Spodoptera littoralis (Boisd) is globally recognized as a destructive polyphagous insect pest of various crops in the world. It is commonly managed by chemical pesticides, which can cause deleterious effects such as environmental pollution, toxicity to non-target organisms and the emergence of secondary pests. Hence, investigations into alternative pest control strategies such as the use of resistant host plant cultivar against S. littoralis is important. This study aimed to explore the nutritional performance of S. littoralis larvae in dependence on total anthocyanin, flavonoid, and phenol levels across 11 bean cultivars (Phaseolus and Vigna spp.) under laboratory conditions. The results revealed that the Mashhad cultivar accumulated the highest amount of total phenols (13.59 mg ml−1), whereas Yaghout and Arabi cultivars posed the lowest total phenols contents (1.80 and 1.90 mg ml−1, respectively). Across larval instars (third to sixth), the highest consumption index and relative consumption rate were recorded on the Mashhad cultivar. The lowest values of efficiency of conversion of ingested food and the efficiency of conversion of digested food of total larval instars were detected in the larvae which were reared on the Mashhad cultivar. Likewise, the lowest value of the index of plant quality (IPQ) was obtained in the Mashhad cultivar; however, IPQ was figured out at the highest level in the Arabi cultivar. Our findings show that the differential accumulation of secondary metabolites would change the nutritional quality of plants for S. littoralis. Based on the findings, the Mashhad cultivar may serve as a candidate for either integrated pest management or breeding programs aiming at controlling this pest.

The effects of different prey regimes on the performance and digestive physiology of the spined soldier bug, Podisus maculiventris (Say) (Hemiptera: Pentatomidae), were assessed. Specifically, P. maculiventris nymphs were fed on Colorado potato beetle (CPB), Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae), larvae; Egyptian cotton leafworm (ECW); Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae); larvae; Calliphora spp. (CAL) (Diptera: Calliphoridae) pupae or a mixture of the three prey. No differences in development and weight gain were observed when P. maculiventris nymphs were fed different prey species (CPB, ECW or CAL). However, an increase in weight gain and a reduction in the duration of the stadia were observed for nymphs fed with a mixture of the three prey. To investigate the physiological background, biochemical analysis were carried out on insects dissected at the end of the feeding assay. We have found that the proteolytic activity in the salivary glands of P. maculiventris nymphs was not affected by prey species, whereas the relative activity of these proteases in the midgut depends on the prey. Moreover, gel assays proved that the proteolytic profiles of midguts from P. maculiventris nymphs feeding on CPB, ECW and CPB closely resembled those of their prey. All together, these results suggest that P. maculiventris may utilize enzymes from the prey they consume that may facilitate the process of digestion.

Environmental risks associated with the use of non-indigenous organisms for augmentative biological control have received growing attention. In Europe, the native pentatomid predator Picromerus bidens (Linnaeus) has been considered a potential alternative to the North American pentatomid Podisus maculiventris (Say) for the control of lepidopteran, coleopteran and hymenopteran defoliator pests. In the current study, prey consumption and developmental duration of the predatory stages of P. bidens and P. maculiventris were investigated at three temperatures (18, 23 and 27°C) in the laboratory using caterpillars of Spodoptera littoralis as prey. Development time from second to fifth instar was longer for P. bidens than for P. maculiventris, taking on average 17–44 and 14–32 days, respectively, at the different temperatures. Total nymphal consumption of fourth instar S. littoralis caterpillars indicated a greater voracity of P. bidens as compared with P. maculiventris at both the low and high temperatures tested (18 and 27°C). At 23°C, however, the predation rate of P. maculiventris nymphs exceeded that of P. bidens nymphs. Effect of temperature on the functional response of P. bidens to densities of fourth instar Spodoptera exigua was assessed on potted green bean plants. Female adults of P. bidens exhibited a type II functional response at 18 and 23°C but a type III response at 27°C. Searching efficiency was not affected by temperature but handling time decreased from 4.2 to 1.4 h as temperature increased from 18 to 23°C. However, the predator spent twice as much time handling prey at 27°C (2.9 h) than at 23°C. This study indicates high predation rates of P. bidens at a wide range of temperatures and suggests that the species may be a valuable asset for the biological control of defoliating caterpillars, provided that obstacles to its mass production can be overcome.

