Stability of resistance to corn planthopper, Peregrinus maid is (Ashmead), was studied over three plant growth stages in 56 sorghum germplasm accessions. Genotype x stage interactions were significant. Plant age exerted a profound influence on the rate of oviposition, establishment of nymph, macropterous and brachypterous adult populations and plant damage. Resistance to corn planthopper was stable over three growth stages in IS 18557, IS 18677 and PJ 8K(R), which also supported low colonization of nymph and adult populations; IS 12308 was unstable due to high deviation. Significantly low rate of oviposition on resistant as compared to susceptible genotypes and the positive and significant correlation between oviposition and plant damage illustrated that antixenosis for oviposition is the primary mechanism of resistance. As a consequence the genotypes preferred for oviposition showed susceptibility due to higher plant damage. Establishment of nymphs was affected on the genotypes, IS 1054, IS 1082, IS 2194, IS 3992, IS 12308, IS 18676 and IS 19349 which may be due to the factors involved either in reduced hatchability of eggs and/or deterrence or poor feeding preference of nymphs.

Selected aspects of ecological interactions with ticks, tick-borne diseases and their hosts are discussed in relation to Integrated Tick Management, The needs to preserve tick-borne disease enzootic stability and to ensure the economic justification for any interventions were emphasized.

The use of surfactants and their blends to improve the penetration of two insect growth regulators (IGRs; hydroprene and R-20458) into wheat kernels was investigated. It was found that formulation of IGRs with a surfactant, Tween-85 (polyoxyethylene trioleate), increased mortality and/or effectiveness of the IGRs. Formulation of hydroprene with a blend of Span-80 (sorbitan monooleate) with Tween-80 (polyoxyethylene monooleate) produced results comparable to those by hydroprene with Tween-85. However, formulations of IGRs with surfactants with high or low hydrophile-lipophile balance (HLB), failed to provide suitable control of the weevil, probably due to the type of emulsions formed. The same results were obtained with hydroprene formulations with blends of Spans and Tweens, even though their HLBs were close to that of Tween-85. Residual half-life for hydroprene was about three months; formulations with Tween-85 or a blend of Span-80 did not enhance the residual activity for hydroprene in wheat.

The concept and practice of IPM has emerged over the past two decades or more. The primary impetus for its development has come from developed countries. IPM technology transfer to developing countries has followed the earlier pattern of the ‘green revolution’. The technology being proposed requires high energy inputs and an intensive infrastructure to support it. These conditions simply do not exist in most developing countries. IPM programs for developing countries must be based on their own socioeconomic situation rather than on simple technology transfer. Better understanding of cropping systems must be the keystone to development of IPM programs. Chemical control should play a secondary role. Cultural and bioligical control and plant resistance adapted to subsistence farming holds the greatest promise. Little attention has been given to the reciprocal feature of studies of traditional agriculture. These practices embrace a wealth of time-honoured ecological wisdom which if unravelled could provide useful leads for modern agriculture. The sequence of steps contributing to this process are proposed.

Neuroendocrine mechanism involved in pupal colour dimorphism in Papilio xuthus L. has been studied using ultrastructural techniques. The browning hormone in the form of neurosecretory material is secreted in the brain during the larval stage and transported to the axonal endings in the prothoracic ganglion, irrespective of the colour of the future pupa. If larvae select for pupation environmental conditions that are conducive for the formation of a brown pupa, release of the browning hormone occurs in the middle of the prepupal stage. No release occurs in larvae that have selected environmental conditions that favour the formation of green pupae. It is suggested that the brain, having integrated and interpreted the environmental conditions selected by the larva for pupation, gives the order to release the browning hormone. Such an order is conveyed via neural path from the brain to either the prothoracic ganglion, or some still unknown neurohaemal organ associated with it, from which release then takes place.

The horseflies in a patch of gallery-forest in a savannah of French Guiana were collected by 1°) for 24 hr with a Malaise trap, and 2° for 2 hr at dawn and at dusk, with a Malaise trap baited with carbon dioxide. The crepuscular horseflies, Cryptotylus unicolor, Chlorotabanus mexicanus and Chlorotabanus inanis, were more abundant in the baited trap (average: 55% of the flies collected) than in the unbaited trap (3%). Seasonal changes in relative abundance of the crepuscular species were evident in the baited trap only. The baited trap caught more flies and more species (averages: 315 flies and 7.5 species per 2hr catch) than the unbaited trap (averages 64 flies and 5.1 species per 24 hr catch). However, the overall number of species collected in each trap during the study did not differ greatly (16 species for 126 catches of 24 hr for the unbaited trap vs. 14 species for 29 catches of 2 hr for the baited trap).

