Some aspects of flight behaviour in the triatomine bug Triatoma sordida were investigated. A strong link between flight initiation and nutritional status as expressed by weight: length ratio was shown. Flight activity was strongly nocturnal and unimodal, commencing with the onset of darkness. A capacity to lay eggs after flight initiation was noted.

A series of experiments involving plots of sole cowpea and sorghum/cowpea intercrops were carried out, on-farm, in Minjibirr village, northern Nigeria between 1986 and 1988. The objectives were to:

(1) elucidate the relationships between sorghum/cowpea Intercropping, insect pest numbers and grain yield reductions in cowpea.

(2) examine the role of sorghum/cowpea intercropping alone or together with reduced Insecticide usage in the management of cowpea insect pests. Different cowpea varieties were grown under both cropping systems in sprayed and unsprayed plots.

The insecticides used were Sherpa Plus and/or Cymbush Super ED. Intercropping reduced the numbers of flower thrips and pod sucking bugs, but made no difference to the numbers of pod borers. Unprotected sole crop and Intercropped cowpea had yields reduced by 55 and 48% respectively, compared to sprayed subplots. The best results were obtained with three Insecticldal sprays, which increased grain yields 4.5-fold. Intercropping with two sprays produced lower, but comparable yields. Thus, it is suggested that intercropping can be used with reduced insecticide levels for the effective management of cowpea insect pests.

Hypoaspis solimani n. sp. was collected from compost from the farm of the Faculty of Agriculture, Cairo University, Giza, Egypt. Morphological characters of the different stages are described, illustrated and a key to the Egyptian species of Hypoaspis presented. H. solimani sp. n. was successfully reared on larvae of house fly, Musca domestica L. and vinegar fly, Drosophila melanogaster Morgan, and the two soil fungi, Macrophomina phaseoli and Fusarium oxysporum. The two kinds of prey proved to be the favoured diet, accelerating development and increasing female longevity and fecundity.

Four maize varieties, 8321–21-W, DMR-LSR-W, ACR-83TZUT-W and TZB were simultaneously fed to Sitophilus zeamais in a completely randomized design. Susceptibility was assessed on such parameters as weight loss of grains caused by the weevil infestation, number of progenies at 42 days after infestation and the percentage of damaged kernels. The least susceptible in terms of loss of weight of grains was TZB. Losses in the other three were not significantly different at 5% level (P ≻ 0.05).

The least percentage mortality of adult weevils and the highest number of punctured kernels were observed in var. 8321–21-W (48%), 27 kernels respectively while var. DMR-LSR-W had the highest mortality score (80%) and ranked second in the total number of kernels punctured (13). Details of the description of maize varieties used and the analysis of damage caused by the weevil are discussed in the paper.

Experiments on development of Amblyseius longispinosus Evans (Acari:Phytoseiidae) as influenced by castor pollen as an alternate food and its interaction with sorghum mite, Oligonychus indicus Hirst (Acari:Tetranychidae) were conducted under laboratory conditions. A. longispinosus showed poor growth on castor pollen. Female and male developmental periods were 2.6 ± 0.30 and 2.42 ± 0.21 days on spider mites, 2.70 ± 0.89 and 2.68 ± 0.39 days on spider mites + castor pollen and 5.12 ± 2.03 and 3.89 ± 1.80 days on castor pollen alone, respectively.

At interaction A. longispinosus suppressed populations of O. indicusat 1:10, 1:20, 1:30, 1:40 and 1:50. Prey elimination was on 12th day in 1:10, 18th day in 1:20, 20th day in 1:30, 24th day in 1:40 and on 30th day in 1:50 ratio.

Four synthetic juvenile hormone analogues (JHAs) with high morphogenetic activity on a variety of insects prevented embryonic development of Tribolium confusum to varying degrees when applied to freshly laid eggs. At 1 ppm (v/v) of the JHAs a few eggs hatched; however, some of the larvae died within a day of hatching. Older eggs were totally insensitive to JHA treatment even at higher concentrations. Larvae that hatched from these eggs appeared to be perfectly normal and continued to develop into apparently normal larvae.