The antifeedant activities of Piper guineense Schum et Thonn (Piperaceae), Aframomum melegueta (Rosk) K. Schum (Zingiberaceae), Aframomum citratum (Pareira) K. Schum (Zingiberaceae) and Afrostyrax kamerunensis Perkins and Gilg (Huaceae) seed extracts were investigated in laboratory dual- and no-choice bioassays using third-instar Spodoptera littoralis (Boisduval) larvae. In the dual-choice test, the hexane and methanol extracts of A. melegueta showed potent dose-dependent antifeedant activity at concentrations of ≥300 ppm and the water extract at ≥500 ppm, as illustrated by significantly lower leaf consumptions. Aframomum citratum methanol and water extracts exhibited antifeedant activity at ≥300 and ≥1000 ppm, respectively, but the hexane and ethanol extracts did not affect feeding at any concentration. Piper guineense ethanol and water extracts showed dose-dependent antifeedant effects at ≥300 and ≥500 ppm, respectively, and the methanol extract was active only at 1000 ppm. None of the extracts of the highly aromatic A. kamerunensis exhibited antifeedant activity at any of the tested concentrations. In the no-choice bioassays, extracts with antifeedant activity in the dual-choice tests also showed dose-dependent feeding inhibition. The hexane and methanol extracts of A. melegueta were effective in the no-choice tests at ≥100 and ≥500 ppm, respectively, and the water extract at ≥300 ppm. Similarly, the A. citratum water and methanol extracts were active at ≥500 ppm and the P. guineense water and ethanol extracts at ≥100 ppm. GC/MS chromatography of A. melegueta hexane and methanol extracts revealed volatile constituents with known anti-insect activity. The hexane and methanol extracts of A. melegueta, the methanol extract of A. citratum and the water and ethanol extracts of P. guineense may have potential for use by subsistence farmers.

Eggs and larvae of Microplitis rufiventris Kok. (Braconidae: Hymenoptera) were exposed to two sublethal concentrations (0.2 and 0.4 ppm) of the chitin synthesis inhibitor lefenuron, by feeding treated artificial diet to their hosts, Spodoptera littoralis (Boisd.) (Noctuidae: Lepidoptera) larvae. Each concentration was initiated during the egg stage or different instars of the parasitoid larvae. Between 4.3 and 33.8% of parasitoid larvae in lefenuron-treated hosts showed morphological and developmental abnormalities. The effect of the compound on the developmental rate and sensitivity of the parasitoid larvae varied according to the parasitoids' age at treatment; the egg stage and older parasitoid larvae were more tolerant to the compound than the first instars. In all treated hosts the developmental rate of the parasitoid was lower than that of controls. The lower lefenuron concentration (0.2 ppm) was more effective at disrupting the development of young parasitoid larvae than the higher one. Delayed or latent effects of the compound were evident in non-emergence of parasitoid adults that were exposed to the compound as first instars. Reduced sensitivity of old parasitoid larvae could be compatible with survival of the parasitoid in integrated control programme of S. littoralis.

Gas-liquid chromatography was used to analyse the saponifiable and unsaponifiable fractions of petroleum ether (PE) extracts of neem fruits and leaves. Both fractions, as well as a crude PE extract, were assayed for biological activity against third instar cotton leafworm, Spodoptera littoralis.

In neem fruits, eighty-eight percent (88%) of the saponifiable matter consisted of saturated fatty acids, while 12% was composed of unsaturated fatty acids. In the neem leaves, the corresponding proportions were 62 and 38%, respectively. Unsaponifiable matter of both fruits and leaves contained varying amounts of hydrocarbons and sterols. All the tested extracts demonstrated significant larvicidal effects against leafworm larvae. They also prolonged larval duration, caused malformations of the resulting pupae and significant adverse effects on the fecundity of resulting adults.

The chitin synthesis inhibitor lefenuron [N-{2,5-dichloro-4-(1, 1, 2, 3, 3, 3-hexafluoropropoxy)-phenylaminocarbonyl}-2, 6-difluorobenzamide] was found to have a negative effect on the encapsulation responses of Spodoptera littoralis larvae towards supernumeraries of Microplitis rufiventris parasitoid. Superparasitised hosts fed on compound-free diet showed strong encapsulation reaction (ca. 40.8%) to surplus parasitoid larvae having scars of physical combat. Treated hosts exhibited a significant reduction in either capsule thickness or encapsulation rate to the excess parasitoid larvae. Even when a capsule was formed, it had a thinner haemocy tic layer than tha t of control hosts. Studies on the differential haemocyte counts showed that failure of treated larvae to encapsulate injured surplus parasitoid larvae could be attributed to the following factors: (1) disturbance in plasmatocytes-granular cells (GR) ratio, e.g. abnormal increase in GR levels possibly causing faint haemocytic reaction to injured parasitoid larva(e); (2) the parasitoid surface becoming less attractive to the granulocytes and plasmatocytes; (3) the haemocytes involved in capsule formation (granulocytes, plasmatocytes) losing their ability to spread out over the surface of parasitoid larvae; and (4) the blood cells of the treated host failing to recognise wounded larvae as foreign bodies. Reduced encapsulation capacity might be due to a secondary effect(s) of IGR treatment inducing a suppression of adhesive activity of the plasmatocytes. These results may be useful for improving our understanding of insect immune reaction and/or manipulating parasitoids activity against nonhabitual Parasitoida.

