Lysiphlebus testaceipes (Cresson) (Hymenoptera: Braconidae, Aphidiinae) is a newly discovered species alien to Benin (West Africa) and the dominating aphid primary parasitoid in vegetable agroecosystems. A study on the preference of this parasitic hymenopteran for three key aphid pests of vegetables (Aphis craccivora Koch, Aphis gossypii Glover and Lipaphis erysimi (Kaltenbach) (Homoptera: Aphididae)) was carried out under choice and no-choice conditions at 26 ± 1 °C in both Petri dishes and cages. The aphidiine rejected L. erysimi and did not oviposit in this aphid species in any of the trials. In all tests, A. gossypii proved to be the aphid host preferred most frequently by L. testaceipes. This study contributes to the fundamental knowledge on the oviposition behaviour of L. testaceipes and provides information for use in the development of sustainable aphid pest management strategies in Benin.

Topical application of crude ethanol extracts (CEs) of the leaves of 43 of 51 Jamaican plants produced varying degrees of multiple acaricidal effects on engorged Boophilus microplus Canst., including mortality (M), inhibition of oviposition (IO) and inhibition of embryogenesis (IE). Acaricidal indices (AI) ranged from 50 to 100 for the CEs of 29 plants, 38 to 47 for 9 plants and from 0 to < 25 for 13 plants. The most active CEs, in decreasing order of activity (AI values in parentheses) were those of: Simarouba glauca (100), Symphytum officinale (99), Nicotiana tabacum (95), Hibiscus rosa-sinensis (93), Ervatamia divaricata = Ricinus communis (82), Salvia serotina (80), Stachytarpheta jamaicensis (79), Blighia sapida = Ocimum micranthum (76), Spigelia anthelmia (75), Cycloptis semicordata (74), Mormordica charantia (71), Bontia daphnoides (69), Azadirachta indica (68), Capsicum annum = Catharantus roseus = Petiveria alliacea (66), Gliricida sepium (64), Lippia alba (62), Cuscuta americana = Erythrina corallodendrum (61), Piper amalago (60), Cannabis sativa = Cecropia peltata (58), Dioscorea polygonoides (56), Artocarpus altilis (53), Crotalaria retusa (51), Citrus aurantium (50).

Steam-distilled floral oils (essences) from several species of Theobroma(Sterculiaceae) (T. cacao Linneaus, T. simiarum Donn. Smith, T. mammosum Cuatr. & Leon, and T. speciosum Willd.) were tested using McPhail traps, in an abandoned Costa Rican cocoa plantation to determine their levels of attraction for flying insects. In each of the three bioassays (two successive dry seasons and one intervening rainy season), the traps were inoculated with floral scents at 1, 10, and 100 ppm, while controls were inoculated with a 10% solution of chloroform solvent in distilled water. Of a total of 223 Diptera captured in all three bioassays, only 5% were found in the controls, indicating attraction to the floral oil. About 72% of all Diptera captured were Cecidomyiidae, of which three species, Mycodiplosis ligulata Gagne, Aphodiplosis triangularas (Felt.) and Ledomyia sp., comprised 59% of the total. Eighty-eight per cent of all midges captured were females. Only 7% of the total were known cocoa-pollinating midges of Ceratopogonidae, and all of these were females. Sixteen per cent were Phoridae, known pollinators of the allied genus Herrania in Costa Rica. Although the chemical composition of floral oils varies greatly among the species of Theobroma, no discernible differences were found in the attraction of midges to floral oils tested. While floral fragrances in Theobroma species may represent a generalized adaptation for dipteran pollination, small numbers of several species of Trigona bees (Hymenoptera: Apidae: Meliponinae) were also attracted to the floral oils.

Conessine, the steroidal alkaloid of Holarrhena antidysenterica Wall, possesses a wide range of activities against four insect species viz. Aedes aegypti, Dysdercus koenigii, Spodoptera litura and Pieris brassicae. In D. koenigii the compound inhibits the egg hatching of treated adults and nymphs. In Ae. aegypti the larval developmental periods are extended, resulting in a high mortality rate. Such effects are produced at very low dosages of 0.5 to lOppm. Antifeedant activity is observed against larvae of S. litura and P. brassicae at concentrations of 0.005 to 0.2 % of conessine.

