The host plant range of two ricefield caseworms, Parapoynx fluctuosalis (Zeller) and P. diminutalis Snellen (Lepidoptera: Pyralidae), was determined from screening rice and 61 weeds in the Philippines. Both species developed best on the aquatic weed Hydrilla verticillata (L.f.) Royle (Hydrocharitaceae). Parapoynx fluctuosalis also completed a full generation from egg to egg on Cyperus brevifolius (Rottb.) Hassk. (Cyperaceae), Commelina diffusa Burm. f. (Commelinaceae), Leptochloa chinensis (L.) Nees, and Paspalum conjugatum Berg (Poaceae). Parapoynx diminutalis completed a generation on Chara vulgaris L. (Characeae), Ottelia alismoides (L.) Vahl and Blyxa auberti Rich. (Hydrocharitaceae), and Cyperus rotundus L. (Cyperaceae).

Survival and development of Chilo partellus were studied on five sorghum cultivars (IS-18363, IS-18520, ICS-1, ICS-2 and IS-4660) in the laboratory at Mbita Point Field Station, Kenya, at 26 ± 2°C and 65 ± 5% RH. Larval developmental period differed significantly on different cultivars. Number of instars was numerically greater for the females than for the males on all cultivars. Average pupal weight varied with sex; females were twice as heavy as males. The pupal period was longer for males than for females on all cultivars, with the exception of ICS-1, where the pupal period of males was equal to that of females. Ovipositional period was significantly longer on IS-18520 (5.18 ± 0.30 days) than on other cultivars. The shortest ovipositional period (3.70 ± 0.27 days) was recorded on IS-4660. There were no statistically significant differences in adult longevity. Sex ratio of the moths also did not affect the adult longevity of C. partellus reared on the five sorghum cultivars. The variations found in the development of C. partellus on different cultivars were attributed to the nutritional value of the food source.

The effects of temperature on the life history of Spilostethus pandurus (Scopoli) were examined by determining the different developmental and reproductive parameters with respect to days of hatching, oviposition, and adult emergence of insects reared in field cages at Giza, Egypt. Hatching, oviposition, and adult emergence continued all year round; the average daily temperature in the coldest month (January) seemed to be above developmental thresholds for different stages. This lygaeid completed six overlapping generations in 1 year. The basic population parameters, i.e. net reproductive rate (R0), gross reproductive rate (GRR), instantaneous rate of natural increase (r), finite rate of natural increase (λ), and mean generation time (T) exhibited a more or less cyclic pattern in successive generations. The highest value of r (rmax) was considered as the intrinsic rate of natural increase of this species.

Random amplified polymorphic DNA (RAPD) amplified by the polymerase chain reaction (PCR) was used to estimate the relatedness of three biotypes of brown planthopper, Nilaparvata lugens (Stål), from the Philippines. Each individual brown planthopper had a unique set of RAPD bands, but no bands were diagnostic for any one biotype. Brown planthopper types 1, 2 and 3 were genetically homogeneous. This supports results of other studies which conclude that brown planthopper biotypes are not sub-specific categories, but merely represent individual variation for virulence to rice cultivars.

Differences in population growth among four variation types of the ladybird beetle, Harmonia axyridis Pallas, namely succinea, conspicua, spectabilis and aulica, were investigated using various growth parameters. The variation types showed three growth patterns from the intrinsic growth rates (rm), with rates of 0.093–0.099 (for conspicua and aulica), 0.073 (for succinea) and 0.040 (for spectabilis). The growth rates of these patterns were realised in different ways. Spectabilis differed from the other three types in the age and per cent distribution of the specific period to the rm values.

The movement of Cicadulina storeyi China (Homoptera: Cicadellidae), vector of maize streak geminivirus, within maize (Zea mays L.) fields was studied using mark, release and recapture experiments. Cicadulina storeyi, marked with fluorescent dye, were released at dusk and monitored for 14 days using yellow sticky traps placed at different distances (5–160 m) and directions from the release point. The suitability of maize growth stage for settling by C. storeyi was also investigated. Catches decreased steadily with distance from the release point and exponentially with time following the release. The mean leafhopper dispersal rate varied between 2.6 and 2.8 m/day for dry season and rainy season tests, respectively. The dispersal rate increased with distance from 1.4 m/day at 5 m to 13.6 m/day at 160 m. Wind was a major factor affecting direction of leafhopper movement with the largest proportion of C. storeyi collected downwind. Investigations on the suitability of maize growth stage for settling by C. storeyi revealed that the leafhopper preferred young plants (2–6 weeks after planting) to old ones.

