The correct title of the paper by Virendra K. Gupta, published in Vol. 12 No. 1/2/3, pp. 9–18,1991, is as follows:

THE PARASITIC HYMENOPTERA AND BIOLOGICAL CONTROL AND OUR KNOWLEDGE OF THE AFRICAN ICHNEUMONIDAE

The immature stages, preferred oviposition sites, hatching patterns and egg morphology of two important rice pest species, Leptocorisa oratorius (Fabricius) and L. acuta (Thunberg) (Heteroptera: Alydidae) were described. Species specific differences were found in all these features. These differences may be useful for identification in fields where these pests occur together.

Studies were conducted for the first time on the gregarious endoparasitoid, Apanteles taragamae Viereck (Hymenoptera: Braconidae) to determine its biology on Diaphania indica (Saunders) (Lepidoptera: Pyralidae). The mean number of eggs laid per host was 24.63 and these eggs increased greatly in size before hatching. Larva passes through three instars as determined by the shape and size of the mandibles. Mean development time from egg to adult was 15.6 days at 24.26°C and 80–85% r.h. The mean number of adults emerging from each host was 14.61 and the sex ratio was 1:1.31 (males:females). The mean number of eggs laid by each female was 242.6. Mean adult longevity on 20% honey was 9.30 days for males and 10.70 for females.

Observations on the reproductive behaviour of the armoured ground cricket, Acanthoplus speiseri Brancsik were made in the laboratory and field. In the field a male ready to mate attracted both receptive females and mature “silent males” by stridulating. A receptive female moved to the stridulating male and upon reaching it courtship begun. Silent males also moved towards the stridulating male, but stopped at a mean distance of 1.07 ± 0.14 m from him and either seduced females that passed their way to the stridulating male, to copulate with them, or joined the stridulating male singing. Chorusing of the calling song involving more than two males was not uncommon in both the field and laboratory.

Due to stiff competition for mates in the environmental chamber in the laboratory male A. speiseri combined acoustic and substrate signals to attract receptive females. The male ground crickets vibrated their appendages, while they stridulated. Substrate signalling through body/appendage vibration or tremulation is here being reported for the first time in the tettigoniid subfamily Hetrodinae, to which A. speiseri belongs. The courtship behaviour, orientations of members of a copulating pair relative to each other, copulation, spermatophore transfer from the male to the female during copulation and oviposition and postoviposition behaviours of the species are described. Finally, the differences in the reproductive behaviour of A. speiseri in the field and laboratory are discussed.

Two juvenile hormone analogues (JHAs), R-20458 (6, 7-epoxy-l (p-ethylphenoxy)-3, 7-dimethyl-2-octene) and ZR-512 (ethyl 3, 7, ll-trimethy1-2, 4-dodecadienoate) were topically applied to various instars of mustard aphid, Lipaphis erysimi (Kalt), delivering doses ranging from 0.000015 to 1.0 μg in acetone on the dorsum of each test insect with the help of a microsyringe. Deformed individuals were categorized as adultoids (crumpled and twisted wings), nymphal-adult intermediates (sclerotized wing pads) and supernumerary nymphs (one extra moulting) and a scale was devised to asssess the extent of deformities. The process of embryogenesis was observed to be normal and the adultoids and nymphal-adult intermediates (with normal gonopores) reproduced normally. Only in case of supernumerary nymphs where gonopores were absent and those intermedites which had occluded gonopores, parturition could not take place. Antennae, legs and cornicles of the deformed individuals also exhibited some degree of deformation due to the hormone treatment. The third, second, fourth and first instar aphids ranked in descending order in developing abnormalities under exposure to the JHAs; a dose as low as 0.000015 μg/aphid of ZR-512, significantly deranged the morphogenesis of the third instar aphids. The lowest doses imparting significant degrees of abnormality to the aphid were 0.0039 and 0.00006 μg/aphid for R-20458 and ZR-512, respectively; showing the latter as more potent agent of morphogenetic abnormalities.

