Four cultivars of maize, Zea mays L. viz., CM 600, Basilocal, CM 500 and Kisan were examined for their relative resistance to the maize stem borer, chilo partellus (Swinhoe) in relation to nutrition. Freshly hatched larvae of C. partellus were allowed to grow on the leaf whorls of the cultivars in the laboratory at 27 ±.2°C and 70–90% r.h. The rate of growth, food consumption and its utilization, egg laying and egg hatchability were studied. The insects showed better growth when fed CM 600 or Basilocal maize; this was shown by a higher percentage pupation (56.8 and 54.8, respectively on CM 600 and Basilocal) as compared to (24.4 and 5.6 respectively) on CM 500 and Kisan. Pupal weights were higher (40.2, 45.2, 34.4 and 32.8 mg for male pupae and 57.6, 63.7, 51.8 and 35.8 mg for female pupae), when larvae were reared on CM 600, Basilocal, CM 500 and Kisan, respectively. The growth index decreased from 1.65 on CM 600 and 1.49 on Basilocal to 0.40 on CM 500 and 0.09 on Kisan. A better consumption and utilization of the cultivars CM 600 and Basilocal was shown as also expressed by the higher weights attained by larvae grown on these two than on CM 500 and Kisan. Growth rate slowed down to 0.068 on CM 500 from 0.161 on CM 600 maize. A similar trend was observed in egg-laying and hatchability of eggs. Number of eggs laid per female decreased from 290 on CM 600 reared C. partellus to 157 on Kisan reared insects and none of the eggs laid by the latter could hatch. The degree of resistance of the cultivars to C. partellus on the basis of nutritional factors in a decreasing order is: Kisan > CM 500 > Basilocal > CM 600.

The title of the paper in Volume 14, No. 3, page 389, by Pushpinder J. Rup and Parvinder K. Kalra should be Antennal Morphology in the Developing Polyphenics of Lipaphis erysimi (Kalt.) (Hemiptera: Aphididae)

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.

Oryctes rhinoceros beetles were infected with an Indian isolate of Oryctes baculovirus and released into the wild population of O. rhinoceros in Minicoy island (India) for the biological suppression of rhinoceros beetle. The virus disease had established itself within 9 months and suppressed the pest population to low levels. Consequently pest damage to coconut palms also declined. A low level of pest population was maintained by the virus disease even after 3.5 years, following the introduction of Oryctes baculovirus into Minicoy island.

Ten sorghum genotypes at three plant growth stages were evaluated for antibiosis component of resistance to Peregrinus maidis expressed in terms of survival, duration and population build-up of nymphs as well as longevity and fecundity of adults. Support of nymphal survival and continued succession in mortality was evidenced on IS 18676, IS 18677 and IS 19349, indicating the influence of antibiosis factor(s) which again was supported by their prolonged duration. The growth index was consistently low at three plant growth stages on IS 18676 and IS 19349, but the genotype, IS 18677 did not express consistency on 45 days old plants. Greater longevity of adult females over males was consistent at different growth stages. Low fecundity was predominantly noticed on IS 18676, while reduced longevity was pronounced on IS 18677 and IS 19349 which was reflected in low population build-up at 15 and 30 days after infestation, when infested with 25 or 50 neonate nymphs. All these parameters contributed together suggest that antibiosis levels in IS 18676, IS 18677 and IS 19349 proportionately increased with plant age and the variability at different growth stages may be attributed to the differences in host genotypes and greatly aid as potential donors in resistance breeding programmes.

Two species of rice leaffolders, Cnaphalocrocis medinalis (Guenée) and Marasmia patnalis Bradley are usually found in association on rice plants in South and Southeast Asia. Larvae of the two species are similar in morphology, as is their feeding behaviour. Spinning, the process of stitching leaf margins together to form a leaf roll before the initiation of feeding process, is an important behaviour of leaffolder larvae. The spinning behaviour of two species of rice leaffolders was compared to find out if accurate differentiation between larvae of the two species is possible. The manner of spinning, average number of stitch bands made, average time spent to complete one band, order of spinning, number of turns taken by the larvae per band made, and feeding behaviour, while spinning a leaf roll were compared. The results revealed that the two leaffolder species have similar spinning behaviour.

