The spotted stem borer, Chilo partellus (Swinhoe) is an economically important pest in many sorghum growing areas of Asia and Africa. A chronological progress made in Indian and other programmes on natural and artificial screening techniques is reviewed. Numerous germpiasm accessions were evaluated and resistant sources identified and documented for various parameters of resistance such as foliar damage, “dead hearts” and stem tunnelling.

Studies on the mechanisms of resistance showed predominance of tolerance, variable degrees of antibiosis and antixenosis as only a factor for oviposition. The morphological characters and biochemical factors associated with resistance are discussed. The nature of resistance is polygenic and partially dominant over susceptibility. The inheritance patterns of resistance to foliar damage and/or “dead hearts”, and stem (stalk and peduncle) tunnelling damage are different and independent. Pedigree breeding with single and multiple crosses has been useful to transfer resistance in more economic background. Continuous screening for stem tunnelling over several generations improves the level of resistance. Recurrent selection was suggested alternatively with and without infestation for resistance and yield, respectively to increase the level of tolerance. The resistant sources utilized in developing commercially released high yielding varieties, hybrids and derivatives with low to moderate levels of resistance are listed. Efforts to develop cultivars with levels of resistance higher than presently grown cultivars and combining cross resistance to stem borers and shootfly are under way. Current progress has been reviewed and future strategies are suggested.

The insect growth inhibitor Alsystin (SIR 8514) was tested for its effects against the immature and adult stages of Culex quinquefasciatus Say under laboratory conditions. A linear correlation was revealed between concentration and larval and pupal mortality. Larval mortality increased from 5% at 0.005 ppm to 74.4% at 0.1 ppm of Alsystin. Complete inhibition of adult emergence resulted after larval exposure to 0.05 ppm. Exposure of eggs (at 0 hr of age) to 0.1 ppm and 10.0 ppm of Alsystin, resulted in considerable decrease of hatching from 87.0% in the control to 61.0% at 1.0 ppm and to 48.0% at 10.0 ppm. The adults of C. quinquefasciatus were seen attracted to the bowls containing 50.0 ppm and 100.0 ppm of Alsystin. However, landing adults died within a short period of time. The different types of deformation in the larva, pupa and adult as a result of exposure to Alsystin are illustrated.

When males of Tribolium castaneum (Herbst) substerilized with 35, 40 or 50 Gy of gamma irradiation (I) were added to untreated (U) pairs of adults at I : U ratios of 1:1, 2:1 and 5:1, the percentage of hatched eggs was increased by increasing the dose administered to males, as not expected, at equal flooding ratio. The calculated degree of competitiveness showed that males irradiated with the lowest dose (35Gy) were more competitive than males irradiated with the highest dose (50 Gy). However, increasing the ratio of irradiated males with 50 Gy to 10 or 20 increased, accordingly, the competitiveness value. The results also indicate that if an equal number of irradiated males and females with 50 Gy, which had given 99.16 % sterility, were placed with untreated pairs of adults at different ratios (1:1, 5:1, 10:1, and 20:1), the effectiveness was more promising. Moreover, the data further suggest that the effectiveness was enhanced when the ratio of irradiated males and females was increased. Thus, the presence of sterile females along with sterile males in the stored products appears to dilute the effectiveness of normal males, which otherwise would mate with normal females.

Field studies were conducted with the synthetic pheromone of peach twig borer to determine the effect of trap distance from host plant, pheromone concentration on number of captured males and seasonal flight patterns in plum and apricot orchards. Traps placed in pomegranate plantation and in fallow land caught significantly fewer males than those placed at the centre and border of plum orchard. However, significantly more moths were caught in traps placed in pomegranate orchard than those in fallow ground. Males captured increased as the concentration of synthetic pheromone increased from 2 to 6 mg per septa. Thereafter, males captured decreased as the concentration increased.

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.

Between May 1984 and December 1985, the population of immature stages of Anopheles arabiensis was sampled by the dip method at sites close to two villages in Mwea Irrigation Scheme, Kenya. Larval presence corresponded to rainy seasons and the flooding phase of the rice cycle. No larvae were found during the postharvest dry season. The instar composition, age distribution and survivorship curves for the different stages were determined. Pupal productivity for Mwea rice fields was estimated to be 1% of the total immature population.

A total of 1244 egg-pods of 12 grasshopper species were collected — 26.7% were from low altitude hills, 23% from Swat valley, 22.1% from Punjab plains, 19.4% from Peshawar region and 8.8% from Potohar plateau. Aiolopus thalassinus was the dominant species comprising 27.7% of the total pods. This was followed by Shirakiacris shirakii (24.5%), Oxya multidentata (13.6%), Trilophidia annulata (9.7%), Spathosternum prasiniferum (9.7%), Atraetomorpha acutipennis(7.4%), Stenohippus sp. (3.8%) and Phlaeoba punteli (1.8%). Others were rare being less than 1%.