Interspecific attraction between Earias vittella and Earias insulana was studied by conducting sex pheromone bioassays and by making visual observations on the behaviour of individual interspecific pairs. Olfactometer bioassays using virgin “calling” females revealed interspecific attraction amongst about 10% males. In bioassays using female sex pheromone, E. insulana did not attract any E. vittella males, but the E. vittella female sex pheromone attracted 8.7% interspecific males. Electroantennogram recordings revealed detection of interspecific sex pheromones by antennae of males of both the species. When kept at a close range and allowed free access to interspecific females, more than 50% of E. insulana males courted and copulated with E. vittella females, but incidence of such courting and copulation was negligible in the reciprocal cross. In both the cases, there was no interspecific insemination. These studies suggested that dissimilarities in: (a) sex pheromone components or their ratio, (b) courtship behaviour and (c) sperm transfer mechanism play a role in the reproductive isolation of these two species.

The biology of Thrips nigropilosus Uzel was studied in a laboratory. The life history was examined at 20°C as well as the effect of temperatures on its life cycle at 12, 20, 25 and 30°C with fixed 70% r.h. The thrips pass through egg, two larval instars, prepupae and pupae to become adults. The development of these pre-adults occur on the pyrethrum plants except that prepupal and pupal stages occur in the soil. The emerged adults display sexual dimorphism, with lower ratio of male to female (2:11) and adult longevity range of 1–21 days.

The thrips development duration decreased with increasing temperatures. When expressed as rates, it was found out that faster development occurred for the second larval and pupal instars than other stages with an increase in temperature. The optimum temperature for the thrips development was 20°C, mortality being higher at other temperatures.

The inheritance of phosphoglucomutase (PGM) was studied electrophoretically in four strains of fig moth, Ephestia cautella. Individual zymograms exhibited one zone of activity with a two-banded pattern in strain A, and one-banded pattern with slow migrating mobility in strains B, C and D. Segregation of banding patterns between parents and progeny in strain A, and chi-square analysis of segregating alleles indicated that the PGM isozymes were regulated by two codominant alleles segregating at a single autosomal locus. No sex linkage was observed in reciprocal crosses. The data also suggest mendelian segregation, and that the PGM isozymes are monomeric in structure. The results of this study indicate that the PGM locus can be a useful marker for studies of E. cautella population dynamics.

Autoradiographic observations using (3H) glycine in the salivary glands of Lethocerus indicus, Laccotrephes rubra and Antilochus coqueberti indicated synthetic activity being performed by the glandular epithelia in all the bugs at short incubation periods. Long incubation periods showed that the site of heavy labelling shifts from outside inwards, with progressive incubation timings, namely from the basal borders and eventually into the lumen. This shifting of the labelling from outside inwards suggests the glandular epithelium is also capable of transporting some of the haemolymph proteins into the gland in all the species and thus indicating heterosynthetic origin of saliva.

The line of contact between G. p. palpalis and G. f. quanzensis passes near Brazzaville, at the south and southwest of the Congolese capital. Observations made between 1948 and 1961 show the advance of G. p. palpalis towards Brazzaville, along the Djoué Valley and the Congo River. Recent captures confirm this spectacular advance of G. p. palpalis to the detriment of G. f. quanzensis along the Djoué Valley. Indeed, G. f. quanzensis is no longer found in a distance of 20 km where it used to co-exist with G. p. palpalis. Ecological competition for food or habitat thus occurs between these two closely related species. It is suggested that both heterospecific copulations and demographic pressure play a crucial part in the exclusion.

Progress in the development of a simple life cycle model, with both deterministic and stochastic components for the brown ear tick, Rhipicephalus appendiculatus Neuman (Acarina: Ixodidae), is described. Control strategies or interventions that are user-manipulated are incorporated.

The model is initially applicable to Rusinga Island, Lake Victoria, Kenya, where parasitic phase data have been accumulated for a 30-months' period, but could be used for any other R. appendiculatus locations.