Published information was used to compile a summary of natural enemies (parasitoids, predators and diseases) reported attacking Spodoptera litura (F) under field conditions. Species (71) of insect parasitoids in seven families of Hymenoptera and two families of Diptera were listed as parasitoids of different stages of S. litura. Predatory insects (36) belonging to 14 families and 12 species of spiders from six families have been reported to feed on this species. Four protozoan, four fungal, seven bacterial, four each of viral and nematode species were also reported to be the pathogens of this species. Published information suggested that periodic releases of large number of egg parasites could help in suppressing populations of this pest. There is a considerable scope for increased attention to the role of natural enemies as component of integrated pest management programmes of S. litura.

Autoradiographic studies using 3H uridine in the salivary glands of three bugs, Lethocerus indicus, Laccotrephes rubra and Antilochus coqueberti show that the nuclei play an important role in contributing RNA. The labelled materials are seen to move into the lumen from the epithelia. RNA shows a tendency to accumulate in the lumen with ascending incubation periods. This behaviour in conjunction with its nucleolar genesis indicates its nature as rRNA. It is also believed that RNA might conjugate with some of the protein available in the lumen to produce RNP.

The groundnut variety ICG 2271 is the most resistant to thrips In our conditions. Despite the existence of some differences between types, the number of thrips per flower In the cowpea is negatively correlated with the total number of flowers present per plant, the rate of pod formation, the internode and pod length, the pod number per plant and grain yield. It Is positively correlated with the percentage of flowers shed per plant.

In the pigeonpea, the characters linked to the number of thrips per flower vary with varieties. However, days to maturity and height at the same stage are more consistent.

The days to 50% flowering are positively correlated with the number of thrips per flower In the cowpea and pigeonpea.

Factors stimulating host seeking behaviour of Eocanthecona furcellata (Wolff), a pentatomid predator, were investigated by using Spodoptera litura (Lepidoptera: Noctuidae) as prey. Faeces of S. litura larvae elicited a host seeking response by the predators. The active material is present in the prey mandibular gland secretions, digestive tract and body surface, which when placed on a filter paper evoked feeding attempts. Predators responded intensely towards the prey artificial diet too. Prey body washings with hexane and acetone also stimulated feeding behaviour.

Physical stimuli such as host shape or movement had no influence on acceptability of the prey to the predator. Larval size correlated with aggressive behaviour which limited predation rather than releasing stimulus for the host acceptance behaviour. Pharate instar stage of the prey was never accepted by E. furcellata. But pupal, egg and adult stages of S. litura stimulated predators to certain extent.

Neither extirpation of antennae nor blinding the vision prevented the bugs from locating the prey. However, excision of rostral tip decreased the prey capture efficiency. It is suggested that the rostral tip contains chemotactile sensillae which are responsible for the prey detection.

The ability of males of Ephestia cautella to mate and transfer sperms aftergamma radiation as 5–6–day old pupae was investigated. The results indicate that gamma radiation had no significant effect on mating, sperm transfer and percentage of egg hatch.

Competition between larvae of Sitophilus oryzae (L.) and Sitotroga cerealella (Oliv.) within sorghum grains was studied at 30°C and 70% r.h. Newly hatched S. cerealella larvae (0 - 24 hr) were allowed to infest single sorghum grain having one S. oryzae egg deposited either on the endosperm half or the germ half. S. cerealella larvae were obtained from eggs of the same age as those of the weevil. The moth larvae entered the grain through the germ half. When S. oryzae egg was deposited in the germ half, S. cerealella survival probability was 0.78. However, when S. oryzae egg was deposited in the endosperm half, S. cerealella survival probability was 0.47. When the data for the two sites were combined the probability that the moth larvae will survive competition (P = 0.58) was not significantly different from that of the weevil. Hence, both larvae have similar chances of surviving competition within the sorghum grain.

Extracts of five plants, namely Argemone mexicana, Artemisia absinthium, Cassia occidentalis, Cymbopogon citratus and Siegesbeckia orientalis were tested for their antifeedant and insecticidal effects on third-instar larvae of the cabbage webworm, Crocidolomia binotalis, which is presently one of the most important pests of cruciferous crops in Mauritius. All the five plant species investigated showed significant antifeedant properties, with A. mexicana showing the highest control potential of the five plant species studied against C. binotalis.