This study investigated the segmental distribution of various types of antennal sensilla in the post-embryonic developmental stages of the brown-banded cockroach, Supella longipalpa Fabricius. Three major types of mechanosensilla and chemosensilla were identified. A progressive increase in the number of various types of sensilla with increase in the number of segments as well as nymphal stages and adults was observed. The density of sensilla chaetica and sensilla basiconica increased approximately 12.5- and 24-fold from first nymphal stage to males respectively, while density of sensilla trichoidea increased 8-fold from 2nd nymphal instar to adult stage. A high degree of correlation between the average total number of sensilla and post-embryonic stages was observed.

A study was conducted to determine the morphology, histology and ultrastructure of the salivary apparatus of Lethocerus indicus. The apparatus was found to consist of a principal and accessory salivary gland. The former is bilobed, having a small superior lobe and a larger inferior lobe, made up of many lobules/acini. Each lobule is made up of a simple glandular layer of syncytial epithelium encompassing the lumen, which is filled with secretory granules that are elaborated from the epithelium predominantly by the apocrine mode of secretion. The accessory salivary gland is vesicular cum tubular. The vesicular part is made up of a thin layer of flat, polygonal cells, having no signs of secretory activity, while the tubular part consists of a single layer of columnar epithelial cells that show signs of secretory activity. Both the principal and accessory glands discharge their secretions through a common salivary duct which opens at the base of the hypopharynx. The ultrastructure of the lobules of the principal salivary gland reveals a thick amorphous, basement membrane (800–1000Å) which supports the glandular epithelium. The basal and apical plasma membranes of the epithelium show basal infoldings and microvilli respectively. The nucleus is highly branched and remains surrounded by a double layered nuclear envelope. The ergastoplasmic membranes show abundance of ribosomes. Many mitochondria are also visible in the cytoplasm. It is concluded that the salivary gland of L. indicus is an organ of high synthetic activity.

Seedlings of 462 sorghum lines were screened to identify resistance to the sugarcane aphid, Melanaphis sacchari (Zehntner). About 7% of the lines exhibited resistance in the seedling stage in greenhouse trials. In an advanced screening experiment, 12 sorghum lines had resistance ratings of 1.0–3.0 (highly resistant or resistant). In a similar test, older and larger plants of the same lines were as resistant as in the seedling stage. Lines IS12664C, IS12609C, IS12158C, and IS12661C were highly resistant in preliminary and advanced screening trials. Antixenosis was shown to be a mechanism of resistance. Sorghum lines IS12664C, IS1144C, IS1598C, and IS12661C were less preferred than ‘Mtode’, a susceptible sorghum. Based on greenhouse and field trials, antibiosis adversely affected aphid longevity, days reproducing, and progeny production. On the least antibiotic sorghums, longevity, days reproducing, and number of nymphs produced were as high as 13.7, 6.0, and 26.6, respectively. On the most antibiotic sorghums, these values were 4.5, 0.0, and 0.0. Resistance appeared to be controlled by a dominant gene, but there were indications of modifiers linked to major genes.

The effect of a 2-month infestation by the cassava mealybug (Phenacoccus manihoti Mat. Ferr.) on the metabolism of nitrogen (amino acids) and carbon (carbohydrates), leaf area and total dry weight of five cassava varieties (Manihot esculenta Crantz), faux-caoutchouc (a hybrid of M. esculenta and M. glaziovii Muell, Arg.), poinsettia (Euphorbia pulcherrima Wild) and talinum (Talinum triangulare Jack) was studied. Free amino acid and free sugar contents as well as relative free amino acid composition in the leaf extracts, although found to be very different from one plant to another, were not significantly modified by P. manihoti infestation, except for the total amino acid contents of the cassava variety 30M7. Variations in one particular amino acid induced by mealybug infestation were not linked to the antibiotic resistance of these plants. Infestation by the cassava mealybug did not modify the total dry weight but reduced the total leaf area although this reduction was only significant in cassava varieties 59M2, 30M7 and M'pembe, and in faux-caoutchouc. Within the genus Manihot, the reduction in leaf area was strongly correlated (r= -0.878, P≤0.05) to the degree of antibiotic resistance and was coupled to an increase in the ratio of sugars to amino acids, suggesting a similarity between the effects of water stress and those of mealybug infestation.

The inheritance of resistance in grain sorghum to the spotted stemborer, Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae) was studied in F3 plants derived from crosses between nine locally adapted inbred lines and two sources of resistance. Antibiosis resistance was measured as the relative growth rate of larvae in the whorls of 6-week-old plants. Most F3 plants were either as resistant as, or more resistant than, the resistant parent. This indicated dominance of resistance over susceptibility and the occurrence of transgressive segregation. The segregation pattern in the F3 generation suggested the presence of at least four dominant genes. Two families homozygous for these genes were identified.

