Heliothis armigera (Hubner) completed five generations in the laboratory, as well as in the field, in a year. The first generation was completed from the first week of December to the fourth week of February, the second generation from the second week of February to first week of April. The third generation from third week of August passing through the extreme summer, the fourth generation during monsoon period and the fifth last generation from the third week of September to the fourth week of November. The seasonal variation in generation time is largely due to extreme variations in ecological factors, temperature (10–45°C), photoperiod (10–14 hr), relative humidity (15–95%) and rainfall. These factors also affect the percentage of pupation, emergence and fecundity of the female moths. Males outnumbered the females in the first, second and fifth generation. The females lived longer than males in all generations.

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.

The cotton boll worm, Heliothis armigera Hbn, was grown under standard conditions. Parameters are given for identification of larval instars on the basis of head capsule width. Intrastadial weight of larvae in terms of fresh weight is presented for a regular time interval of 12 hr. The maximum larval growth in all the stadia was observed in the first 24 hr after the preceding moult. Weight of larvae was almost constant in the last quarter of the stadium, till they moulted into the next. Although the last instar larvae gained maximum weight amongst all the stadia, their actual growth was minimum. First instar larvae recorded a 13 times increase in body weight in comparison to the last instar larvae with 3.9 times. Fifth instar larvae entered into the prepupal stage after they had completed an age of 60 hr. Temperature had a profound influence on the incubation period of eggs; the higher the temperature, the shorter it was. Between 28 and 36°C the incubation period was almost the same. The maximum tolerance level of constant temperature for the eggs of Heliothis armigera was 37°C.

Based on a semi-synthetic diet, a standard rearing method for the cotton bollworm, Hetiothis armigera Hübner, is described. The diet is composed of chickpea (Cicer arietinum) flour, yeast powder, sucrose, ascorbic acid, cholesterol, choiine chloride, wheat germ oil, vitamin mixture and a combination of preservatives. A plastic container for individual rearing of the cannibalistic larvae and a cage for mating of adult moths are described. After inoculation with the neonate larvae, development of the different stages was synchronouson this diet. The larval and pupal development period was 14.3 ± 1.2 and 11.7 ± 0.82 days, respectively. Females reared on this diet produced an average of 2000 eggs. Adult longevity was 22 days. The female moths retained their oviposition rhythm even after 3 years of laboratory rearing. A method for introduction of wild populations into the laboratory culture is discussed. The reliability of the technique was checked by monitoring the insects' performance for at least 25 generations.

Commercial cotton growing in the Sudan dates from 1867. At present, about 400,000 ha of various cotton cultivars are grown under different irrigation systems. The production of this main cash crop has been faced with a multitude of entomological and pathological problems, some of which were tackled through the adoption of specific cultural practices or enforcement of legislative regulations.

When cotton treatment with synthetic organic insecticides was initiated in the mid 1940s against Empoasca lybica de Berg, the impressive preliminary results have encouraged over-reliance on chemical control at the expense of other measures. This rather limited approach of control strategy has contributed partially to the appearance of new pests in damaging levels e.g. Heliothis armigera (Hbn.), Bemisia tabaci (Genn), Aphis gossypii (Glov) and Spodoptera littoralis. The principal measure for their control is insecticide application.

The cost of crop protection soared to ten-fold during the last 20 years. The annual number of sprays applied to cotton increased from one to seven sprays. To overcome the ever increasing use and high costs of pesticides on cotton growing, the Agricultural Research Corporation undertook intensive research programmes to find answers to major crop protection problems. Since 1978 researchers are directing their efforts towards the development and implementation of integrated pest management strategies to include cultural and legislative measures, as well as the use of more selective insecticides.

An experimental microspodiosis has been stimulated within Heliothis armigera (Lepidoptera, Noctuidae). The microsporidian used was Nosema manierae, a natural parasite of Chilo zacconius (Lepidoptera, Pyralidae). Nosema manierae causes high mortality in the larvae and the nymphs.

