Collections of mosquitoes of the Anopheles gambiae Giles complex were made from the geothermal springs and surrounding area in the Semliki Valley, Bwamba County, Uganda, which is the only known locality of A. bwambae White. Specimens were analysed in one of three ways: rDNA-PCR for unequivocal species identification, allozyme electrophoresis to determine superoxide dismutase (Sod) and octanol dehydrogenase (Odh) genotypes, or both methods. Ribosomal DNA-PCR identification revealed the presence of A. bwambae and A. gambiae. Allozyme electrophoresis of 181 individuals showed that A. bwambae possessed the Sod105and Sod100 alleles and was not monomorphic for Sod105as reported previously. In adults reared from collections made in the vicinity of the geothermal springs, the frequency of Sod105 was found to be 0.614. Anopheles gambiae was fixed for Sod100. The majority of individuals homozygous for the Sod100 allele could be identified to species using Odh. Odh95 was found to be common in A. bwambae (frequency = 0.988) while A. gambiae appeared to be fixed for Odh100. Since Odh100occurred at a frequency of 1.2% in A. bwambae (concomitant with Sodgenotypes of 105/105, 100/105 or 100/100), individuals homozygous for Sod100 and Odh100 could be either species. Among 25 A. bwambae specimens homozygous for Sod100, one (4%) was also homozygous for Odh100. At present, this subset of the A. bwambae population can only be correctly identified to species using rDNA-PCR analysis.

Fifty-five species of exotic dung beetles have been introduced into Australia and in many areas, several species are now established and often abundant. Controversy exists in the dung beetle literature concerning the use of ivermectin as an anthelmintic treatment for livestock and its subsequent lethal and sub-lethal effects on adult dung beetles. A study was conducted in the field exposing replicate dung pats containing residues of ivermectin excreted 0–15 days post-injection. At the time of the study, the introduced species of dung beetle Onthophagus taurus (Schreber) was present in high numbers (>1000 beetles per pat). After 24 h exposure, dung pats collected from cattle treated 7 and 10 days earlier with ivermectin were dispersed significantly less than untreated dung. A similar pattern was evident in the numbers of dung beetles present in each pat. This study is discussed in the context of anthelmintic usage in cattle and their potential ecotoxic effects against dung beetles.

Termites were sampled using randomized soil pits in 64 cropping plots, each 25 x 25 m, forming an experimental agrisilvicultural system in both a 6- and an 18-year-old Terminalia ivorensis plantation, in which canopy cover, crop, cropping system and land preparation were the principal treatment variables. The treatments were established in April 1995 and sampling was carried out in November 1995, February 1996 and July 1996. A total of 82 termite species were found, of which 67 were soil-feeders. Overall termite abundance and the abundance of soil-feeders increased between November 1995 and July 1996, reaching a mean of nearly 6000 m-2. Pooling termite data from these sampling dates, in the old plantation, the high canopy cover treatment (192 stems ha-1) had a greater abundance of termites, compared with the low canopy cover treatment (64 stems ha-1) and this effect was independent of crop type (plantain or cocoyam), cropping system (single stands or mixed crops) and land preparation (mulch retained or burned, plantain only). The young tree plantation (same tree densities as in the old plantation) showed no significant difference in termite abundance between high and low canopy (levels of tree foliage) densities, though the high canopy sheltered a greater number of termites. Analysis of covariance showed that crop yield (both plantain and cocoyam) was not directly linked to the abundance of all termite populations, but that the cocoyam yield was positively correlated with the abundance of soil-feeding termites (the majority in the assemblage) in the young plantation. This may be due to the beneficial conditioning of soil resulting from the foraging and construction activities of soil-feeders.