Nineteen different tick species have been identified in Western Ethiopia. The most important ticks belong to the genera Amblyomma, Boophilus, Hyalomma and Rhipicephalus, while the major cattle tick-borne diseases are anaplasmosis, babesiosis and theileriosis, T. mutans.

Dipping, hand spraying and spray races for ticks are only practised in the state dairy farms where cross-bred cattle are kept. The main acaricide in use is the chlorinated hydrocarbon, toxaphene. Flumethrin bayticol pour-on is now being used to a limited degree on dairy cattle. Traditional tick control methods which include hand-picking and the application of plant preparations are widely used on indigenous cattle.

The biosystematics of species in the Cotesia flavipes complex is reviewed with reference to studies conducted on their morphology, morphometrics, enzyme electrophoresis and hybridisation. A survey of 5 morphological characters scored from 17 populations indicated that the scuto-scutellar sulcus and the rugosity on the propodeum could be used to separate the species. The shape of the male genitalia was valid for separating the populations of C. flavipes from those of C. sesamiae and C. chilonis. Canonical variate analysis separated the complex into three distinct clusters with populations from Africa together, populations from Asia and the neotropics forming a second cluster, and material from China and Japan forming the third cluster. Electrophoretic studies showed that esterase, glucosephosphate isomerase, hexokinase, sorbital dehydrogenase and phosphogluconate dehydrogenase, among others, had fixed alelles and could be used to distinguish the species. Cladistic analysis of the allozyme data indicated that allopatric populations currently included in C. flavipes may not be a monophyletic group. Interspecific crosses revealed that males of C. sesamiae could mate with females of C. chilonis and produce viable females.

Tsetse flies have been eradicated from an area of 48,000 km2 in Zimbabwe since 1981. The main approach has been pesticidal control, involving ground spraying, aerial spraying, cattle dipping and artificial bait techniques, in some circumstances in combination. This represents a change in tactic from the pre-independence period when control relied solely on ground spraying. Factors which have influenced choice of technique are discussed in the paper, including scale of trypanosomiasis problem, technical limitations of the technique, cost-effectiveness and environmental considerations.

Ground spraying, the mainstay of tsetse control operations in Zimbabwe prior to 1980, is becoming increasingly unfavourable because of high logistical requirements and environmental reasons, but remains an effective technique under a wide range of circumstances. Aerial spraying has proved very effective for management of crisis situations but is comparatively expensive, capital intensive in hilly terrain and less effective against Glossina pallidipes than G. morsitans. Vector control by applying insecticide (deltamethrin) to cattle appears technically feasible at a very competitive cost. This is a most promising technique in areas where there are already cattle and few wild hosts.

Control of tsetse using odour-baited and insecticide-treated screens has proven technically feasible in a wide range of terrain, and appears economically competitive with ground spraying. Both technical and financial performance of the technique are still being improved. Bait technology offers scope for the new approaches to the control of the fly and defence of cleared areas from reinvasion.

Literature on the distribution, biology, seasonal population fluctuations, economic importance, acaricidal susceptibility and measures for the control of the cattle ticks Boophilus microplus Canst., Amblyomma cajennense Fab., A. variegatum. Fab. in the Caribbean has been critically reviewed. The ticks, which inflict about $62 million annual loss on the region's livestock industry, are still susceptible to acaricides, despite a few populations of B. microplus showing 31- to 227-fold resistance to lindane and 15- to 67-fold resistance to carbaryl, chlorfenvinphos, dimethoate and crotoxyphos.

The screwworm, Cochliomyia hominivorax Coq. is widespread, except in Puerto Rico and Curacao, from where it has been eradicated. The annual cost of surveillance against the fly and treatment of cattle for myiasis is estimated to be about $59 million. Its eradication from the entire Caribbean region by insect sterile method is advocated.

