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.

Larval growth of the two main maize stemborers, Busseola fusca (Fuller) (Lepidoptera, Noctuidae) and Eldana saccharina Walker (Lepidoptera, Pyralidae), in Côte d'Ivoire was studied as a function of temperature sums. Tunnelling by unit weight was similar for both species. Early attacks by B. fusca (infestation until 17 days after maize emergence) resulted in deadhearts or in growth reduction. A relation combining the date of infestation, the level of attack and the development stage of maize explains the observed damage. Later attacks by both borers result in differences in damage, which are related to the larval distribution in the stem, the compensation between maize yield components, and also to the presence of a more or less active larva in the cavity.

The effect of photoperiod on the haemolymph protein profile in the silkworm, Bombyx mori L. larvae was investigated at photoperiod treatments of light to dark (L:D) ratios of 13:11 (control), 24:0, 18:6, 12:12, 6:18 and 0:24 hours using fifth instar larvae. The intensity of protein bands in haemolymph extracts from larvae was measured with a densitometer. The intensity was highest in the haemolymph from larvae in the 24:0 (L:D) h photoperiod. Strongly reactive antigens of SP-1 and SP-2 and weakly reactive bands of storage proteins for both male and female larvae were observed in the 24:0 (L:D) h photoperiod.

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.

The effect of four biologically active and naturally occurring plant quinones, namely maesanin, maesaquinone, embelin and juglone on the respiration of mitochondria isolated from Glossina morsitans morsitans, Schistoscerca gregaria and Periplaneta americana was investigated. The rate of oxygen consumption by the mitochondria was measured using an oxygen electrode. Maesanin inhibited the mitochondrial electron transport chain at a level before cytochrome C whereas maesaquinone and embelin uncoupled the mitochondria. Juglone inhibited respiration in G. m. morsitans mitochondria and uncoupled those of S. gregaria and P. americana.

Dormancy is described for adults of the stalk-eyed fly, Diopsis longicornis Macquart (Diopsidae: Diptera) in the tropical savanna of coastal Guinée, West Africa. Populations of diopsids maintained themselves within each chosen refugium throughout the dry season unless the site dried up. Sex ratio within the populations at each refugium remained constant throughout the dry period. Slightly more females than males were found (56%), and of these only 0.8% were gravid. Movement of stalk-eyed fly adults from the rice field to the refugia corresponded with the end of the rice cropping period (stage of ripening and harvest) at the end of the wet season (late October to November), whereas movement from the refugia to the rice field occurred towards the end of the dry season Gate (May/early June), but well in advance of the rice crop planting (July and August) of the following wet season. Insects retained their state of reproductive arrest in the dry season even when offered suitable oviposition sites, i.e. rice plants. Secondary host plants were investigated as possible oviposition sites and food sources for adult flies.

The fecundity and duration of oviposition in three strains of Callosobruchus rhodesianus from the highveld, middleveld and lowveld regions of Zimbabwe and a laboratory strain were recorded on cowpea and greengram. Within-legume variability for both parameters was high among the four strains. The lowveld strain was the least fecund and had the longest duration of oviposition. The middleveld strain showed the highest fecundity on cowpea, but did not differ significantly from the other three strains on greengram.

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.

This study was conducted to identify the individual biochemical factors involved in the resistance observed in a few Mexican bean accessions against the bean weevil, Acanthoscelides obtectus (Say) (Coleoptera: Bruchidae). Soluble proteins from different bean genotypes were separated by fractionated acetone precipitation. Insects were reared on artifical seeds composed of a susceptible background bean flour enriched with the different protein fractions. At low doses (2% w/w), the 0–20% and 20–40% acetone fractions of the resistant bean accessions G 12954 and G 12880 inhibited larval growth of the bean weevil, but not of a related species, the Mexican bean weevil, Zabrotes subfasciatus (Boheman). The 0–20% fraction caused the highest mortality of first instar larvae. The 60–80% acetone fraction contains general resistance factors, like α-amylase and protease inhibitors, which when enriched in artifical seeds led to a strong depression of insect growth for resistant and susceptible bean accessions alike. These factors should also be taken into account in breeding for multigenic, durable resistance, in order to exploit the synergism between general and specific resistance factors.