Nineteen accessions from seven Lycopersicon species were bioassayed for their resistance to Heliothis armigera (Hübner) (Lepidoptera: Noctuidae) in laboratory tests at 29 ± 1°C and 65 ± 2% r.h. Data on larval developmental duration (days), survival (%) and pupal weights (mg) revealed that maximum resistance to H. armigera occurred in accessions of L. hirsutum f. glabratum and L. hirsutum. When the larvae were fed on the foliage of PI 134417 and PI 126449 accessions (L. hirsutum f. glabratum), the developmental time was longer, and survival rate and pupal weights were lower than when the larvae were fed on cultivars of L. esculentum. Rearing of H. armigera larvae through third instar is sufficient to evaluate the resistance of wild tomato foliage since most of the larval mortality occurs prior to this stage. Accessions of L. peruvianum, L. chilense, L. cheesmanii and L. pimpinellifolium proved less resistant than L. hirsutum f. glabratum and L. hirsutum but significantly more resistant than L. esculentum. Thus, among the various Lycopersicon spp. bioassayed, accessions of L. hirsutum f. glabratum seem to have most potential for breeding H. armigera resistant cultivars.

As a background to an IPM project, this paper describes pesticide treatment of cotton in Sudan Gezira, starting in 1945/46. Until the end of the 1950's, one treatment per season was sufficient to control the only important pest, the jassid, Empoasca lybica, but the number of treatments increased during the 1960's (from 3 to 5) and has since the early 1970's been 6–9.

The continuous use of pesticides has resulted in changes of the pest complex, ultimately creating “hyper” pests such as the whitefly (Bemisia tabaci), cotton bollworm (Heliothis armigera) and aphids (Aphis gossypii). The increase in number of applications of pesticide is coupled with the rising costs of pest control and a stagnant yield. The stickiness problem created by the honey dew of whitefly and aphids increased with the rising number of sprays. The exclusive use of chemical control not only failed to improve the quality or quantity of the yield, but put a great strain on the national economy as well.

The Sudan therefore requested the FAO to initiate an IPM project starting in 1979, with financial support from the Netherlands. During the past 2 years support has also been given by the World Bank. The IPM approach has given very valuable results during the last two seasons when large (more than 100 acres) plots in the Gezira and Rahad Schemes were left unsprayed with the objective of investigating the potential of the natural enemies in the absence of pesticides, and to compare findings with population trends of pest and beneficial organisms in the fields subjected to conventional chemical control.

The first significant finding was that Bemisia tabaci and Aphis gossypii can be managed at desirable levels by their indigenous natural enemies, and that their outbreaks are attributed to the decimation of these natural enemies by chemical treatment. Populations of beneficial arthropods were consistently much lower in the fields which received regular pesticide applications.

The result of the large-scale experiments indicate that Empoasca lybica is the only really damaging pest (“key pest”) in the Gezira because of the absence of natural enemies to regulate its population. Control of E. lybica in the 1940's and 1950's resulted in the creation of Heliothis armigera as a major pest. This situation necessitated early season applications of pesticides to suppress H. armigera, which further reduced the role of the natural enemies of B. tabaci and A. gossypii. Both have developed into major pests of regular occurrence.

Cotton farmers in Gezira are now faced with a complex of very serious pests. In order to solve this problem, we will have to make drastic changes in pest control strategies and to adopt an IPM approach as soon as possible. The biological control H. armigera is considered as first priority in order to avoid the early season application of pesticides. Trichogramma pretiosum was introduced from the USA and released in the Rahad Scheme in 1988/89. The preliminary results are very promising.

Cultural and biological control of E. lybica will be attempted in order to further reduce pesticide applications. The control of this pest by the use of “milder” pesticides is also included in the programme.

The presently used threshold levels for all major pests are very low, and are under revision through properly conducted large-scale experiments.