The susceptibility of head lice, Pediculus humanus capitis collected from children in Israel and that ofa laboratory colony of body lice, Pediculus humanus humanus to the insecticides malathion, deltamethrin, permethrin, fenitrothion and dieldrin has been evaluated using standard WHO papers. The LT50 and LT95 were established using different exposure times. Deltamethrin had the highest“knock-down”effect, followed by permethrinand malathion. All insecticidesexcept dieldrin gave higher mortality for body lice than for head lice. No differences in the susceptibility between adult and nymph lice could be observed.

Trypanosome infection rates in tsetse, Glossina pallidipes Austenin five areas along the Kenya coast were studied for 2 years (1980–1982). The total percentage infection rates were 12.62, 7.24, 9.50, 7.86 and 7.97 for Ukunda, Diani, Muhaka, Shimba Hills and Mwalewa, respectively. The respective values for males were 3.13, 4.16, 5.17, 5.03 and 8.13. Overall there were more trypanosome infections due to; Trypanosome congolense followed by T. vivax and T. brucei, although these varied among the localities. The age of the flies, their feeding patterns and regular use of chemoprophylaxis in local cattle were the main factors affecting infection rates.

The permanent mass rearing of rice stem borer, Chilo zacconius in West Africa; rice stem borer, Chilo suppressalis, in Asia and Europe; and sugar-cane stalk borer, Chilo sacchariphagus, in Asia and Indian Ocean was perfected in the laboratory to enable us multiply some parasites such as Apanteles spp., Goniozus procerae, Tetrastichus spp., Trichospilus spp. or the tacbinids, Diatraophaga striatalis and Lixophaga diatraeae.

The principal difficulties appear during mating of several hosts and parasites, development of pyralid young larvae or when it is necessary to protect reared insects or artificial medium against pathogens.

A survey of the parasites, parasitoids and predators of the nymphs and adults of Oedaleus senegalensis showed that three dipterous insects and a red mite were common parasitoids of the grasshopper. Seven arthropod species were observed preying on the nymphs. Among the vertebrates, two reptile species, one amphibian and 20 species of birds were observed preying on both the nymphs and adults of the grasshopper.

The suitability of some plant products (leaf powders and volatile oils) in protecting cowpea seeds from attack by Callosobruchus maculatus F. during storage was evaluated at a range of 0.5–4 g powder and 0.5–30μ1 for oils. Oils of the plants studied: Lantana camara L., Cymbopogon citratus (DC) Stapf., Eugenia uniflora L. and Lippia adoensis Hoschst. were more potent than their respective powders in reducing or inhibiting oviposition and adult emergence. Effectiveness of the oils as protectants for stored cowpea in decreasing order is: L. adoensis = C. citratus > L. camara and E. uniflora. Only the powdered leaves of E. uniflora and L. adoensis were effective in providing a high level of bruchid control. However, dressing with all the oils and powder of E. uniflora left the seeds fresh at 54 days after treatment. The significance of these findings in protecting cowpea against the storage pest is discussed.

It is evident that our environment has been flooded with pesticides and that some of these have had effects other than those intended. There is no doubt that indiscriminate use of pesticides has the potential to upset temporarily many ecological patterns. Whether this is significant in the long run remains to be seen.

It is sincerely hoped that the experience of the past (especially in the first world) will ensure wiser use of the pesticides in the future (primarily in the third world). It is likely that new pesticides will be developed and that they will bring new problems. Some of these problems may have far-reaching environmental implications in terms of their potential benefits and their propensity for damage. These problems will be compounded by residues of pesticides and a host of other contaminants already present. Therefore, it should and must be everyone's responsibility that the potential benefits from pesticides are maximised. However, such maximisation will be realised only if the environmental implications of their use is understood, and if they are applied with discretion to minimise their side effects.

The quantitative and qualitative changes of bacterial flora associated with the silkworm (Bombyx mori) at different stages of its life cycle were studied. Larvae reared on mulberry leaves were dissected and their bacterial populations counted after a 3-day incubation period at 28 ± 2°C. The results showed a higher heterotrophic bacterial population in the fourth and the fifth instars, which coincide with the active feeding stage of the larvae. The similarity of the genera observed in the digestive tract and that observed on the leaves fed to the larvae suggests colonisation of food microflora in the gut following ingestion. The bacteria inhabiting the gut of silkworm were found to be elaborating amylase, caseinase, gelatinase, lipase and urease. The highest percentage of isolates were protease producers followed by lipid and polysaccharide splitters. The results indicate that the bacterial flora play an important role in the digestion of ingested food material.