A review is provided of the status of integrated management technologies for the stemborers Busseola fusca and Chilo partellus in Lesotho. Busseola fusca is the most important stemborer of maize and sorghum while C. partellus is only important on sorghum. No stemborer-resistant maize or sorghum varieties are available and farmers mainly plant land races of these crops. Cultural control practices such as the use of crop residue management practices have potential in suppressing borer numbers. Chilo partellus numbers, especially, can be suppressed through the destruction of sorghum crop residues. Studies indicated that adaptation of planting date can lead to escape of damage and reduced yield losses. Surveys indicate that insecticide use is on the increase in Lesotho, but the efficacy of insecticides used for borer control is not always adequate. The most promising area for change towards a pest management system lies in crop residue management. Changing crop residue management practices, especially where sorghum residues are left in the fields, should be encouraged. There is a high likelihood of adoption of a system in which Napier grass is planted around maize fields since farmers place a premium on livestock feed. Development and adoption of an integrated pest management system will, however, only be successful if farmers are involved in its development.

Nilaparvata lugens (Stål) biotype 1, 2 and 3 populations maintained as stock cultures for several years showed distinct morphological segregation based on multiple discriminant analysis using Wilk's Lambda method. Morphological characters of the rostrum, legs and antennae of both brachypterous and macropterous males and females provided a significant degree of certainty in classifying the three biotypes. The predicted biotype composition of the brown planthopper populations formed separate clusters.

Experiments were carried out to determine the factors that influence the feeding behaviour of Culex tigripes, a mosquito whose larvae are predators of other mosquito larvae. The results indicated that the efficiency of predatory activities of Cx tigripes larvae increased as they developed from 1st to 4th instar with regard to the number of mosquito prey larvae they consumed in a given period of time. Fourth instars of Cx tigripes are the most voracious of all the stages and are better adapted for catching and consuming all stages of mosquito larvae. The mean number of mosquito larvae consumed in 24 hours increased with increasing prey density. When offered a mixture of different prey species and larval stages, Cx tigripes larvae consistently selected 4th instars of mosquitoes over pupae and preferred Aedes aegypti larvae to the larvae of Cx quinquefasciatus and Anopheles gambiae. Prey size, density and mobility were also found to influence prey selection by Cx tigripes.

Austracris guttulosa in northern Australia is similar to Nomadacris septemfasciata in the southern half of Africa in having one generation per year, mainly in tall grass plains that are seasonally flooded by rainfall and flooding rivers. Locusts survive the dry season as adults and after the early rains of the wet season, oviposit in bare areas. Young offspring nymphs hatch out and feed on adjacent short ephemeral grasses while older nymphs and young adults are in taller vegetation. While locusts usually do not breed well outside tall grass plains of the source area, rain is critical to overall population increase of A. guttulosa, allowing egg and nymphal survival in the normally dry open plains south of the source area. When such rain falls, a preventive control programme is instituted, which begins with forecasts of population increase in areas receiving rain for offspring survival; any high populations found are delineated for control. While swarms within the source areas are often not controlled, those further south nearer cropping areas usually are. Austracis guttulosa does not form bands, so control is usually left until the adult stage when swarms form. Current practice involves the use of chemical insecticides, though promising research indicates that the entomopathogenic fungus Metarhizium anisopliae may form part of an integrated pest management programme in the future.

With N. septemfasciata, outbreaks seem to be related to dry periods, but the precise factors leading to outbreaks are not well understood. Until further research that allows accurate forecasting is undertaken, regular monitoring of outbreak areas and control of any bands and swarms that form will be an essential part of any preventive control programme. Both bands and swarms are present for long periods, giving ample opportunity for preventive control particularly in localities where crops are grown near outbreak areas.

