Papers on tolerance of alfalfa, barley, sorghum, corn, rice, wheat, cotton, vegetables and tea to insects are reviewed. Research methods used in identifying tolerant cultivars and the role of tolerance, as one of the three mechanisms of resistance, are discussed.

Three polyvinyl chloride (PVC) formulations of malathion were prepared and tested as controlled-release formulations against mosquito larvae of Culex pipiens L. Non-expanded formulations gave effective control, with 100% larval mortalities, for 23–51 days, followed by expanded (16–33 days) and foamed (14–27 days) formulations. The results indicate that increasing the percentage of active ingredient in the present formulations increased their effective control against mosquito larvae for longer periods.

Larval treatments with these formulations of malathion led apart from lethal action to a decrease in the reproductive potential and in longevity of mosquito adults which survived from these treatments.

Nosema sp. naturally occurred in both Spodoptera littoralis (Boisd.) and S. exigua (Hübner) laboratory colonies in Alexandria, Egypt (since November 1984). It was responsible for the dramatic suppression of their laboratory populations. Both young (3-day-old) and old (9-day-old) larvae of S. littoralis were susceptible to Nosema sp. However, the pathogen was more effective against the young larvae, especially at high doses, than the old ones. The estimated LC50 was 4.0 × 107 spores'ml, for 3-day-old larvae. The slope value was low (1.2) as typical of protozoan insect pathogens. Heavily infected 9-day-old larvae tended to die as larvae; while less infected ones either pupate or produce larval-pupal intermediate forms (12–23%). The developmental period of both infected larvae and pupae was increased by 4–6 and 3–5 days, respectively. The number of infected insects that reached the adult stage was decreased as the concentration of Nosema sp. spores was increased. Furthermore, infection was shown to reduce adult longevity and fecundity, and viability of the eggs. Larval faecal pellets harboured large numbers of viable spores. Transovum transmission of infection occurred. Two dipterous species, Culex pipiens and Aedes aegypti, were not susceptible to Nosema sp.

The study revealed that there was quantitative recruitment in colonies of Amitermes evuncifer, whenever food was discovered by the scouting foragers. Discovered food stimulated the termites to accelerate their running speed, to and from the food source. Increased trail-laying activity, accelerated movement and carrying of food by the returning workers facilitated recruitment of other confederates from their nest. These activities equally directed the recruited termites to the food source.

Amitermes evuncifer was observed to regulate traffic in relation to newly discovered food source. The results showed that there was rapid communication between the termites of food source within 3–4 min. It was further observed that the trail to newly found food source did not become dominant over the trail to the already existing food source. The results showed clearly the effect of food on vital activities of termites.

Heterosis in Antheraea assama Westwood in respect of oviposition is observed over mid-parental value only in respect of four crosses viz. N × W1, N × W2, Y × W1, and Y × W2 and there is no inbreeding depression in oviposition rate until F3 generation. The cocoon weight and silk content in all the six crosses exhibit significant heterosis over both mid-parental and better parental values. In the F3 generation significant inbreeding depression is noted for both the characters and the values are at par to the mid-parental value. Commercial exploitation of hybrid vigour therefore should be limited up to F2 generation.

Studies on breeding sites of Phlebotomus duboscqi, a vector of Leishmania major, were intensified in Marigat, Baringo District, Kenya using the soil incubation technique, following the previously successful attempt to look for sandfly breeding sites. Soil samples obtained from nest areas of the animal burrows yielded Phlebotomus duboscqi and Sergentomyia ingrami. These two species had been shown to harbour L. major parasites inside animal burrows. Other phlebotomine sandflies recovered from these same breeding sites included P. martini, P. rhodhaini, S. bedfordi, S. africanus, S. antennatus and S. graingeri

Five (Sergentomyia antennatus, S. garnhami, S. schwetzi, S. ingrami and S. adleri) of the six species of sandflies fed on mammalian blood containing cultured Leishmania donovani promastigotes on day 0, were able to feed through cockerel skin membranes at 5.5, 10, 34.3, 45.7 and 95% feeding rates, respectively. Sergentomyia bedfordi was able to feed on mammalian blood only through a lizard skin membrane at 100% feeding rate. Promastigotes were found in 9.3, 25 and 37.5% of S. schwetzi, S. adleri and S. ingrami respectively, dissected on days 3–9.