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.

Bioenergetica, efficiencies of energy transfer and growth of Spodoptera litura larvae reared on mulberry, cabbage, castor and wild hempweed leaves were determined using calorimetrie procedures. Energy contents (J mg−1 ash-free tissue) of castor leaves were higher than those of cabbage, mulberry and wild hempweed. Fresh leaves had slightly higher energy contents than those left over. The rates of ingestion and egestion of food energy increased linearly with the age of larvae. Energy consumption decreased exponentially with larval age, and this decreasing trend showed an intermediate rise at the fifth instar. Assimilation efficiencies were highest and lowest for the first and sixth instar larvae respectively. Efficiencies of gross and net larval production showed linear increases with instar stage, except at the fifth instar which showed dramatic declines in conversion of ingested and assimilated energy into insect biomass. Efficiencies of gross and net productions during early first to third instars were low, but those during the sixth instar were high. The pathways of energy transfer indicated that an average of 58.5% of the total energy ingested was lost directly through faeces, respiration and exuviae, while about 42.2% of the total energy ingested was actually converted into growth of an S. litura larva.

The development of Helicoverpa (= Heliothis) armigera (Hb.) (Lepidoptera: Noctuidae) on foliage, squares and bolls of four cotton cultivare [G 27, HD 167 (Gossypium arboreum), H 777 and H 974 (G. hirsutum)] and one hybrid (HHH 81) was studied under controlled conditions. The results indicated that some biological parameters were influenced only by plant parts and not by cultivar/hybrid. The larvae died as first instars when reared on the foliage of cv. G 27 and HD 167. Irrespective of cultivar, the larvae and pupae weighed more when the larvae were reared on cotton bolls than on squares and foliage. The larval and pupal periods were shortest for larvae reared on bolls, followed by squares and foliage. The fecundity of the female was highest when the insect was reared on bolls, followed by foliage and squares. The longevity of the female moth was highest in insects reared on bolls, followed by insects reared on squares, and on foliage. The longevity of the male moth was not influenced by rearing on the different plant parts. The duration of the life cycle was shortest for insects reared on bolls, followed by squares and foliage.

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 response of two cotton varieties (TCH 1002 and 77/10) and two hybrids (TCHB 213 and DCH 32) to damage caused by the American bollworm, Helicoverpa armigera was evaluated under two spacings and three fertiliser levels each. Variety TCH 1002 was less damaged than 77/10, whereas between hybrids, DCH 32 was less preferred than TCHB 213. Damage was higher when the varieties were grown at a spacing of 50 × 20 cm and the hybrids at a spacing of 120 × 45 cm compared to 75 × 30 and 120 × 60 cm, respectively. Increasing the amount of fertiliser applied did not have any significant effect on damage caused by the pest. Tannin and gossypol contents were found to influence levels of damage caused by H. armigera. A combination of high tannin and gossypol resulted in reduced damage. The highest tannin content in varieties was recorded in leaves of TCH 1002 grown at a spacing of 75 × 30 cm, with a fertiliser level of 120:60:60 NPK kg/ha. The highest gossypol content was recorded in flowers of TCH 1002 under similar spacing and management levels. In the hybrids, the highest tannin and gossypol contents were recorded when DCH 32 was grown at 120 × 60 cm spacing with a fertiliser regime of 120:60:60 NPK kg/ha. Cotton was damaged to a greater extent when grown at a closer spacing. Increasing levels of nitrogen resulted in higher damage levels.

The development time and survival of the castor whitefly, Trialeurodes ricini Misra were measured at four constant temperatures. The duration of the egg stage varied from 15 days at 20°C to 4.6 days at 35°C. No eggs hatched at a constant 40°C. The minimum temperature threshold for egg development was calculated to be 17°C. The total development time from egg to adult ranged from 54.4 days at 20°C to 16.8 days at 30°C. Development of the egg and the first-to fifth-instar larva required 63 and 180 degree-days respectively above the threshold value. Immature survival increased from 64.5% at 20°C to 92.8% at 30°C. Trialeurodes ricini is well adapted to high temperatures and may extend its distribution if mean world temperatures increase as a result of global warming.

