Cephalonomia stephanoderis Betrem and Prorops nasuta Waterston are two bethylid parasitoids obtained from Africa for the biological control of the coffee berry borer, Hypothenemus hampei (Ferrari) in Mexico and Ecuador. Rearing methods and life-cycle studies carried out under controlled conditions are described for both the parasitoids and H. hampei. Scanning electron micrographs are shown of the developmental stages of the parasitoids. Data are given on development times, pre-oviposition period and on the mating and oviposition behaviour of C. stephanoderis.

It is fitting that this, first, Guest Editorial to the new-format Bulletin should be devoted to stored-product entomology since 1990 celebrates 50 years of the formal establishment of stored-product insect research and control programmes in Britain. It was in 1940 that the Pest Infestation Laboratory was established at Slough under the, then, Department of Scientific and Industrial Research, consolidating the work begun some 15 years earlier under Professor J. W. Munro in the Entomology Department of Imperial College; almost at the same time, the Infestation Control Division of the Ministry of Food (now MAFF) was set up as an inspectorial and advisory body. Much has been achieved and many organisational changes have taken place since then. The original organisations have come together under the umbrella of the Ministry of Agriculture, Fisheries and Food (MAFF) whilst the group which was initiated at Slough in 1951 to address problems of storage in tropical areas is now the Storage Department of the Overseas Development Natural Resources Institute (ODNRI), the scientific unit of the Overseas Development Administration, UK (ODA). Slough has become synonymous with stored product research in Britain and beyond; sadly, however, the ‘Slough connection’ is destined to end—the ODNRI department will move this year to join its sister departments in the institute's new major laboratory development at Chatham, Kent, whilst plans are in hand for the eventual relocation of the MAFF laboratory as part of the Central Science Laboratory of the Agricultural Development and Advistory Service (ADAS).

Two field-collected strains of Culex quinquefasciatus Say, collected 50 km apart in Havana City, Cuba, were both resistant to malathion and propoxur, while one population also showed low level resistance to temephos. Laboratory selection of the latter population with malathion for 22 generations increased the malathion resistance 1050-fold, temephos resistance 24-fold and propoxur resistance 453-fold compared to the standard laboratory susceptible strain. Synergist studies and biochemical tests indicated that two mechanisms, an elevated esterase and an insensitive acetylcholinesterase, were operative in these strains. The esterase mechanism conferred resistance to malathion, but not to temephos or propoxur. The acetylcholinesterase mechanism increased the level of malathion resistance and extended the cross-resistance spectrum to temephos and propoxur.

The distribution and species composition of lepidopterous maize borers was studied in six locations in southern Nigeria during the second planting season (August-November) of 1985 and 1986. Sesamia calamistis Hampson (Noctuidae) and Eldana saccharina Walker (Pyralidae) were the stem borers most abundantly found in the locations sampled. S. calamistis was the dominant species up to eight weeks after planting in all locations. E. saccharina was the most abundant species from nine weeks after planting onwards, except at Umuahia where S. calamistis always comprised over 50% of the borer population. Mussidia nigrivenella Ragonot (Pyralidae) was found attacking maize ears in all locations, while Busseola fusca Fuller (Noctuidae) was found only at Idah and Alabata, and even there constituted only a small proportion of the population. Other borer species found were Coniesta (= Acigona) ignefusalis (Hampson) (Pyralidae) and Cryptophlebia species (Olethreutidae).

Endosulfan resistance in the coffee berry borer Hypothenemus hampei (Ferrari) was discovered in New Caledonia after six years of lindane and 12 years of endosulfan biannual applications. The direct spray technique was used to study cross resistance with lindane and to monitor resistance to both pesticides in 15 regions of New Caledonia. An easier monitoring technique was developed for early detection by field laboratories. Results from this simple method, using twice the LC99 of endosulfan to susceptibles (400 ppm) showed a comparable distribution of resistance to the direct spray method in five regions where resistance was detected. The percentage of surveyed fields containing resistant insects in these areas was: Poindimié, 100%, Ponérihouen, 97%; Touho, 63%; Houailou, 10%; Hienghène, 6%. Resistant insects were significantly more frequent in the new sunny fields than in older shady plantations (P<0.05), and fields with endosulfan used in the preceding year (P<0.001). The possible reasons for the observed distribution of resistance are discussed.

