: Cecidomyiidae), and two parasitoids, Platygaster diplosisae Risbec and Aprostocetus procerae (Risbec)[= Tetrastichus pachy diplosisae Risbec], were recorded in replicated experiments on farmers' fields at Karfiguéla, Burkina Faso in the 1992 wet season and the 1993 dry season. In each season, four plantings were made at 14-day intervals and samples taken at weekly intervals for 10 weeks. Gall midge populations in the wet season developed through three distinct phases: an initial slow increase, followed by a period of rapid increase coinciding with maximum tillering, and then a final decline. On average, the highest midge populations and highest levels of parasitism developed in the later plantings. During the dry season midge infestations were low and no parasites were detected.

The predation of the booklouse, Liposcelis entomophila (Enderlein) (Psocoptera; Liposcelidae) by the mite Blattisocius dentriticus (Berlese) (Acari; Ascidae) was studied in a series of laboratory experiments. Known numbers of mites and booklice were placed together in small tubes and counted after various durations. Fewer booklice were found in mite-infested tubes and it was possible to rear the mite on booklice, which supports the view that the mite is a natural predator of L. entomophila. Comparative susceptibility of the mite and booklouse to deltamethrin and fenitrothion was assessed by exposing both arthropod species to deposits of the two insecticides. The mite was found to be very susceptible to both deltamethrin and fenitrothion whereas the booklouse was only susceptible to the latter. The increased prevalence of L. entomophila in tobacco storage and grading buildings in recent years may therefore be attributed, at least in part, to the use of deltamethrin which suppresses its natural enemies.

In Zambia, termites have been recognized as pests of agricultural crops, plantation trees, structural timber, manufactured wooden goods as well as paper. This makes their control imperative. In line with the concept of pest management, appropriate control measures of termites must take into account their taxonomy, biology and ecology, as well the assessment of crop damage and yield losses. This paper discusses some of the problems inherent in developing such a scheme in Zambia and provides alternative solutions.

A comparison of the metabolic rates of different castes and instars was estimated by measuring the biological half-life of the radioisotope I131. The metabolism in the soldier caste was not only higher than alates and dealates, but also pre-soldiers. The rate of metabolism increased with an increase in the age of the nymphs. The termites which were provided with food had slow metabolism compared to those kept under starvation. The studies are helpful in understanding the phenomenon of ‘temporal polyethism’ among termites.

The transformation from larval caterpillar to non-feeding pupa and adult moth involves a complete remodelling and restructuring of an insect and its organs. In the groundnut pest Amsacta albistriga Walker, the female sex-specific storage protein 1 (SP1) was monitored from last larval instars, during pupal development to the adult stage. Staining intensity of SP1 (which resolved at 82 kDa) in the peripheral fat body (PF) tissues subjected to 10% SDS-PAGE was maximum at mid-stage last larval instars and declined subsequently. However, in perivisceral fat body (PVF) tissues, the staining intensity of SP1 increased significantly from mid-stage final instar. The presence of SP1 during pupal ovary and adult ovariole development and its availability during egg development was confirmed by immunoblot analysis. Electron microscopy data revealed that the decline of biosynthesis of SP1 in PF tissues and its disintegration were associated with the appearance of irregular nucleus and autophagic vacuoles during transformation of larva to pupa. In vitro and in vivo studies using [35S]-methionine-labelled storage proteins showed that, unlike PF tissues, PVF tissue sequestered a significant amount of labelled SP1. During this transformation, SP1 was mainly sequestered as storage protein granules until they served as sources of amino acids for the production of egg yolk proteins. Localization of clathrin-coated pits and crystalline storage proteins was confirmed by immunogold tracer techniques.

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.

Field data of counts of eggs and larvae of Heliothis virescens (Fabricius) (Lepidoptera: Noctuidae) in 12 uncultivated plants in Tolima, Colombia, were used to conduct analyses of variance of the relative importance of the 12 for the insect. Analyses were based on the number of eggs and larvae found per terminal and per 5 g of terminal material of each host.

Regardless of the analysis, more eggs and larvae of H. virescens were found on Desmodium tortuosum (Sw) DC (Papilionaceae) than on the other 11 hosts. In general, more eggs were found on pubescent plants, especially those with glandular trichomes.

A relatively high ratio of larvae:eggs for Ipomea triloba L. (Convolvulaceae) was interpreted to mean that larvae of H. virescens migrated to this plant from eggs laid on other hosts.

The removal rate of eggs from seven hosts due to unknown reasons was estimated to differ between the seven.