Larval and adult predators comprise the largest component of the natural enemy fauna which attack the semi-aquatic rice caseworm Nymphula depunctalis (Guenée). Spiders, birds, and adult dragonflies/damselflies were the dominant predators of caseworm adults, while aquatic beetle larvae, aquatic bug nymphs and adults, and ants preyed on caseworm larvae. Egg parasitoids are unknown in nature and larval/pupal parasitoids are rare. A nuclear polyhedrosis virus, the only recorded pathogen, occurs but rarely. A ricefield pulmonate snail Lymnaea quadrasi (Mollendorff), which forages on algae, causes limited caseworm egg mortality in a passive and fortuitous manner. Water beetles—the dytiscid Cybister tripunctatus orientals Gschwendtner and hydrophilid Sternolophus rufipes Fabricius—are voracious larval predators. Prey consumption by these water beetles is higher on older caseworm larvae whose larger size creates more movement while the larvae are crossing the water surface. Also, older caseworms are more prone to leave the protection of their cases while under attack. Younger caseworm larvae, however, tend to retract and remain motionless when attacked. The last instar dytiscid preyed on an average of 11.4 caseworm larvae per day while that of the hydrophilid preyed on 6.7 larvae per day.

The effect of temperature and relative humidity on mating and commencement of oviposition in Plodia interpunctella (Hubner) was studied in the laboratory. Mating was most successful at 20 and 30°C and was less so at temperatures of 15 and 35°C. Increased relative humidity appeared to have favoured mating at higher temperatures investigated which were 30 and 35°C.

The onset time for mating was higher at 30 and 35°C than at 15 and 20°C. Mating started earlier at the lower temperatures than at higher temperatures. The mean duration of mating was higher at 15 and 20°C than at 30 and 35°C at which high relative humidity favoured increase in mating time.

At 20 and 30°C oviposition started within the first 2 days of mating whereas at 15°C oviposition started about 8 days after mating. At 35°C oviposition commenced within 4 days. Low relative humidity caused early commencement of oviposition at 15 and 35°C.

Field studies were conducted to characterise the effects of infestations by adult and nymphal stages of cowpea aphid, Aphis craccivora Koch, on the growth and yield of cowpea, Vigna unguiculata (L.) Walp. Seedling, flowering, and podding stage plants of aphid-resistant (cv. ICV-12) and aphid-susceptible (cv. ICV-1) cowpea cultivars were used in the studies. Four treatments (consisting of infestations with adult and nymphal aphids, caged controls and uncaged controls) were administered on plants for 22 days post-treatment. Eight parameters of crop success were measured: extended leaf heights (ELH); plant mortality; incidence of sooty mould; incidence and abundance of natural enemy species; crop growth parameters (net assimilation rate, [NAR] in g/ dm2/day, and crop growth rate [CGR] in g/dm2 land surface/day); and plant yields (seeds per pod, weight per seed). Data were analysed using analysis of variance (ANOVA), orthogonal contrasts and 95% confidence intervals (C.I.). There were no significant (P > 0.05) differences between adult and nymphal infestations or between caged and uncaged controls, so the respective sets of data were combined for comparisons of aphid infestations with control treatments. Infestations caused severe plant stunting and other growth deformities, drastic yield reductions, higher plant mortality, greater incidence of natural enemies and abundance of Cheilomenes spp. on cv. ICV-1 than on cv. ICV-12, and on infested and uninfested plants. Aphid infestations did not significantly affect the incidence of sooty mould on plants of cv. ICV-12 or cv. ICV-1.

Biological and morphometric studies of the different stages of Lucilia caesar, were carried out using three rearing media prepared from local materials as the test media, and the standard Snyder's medium as control. The materials for the test media were: (i) Garri, soybeans, palmwine and liver (GSPL), (ii) Garri, soybeansand palmwine (GSP) and (iii) Pap, nono, cabbage and liver (PNCL). The Snyder's medium consists of milk, yeast and bacto agar (M Y A). There was no significant difference in the duration of larval instars and adult emergence for the blowflies reared in the standard, PNCLand GSPL media. For blowflies reared in GSP, duration of larval and adult stages was prolonged by about 48 hr and 5 days respectively, when compared with the flies reared from the other three media. The average length and width of each larval stage reared from the four media were not significantly different. Morphometrics of the adults showed that those reared from the GSPL and control media were longer, heavier, and laid significantly more eggs per female than adults reared from PNCL and GSP media. The GSPL medium was considered to be the most suitable alternative to MYA.