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.

In order to develop suitable sampling methods for the arthropods of four mint species, namely Japanese mint (Mentha arvensis L.- var. Hybrid 77), peppermint (M. piperitaL.-var. MP-1), bergamot mint (M. citrata Ehrhrt- var. Kiran) and spearmint (M. spicata L.- var. MSS-5), six general sampling methods viz. ground cloth, sticker, sweep net, water trap, whole plant observation (WPO) and whole plant harvest (WPH) were evaluated under field conditions at the Research Farm of Central Institute of Medicinal and Aromatic Plants, Lucknow, India. The mint pest complex on all the mint species included Aphis craccivora, Chrotogonus trachypterus, Leptocorisa varicornis, Coccinella septempunctata, Bemisia tabaci, an unidentified lygeid bug, Brumoides suturalis, Propylea dissecta, Crysolina exanthematica, Dysdercus cingulatus and Plusia orichalcea. Overall, the ground cloth, sweep net, water trap and sticker methods were found to be more efficient and successful for sampling the arthropods of mint crops than the WPO and WPH methods. The shortest sampling time was required when using the sticker (3–6 seconds per sweep) and the sweep net (7–8 seconds per sweep) methods. This information may be useful in developing an integrated pest management programme for mint.

An investigation was carried out on the effects of three patterns of sorghum (Sorghum bicolor) and cowpea (Vigna unguiculata) intercrops on larval establishment of the spotted stemborer, Chilo partellus, on sorghum at different growth stages. The intercrop patterns were: sorghum sown simultaneously with cowpea, sorghum sown 2 weeks before cowpea and sorghum sown 2 weeks after cowpea. Sole sorghum and sole cowpea were controls. Sorghum plants were infested at 4, 6 and 8 weeks after emergence (WAE). Ten days after infestation, the infested plants and their immediate neighbours in the same row were uprooted and dissected. The number of larvae recovered and their stages of development were recorded. Some predatory arthropods were monitored by direct egg counts and use of pitfall traps. Grain yields were recorded at harvest to determine land productivity. Larval establishment was significantly (P < 0.05) higher on sorghum plants in sole crop than in intercrops; it was also higher on sorghum plants infested 6 WAE than on other dates. More C. partellus larvae were lost from sorghum sown after cowpea than in other cropping patterns, and more larvae were lost from sorghum plants infested at 4 WAE than on other dates. More predatory arthropods were observed in cowpea cover compared to those found in sole sorghum—the arthropods may be responsible for the observed loss in C. partellus larvae in the intercrop. Land productivity was higher in sorghum sown simultaneously with or after cowpea than in other cropping patterns. Thus, intercropping increased larval loss in C. partellus and improved productivity.

Some aspects of the biology of Callosobruchus maculatus (F.) on three varieties of bambara groundnut, Voandzeia subterranea (L.) Thou and a local brown cowpea variety, Vigna unguiculata (L.) Walp were studied under ambient laboratory conditions. Egg hatchability of C. maculatus was above 90% on all the legume varieties. The mean developmental period of C. maculatus ranged from 23.7 days on cowpea to 28.5 days on the Piele kargu variety of groundnut. The percent emergence of C. maculatus ranged from 61.1% on var. Piele kargu to 89.5% on var. Piele balgu. There was a significant difference (P < 0.05) between the damage caused to the brown cowpea and the bambara groundnut varieties. However, there were no significant differences (P > 0.05) in damage among the three groundnut varieties. In experiments to assess the insecticidal potential of three plant materials against C. maculatus, Azadirachta indica (neem) seed powder showed a higher efficacy than both Citrus sinensis peel powder and the powder of Chromolaena odorata leaves. At 1.0 g per 40 g of legume seed, it was twice as effective as Ci. sinensis and Ch. odorata over a period of 40 days.