Termites were sampled using randomized soil pits in 64 cropping plots, each 25 x 25 m, forming an experimental agrisilvicultural system in both a 6- and an 18-year-old Terminalia ivorensis plantation, in which canopy cover, crop, cropping system and land preparation were the principal treatment variables. The treatments were established in April 1995 and sampling was carried out in November 1995, February 1996 and July 1996. A total of 82 termite species were found, of which 67 were soil-feeders. Overall termite abundance and the abundance of soil-feeders increased between November 1995 and July 1996, reaching a mean of nearly 6000 m-2. Pooling termite data from these sampling dates, in the old plantation, the high canopy cover treatment (192 stems ha-1) had a greater abundance of termites, compared with the low canopy cover treatment (64 stems ha-1) and this effect was independent of crop type (plantain or cocoyam), cropping system (single stands or mixed crops) and land preparation (mulch retained or burned, plantain only). The young tree plantation (same tree densities as in the old plantation) showed no significant difference in termite abundance between high and low canopy (levels of tree foliage) densities, though the high canopy sheltered a greater number of termites. Analysis of covariance showed that crop yield (both plantain and cocoyam) was not directly linked to the abundance of all termite populations, but that the cocoyam yield was positively correlated with the abundance of soil-feeding termites (the majority in the assemblage) in the young plantation. This may be due to the beneficial conditioning of soil resulting from the foraging and construction activities of soil-feeders.

Lutzomyia lichyi (Floch & Abbonenc) is a suggested secondary vector of Leishmania in Colombia. Taxonomically, L. lichyi is very closely related to the L. longipalpis (Lutz & Neiva) species complex. Male members of the complex can be distinguished by their sex pheromones which are produced in papules found grouped together in pale patches on tergites 3 or tergites 3 and 4. Male L. lichyi also have papules, very similar in appearance to those of the L. longipalpis species complex but distributed on tergites 4, 5, 6 and 7. Chemical analysis of male L. lichyi hexane extracts has revealed the presence of two novel oxygenated methylsesquiterpenes. The two major oxygenated terpenes found in the extract of L. lichyi males are tentatively characterized as a primary and tertiary alcohol. The mass spectrum of the proposed primary alcohol is very similar to the published mass spectrum of 3-methyl-α-himachalene, the sex pheromone produced by the Jacobina chemotype of the L. longipalpis complex. The mass spectrum of the proposed tertiary alcohol also has similarities to the 3-methyl-α-himachalene sex pheromone.

The biocontrol potential of a microsporidian pathogen, Vairimorpha sp., obtained from field collected diamondback moth, Plutella xylostella Linnaeus, was assessed in a laboratory colony of this insect. The pathogenicity was quantified using a standard bioassay procedure by infecting second instar larvae per os with variable dose levels of the pathogen. Vairimorpha sp. caused 100% mortality even at a dosage of 1.5 x 103 spores per larva. The median lethal dose (LD50) was 2.2 x 104 spores per larva on day 5 post-inoculation. The time taken to achieve 90–100% mortality was dose dependent and varied from 5 days with 1.5 x 106 spores per larva to 11 days with 1.5 x 103 spores per larva. The pathogen reduced the food consumption of P. xylostella larvae by 75%, 93% and 95% at doses 1.5 x 104, 1.5 x 105 and 1.5 x 106 spores per larva, respectively. Histological observations showed that the pathogen preferentially infected adipose tissue cells but spread to almost all tissues. The pathogen was transmitted transovarially as well as horizontally and had a marked influence on progeny performance. It was concluded that Vairimorpha sp. has sufficient potential to be tested in the field as a biocontrol agent for P. xylostella.

Experimental comparisons were made between samples of moths obtained by Rothamsted tungsten-filament and Robinson mercury-vapour light-traps operating in a lowland dipterocarp forest in Peninsular Malaysia. The Rothamsted trap gave more uniform and consistent samples and performed better in the tropical conditions than the Robinson trap. There were no significant differences between the overall measurement of diversity for the group Geometroidea between the two trap designs although the Robinson trap was much more erratic from night to night. The total catch of non-Geometroidea moths was remarkably similar in the two trap types. The choice of appropriate light-trap designs for biodiversity studies in tropical rainforest is discussed.