The impact of larval defoliation by Aproaerema modicella (Deventer) on the growth, development and yield of two groundnut cultivars (Kadiri 3 and NC Ac 17090) was studied under a naturally occurring, high density infestation. Defoliation by leaf-mining larvae did not increase plant mortality in either cultivar. In both cultivars, leaf and stem production were significantly lower in untreated plots than in the treated plots. Unsprayed plants of both cultivars produced fewer flowers, pegs, and pods per plant compared to plants of the same cultivar protected with monocrotophos. Fruit growth rates, however, were marginally higher in control plots than in treated plots. Pod yields were 35 and 44% lower, and haulm yields 25 and 20% lower, in Kadiri 3 and NC Ac 17090, respectively in untreated control plots compared to plots treated with insecticide. A linear relationship between leafminer density and pod and haulm yields was observed, and differences between cultivars were not significant.

The efficiency and profitability of an integrated pest management system consisting of a phytosanitary survey and threshold interventions (based on levels of insect damage) was tested at the Vallée du Kou irrigated rice scheme in Burkina Faso, for two consecutive crop seasons in 1987. There was a considerable advantage in cost, number of insecticidal applications and yield of a threshold intervention-based system over arbitrary or routine insecticidal application methods. The proposed method is considered to be environmentally friendly.

Survey questionnaires were administered to 50 farmers in three chiefdoms in the Moyamba District of southern Sierra Leone. The study was undertaken to gain insight into the indigenous farming practices for cowpea with emphasis on pest management. This is to serve as a guide in drawing up a research agenda and identifying appropriate measures for the control of cowpea pests. Farm sizes were generally small, usually less than 2 ha of intercropped cowpea. This suggests that the farmers were mostly subsistent and would require low cost inputs to boost production. Vertebrate and insect pests were identified by the farmers as limiting cowpea grain production. Insect pests were considered more serious than vertebrates. Pest control was mostly traditional and involved cultural measures such as weeding of plots, fencing, trapping and scaring of birds. These may be inefficient and labour intensive. Varieties planted by the farmers were mostly land races that have low yield potential and lack some other desirable agronomic character like semi-erectness and bold seeds. Selection criteria in breeding programmes should incorporate farmers' preferences which include high yields, sweet taste, resistance to pests and diseases, compatibility with the farming systems and acceptable seed appearance that would enhance marketing. The study further revealed that at present cowpea is grown mostly as a secondary crop. Therefore, introduced pest control efforts would have to be cheap, easy to adopt and integrative. These would include:

(a) education on control options hitherto unknown to the farmers;

(b) identifying and developing effective strategies that are low cost, labour insensitive, environmentally friendly and compatible with the socioculturel background of the farming community; and

(c) creating awareness on the necessity for the inputs to be readily available and affordable at the local government level.

Studies were carried out to compare the efficacy of insecticide schedules based on calendar intervals with those based on plant growth stages for the control of cowpea insect pests. Spray schedules based on calendar intervals and plant growth stage gave reasonable control of the pest complex and increased grain yields significantly. However, spray schedules based on plant growth stages alone were more efficient for two of the three cowpea varieties tested. This was attributed to differences in maturity periods which made spraying by regular calendar intervals slightly out of phase with attack by key insect pests. Thus, spray schedules based on plant growth stages are recommended for the control of insect pests of cowpea.

Permethrin, deltamethrin, fenvalerate and cypermethrin were evaluated for their termiticidal efficacy in a graveyard test. Semul wood, Salmalia malabaricum veneers (size 15.00 × 6.00 × 0.06 cm) were impregnated with concentrations of 0.25, 0.50 and 0.75% aqueous solution of these chemicals. Fenvalerate provided 100% protection for 44 months at all three concentrations. Cypermethrin provided 100% protection at 0.50 and 0.75% concentrations, while permethrin and deltamethrin provided 100% protection at 0.75% concentration for 7 and 10 months, respectively.

Mature fruits from 21 mango, Mangifera indica L., cultivare grown in the Miami National Clonal Germplasm Repository were examined for resistance under laboratory conditions to identify those resistant (antibiotic or antixenotic) to the eggs and larvae of the Caribbean fruit fly, Anastrepha suspensa (Leow). The bioassay consisted of artificially infesting a slice of fruit with eggs obtained from a laboratory colony and counting the adults that emerged. Emergence ranged from 26.6% (on Tobago Small Red) to 119.0% (on Sabre) of controls (on artifical diet). Tobago Small Red, Becky, Saigon Seedling, Zilate, Sandersha, 13–1, Keitt, Turpentine, Rumani, Tommy Atkins, Irwin and Peach had the highest level of resistance observed with less than 80% emergence. The most resistant cultivars are promoted to breeders and growers for production in areas under quarantine for Caribbean fruit fly.