The results open way for artificial feeding of Kenyan sandflies on mammalian blood through membranes, and indicate that it is necessary to select the type of membrane depending on sandfly species. The ability of L. donovani to develop in Kenyan sandflies is being investigated to experimentally establish and confirm the importance of various genera and species in the epidemiology of leishmaniasis.

Distribution patterns of the critical stages of the major pod borer, Adisura atkinsoni (Moore) of field bean were studied at Bangalore, India. Eggs of A. atkinsoni and the pods damaged by its caterpillar followed negative binomial distribution. Eggs were distributed mostly on tender pods and those on tender pods (<0.5 cm wide) were highly correlated with total number of eggs laid on the inflorescence. Flat bored pods of 0.6–1.5 cm width were highly correlated with total number of bored pods per inflorescence. Compared with matured bored pods, flat pods also had more borers inside. 69.23% of the matured bored pods were without borers. Hence it is suggested that the eggs on tender pods and borer damage on flat pods, should both be observed before control measures are initiated.

Laboratory examination of blood smears from water buffaloes in an area of high fly challenge indicated an infection rate of 51.11 % caused by both Trypanosoma congolense and T. vivax. A similar study in cattle raised in a low fly challenge area showed an infection rate of 22.73% caused by T. congolense only. Diminazene aceturate administered as a single dose at 3.5 mg/kg body weight cured the infection in cattle, while a similar dose at 7 mg/kg body weight failed to cure the water buffaloes. Cattle were further protected by a single dose of isometamidium chloride administered at 0.5 mg/kg body weight for 6 weeks of this study. On the other hand, isometamidium chloride administered at 1 mg/kg body weight cured transiently 90% of the infected water buffaloes and 10% persisted with a T. congolense infection. It was concluded that the lower dose rates approved by the manufacturers for the two trypanocides treated adequately infected cattle in a low challenge area, but such results were not achieved with the higher dose rates for infected water buffaloes in a high fly challenge area.

The prepupal stage of Spodoptera littoralis was affected by Bacillus thuringiensis kurstaki HD-1 (Dipel) at high concentration (5%), when sprayed or kept in soil treated with the pathogen. The emerged moths showed a short longevity associated with low egg production and low fertility. Increase in malformed individuals was observed. Treatment of the pupae of S. littoralis with B. thuringiensis during different ages showed an increased effect when treatment was applied, immediately after pupation.

Sixty-four sorghum accessions were screened for resistance to the grain midge, Contarinia sorghicola Coq., under natural infestation conditions at Tamil Nadu Agricultural University, Coimbatore during 1982. Absolute resistance was not found in any of them. Low grain damage was recorded in PVK 50 (6.61%), PVK 55 (11.58%), AF 28 (17.03%) and DJ 6514 (17.05%) while the susceptible accession, SPV 234 recorded high grain damage (92.72%) in the screening trial. The ovipositional preference studies at insectary revealed significantly reduced grain damage in the resistant accessions. Among them, the lowest damage (8.33%) was recorded in PVK 50 followed by AF 28, DJ 6514 and PVK 55 while the susceptible accession, SPV 234 recorded 21.57% grain damage. In the choice experiments, SPV 234 had 11.22–35.36% more infestation than in the resistant accessions evaluated along with it. Studies on development and biology of the midge revealed that antibiosis is one of the mechanisms of resistance in the lines, PVK 50, DJ 6514, AF 28 and PVK 55.

Ground spraying trials involving a new formulation of synthetic pyrethroid, alphamethrin (OMS 3004, WL 85 871) e.c. 10% were carried out in January 1983 against G. palpalis palpalis in the Bouaflé human trypanosomiasis focus, Ivory Coast. Four dosages were tested in five localities: 12 g of active ingredient (a.i.) per hectare; 24, 36 and 48 g (a.i.)/ha. Each dosage was applied once as a residual spray. The atomiser SOLO PORT 423 was used for spraying and the total area treated was estimated at 20 ha.