Margosan-O®, a commercial neem-based insecticide, incorporated into an artificial diet prolonged the development of larvae of Spodoptera littoralis Boisduval. It also affected the rate of adult emergence at the end of pupation. Larvae treated during one stadium continued to show the effects of their previous exposure. The susceptibility to Margosan-O was more pronounced when larvae ate the diets containing Margosan-O for the first time during the fifth or sixth instar. The results indicate that Margosan-O has an activity similar to that of other neem-seed extracts. In the course of this work morphological anomalies were also recorded. The most striking was the appearance of black stripes on the abdominal tergites of the fifth and sixth instar larvae fed on diets containing 0.01, 0.05 or 0.1% of Margosan-O.

Successive extraction of the green alga, Scenedesmus acutus 276–3a with different solvents indicated that the petroleum ether extract was the most repellent to the hatched larvae of Spodoptera littoralis. The application of spray emulsified 1 % petroleum ether extract inhibited egg laying. At 0.25% concentration the moths laid only 52.4 of their egg masses on the treated oviposition sites in comparison to the untreated control. Concentration of 1% was protective against the immature stage by hindering the third instar larvae to feed on treated leaf discs. In addition, the water emulsion of petroleum ether extract was insecticidal. The percentage mortality was directly proportional to the concentration applied and to the duration of exposure.

An additive effect was obtained after treatment of Spodoptera littoralis (Boisd.) larvae with a combination of Bacillus thuringiensis and nuclear polyhedrosis virus (NPVs). The NPVs was the more pathogenic followed by B. t., cytopathologically. Simultaneous application of B. t. and NPVs affected the midgut cells by causing a very specific appearance of cell hypertrophy with some deposits of B. t. crystals on the fourth day of infection as shown by scanning electron microscopy. Transmission electron microscopy showed that the vegetative cells and spores of B. t. entered the midgut epithelial cells followed by the virus. It is possible that the initial destruction caused by the B. t. toxin facilitated penetration and entry of the virus.

Rates of virus-induced mortality and values of the LC50 and LT50 showed that, in general, parasitism by Microptitis rufiventris Kok. increased the susceptibility of the Egyptian cotton leafworm, Spodoptera littoralis second-instar larvae to its nuclear polyhedrosis virus (SLNPV). By comparing the LC50 values, data revealed that virus-infected parasitized larvae were ca. 3.5 and 4.8 times more susceptible to SLNPV than virus-infected unparasitized ones at 8 and 12 days post-infection, respectively. Also, in virus-infected unparasitized larvae, the time required to attain a 50% mortality was significantly longer than that in virus-infected parasitized ones.

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.

Bioassays against the fourth instar larvae of mosquito, Culex pipiens pipiens showed that the non polar part of the duck weed, Lemna minor extracts has a high insecticidal action. On the other hand, these extracts contained synomones of the duck weed which repelled the ovipositing females. By using concentrations equivalent to LC25, the survival resulting by the n. hexane was the least. The tolerance for the sublethal doses was associated with malformations in all stages. First instar larvae and recent pupae were more susceptible to the duck weed synomones than the other larval instars. The duck weed synomones repelled the ovipositing females of Piophila casei and have had an insecticidal effect on larvae and reduced resulting adults. When larvae of Spodoptera littoralis were subjected to sublethal doses of duck weed extract, malformations in the subsequent stages were found.

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.

A range of materials were collected from a number of ecological and environmental zones within Kenya as being likely sources of entomopathogenic bacteria. These were soils, insect frass and dead insect material. Using an isolation protocol involving use of a selective medium, over 150 Bacillus thuringiensis (B. t.) strains were recovered from the sample material. Their identity as B. t. strains was confirmed by their growth characteristics, morphology and presence of a parasporal delta-endotoxin crystal.

All strains were screened for activity against two Lepidopteran pest species, the spotted stem borer, Chilo partellus and the African army worm, Spodoptera exempta. Isolates causing over 80% mortality in the screening assays were retained for further evaluation. The selected isolates were subjected to bioassay against C. partellus and S. littoralis. Following bioassay, the most toxic isolates were selected for screenhouse trials against C. partellus and field trials against a natural outbreak of S. exempta.

In the screenhouse trials all of the B. t. treated plants showed reduced levels of damage and yields were 5 to 7 times higher than the yield obtained from the untreated, infested control plots. Three isolates, A-3, A-C-2 (isolated from insect material) and M-44–2 (isolated from soil) seemed to offer superior levels of protection. Two new B. t. isolates, K-26–21 and MF-4B-2, both isolated from soils, showed high levels of toxicity to S. littoralis and S. exempta in the laboratory. When isolate K-26–21 was applied to maize seedlings in the field, almost total control of the larval population was achieved within 48 hr at each of the concentration levels tested.