The effect of artificial and natural sources of adult food on the survival and reproduction of the tropical fruit fly, Anastrephaserpentina (Wiedemann) was studied. Caged adult flies were exposed during their whole lifespan to water and one of the following diets: sucrose, intact fruit, open fruit, bird faeces, sucrose plus intact fruit, sucrose plus open fruit, sucrose plus yeast hydrolysate, and sucrose plus bird faeces. All flies exposed to intact fruit or bird faeces died within the first five days of adult life without laying eggs. Females exposed to open fruit exhibited the greatest mean longevity (56.7 days). The highest net fecundity rate was recorded from individuals exposed to sucrose plus yeast hydrolysate (164 eggs per female), followed by those exposed to bird faeces plus sucrose and open fruit (38 and 26 eggs per female, respectively). Some individuals were able to lay viable eggs late in life (>105 days of age). Only populations in which adult flies had access to either sucrose plus yeast hydrolysate, open fruit, or sucrose plus bird faeces exhibited positive intrinsic rates of increase (r). Flies offered a combination of dry sucrose plus open fruit exhibited greatly reduced net fecundity levels when compared with those individuals exposed to open fruit. Even more significantly, populations of flies offered the combination of open fruit plus sucrose exhibited negative rates of increase while those exposed to open fruit alone, grew. We postulate that this reduction in egg production can be explained by a ‘junk food syndrome’.

The responses of Glossina fuscipes fuscipes Newstead and other Diptera to carbon dioxide were studied in linear and dense forests along the shores of Lake Victoria, Kenya. Flies were caught in biconical traps and were intercepted with electric nets while in flight near traps. Carbon dioxide dispensed at a high rate (5 l min–1) in linear forest failed to increase the numbers of tsetse attracted to or caught in traps. In contrast, catches of non-biting Muscidae, Stomoxyinae and Tabanidae were improved by up to 11 times. Inside dense forest, carbon dioxide released at half this rate increased both the numbers of female tsetse attracted to a trap and the catches in a trap by about 2–3 times. Catches of male tsetse were, however, not affected. Striking improvements for other Diptera were also realized (up to 102 times). Under a variety of conditions, unbaited biconical traps attracted many Diptera to the vicinity of a trap, but caught few flies due to low capture efficiencies (typically less than 10%). In contrast, efficiency estimates for G. f. fuscipes were good, varying from 37 to 82% in different habitats and seasons. These results are discussed in relation to the search for practical odour attractants for riverine tsetse.

Cotesia flavipes Cameron, a gregarious larval endoparasitoid native to the Indo-Australian region, was imported from Pakistan and released in Kenya in 1993 for management of the exotic stemborer, Chilo partellus (Swinhoe). Recent reports confirmed the successful establishment of the parasitoid in three locations in Kenya and in northern Tanzania. Functional response studies on this parasitoid and an indigenous congener, Cotesia sesamiae (Cameron), indicated that C. flavipes had a higher searching ability and attacked more larvae when Chilo partellus was the host. When a native stemborer, Sesamia calamistis Hampson, was the host, there was no significant difference between numbers attacked by both parasitoids. Numerical response studies showed that Cotesia flavipes produced more total progeny and female progeny per female parasitoid on Chilo partellus than did Cotesia sesamiae. No significant difference in progeny production was detected between the two parasitoids on S. calamistis. Functional and numerical responses tested in the laboratory gave the same ranking of the two parasitoids on the two hosts as in the field. This study suggests that Cotesia flavipes is a more efficient parasitoid and it is anticipated that it will contribute to the control of both exotic and native stemborers in Kenya.

A parasitoid community on agromyzid leafminers from Cordoba, Argentina was analysed in terms of parasitoid assemblage size and host ranges of parasitoid species. Samples were taken during 1991–1995 at natural, urban and agricultural habitats. The system consisted of 69 parasitoid species and 51 leafminer species on 109 plant species. On average, 12 species parasitized each host, when only numerically well represented leafminer species were considered for analysis. Each parasitoid species exploited on average seven species and three genera of agromyzid leafminers. Both parasitoid assemblage size and parasitoid host range were notably high when compared with similar systems from other regions.