The influence of the host plants tobacco, chilli and brinjal on the susceptibility of Myzus persicae (Sulz.) to five OP insecticides was assessed. The order of toxicity of the insecticides to the aphids on tobacco was monocrotophos > demeton methyl > dimethoate > methamidophos > acephate, on chilli; methamidophos = monocrotophos > demeton methyl = acephate > dimethoate and on brinjal, methamidophos = monocrotophos > acephate > demeton methyl = dimethoate. Among the five insecticides, monocrotophos had the highest inhibitory potency in vitro as indicated by I50 and ka values, followed by demeton methyl, dimethoate, methamidophos and acephate. Electrophoretograms of homogenates of aphids adopted to chilli and brinjal showed a higher activity of the detoxicating enzyme carboxylesterase than found in aphids on tobacco.

The effects of host age, age of Cotesia marginiventris Cresson adults and temperature on interspecific competition between fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), larval parasitoids C. marginiventris, Microplitis manilae Ashm. and the egg-larval parasitoid, Chelonus insularis Cresson were studied. All parasitization results for C. marginiventris and M. manilae were from FAW larvae parasitized as eggs by C. insularis. The maximum reproductive potential for C. marginiventris was achieved in hosts initially parasitized by C. insularis and were 36 to 48 hours old and at a temperature of 25°C. No host discrimination was found for C. marginiventris between larvae containing a developing C. insularis and non-parasitized larvae. The optimum parasitoid age for C. marginiventris during the host exposure period was 48 to 96 hr. Younger or older parasitoids were not able to compete as successfully against C. insularis. A sex ratio of approximately 65% males was present in C. marginiventris progeny produced from parents ranging in age from 24 to 108 hr old. Egg to adult development times at 25°C were 17 and 26 days for C. marginiventris and C. insularis, respectively. In multiple parasitized larvae, C. marginiventris appeared to physically attack and destroy the larvae of C. insularis. However, M. manilae larvae died after 6 days without appearing to have been physically attacked in hosts containing C. insularis.

Behavioural and electrophysiological (EAG) studies were undertaken to determine the olfactory selectivity of the antennae of Glossina morsitans morsitans Westwood and Glossina pallidipes Austen to phenolic kairomones. Responses of both species to 3-alkylphenols increased as the alkyl chain increased from one carbon atom to three, while the opposite trend was observed with 4-alkylphenols. These results indicated that 4-cresol and 3-n-propylphenol are the most stimulatory of the two respective groups of phenols. However, comparison of the responses indicated differences in the sensitivities of the chemoreceptor systems of the two species. Hence different compositions of the phenols may be required to best attract these species. Probable interactions of the phenols with the binding sites on the receptor surface are discussed.

Laboratory experiments were carried out to study the effect of irradiating T. confusum pupae on the susceptibility of their adults to four insecticides. Results indicate that gamma irradiation significantly decreased the tolerance of adults from pupae irradiated 1 and 2 days before eclosion to Duradin. On the contrary, malathion and formothion, belonging to the same chemical group, i.e. organophosphate, were similar in their toxicity to adults, showing that irradiation of pupae afforded some protection to adults from death. However, s. fenvalerate exhibited the same trend noticed for malathion and formothion where irradiation of pupae reduced its effectiveness to adults. In general, adults from pupae irradiated 1 and 2 days before eclosion were less tolerant to tested insecticides than those from pupae irradiated 3 days before eclosion. Studying of tolerance ratio of various insecticides revealed that at 24 hr post-treatment, the most obvious trend is that adults from irradiated pupae, 3 days before eclosion, showed a moderate level of tolerance to formothion (3.29-fold) and s. fenvalerate (3.62-fold), and high level of tolerance to malathion (16.30-fold). While all adults from irradiated pupae elucidated different levels of tolerance to malathion, formothion and s. fenvalerate, the effectiveness of Duradin on those adults was significantly enhanced. This means that the application of Duradin in combination with gamma radiation is more effective than their separate applications. The dissimilarity of adult responses to the insecticides may be attributed to the enzyme alterations, either quantitative or qualitative and are the key to these irradiation effects on toxicity of insecticides to insects.