Studies were conducted in Niger in 1986 and 1987 on the population dynamics and parasitism of the millet stem borer, Coniesta (= Haimbachia) ignefusalis (Hampson) (Lepidoptera:Pyralidae), Sesamia calamistis Hampson, and the millet head caterpillar, Heliocheilus albipunctella de Joannis (Lepidoptera: Noctuidae). Planting dates were assessed for effects on population densities of C. ignefusalis and H. albipunctella. Population densities of C. ignefusalis were not reduced by adjusting millet planting dates, but were affected by millet growth stage. Platytelenomus sp. (Hymenoptera: Scelionidae) was the most common parasite of C. ignefusalis on millet. Parasitism of C. ignefusalis larvae and pupae was rare. Sesamia calamistis was a minor pest of millet in Niger, and was rarely parasitized. Population densities of H. albipunctella were reduced by delaying millet planting dates. Bracon hebetor (Hymenoptera: Braconidae) was the most common parasite of H. albipunctella.

This short communication describes the morphological features of three specimens of Hyalomma truncatum which dropped off artificially infested rabbits in the laboratory.

Studies involved the evaluation of two types of pyrethroids and two controls in a single study village settlement. A total of 1277 bednets were distributed to 75% of 420 houses in the village, in July 1989, 378 were treated with lambda cyhalothrin (Icon°), 411 with deltamethrin and 331 were untreated. A total of 336 people were not given any nets. Entomological evaluation showed that both pyrethroids have an excito-repellent and lethal effect on mosquito vector species. In assessment of malaria reduction in children as the target group, those sleeping in deltamethrin treated houses showed a greater reduction in parasite rate than those sleeping in lambda cyhalothrin nets: Overall reduction of malaria parasite rate of school children examined was 68%. Biological efficacy in both pyrethroid treated nets persisted over a period of 6 months. Another added advantage was that the individual using the net was protected against mosquitoes and other pests such as cockroaches, fleas, lice and bedbugs. Incorporation of pyrethroid impregnated nets in malaria control programmes involving community participation is recommended.

Population of Spodoptera litura F. were monitored through pheromone-baited traps during the rainy season 1988 and 1989 in groundnut fields in relation to oviposition on leaves. Four peaks of adult catches were recorded. First and second peaks were smaller and caused no threat to crop. Third peak was observed at the pegging and pod-initiation stage during first week of September and coincided with the greatest oviposition on leaves. The fourth peak was greatest and occurred between 40th and 43rd standard week. However, no oviposition was recorded on groundnut during this period. The moths possibly dispersed and/or migrated to other areas with crops at an appropriate stage of susceptibility.

The Insect Rearing Management (IRM) system was used to rear the black lyre leafroller, Cnephasia jactatana (Walker) (Lepidoptera: Tortricidae). The results obtained include life cycle development at various temperatures, application of “day-degrees” in manipulating the life cycle, and use of low temperature for storage of life stages. IRM is a valuable system for regulating production of different life stages as it produces insects of specified quality as required. IRM can be adapted for rearing facilities which handle multiple-species rearing.

Studies on cannibalism by Heliothis armigera (Hubn.) larvae on nuclear polyhedrosis virus (NPV)-infected larvae and feeding on virosed cadavers indicated that feeding was significantly higher on 4-day-old virosed cadavers followed by 1-day-old cadavers than on healthy or NPV-infected living larvae. The data revealed that cannibalism was significantly higher on NPV-infected (3 days post inoculation) larvae than either healthy larvae or those which had been just inoculated. However, the extent of feeding was higher on healthy larvae (cannibalistic feeding) than on cadavers. Significantly more number of larvae became infected by NPV when they fed on NPV-killed cadavers than on NPV-infected living larvae. Some of the larvae which had fed on either virosed cadavers or NPV-infected larvae survived. But, the disease was expressed in the pupal stage. Pupal mortality was significantly higher in larvae which fed on NPV-inoculated larvae (3 days post inoculation). The multiple choice test to find out the feeding preference of the larvae showed that the larvae had a greater preference to feed on virosed cadavers than either the healthy larvae or the host plant. The role of cannibalistic behaviour in the dissemination of the virus disease under field conditions is discussed.