Light and pheromone traps were compared for their relative efficiecy and importance in monitoring the Heliothis armigera (Hubner) moths at the farm of Rajasthan Agriculture University, Udaipur, Rajasthan, India, during the years 1984/85 (4 June 1984 to 3 June 1985) and 1985/86 (4 June 1985 to 3 June 1986). Both kinds of traps showed three periods of moth activity during both the cropping years. Both types of traps showed almost a similar trend in population fluctuation during the cropping years and there were significant positive correlations between light and pheromone trap catches, (r=0.87 for 1984/85 and r=0.93 for 1985/86). However, pheromone traps had many advantages over light trap in monitoring the Heliothis armigera moths.

Laboratory bioassay tests showed that Bacillus thuringiensis (B.t.) (Bactospeine) treatment of second instar larvae of Heliothis armigera (Hbn.) and Spodoptera litura F. increased their susceptibility to endosulfan, monocrotophos, fenvalerate and cypermethrin. The LC50 of these insecticides to both the species of larvae were lowered when treated with B.t. Comparison of susceptibility ratios showed that the increased susceptibility to insecticides was more in H. armigera than in S. litura larvae.

Oviposition behaviour of the cotton bollworm, Heliothis armigera, and its relation to day-night cycle was examined under laboratory conditions. Eggs were laid both in large quantities of clumped eggs at one place, and singly distributed in the oviposition cage, always glued on the substrate. The maximum individual life time fecundity recorded was 3080, and the highest number of eggs delivered in 1 day was 949. The mean pre-oviposition period was 2.9 days. Peak fecundity occurred between days 5–9 and the highest mating frequency from days 4–6 after emergence. Maximum age for egg laying was 29 days, average life expectancy was 22 days, with longest individual survival of 32 days. Male longevity did not vary from that of females. There was a significant difference in the longevity of mated and virgin females; the mated females lived for a shorter time but produced a significantly higher number of eggs. Also, mating induced a sudden surge in oviposition. Almost 90% of the total eggs were laid in the darkness. Out of them, 60% were from the first and 30% from the second half of the dark period.

Eight desi chickpea genotypes of mid-maturity group were screened by using an open-field screening technique. The genotypes ICC-3137, K-850 and ICC-1403 were found to be more susceptible than the others. More eggs were laid and more larvae were recorded on more susceptible genotypes. A low amount of acidity in the leaf extracts of genotypes was found to be associated with susceptibility to gram pod borer, Heliothis armigera (Hubner).

Per cent survival, larval period and weight, pupal duration and weight, emergence, adult longevity and fecundity of Heliothis armigera (Hubner) were affected by the pulse species on which it was reared. The pulses could be classified into two groups i.e. pigeon pea and chick pea which were suitable for growth, development and fecundity and black gram, sweet pea, green gram, broad bean and lentil which were unsuitable.

Several insects attack the groundnut, which is a major crop in Senegal. Sporadic attacks of Heliothis ( = Helicoverpa) armigera Hbn. and other insects have been recently noted. In order to reduce the pest attack, neem cake extract (1 and 3%) was compared with cypermethrin and a mixture of dimethoate and deltamethrin and gave satisfactory results. However, yield was not significantly increased.

A field evaluation of nine chemicals was conducted at Cotton Research Station Kibos for their efficacy against bollworm and cotton stainer species attacking cotton in Kenya. Based on the yield and percentage stained seed cotton, Decis'Triazophos, pp 321 Karate and Baythroid and Decis were the most effective insecticides in 1985 and 1986 respectively. However, there was no consistency in results of performance of insecticides tested against cotton insects in the 2 years. The apparent poor performance of most insecticides tested against cotton insects was attributed to fixed insecticide spray schedule which resulted in superfluous and often mistimed chemical applications. It is therefore necessary to establish damaging threshold(s) of major cotton pests in this country so that chemicals can be efficiently used to control them with minimum adverse effects on our environment.