Egg-pod density was effected by several closely related factors. Mean annual temperatures (15.6 − 23.4°C) and average precipitation (310 − 2100 mm) of the localities were not the ultimate controlling factors. Parasitism however, appears to play an important role. Highest parasitism of Scelio spp. was 10% on the Potohar plateau where egg-pod population was lowest. A. thalassinus was the most preferred host(41.7%) followed by S. prasiniferum (35.4%), S. shirakii (14.6%), O. multidentata (8.3%), T. annulata and Stenohippus sp. (2.1% each). Soil-type (clay-loam, loam, sandy-loam) and type of vegetation(cultivated area, grasslands) also have a considerable bearing on the microclimate in which the insects live.

The sensitivity of different larval stage duration pupae of Mediterranean fruit-fly, Ceratitis capitata to gamma irradiation, was tested by exposing pupae, 1 day before adult eclosion, to various gamma ray doses (60, 80 and 100 Gy). The treated pupae were biologically different in their larval span (5, 7 and 9 days). The pupae of med-fly having shorter larval period (5 days) were more resistant to sterilizing effects of gamma irradiation than those having longer larval period (9 days). The longevity of sterilized females developing from irradiated pupae, which had 5-and 7-day larval span, was increased considerably. Treatment of pupae which had 5-day larval span with a dose of 80 Gy, resulted in females which lived 84.3 days, but laid only 2.33 eggs as compared with their control females which lived 51.4 days and laid 976.71 eggs. In general, irradiation of pupae of different larval stage duration with a dose of 60 Gy or greater did not adversely affect the longevity of emerging adults. It is concluded that 60 Gy-irradiation of pupae having long larval span (9 days) should be used in the sterile insect release method for population suppression of Ceratitis capitata.

Adult survival, puparial production, weight and viability, and the sex ratio of adults emerging from puparia of Glossina morsitans morsitans Westwood maintained through four successive reproductive cycles on daily (SO), every other day (SI) and every third day (S2) feeding regimen, respectively were investigated at Chilanga, Zambia. Only in puparial production (0.8 under S0 and S1, 0.7 under S2) and puparial weight (25.1±0.2mg under S0, 24.1±0.3mg under S1, 22.5±0.3mg under S2) were significant differences (P<0.05 and <0.01 respectively) detected between feeding regimens. Nevertheless, a combination of S1 and S2 regimens is recommended for further evaluation as a more convenient and economical alternative to the S0 regimen for tsetse mass production in Africa.

Studies on relative susceptibility of 78 citrus varieties/hybrids to the incidence of black citrus aphid, T. aurantii under tropical humid conditions in south India revealed that none of the varieties was completely free from aphid incidence. The varieties Nagpur Mandarin and Ikeda Unshiu among mandarins; Longsport Valencia, Campbell Valencia and Washington Navel among sweet oranges; and Carrizo Citrange a hybrid and Dessert Orange, Eureka Lemon, Grape Fruit Pink and Jatti Khatti, among acid citrus group, recorded significantly least mean number of aphids per flush and can be effectively used in breeding programmes.

Various neem products were compared with copra oil, palm oil and 0.25% diazinon dust for protection of stored maize against the grain weevil, Sitophilus zeamais Motsch. Maize kernels treated with neem oil or ash were damaged less than the control. Although copra and palm kernel oil reduced S. zeamais attack, these edible oils were not as effective as neem oil. Neem wood ash was however, less effective than 0.25% diazinon dust. Neem derivatives inhibited oviposition and/or deterred feeding.

Steam-distilled floral oils (essences) from several species of Theobroma(Sterculiaceae) (T. cacao Linneaus, T. simiarum Donn. Smith, T. mammosum Cuatr. & Leon, and T. speciosum Willd.) were tested using McPhail traps, in an abandoned Costa Rican cocoa plantation to determine their levels of attraction for flying insects. In each of the three bioassays (two successive dry seasons and one intervening rainy season), the traps were inoculated with floral scents at 1, 10, and 100 ppm, while controls were inoculated with a 10% solution of chloroform solvent in distilled water. Of a total of 223 Diptera captured in all three bioassays, only 5% were found in the controls, indicating attraction to the floral oil. About 72% of all Diptera captured were Cecidomyiidae, of which three species, Mycodiplosis ligulata Gagne, Aphodiplosis triangularas (Felt.) and Ledomyia sp., comprised 59% of the total. Eighty-eight per cent of all midges captured were females. Only 7% of the total were known cocoa-pollinating midges of Ceratopogonidae, and all of these were females. Sixteen per cent were Phoridae, known pollinators of the allied genus Herrania in Costa Rica. Although the chemical composition of floral oils varies greatly among the species of Theobroma, no discernible differences were found in the attraction of midges to floral oils tested. While floral fragrances in Theobroma species may represent a generalized adaptation for dipteran pollination, small numbers of several species of Trigona bees (Hymenoptera: Apidae: Meliponinae) were also attracted to the floral oils.

Blister beetles have recently become the key pests of food crops in Mali and Senegal. The endemic areas of most destructive species, Psalydolytta fusca Oliv., P. vestita Duf., are situated in Northeast Mali and Central South Senegal. Host plants of certain species were identified. Light traps were used to study population dynamics of major species at Béma and Samé (Mali), and at Bambey, Gossas, Sokone and Nioro du rup (Senegal). Abundance of P. fusca and P. vestita populations in September–October generally coincided with sorghum and pearl millet flowering. Number of P. vestita beetles trapped was higher than that of P. fusca.