The biology of the pea aphid, Acyrthosiphon pisum (Harris) (Homoptera: Aphididae), on four legumes (faba bean, field pea, lentil and grass pea) was studied in a greenhouse during the 1999/2000 seasons. There was no significant difference in length of nymphal period and number of moults (instars) among the crop species tested. The aphids generally took 9 to 11 days to reach the adult stage with a maximum of 3 moults. Lifespan was significantly longer on lentils than on other crops. Significantly more aphids survived beyond 15 days on lentil than on other crops. Similarly, the reproductive and post-reproductive period and adult longevity were longer on lentil. The pre-reproductive period was significantly higher on field pea than on the other crops. The net reproductive rate (R0) was highest on lentil (103.56 females /female) arid the intrinsic rate of increase (r) was highest on faba bean due to a short generation time (14.27 days). Generally, lifetime fecundity was higher on lentil (115.10/female) due to a higher daily reproduction rate (6.7 nymphs/female/day) on this crop. Nymphal production per aphid was strongly and positively correlated with lifespan, reproductive period and adult longevity but not of the nymphal period. Daily nymph production was significantly correlated with minimum temperature on lentil alone (F = 4.61, P < 0.05). Knowledge of the crop species and varieties susceptible to pea aphid is useful for identifying diets for the mass rearing of aphids for use in resistant variety selection and as diet for artificial natural enemy production. The present experiment indicates that lentil is suitable for both purposes.

In the present study, Y-tube olfactometric assays confirmed that volatiles from maize seedlings infested with Chilo partellus larvae were more attractive to the borer's larval endoparasitoid Cotesia flavipes, than volatiles from uninfested maize. Coupled gas chromatography-electroantennographic detector (GC-EAD) analysis of the volatiles from larvae-infested maize revealed six electrophysiologically active compounds on the antennae of the female parasitoid. These compounds were identified by GC-MS as (Z)-3-hexenyl acetate, linalool, (E)-4, 8-dimethyl-1, 3, 7-nonatriene, heptanal, (E)-β-ocimene and a C-5 aliphatic compound. (E)-4, 8-Dimethyl-1, 3, 7-nonatriene was present in EAG-detectable amounts in the volatiles of uninfested seedlings. In bioassays, a blend comprised of (Z)-3-hexenyl acetate, linalool, (E)-4, 8-dimethyl-1,3,7-nonatriene, (E)-β-ocimene and heptanal was significantly attractive to the parasitoid. Of the individual compounds, (Z)-3-hexenyl acetate was attractive at the doses tested while (E)-4,8-dimethyl-1,3,7-nonatriene and heptanal showed varying degree of attractiveness to the parasitoid at different doses. Linalool and (E)-β-ocimene were unattractive at the same doses. The significance of these results is discussed.

The unsaponifiable matter and fatty acid methyl esters of the petroleum ether extract of seven plants with known acaricidal activity were fractionated and identified by GC chromatography, and their biological activity against the two-spotted spider mite, Tetranychus urticae Koch. (Acariforms: Tetranychidae) assayed. In general, unsaponifiable matter showed higher acaricidal activity than the saponifiable matter. The unsaponifiable matter of Dodonaea viscosa leaves was the most toxic and that of Callistemon lanceolatus leaves the least toxic. The saponifiable matter (fatty acids) of Curcuma longa was the most potent.

Laboratory parasitisation rates of a native (Indian) and an exotic (Indonesian) population of the gregarious larval endoparasitoid Cotesia flavipes Cameron (Hymenoptera: Braconidae), mass reared by the group-exposure method in glass chimneys, were examined during 1990–1994 on three hosts, namely the sugarcane shoot borer Chilo infuscatellus Snellen, sugarcane internode borer Chilo sacchariphagus indicus (Kapur) and spotted stemborer Chilo partellus (Swinhoe) (Lepidoptera: Crambidae). Parasitisation rates of both the Indian and Indonesian populations in individual rearing batches showed considerable variation. Correlation and multiple regression analysis of parasitisation rates in rearing batches and three rearing parameters, viz. percent males, number of larvae and number of larvae per female parasitoid, indicated variable influence of the rearing parameters. Parasitisation rates of the Indian population were positively related to percent males and negatively related to number of larvae and number of larvae per female parasitoid in some hosts. The parasitisation rates of the Indonesian population were negatively related to percent males only in Ch. partellus. Mean monthly parasitisation rates of both populations during the study period fluctuated considerably in different hosts. The role of rearing parameters as well as rearing history of host and parasitoid cultures in parasitisation rates is discussed.