Pearl millet, sorghum, maize and cowpea are important food crops in dryland areas of the Sahel. Losses caused by insects on these low input crops are variable but generally substantial. Basic information on the role of natural enemies is scant. An example of a recent applied research which is mainly directed towards the management of millet earhead caterpillar, Raghuva albipunctella Joannis is narrated. Results of a study initiated on conservation and encouragement of Bracon hebetor Say against Raghuva in a traditional village environment are highlighted. These results demonstrate that such an approach of biological control has a place in even the temporary, already fragile agro-ecosystems and in habitats of low durational stability in the drought-hit Sahel.

Extensive additional base field data have been assembled since 1981 on the natural enemies of other pests, including Heliothis armigera (Hb.) in Senegal. Based on these results, the scope of conservation and encouragement on natural enemies in the Sahelian zone is discussed. Future research, development and training needs, for both short and more importantly long-term planning in this important aspect of pest management are briefly mentioned.

Growth and reproduction in Heliothis armigera is known to be controlled by temperature, relative humidity and host plants. Photoperiod was also found to be an important extrinsic factor regulating the different biological aspects of H. armigera. The effect of five alternating light and dark cycles on the adult as well as on the immature stages of this pest was studied at 25 ± 2°C.

The results obtained showed that the photoperiod regimes tested on the adult stage has a high significant effect on reproduction and longevity. Also 16 hr photoperiod was the most suitable condition for maximum egg deposition and maximum percentage of egg hatching.

The immature photoperiod regimes had a high significant effect on the larval duration, pupal weight and percentage of emergence of adults, but had no effect on the pupal duration. Combined effect of immature and adult photoperiod regimes affected greatly the fecundity and longevity of the adults.

The location of olfactory and gustatory sense organs in the larvae of the American bollworm, Heliothis armigera, have been studied using the scanning and transmission electron microscopy. The olfactory chemoreceptors of the larvae are located on the antennae, mostly on the top of the second antennal segment in the form of two trichoid sensilla, two basiconic sensilla, two styloconic sensilla, campaniform sensilla and a uniporous peg sensillum. The third antennal segment bears one basiconic sensillum and two styloconic sensilla. The gustatory sense organs are located on the mouthparts including the labrum, mandibles, hypopharynx, maxillary palps and labium. Trichoid sensilla have been located on the labrum. Epipharyngeal setae as well as long short spines are located in the epipharyngeal membrane. The basal segment of the maxillary palp bears three trichoid sensilla and one campaniform sensilla. The maxillary palp also bears four styloconic sensilla on the distal portion of the lateral protuberance and one styloconic sensillum at the apex of the medial protuberance. Close to the bases of the protuberances, there are three basiconic sensilla and one campaniform sensillum. The third apical segment of the maxillary palp carries three campaniform sensilla on its lateral side, while on its top, eight small basiconic sensilla are distributed.

Tests on the quantitative adsorption of polyhedra of nuclear polyhedrosis virus of Heliothis armigera to black and red soil showed an increase in the adsorption of polyhedra with an increase in the amount of soil. The increase was higher in the red soil than black soil, but the number of polyhedra adsorbed per unit weight of soil decreased as the amount of soil increased; the rate of decrease being faster in black soil than in red soil. The adsorption of polyhedra of nuclear polyhedrosis virus of Heliothis armigera is discussed based on certain physico-chemical properties of both red and black soils.

In tomato, infestation by the natural population of the fruit borer, Heliothis armigera (Hubner), on number basis was positively correlated with infestation on weight basis. Infestation was negatively correlated with the number of flowers per inflorescence. Surface texture of calyx also affected the susceptibility of the genotype. Reducing sugars in fruits were positively correlated, while zinc and iron content in foliage and ascorbic acid contents in fruits were negatively correlated with degree of infestation. Coefficient of determination revealed that 87% variability in borer infestation was due to zinc, iron, ascorbic acid and reducing sugar content.