Field investigations were carried out in northern Nigeria to determine the prominent natural habitats of phlebotomine sandflies. Two biotopes, termite hills and rock crevices, were identified as the major habitats with the termite hills being the most significant. All the 12 species (Phlebotomus duboscqi, P. rodhaini, Sergentomyia antennula, S. bedfordi, S. africana, S. schwetzi, S. ingrami, S. adleri, S. clydei, S. buxtoni, S. affinis and S. christophersi) identified in this study came from this source. Only a small number of samples representing a few species were collected from the three other habitats (tree holes, animal burrows and a cave) investigated. The distribution of the sandflies was found to be influenced by the availability of suitable biotopes and physico-chemical composition of the soil.

Incorporated in this paper were the results of a study made on the quantitative variation of total carbohydrate, protein and lipid in whole body, fat body and integument of the larval and pupal developmental stages in rice moth, Corcyra cephalonica (St.) a storage grain pest. All three macromolecules referred to in case of whole body, exhibited a progressively decreasing trend from larva to pupa. In fat body total carbohydrate and protein contents were more in pupa than larva, while in integument the said nutrients were less in pupa than larva, showing the reverse results. The lowering down of the nutrients' level under stress caused by pyrethrum (a botanical insecticide) was also observed. The physiological and statistical significance of these findings was discussed.

Local West African strains of Sitophilus oryzae (L.) and Tribolium castaneum (Herbst) were placed in 200 g of wheat samples, one species after the other, during 6 weeks. The rate of infestation for S. oryzae was 6, 12, 24 or 48 pairs of adults, while it was fixed to 20 for T. castaneum. The generation of S. oryzae was killed by fumigation before T. castaneum infestation of the grain samples. The loss in dry weight and the frass production were recorded at the end of each rearing period of time for each species.

The dry matter loss caused by S. oryzae was highly correlated with the rate of adult infestation and measured as high as 600 mg per infesting pair of weevils. The frass production for both S. oryzae and T. castaneum was highly correlated with the rate of infestation by weevils only. For S. oryzae, the average frass production was about 60 mg per adult pair, while for T. castaneum it was variable from 27 to 44 mg per pair of the primary infestation level by the weevils.

The importance of these results is discussed in relation to standard loss assessment methods when there are several infesting species and particularly when there is a preponderance of secondary species over primary species.

Insects exhibiting swarming habits in Lake Victoria include mainly the Chironomidae, the Chaoboridae and Povilla adusta (Ephemeroptera). Their early life cycles are spent in the lake as benthos and standard bathymetrie procedures were undertaken to estimate the standing crop biomass of the larvae in Murchison Bay. Povilla was principally a boring invertebrate preferring dried logs (113 g Povilla nymphs per kg of host plant material). Cyperus papyrus carried 5 g C. denudalas 2.5 g and Phragmites mauritanus 1.0 g of Povilla per kg of host plant material. Povilla also occurred in the benthos at 40 g/m2. The Chironomidae and Chaoboridae had a mean standing crop biomass of 80 g/m2 and 3 g/m2 respectively. Their total biomass for the bay was estimated at 16060 metric tonnes for the Chironomidae, 7920 m. t. for Povilla and 660 m. t. for the Chaoborids. Adult swarming habits of the lakefly were closely correlated with lunar phases and the adults were easily trapped at night using kerosene lamps. Biochemical tests of the nutrient value of lakefly showed high levels of protein content (62%), minerals (18%), a low fat content (3.9%) and low moisture content (9%). This makes the lakefly ideal as an additive in animal feeds and growth experiments with poultry and aquaculture fish are currently going on to test the suitability of lakefly as an ingredient in animal feeds.

Eucalyptus oil vapour treatment provided to Dysdercus koenigii female individuals as virgin adults or during their fifth instar nymphal life led to a fall in the total protein content accompanied by a rise in the free amino acid titre of haemolymph and fat body. However, the level of total lipids in these two tissues under such condition varied in that a decrease and an increase were recorded in haemolymph and fat body respectively. In the ovary of this adult female, the amounts of total proteins and lipids were low, while the value for total free amino acids was high. The implications of all these findings are discussed chiefly in relation to transport, synthesis and degradation of biochemical constituents in the three tested tissues.