Phymastichus coffea, a new genus and species of tetrastichine Eulophidae, is described. This species is parasitic on the coffee berry borer, Hypothenemus hampei (Ferrari), in Africa and is currently under investigation as a possible biological control agent for this borer

Mean survival times for unfed ticks, Rhipicephalus appendiculatus Neumann exposed initially during the hot dry season (January) in Kenya were significantly higher than those of ticks exposed during the wet season (May). This was partly due to the timing of the next hot dry season which triggered the beginning of decline in survival, and partly due to the overall severity of the weather. The implication is that the time when the ticks feed affects the survival of the subsequent instar. The mean survival times for nymphs exposed initially during the wet and the hot dry seasons were 30 weeks and 44 weeks, respectively. Those for adult ticks ranged between 59–75 weeks and 62–79 weeks, respectively. Maximum survival times were, however, similar for adults but not for nymphs. Adult ticks had an initial period of 32–48 weeks of excellent survival, apparently independent of weather factors. Thereafter, mortality rates and adverse environmental factors were correlated. The survival of ticks fed on hosts of differing resistance status was also different. The most resistant host produced the smallest adult ticks and these gave the lowest survival, and vice versa. Male and female ticks from highly resistant hosts had similar survival, but the females from a moderately resistant host survived significantly better than the males. These results indicate the importance of weather and host resistance in R. appendiculatus survival.

Laboratory investigations were conducted into factors affecting oviposition, larval growth and mortality in the blowfly Chrysomya megacephala (Fabricius), an important cause of losses of salted dried fish in south-east Asia. When presented with a choice of fish spiked with recently laid C. megacephala eggs and unspiked fish, the flies preferentially oviposited on the spiked fish. Subsequently choice experiments indicated that the attraction exerted by the eggs was mainly olfactory in nature. When presented with oviposition media of a range of salt concentrations, C. megacephala preferentially oviposited on the medium of lowest concentration. In the absence of choice, C. megacephala readily oviposited on fish that had been salted to levels of up to 40% dry weight basis (dwb). Trials investigating the effects of feeding medium salt concentration on larval growth and mortality indicated that a high salt concentration of about 40% (dwb) is necessary to effectively control infestation of salted fish by C. megacephala. Such high salt concentrations are rarely obtained in commercially produced salted dried fish in south-east Asia and would be unlikely to gain consumer acceptance.

Population densities of mealybugs and other honeydew-producing Homoptera were assessed in six cocoa (Theobroma cacao Linnaeus) trials by inspecting trees from ground to eye level, and also by dissecting samples of terminal buds. A total of 68 cocoa progenies was examined, mainly inter-crosses of six clones. Progenies differed in their levels of infestation with total mealybugs, Planococcoides njalensis (Laing), Planococcus citri (Risso), Phenacoccus hargreavesi (Laing), (Pseudococcidae), Toxoptera aurantii (Boyer de Fonscolombe) (Aphididae), and Mesohomotoma tessmanni (Aulmann) (Psyllidae). Crosses with Amelonado or T63/971 were generally more densely infested with mealybugs than those for example of NA34 and T63/967. Trees of T17/524 parentage were sparsely infested with mealybugs. Rankings of progenies by infestation with mealybugs from the two different sampling procedures were positively correlated, but the relative abundances of individual mealybug species on the trunk and in the canopy differed. Several species of mealybug found in buds were either rare or never found by inspecting trees up to eye level. Correlations between rankings of progenies by order of abundance of Planococcoides njalensis and Planococcus citri were positive and statistically significant, as were those between mealybugs and infestation of buds by T. aurantii or M. tessmanni. The above rankings were negatively correlated with those by aphid and psyllid abundance assessed from inspecting trees up to eye level. The two sampling procedures were complementary but, for economy, samples of buds gave the clearest indication of a progeny's suitability for mealybugs.

The effectiveness of pitfall traps baited with cattle dung enclosed in a gauze bag and pads of cattle dung on soil as methods for sampling dung beetle populations was assessed in the summer-rainfall regions of South Africa using 17 species of nocturnal/crepuscular tunnelling beetles. Pitfall traps accumulated the catch and prevented both access to and emigration from the dung bait. In contrast, beetles had direct access to dung pads on soil which allowed colonists to modify the bait and to emigrate. The number of beetles collected was therefore the net result of immigration and emigration. On each of five occasions in November–December 1985, 40 pitfall traps and 40 dung pads were set out in the evening and the trapped beetles recovered the following morning. Overall, 3774 individuals were trapped. For most species there was no significant difference between trap types in the numbers caught but two species were significantly more numerous in pitfall traps and one species was more numerous in the dung pads. However, both methods produced similar patterns of rank abundance of species (r=0.95). There was no evidence that beetles were more evenly distributed between dung pad baits than between pitfall traps.

Adult male German cockroaches were exposed to deposits of amorphous precipitated and pyrogenic silicas in continuous and discontinuous contact bioassays. LC50S of precipitated silicas in the former case generally increased with oil adsorption capacity of the dusts; variability in response in discontinuous contact bioassays was apparently due to grooming of appendages following pick-up of dust aggregates. The toxicity of silica deposits in half-treated choice boxes varied with relative humidity and was effectively eliminated at 95% r.h. or when free water was provided. Cockroaches accumulated in the untreated side of the box irrespective of r.h.; the mechanism of this effect is discussed.