The results were evaluated with Challier-Laveissière biconical traps. The knock-down and short term effects of the insecticide were very satisfactory, 96–100% reduction in apparent density of the vector obtained with all the four dosages applied during the first 2 months after treatment.

Three to five months after spraying, more than 98% reduction in apparent density of G. palpalis palpalis was achieved even with the lowest dosage of 12 g (a.i.)/ha. The highest dosages tested did not seem to increase the persistence of the insecticide nor the mortality rate of the vector in the study area.

Due to adverse side effects on man at high dosages during and after treatment, it is recommended that in residual ground spraying, alphamethrin e.c. 10% be applied at a maximum dosage of 12 g (a.i.)/ha and at a concentration not exceeding 0.016% of active ingredient.

Ground spraying trials involving three synthetic pyrethroids: OMS 2012 (BAY FCR 1272, cyfluthrin) w.p. 10%, OMS 2013 (BAY NAK 1654, fenfluthrin) w.p. 5%, OMS 3004 (WL 85871, alphamethrin) w.p. 5%, were carried out in January 1984 against G. palpalis palpalis and G. tachinoides in the Bouaflé human trypanosomiasis focus, Ivory Coast. Two dosages of each formulation were tested as residual spray: 12 g of active ingredient (a.i.) per hectare at a concentration of 0.016% and 48 g (a.i.)/ha at 0.064%, The insecticide was applied by means of the atomiser SOLO PORT 423 and the total area treated was estimated at 29 ha. The results were evaluated during 5 months with Challier—Laveissière biconical traps.

OMS 2013 w.p. 5% at 12 g (a.i.)/ha, had unsatisfactory effect on G. palpalis palpalis and G. tachinoides from the first month after spray. At 48 g (a.i.)/ha this formulation showed a moderate effect on both vectors during the first 3 months after treatment, rate of reduction in apparent density by trapping (A.D.T.) varying between 70 and 90%.

OMS 2012 w.p. 10% at 48 g (a.i.)/ha gave satisfactory results, 92% reduction in A.D.T. of G. p. palpalis during the first 3 months after treatment. OMS 2012 w.p. 10% at 12 g (a.i.)/ha gave 94% reduction in A.D.T. of G. tachinoides during the first 2 months after treatment. At the dosage of 48 g (a.i.)/ha, 97% reduction in A.D.T. of G. tachinoides was recorded through the evaluation period.

OMS 3004 w.p. 5% at 12 g (a.i.)/ha, gave 97% reduction in A.D.T. of G. palpalis palpalis during the first 3 months after treatment. At 48 g (a.i.)/ha, 91–98% reduction in apparent density of G. p. palpalis was achieved during the period of evaluation. The effect of this formulation at 12 g (a.i.)/ha on G. tachinoides, was very pronounced during the first 3 months after treatment, being 99% reduction in A.D.T. At 48 g (a.i.)/ha, 100% reduction was obtained during the first 4 months and more than 99% reduction in 5 months after spray.

Behavioural-antennal responses of tsetse to buffalo urine, which has been identified as a potent olfactory attractant, were investigated. Tsetse Glossina morsitans morsitans rapidly raised their antennae upon stimulation with the odour of buffalo urine. Flies showed a clear preference for the undiluted urine, though antennal responses even to 100,000 × diluted urine were significantly different from control, indicating the high efficacy of the attracting compounds present in it. Fresh buffalo urine was the most attracting as compared to 4- and 8-day-old urine. The dichloromethane extract of fresh urine was as active as the natural product, indicating that the attracting compounds were extractable into dichloromethane. Under laboratory conditions, responses of males to the urine were significantly more than females.

Cohort tests in screened cages confirmed that the cowpea varieties TVu 2994, TVu 3709, EW/1, BPL-3–1, ER-7 and Vita 5 have promising levels of resistance to Cydia ptychora (Meyrick). The resistance was found to be mainly explained by antixenosis with respect to oviposition.

In no-choice tests in the laboratory, high larval mortality was recorded in TVu 3709 and BPL-3–1. Additionally, comparatively lighter-weight final instar larvae and adult females with reduced fecundity, fertility and longevity were reared from TVu 3709 and TVu 2994. Larvae reared on Vita 5 were slower in developing to adults than on other varieties; they were also relatively lighter in weight, while adults emerging from them showed reduction in size and fecundity. It is therefore concluded that resistance in TVu 3709, TVu 2994, BPL-3–1 and Vita 5 is partly due to larval antibiosis.