Investigations have been made to evaluate the development of Spodoptera littoralis as affected by feeding on a standard artificial diet containing powder of some plant species known to be resistant to the infestation of this insect. Trials were also made to find out whether the effect of these plants facilitate the potency of Bacillus thuringiensis var entomocidus HD-635 vs. the target insect. The results revealed that powders of pomegranate peel, guava leaves and lemon grass, greatly affected the insect development in terms of larval duration, larval and pupal weights, deformities in pupae and moths, percentage of emergence, egg production and hatching. This may be correlated to the chemical constituents of these plants. A marked increase was observed in the potency of B. thuringiensis endotoxin preparation vs. S. littoralis when combined with some of the tested powdered plants or its extracts but in varying degrees.

A nuclear polyhedrosis virus isolated from the Egyptian cotton leafworm, Spodoptera littoralis, was found to infect termite castes of Kalotermes flavicollis. Laboratory studies indicated that no specific trend toward mortality responses among the different individuals of termites was noted. All test castes of termites, young, middle-sized, old and reproductive nymphs, and soldiers, were quite equal in their response to the virus infection, regardless of whether the virus concentration was high or low; a concentration of 6.4 × 108 polyhedra/ml, killed only 64% of the treated individuals, while the dosage of 6.4 × 107 polyhedra/ml produced over 90% mortality. Also, thesame trend of response was recorded with the survivors which received challenge doses of NPV suspension each 9 or 10 days. On the other hand, these results revealed that if the NPV is used to control termites, periodic applications would be more efficacious thanone treatment. Virus symptoms were recorded in all affected insects.

The most important cotton pests in Egypt are the Egyptian cotton leafworm, Spodoptera littoralis, and the pink bollworm, Pectinophora gossypiella, together with localized infestations of spiny bollworm, Earias insulana.

Control of S. littoralis is achieved by the hand collection of egg-masses every 3 days during the early part of the cotton season by teams of children. Alternative control techniques currently being investigated include the use of microbial pesticides and insect growth regulators.

Large scale commercial applications of slow-release pheromone formulations are used to control P. gossypiella by the mating disruption technique as an alternative to four or five sprays of conventional pesticides. Similar pheromone formulations are being developed for control of E. insulana, which occurs towards the end of the cotton season.

As a result of using such a combination of selective control methods, beneficial insect populations have remained at high levels throughout the season and acceptable levels of infestation have been achieved associated with relatively few applications of conventional pesticides.

The relative activity of three concentrations of Spodoptera littoralis nuclear polyhedrosis virus (SLNPV) against Ceratitis capitata were determined by (a) submerging two egg age groups, freshly laid eggs (0–2.5 hr) and more older ones (0–24 hr) in viral concentrations, and (b) feeding newly hatched larvae on viral contaminated media. Pupations that resulted from all viral treatments were decreased with increase of virus dose. Hatchability showed the same relation, but hatchability of treated old eggs were not significantly influenced by increases in viral concentration. Adult emergence was significantly reduced due to viral treatments to eggs, however, it was increased in the case of feeding the larvae on contaminated diet. The most hypothetical probability of this deleterious effect may be attributed to an activation of an indigenous virus already present in C. capitata. More research is required to understand the basis for the deleterious effect of SLNPV on the fruit fly.

Nosema sp. naturally occurred in both Spodoptera littoralis (Boisd.) and S. exigua (Hübner) laboratory colonies in Alexandria, Egypt (since November 1984). It was responsible for the dramatic suppression of their laboratory populations. Both young (3-day-old) and old (9-day-old) larvae of S. littoralis were susceptible to Nosema sp. However, the pathogen was more effective against the young larvae, especially at high doses, than the old ones. The estimated LC50 was 4.0 × 107 spores'ml, for 3-day-old larvae. The slope value was low (1.2) as typical of protozoan insect pathogens. Heavily infected 9-day-old larvae tended to die as larvae; while less infected ones either pupate or produce larval-pupal intermediate forms (12–23%). The developmental period of both infected larvae and pupae was increased by 4–6 and 3–5 days, respectively. The number of infected insects that reached the adult stage was decreased as the concentration of Nosema sp. spores was increased. Furthermore, infection was shown to reduce adult longevity and fecundity, and viability of the eggs. Larval faecal pellets harboured large numbers of viable spores. Transovum transmission of infection occurred. Two dipterous species, Culex pipiens and Aedes aegypti, were not susceptible to Nosema sp.