Studies on developmental biology and feeding and ovipositional preferences of the pea leaf miner, Chromatomyia horticola (Goureau), were carried out on 11 varieties of field peas, Pisum sativum L. Two varieties, P-200 and P-402, offered maximum resistance to the development of pea leaf miner by inhibiting growth as both larval and puparial development were prolonged, and adult longevity, survival and fecundity reduced. These varieties were also least preferred for feeding and oviposition. Differences between the moderately resistant HFP-4 and highly susceptible varieties HFP-5, HFP-6, HFP-12, PG-3, RAU-21, RAU-25, RAU-37and T-163 were not well marked, as most of these had a relatively high value for the developmental success index, based on indices for larval-puparial development, adult longevity, survival and fecundity, and were also highly preferred by the ovipositing females. Variety PG-3, though offering some resistance to development, was highly preferred for oviposition. The local variety T-163, was the most susceptible variety, as it had the maximum value for the developmental success index, and was highly preferred by ovipositing females. The physiological basis of resistance in the two pea varieties is suggested to be mainly non-preference and antibiosis.

An experiment to examine the effects of four agrometeorological factors on population fluctuations in legume pod borer, Monica testulalis (Geyer) in two cowpea varieties was carried out under field conditions in Ibadan, Nigeria. Plots, 5 x 10 m each, of cowpea varieties IT84S-2246–4 and Dan ilan were planted fortnightly between 5 May and 5 October 1988 (12 plantings in all for each variety). Three peaks of the pod borer populations were observed on the cowpeas. There were smaller peaks on crops planted between 5 May and 1 June and again between 29 June and 13 July and a larger one on those planted between 24 August and 7 September. These two peaks coincided with the peaks of the rainfall.

Significant relationships were obtained between pod borer counts and (a) cumulative rainfall (R2 = 0.41; P = 0.004) (b) number of rainy days (R2 = 0.17; P = 0.04) from plant emergence to 50% flowering. These results suggest though, the distribution of rainfall over time is more crucial than the total amount in determining the fluctuations of pod borer populations. Thus, the adjustment of planting dates is suggested as an IPM tactic to avoid the development of damaging levels of pod borer infestations.

Investigations were carried out to establish the phagostimulatory effects of cheaply available materials (bag sugar, sucrose, molasses) on Chilo partellus larvae. Sugar and analytical grade sucrose (1% w/v solutions) were the best phagostimulants tested. Molasses was the least effective but a 10% w/v solution induced a significant feeding response. These stimulants, in combination with a Bacillus thuringiensis treatment, were tested to determine their effects on increasing the efficacy of the pathogen against this pest species. Larval mortality levels were significantly higher in the presence of a feeding stimulant than when B. thuringiensis alone was administered; inclusion of such adjuvants in a B. thuringiensis preparation could significantly enhance the field efficacy of the pathogen against C. partellus.

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.

The life cycle of Cathartus quadricollis (Guerin-Meneville) was studied under ambient laboratory condition on maize, sorghum, wheat, cowpea and melon. Egg hatchability was found to be 95.5% with an incubation period of 3–7 days. Five larval instars were recorded based on head-capsule width measurements. The growth ratio of the head-capsule width ranged from 1.05–1.20 with a grand mean of 1.12. This range falls within the acceptable range in Dyar's rule. The mean growth rate of C. quadricollis after 2 weeks of rearing on maize, sorghum, melon, wheat and cowpea, ranged from 22.4 to 1.6. While the mean developmental periods of C. quadricollis on the selected food media ranged from 18.80 days on cut maize to 30.70 days on cut cowpea.

The Senegalese grasshopper, Oedaleus senegalensis (Krauss, 1877) (Acrididae, Oedipodinae) survives the dry season under natural conditions as diapausing eggs. Females, reared under short photoperiod (10/24 hr), produced eggs which were mostly diapausing eggs, while those reared under long photoperiod (14/24 hr) laid essentially no diapausing ones (less than 3% of diapausing eggs). In addition, females submitted to a photoperiod of 10/24 hr, the percentage of diapausing eggs decreased with increasing female age.

Five insecticides and three mixtures were tested on the cotton flea beetle (CFB), Podagricapuncticotis (Weise), the spiny bollworm (SBW), Earias insulana (Boisd.), and the cotton aphids (CA), Aphis gossypii (Glov.). The relative potency (in terms of LD50 and or LC50) for CFB followed this order: endosulfan + dimethoate > endosulfan + chlorpyrifos > dimethoate > fenvalerate > endosulfan > endosulfan + amitraz > amitraz. The LCS0 values ranged from 12. 0–1150 ppm. For SBW, the following order was obtained: fenvalerate > endosulfan + dimethoate, endosulfan + chlorpyrifos > endosulfan > dimethoate > chlorpyrifos > endosulfan + amitraz > amitraz. LC50 ranged between 0.35 and 3388 ppm. With regard to CA endosulfan + chlorpyrifos > endosulfan + dimethoate > endosulfan + amitraz > chlorpyrifos > endosulfan > fenvalerate > dimethoate > amitraz.