Laboratory studies were conducted to assess the infestation potential of Callosobruchus maculalus (Fab.) on 12 elite and one local cowpea cultivars which were stored under subtropical conditions. Index of susceptibility, loss in grain quality and the number of adult progeny that emerged from previously infested grain were the criteria used to assess the vulnerability of the cowpeas to post-harvest infestation. Cultivars TV × 309–1C and TV × 1193–10F showed some degree of resistance to post-harvest infestation by C. maculalus and could therefore be stored safely for a relatively long time. TV × 1192–01D and TV × 1999-1D were the most susceptible cultivars to post-harvest attack by C. maculatus. Length of storage adversely affected the ability of the cultivars to resist the insect attack. Crop resistance, adequately supplemented with good sanitation, can be profitably applied to control insect infestations in grains during storage.

Field and laboratory observations of Epicerura pulverulenta Hampson (Lepidoptera: Notodontidae) elucidated the role of biotic factors in the moth's populations. Natural enemies recorded included. Gryon and Telenomus spp (Hymenoptera: Scelionidae) which parasitized 33% of eggs studied. Also, about 4% of the larvae were parasitized by the dipterous tachinids Zygobothria atropivora Robineau-Desvoidy, Exorista xanthaspis Wiedeman, Blepharella sp., and P. quadrizonula (Thompson); and the perilampid Perilampus dubius (Walker), all solitary endoparasitoids. The predators included Belanogaster dubius Kohl. (Vespidae), Glypsus erubescens Dist. (Pentatomidae), Camponotus maculatus F. (Formicidae) and a kite (bird). They accounted for 12% of larval mortality. In addition, 27% of the 4346 larvae studied developed mycosis caused by Paecilomyces farinosus (Dickson ex Fries) Browne and Smith. A nematode, Hexamermis sp. was also associated with the larvae killing 1.5% of them. High pupal mortality was observed, but the cause was unknown.

From early March 1981 to late May 1982, the aphid population trend on 2-year-old Raphia hookeri palm plantation in Nigerian Institute for Oil Palm Research Benin, was studied in relation to ambient weather conditions. The population, taken from the central ‘spear’ and leaflets of Raphia, where it is most abundant, was high from March to April 1981. This declined to a low level in July and August 1981 following a heavy rainfall. Another peak was observed in September, but this however declined gradually to a very low level at the end of March 1982. However, in mid-April, there was an incipient peak which was quickly lowered again in early May by larvae of the ladybird, Platynaspis sp. The number of adult alatae correlated positively with the total aphid population on spear and leaflets (r = 0.68). There was no direct relationship between the measured environmental factors and the aphid population fluctuation.

Four instars of Cerataphis palmae (Ghesquierei) ( = Cerataphis variabilis H.R.L.) were identified from laboratory-bred and field-collected alatoid and apterous immatures through morphometric studies. These were distinguished most readily by the number and shape of antennal segments, body size, degree of development of the thorax, the presence or absence of wing pads and crenulations on body margin.

The nutrition, growth, development and mortality of the cotton leafworm, Spodoptera littoralis, were followed on six different artificial diets. As compared with the reference diet of Poitout et al. (1972) (Entomologia exp. appl.15, 341–350), our new media exhibit some interesting technical features:

(1) The agar is replaced by a new gelling substrate of which two types exist: Korano gels 400 and 411.

(2) These gels allow the preparation of a dry, sterile and ready-to-use mixture in convenient plastic packings. The powder is obtained by grinding the insoluble components and the nebulization of the soluble ones. When needed, the powder is simply added to hot distilled water (60–70°C) and stirred.

Different conditioning processes have been tested and this work was carried out to ensure that the two Korano gelling powders have the same biological quality as agar. The prepacked diets have proven to be very easy to store and to handle, and overall they are quite efficient and time-saving. Furthermore, they are much cheaper than the laboratory-prepared control diet. They supported the complete and normal development of S. littoralis, and even at a slightly better rate than agar-containing diets (M1 and M2b diets).