The parasitoid Aphidius rhopalosiphi De Stefani-Perez was imported into New Zealand as a biological control agent against the rose-grain aphid (Metopolophium dirhodum (Walker)) in 1985. In 1988–89, the rate of parasitism by A. rhopalosiphi was studied by rearing fourth instar M. dirhodum collected from barley at Lincoln and other sites in Canterbury. The rate of parasitism at the time of peak aphid numbers at Lincoln was approximately 50% in winter barley and 100% in spring barley. In spring barley, peak numbers did not exceed five aphids per tiller, and regulation of aphid population density below this level was attributed to parasitism following a large immigration of adult A. rhopalosiphi. Suction trap catches of A. rhopalosiphi increased between 1984, prior to release, and 1989, while catches of M. dirhodum showed a corresponding decline.

Two field experiments examined the effect of dung fauna on the breeding success of Haematobia irritans exigua DeMeijere at Rockhampton, Australia, and Haematobia thirouxi potans (Bezzi) at Hluhluwe Game Reserve, Republic of South Africa. Dung pads naturally infested with Haematobia eggs were produced by cattle at Rockhampton and by Cape buffalo at Hluhluwe. Pads were either exposed to, or protected from, all dung fauna for various periods up to four days. The effect of dung fauna on the immature stages of Haematobia spp. was estimated from differences in the numbers and size of flies that emerged from treated and control pads. In the first experiment, pads produced during the morning and afternoon were exposed for one, two or four days on seven different occasions. At Rockhampton, fauna-induced mortality was substantial but did not increase significantly after the pads had been exposed for one day. At Hluhluwe, in pads produced during the morning, fauna-induced mortality rose substantially with duration of exposure; in afternoon pads the increase was not statistically significant. Fly size, indicated by the mean headcapsule width of surviving females, decreased as exposure of pads to dung fauna increased from zero to four days, except in the afternoon pads at Rockhampton. In the second experiment, pads produced in the afternoon were exposed in the field for four days on 16 occasions at Rockhampton, and on 17 at Hluhluwe. Fauna-induced mortality averaged 79% and 84%, respectively. The activities of the dung fauna reduced the headcapsule widths of surviving flies by an average 2% at Rockhampton and by 7% at Hluhluwe, despite similar levels of dung dispersal. The dung fauna associated with the highest mortality of H. irriatans exigua at Rockhampton were Scarabaeinae and Macrocheles spp., while there were no significant associations between fly mortality and particular fauna in the Hluhluwe data.

The amidinohydrazone insecticide hydramethylnon, exhibited delayed toxicity to workers of Reticulitermes santonensis Feytaud and Microtermes lepidus Sjöstedt over a range of concentrations, with deaths starting two to six days after exposure. R. santonensis workers which had been exposed to hydramethylnon passed the insecticide to untreated termite workers, larvae and nymphs by trophallaxis. Laboratory colonies of R. santonensis exposed to hydramethylnon were killed completely within 20 days. The possible use of hydramethylnon impregnated baits for the control of subterranean termites is discussed.

A field trial was carried out in a Maasai group ranch to assess the use of odour-baited traps for suppression of a population of the tsetse fly Glossina pallidipes Austen. In January, 1987, local people made 100 NG2B traps in their homesteads. These were then deployed within the suppression zone of about 100 km2, primarily in the areas of woodland where flies aggregate in the dry season. Traps were baited with acetone (ca. 150 mg/h) and cow urine (ca. 1000 mg/h) and checked at monthly intervals in order to replenish odours and repair damage. A further 90 traps were added between October and December to enlarge the suppression area slightly and to strengthen the trap barriers. The population was monitored using biconical and NG2B traps as well as by mark-release-recapture estimates of population size. By October the number of G. pallidipes in the suppression zone was reduced by 98–99% relative to the number 3 km outside the suppression zone. Some reinvasion, mainly of parous females, occurred in November during the short rains but these flies were rapidly trapped out again. Average mortality rates due to trapping were estimated at 4–5% per day, which, combined with the natural mortality, reduced the adult population at a rate of about 2.6% per day during the dry season. The traps had less effect on the smaller population of G. longipennis Corti but still gave a reduction of up to 90% in the dry season. The use of this low technology approach offers good prospects for future community-based tsetse control operations.

The relative attractiveness of coloured sticky board traps to the carrot fly (Psila rosae (Fabricius)) is described by a model in which fly catch is related positively to the amount of light reflected from the trap in the green-yellow (550–570 nm) band of the spectrum and negatively to the amount reflected in the violet-green (390–550 nm) band. The model allows the performance of new coloured traps to be predicted solely from spectral reflectivity measurements. Similar numbers of carrot flies were caught/unit area on traps varying in size from 150 cm2 to 4800 cm2. Most flies were caught on traps resting on the ground. The number of flies caught was reduced by 0.84% for each cm the trap was raised above 10 cm from the ground. One-sided sticky traps angled at 45° to the vertical doubled the numbers of carrot flies caught/unit trapping area and reduced by 90% the numbers of non-target species caught.