The structural components and physical characteristics of sorghum kernels were studied as factors of resistance against Sitotroga cerealella (Oliv.) and Sitophilus oryzae (L.). Specifically, the effects of kernel glumes, weight, size and hardness on larval entry site, oviposition site, emergence site, progeny production, and kernel damage and weight loss, were investigated. The larvae of S. cerealella entered kernels primarily in the germ end and its periphery. Females of S. oryzae oviposited eggsmainly in the endosperm portion of kernels. Larval entry into kernels, and subsequent development of S. cerealella was enhanced in kernels that were enclosed by glumes. In addition, S. cerealella caused greater damage and weight loss in kernels with glumes. In contrast, kernels with glumes yielded less adult progeny of S. oryzae, and sustained less kernel damage and weight loss. The emergence holes of S. cerealella were located mainly in the crown end, whereas those of S. oryzae were mostly in the endosperm portion of kernels. The heavier and larger kernels produced heavier and larger adult progeny of both species of insect.

The effectiveness of aqueous neem leaf and seed extracts for the control of the diamondback moth (DBM), Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae) on cabbage was evaluated in field tests at Chokwe, Mozambique and compared with parallel dimethoate + cypermethrin treatments. All the neem treatments recorded significantly higher yield of marketable heads of cabbage and significantly better control of diamondback moth than the commonly used mixture of pyrethroids or the untreated control. The neem seed extracts provided the best control of DBM. The possibility of using neem extracts as part of an integrated pest management system for DBM control in smallholder farms is discussed.

The effects of larval population density and food quality on the velvetbean caterpillar, Anticarsia gemmatalis Hübner, were compared with investigations of other migratory noctuids. Crowded larvae of the velvetbean caterpillar responded with: (1) an increase in the degree of dark pigmentation; (2) a decrease in larval, pupal and adult size; (3) a prolongation of the larval stage and a decrease in weight gain in the ultimate stadium; and (4) low juvenile hormone and juvenile hormone esterase haemolymph titres.

The effects of flight, throughout a 4 hr flight period, on the haemolymph titres and whole body contents of carbohydrate and lipid are presented for the velvetbean caterpillar and discussed relative to other noctuid moths. Total carbohydrate concentration decreased during the first 30–45 min of flight, and total fatty acid concentration increased during the first 30–60 min of flight, after which it declined and stabilized at preflight levels. Lipid reserves and the small amount of lipid depletion after long periods of flight indicated that velvetbean caterpillar adults are capable of making long distance movements in which lipid is the principal flight fuel.

Juvenile hormone regulated the effect of density on larval colour, size and growth rate. Applications of juvenile hormone to crowded larvae increased the proportion of the lighter (green), larger and faster developing phase. This hormone action suggests that the juvenile hormone titre of crowded larvae is lower than that of uncrowded larvae.

Genetic differentiation among populations of velvetbean caterpillars suggests that south-central United States populations originate from overwintering populations in Mexico or south Texas. A system has been developed, using pheromone-baited bucket-type traps, to investigate the population dynamics and migration of the velvetbean caterpillar in Louisiana and Texas.

Various components of the neem tree, Azadirachta indica A. Juss were tested for their insecticidal effects on Sitophilus zeamais Motsen in stored maize. Seed kernel, leaf, flower and bark from the tree in powdered and extract (80% ethanol) form were used at the rate of 2.5g and 2ml respectively per 50g of grain, infested with 20 insects. Pirimiphos methyl and ethanol applied at 25mg and 2ml served as comparative treatment, and control neem products were efficient where used as a preventive measure. The degree of infestation was 3.2 as compared with 53 recorded in curative assay. Ethanolic extracts showed higher toxicity to S. zeamais than the powdered form. Insects after being confined 72 hr to treated grains had a mortality ranging between 29 and 96.4% (powder) and 32.5 to 100% (extract). The index of susceptibility varied from 0.45 (kernel) to 3.87 (bark) in powdered and 0 (kernel or leaf) to 1.76 (bark) for extracts. When leaf or kernel powder was used to protect grain over a 60 day storage period in aerated and non-aerated environment, insect mortality was 100% (kernel), whereas the leaf powder did not show complete insect control in aerated environment (88.1 %). A very high rate of population increase of S. zeamais was observed in the control.

This paper describes the immature stages of the striped caterpillar Epicerura pulverulenta Hampson, a notodontid defoliator of combretaceous trees, viz., Terminalia ivorensis, T. superba, T. catappa and Anogeissus leiocarpus. The structure and chaetotaxy of the mature (fifth stage) larva is described in detail with illustrations to aid easy field identification of the moth.

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.