Forty forage sorghum genotypes, including 30 hybrids, 5 inbred forage varieties and 3 resistant and 2 susceptible checks were screened for resistance to the sorghum shootfly, Atherigona soccata (Rondani) (Diptera: Muscidae) and the spotted stemborer, Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae) under natural infestation in July-September 1996 and 1997. Six sorghum genotypes including two forage sorghum hybrids, HH 1 and NFSH 10659, three resistant check entries, IS 2205, IS 5469 and IS 18551 and inbred forage variety HC 171 showed multiple resistance to both the shootfly and the stemborer. The forage sorghum hybrid HH 1 also gave the highest green fodder yield. It is therefore suggested that this cultivar may be used in breeding programmes as a donor parent for developing sorghum cultivars resistant to A. soccata and C. partellus, or used directly for general cultivation.

Acetylcholinesterase (AChE), arylesterase (AE), carboxylesterase (CE), and cholinesterase (ChE) activities were determined in six adult populations of the lesser grain borer, Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae) collected from grain warehouses in various areas of Punjab, namely Lahore (L), Sialkot (S), Wazirabad (W), Multan (M), Chkhawatni (C), and Karachi (K). The multiple forms of esterases were resolved by polyacrylamide gel electrophoresis (PAGE) and activities determined biochemically, using a spectrophotometer. All the strains had the same AChE activity except Sialkot strain, which had 46% more activity than the susceptible K strain. Similarly K, S, W, L, and C strains exhibited almost the same AE level, whereas the M strain showed 29% lower activity than K strain. The CE activity of L (352%), S (198%) and C (214%) strains and ChE activity of L (178%) and C (317%) strains were significantly higher than that of K strain. The total esterases of L, S and C strains showed respectively 152%, 63% and 73% higher activity than the susceptible K strain. The PAGE pattern of various esterases coincided with the biochemical analysis. The variable thickness of the bands in the gel indicated relative esterase induction that could be correlated with the development of resistance in R. dominica.

A two-year survey was undertaken to determine the trypanosomosis risk of Egbe, a town in Kogi state of Nigeria, and its suitability for cattle raising. Tsetse flies were trapped using biconical traps and examined for trypanosome infection, and blood samples from cattle and goats were examined by blood film and haematocrit centrifugation technique (HCT) for trypanosome parasites. No infection was detected from the 152 Glossina palpalis palpalis and 52 G. tachinoides dissected over the period. Blood film examination of 181 cattle and 14 goats also gave negative results. Examination by HCT of 21 cattle from a local abattoir showed 14.3% Trypanosoma vivax infection, but the 10 resident cattle and 14 goats similarly examined were negative. The average age of the caught flies, determined by mean wing fray values (for males) and ovarian analysis (for females), was between 11 and 14 days, which is too low to sustain an infective population. Coupled with the absence of G. morsitans submorsitans, the most important vector of animal trypanosomosis in Nigeria, and the disappearance of large game from Egbe, our results would point to the area being a low trypanosomosis risk one.

Two studies were undertaken to determine the species composition of the phlebotomine sandfly fauna in the Mokolo region, an endemic focus of cutaneous leishmaniasis in northern Cameroon. The preliminary survey conducted in July 1994 using sticky paper traps recorded 843 sandfly specimens, all belonging to the two genera of the Old World sandflies, Sergentomyia and Phlebotomits. The species included S. (Sergentomyia) schzvetzi, S. (Sergentomyia) antennata, S. (Parrotomyia) africana and P. (Phlebotomus) duboscqi: From January 1996 to December 1996, a total of 3241 sandflies were collected using sticky paper traps. In this sampling, six out of the total of eight species recorded were of the genus Sergentomyia. In addition to the species recorded in the preliminary study, S. (S.) bedfordi, S. (Grassomyia) squamipleuris, S. (Sintonius), clydei and P. (Anaphlebotomus) rodhaini were sampled in 1996. This is the first report of S. squamipleuris ir Cameroon. The implications of this study to the transmission of cutaneous leishmaniasis are discussed with particular reference to P. duboscqi, a known vector of the disease in the region.

Two-dimensional gel electrophoresis was used to compare the protein profiles of two geographically isolated populations of the tick Rhipicephalus appendiculatus Neumann (Acari: Ixodidae) in Kenya. Most of the protein spots were common to both populations, but a number were specific to each population. Since proteins are encoded by genes, the presence of population-specific proteins suggests that there may be genetic differences between the two populations. It is proposed that some of these population-specific proteins might be related to the differences in susceptibility of the ticks to Tlwileria pnrva infection.

Volume 19 Number 4 (1999), page 304. In the article ‘IRLCS, 1955–1958: Three years of development and progress in controlling the red locust, Nomadacris septemfasciata’ by A. J. M. Carnegie. Column 2, para 5 should read ‘In parallel with the fire prevention campaign, a more concentrated experiment was conducted on a 6-mile by 1-mile (9.7 km by 1.6 km) strip of grassland…’