In general, C A was relatively tolerant to most tested insecticides when compared with the other two pests. The SBW was the most susceptible.

Acanthoplus speiseri Brancsik, a pest of grain crops in Zambia, was reared in the laboratory at different temperatures. Mean development times of the eggs, nymphs and adults were determined at the different temperatures and used to develop a thermal unit model for use by farmers to predict the appearance dates of the different nymphal instars and the adults in the field in a given season. The predictions generated by the developed model for the 1990/1991 season, were compared to the actual dates on which the first specimen of each developmental stage was collected in the field during the season. The predicted dates of appearance all fell within 1 week of the observed dates of collection. Reasons for the slight deviations between the predicted and observed dates and the significance of the developed thermal unit model to the future control of A. speiseri in Zambia, are discussed.

Normal variations of ovarian glycogen content and the effect of different doses of thyroxine (T4) on this cellular constituent were investigated from 3rd day of fifth larval instar to adult emergence in Bombyx mori L. Ovarian glycogen remained higher during fifth larval stage with a peak on 7th day. At the end of 5th larval stage the glycogen content declined and this lower level continued upto 4th day of pupal age. Thereafter, this cellular constituent again sharply increased and reached a peak on pupal day 6, followed by a fall upto adult emergence. A single injection of different doses (0.5, 1, 2 and 5 μg/g body weight) of thyroxine, caused a significant decrease in glycogen content of ovary, during larval stage and an increase during pupal and adult stages of development with few exceptions. Thyroxine at the doses of 0.1 and 0.25 μg/g remained ineffective throughout the study period with an exception on day 2 after injection. The specific pattern of variation of the ovarian glycogen content as observed during normal stages of development was not altered by thyroxin though this hormone changed the level of glycogen. Thus, the results indicated that both glycogenolysis and glycogenesis occur in ovary after thyroxine treatment.

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.

Occurrence of mortality due to bacterial infection by a gram negative bacterium and the hymenopteran entomophagous parasite Apanteles glomeratus (L.) was observed in a natural population of Catopsilia crocale Cramer, a defoliator of the ornamental and medicinal plant Cassia alata. On regular field observation during the seasons 1980–1981 and 1981–1982, it was found that mortality due to these factors was mostly confined to the Final larval instar and the pupa of C. crocale. A direct correlation was obtained between population density of C. crocale and the number of larvae'pupae killed due to these factors. As the incidence of the hymenopteran parasite and bacteria fluctuate along with the C. crocale population, consideration of the foregoing factors as potential biological control agents for the pest population of C. crocale, is suggested.

An emulsion concentrate (locust lotion) containing 20% v/v neem oil and 40% w/v aqueous extract of Tetrapleura tetraptera L. was found to be most stable when subjected to viscoslty measurement, creaming rate determination, droplet size analysis and accelerated stability tests. The emulsion supported the growth of microorganisms which was prevented by a combination of 0.2% w/v methylparaben and 0.1% w/v propylparaben. Octylgallate, 0.1% w/v was added as an antioxkiant to prevent the oxidation of neem oil in the locust lotion concentrate. The recommended use concentration for protection ot cassava Manihotesculenta Crantz from damage by grasshopper Zonocerus variegatus L. was 1.8–2.2%. At 2.5%, locust lotion was phytotoxic to cassava.

In laboratory assays, two Bacillus thuringiensis var. kurstaki preparations, HD-263a WP and HD-263c WP, were highly effective against larvae of the honeydew moth, Cryptoblabes gnidiella Millière (Lepidoptera: Pyralidae), especially against the first and second instars. Both preparations were more effective than DipelR WP at most concentrations tested. Two viral preparations, AcMNPV and Amorbia cuneana NPV, were ineffective.

The effects of plant growth habit (erect versus spreading and flowering pattern) on the resistance of cowpea Vigna unguiculata (L.) Walp., to the legume pod borer, Maruca testulalis Geyer, were studied in Nigeria. Five cowpea cultivars of known agronomic and architectural characteristics were selected for the study: TVu 946, IT82D-716, VITA-3, Oloka local and Kamboinse local. Seed and pod damage assessment values were better in profuse flowering than in non-profuse flowering cultivars and in erect cultivars than in spreading cultivars. Best performances were obtained from TVu 946 (profuse flowering and erect resistant), and worst results from Oloka local (spreading susceptible) and VITA-3 (susceptible non-profuse) respectively. Erect and profuse flowering cowpea cultivars are proposed as having good architectural components for reducing M. testulalis damage to cowpea. The implications of architectural variations in cowpea are discussed.