Storage pests cause considerable damage to stored grains in Eritrea. A study on storage pest control was conducted at room temperature (25 °C) and 57% relative humidity, to evaluate the efficacy of botanicals and sodium chloride (table salt) against Zabrotes subfasciatus Boheman on field pea (Pisum sativum L.). The experiment was conducted in a completely randomized design (CRD) in three replications. The treatments used were: neem (Azadirachta indica), red pepper (Capsicum frutescens L.), sesame (Sesamum indicum L.) oil, datura (Datura stramonium L.), eucalyptus (Eucalyptus globulus Labill), table salt (sodium chloride) and a control without pesticide. Data collected were weight loss, damage percent and germination percent of field pea grain, and also adult mortality of Z. subfasciatus. Rates of application for all the treatments were 3% w/w and an untreated control. Results of the study showed that E. globulus leaf powder caused 88.89% mortality of Z. subfasciatus and sesame oil caused 100% mortality, three days after treatment. The other treatments were less effective in causing mortality of the insect. After five months of storage, the lowest weight loss was observed in grain treated with sesame oil (1.81%) and neem (4.02%) compared with the control that had 16.68% loss. Grain weight loss was 7.45% for treatment with table salt, 8.11% for eucalyptus, 9.62% for red pepper and 15.29% for datura. Grain damage and weight loss increased as storage time increased. Moreover, these plant materials and table salt had no effect on the germination capacity of field pea. In general, the results obtained indicate that these plant materials and table salt can be used for the control of Z. subfasciatus.

Eggs of Heliocheilus albipunctella de Joannis were picked up during ear formation of millet at Bambey in 1988 and were followed up in the laboratory at temperatures 25–30°C and 60–70% r.h. Trichogrammatoïdea sp. probably T. armigera parasitized 60.3% of them. During the period in which eggs were collected, percentage of parasitism increased, which certainly means a build-up of parasite populations.

Pheromone traps were used for monitoring flight activity of peach twig borer, Anarsia lineatella (Zeller), during a 3 year period between 1983–1985 in Iraq at Tarmiya and Madain regions, and cumulative emergence was related to physiological time (degree-days, DDs). Data of moth catches indicated the presence of two generations per year and perhaps a partial third generation. Flight in both regions peaked from April to mid-May and from early June to mid-June. First capture of peach twig male ranged from 16 to 29 March and corresponded to a mean DD accumulation from 1 March of 138 in Tarmiya and 127 in Madain. Such results are very important for managing this pest.

A 2-year study was conducted to determine the abundance of rice arthropods as affected by weeding regimes and toposequence sites, from upland to lowland, in an inland valley in Côte d'Ivoire, West Africa. Toposequence site had an effect on insect populations. Most insects were found in the moist, lower portion of the slope (hydromorphic or phreatic zone) and in the valley bottom (irrigated lowland). Among these were the white leafhoppers Cofana spectra and C. unimaciilata (Hemiptera: Cicadellidae), the green leafhoppers Nephotettix spp. (Hemiptera: Cicadellidae), and the diopsids Diopsis longicornis and D. apicalis (Diptera: Diopsidae). Stemborer damage was generally most severe in the lowland ecology. Weed dry weights and weed species composition were affected by toposequence site. Cyperns difformis L. was most abundant in the lowland and Digitarla horizontalis Willd. in the upland sites. Weeding regime had an effect on the abundance of insect pests and natural enemies (spiders and damselflies) and on the extent of stemborer damage, the effect varying with toposequence site. Implications of the results for the integrated management of weeds and insects are discussed.

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.

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.

Cotesia flavipes Cameron (Hymenoptera: Braconidae), a gregarious larval endoparasitoid of Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) and other stemborers in the Indo-Australian region, was released in Mozambique for the first time in 1996. Before its release, countrywide surveys on stemborers and their natural enemies were conducted in several places. However, all led to the same conclusion: that Ch. partellus was the most abundant stemborer at the majority of locations, and that the rate of larval parasitism was very low (< 5 %). To evaluate the effect of stemborer species composition on the establishment of Co. flavipes, two releases were made at two agroecologically different sites during the 1998/1999 and 1999/2000 growing seasons. Cotesia flavipes was recovered from all the three stemborer species found at each site during the season of release and a year later. However, the rates of parasitism were very low, ranging from 0.6 to 1.9 % on Ch. partellus, 3.2 % on Sesamia calamistis Hampson (Lepidoptera: Noctuidae) and 2.6 % on Busseola fusca Fuller (Lepidoptera: Noctuidae). The native natural enemy, Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) was the most common larval parasitoid at the two sites. The recoveries of Co. flavipes during the release period and a year later indicate that this exotic parasitoid has become established at the two locations in the southern and central regipns of Mozambique, in spite of differences in stemborer species composition. However, it is too early to evaluate the impact of Co. flavipes on the stemborer populations.