The objectives of this study were to identify the preimaginal development of instars of Diachasmimorpha tryoni (Cameron) (Hymenoptera: Braconidae: Opiinae), a larvo-pupal parasitoid of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), and to define its thermal requirements. Development was followed daily and parasitoid stage and size were noted. Larval samples were observed under a scanning electron microscope. Developmental rate as a function of temperature was studied with the Sharpe-DeMichele 6-parameter biophysical model and thermal requirements (lower developmental threshold and thermal constant) calculated using a linear regression. The duration of parasitoid development at seven temperatures ranged from 16.52 ± 0.96 days at 28 °C to 57.62 ± 1.85 days at 15 °C (males) and from 18.00 ± 0.79 days at 28 °C to 63.60 ± 1.52 days at 15 °C (females). Male development always took shorter than female development. No parasitoids emerged at 29 and 30 °C, which seems to be close to maximal temperature. The development required 322.6 ± 17.6 degree-days above a thermal threshold of 9.19 °C (both sexes cumulated). These data are compared with those of the host fruit fly, and the suitability of D. tryoni in controlling the Mediterranean fruit fly in Reunion Island is discussed.

Non-setting adhesives available were assessed for catching insects of medical and veterinary importance. Physical, chemical and handling properties are described. The results of tests are given using the most suitable adhesives against Glossina spp. (tsetse), Aedes aegypti (mosquito), Lutzomyia longipalpis (sandfly), triatomid bugs and cockroaches. Details are given of a formulation suitable for the capture of most insects in a variety of climatic conditions. The manufacturer's addresses are given to prevent difficulties in ordering and obtaining these products.

Species composition and behavioural patterns were determined for anopheline mosquito samples collected between October and September 1990, from Gambella region, south west Ethiopia. At least eight anopheline species, which differed in their habits, were found to be prevalent in the region. Findings of indoor-resting collection and hut density determinations showed the relative prevalence, in decreasing order of magnitude, to be Anopheles pharoensis, A. gambiae s.l., A. nili, A. coustani, and A. ziemanni. On the other hand, the relative frequency of occurrence based on outdoor human-bait capture was A. pharoensis, A. ziemmani, A. coustani, A. squamosus, A. paludis and A. funestus, in decreasing order of importance. The rate of human feeding of A. nili, A. gambiae s.l., A.pharoensis and A. coustani were 37.5, 33.0, 22.5 and 6.7%, respectively. Among the endophilic mosquitoes assayed, the overall infectivity rate was found to be 0.56%. Sporozoite rates of 0.77% for A. gambiae s.l. and 0.47% for A. pharoensis were determined.

A series of life tables (22 generations) for the rice yellow stem borer, Scirpophaga incertulas (Walker), a major pest of rice in Bangladesh, was constructed. In a deepwater rice ecosystem, the S. incertulas population dropped to a low level in the second or third generation (May-June), then reached the annual peak level in the fifth generation during September-October. The population dropped again to the lowest level in the sixth generation (November-February) when the larvae remained in diapause for about 3 months. In general, the population suffered very high mortality (99%). The estimated egg mortality was 49%; about 96% of the hatched larvae failed to penetrate into the rice stem; 39% larvae and 27% pupae died inside the stem. The population suffered very high mortality (96 %) at the early larval stage and the resultant survivorship curve was type III. Key factor analysis revealed that the disappearance of newly hatched larvae before penetration into the rice stem was the key mortality factor responsible for population fluctuations between generations. Disappearance of young larvae and egg mortality were density-dependent, but of a weak type.

Studies on damage by larvae of Eldana saccharina Walker, Chilo zacconius Bleszynski and Sesamia spp. to sugar-cane stands revealed a high degree of correlation between internode damage and stalk damage as well as between internode damage and sugar content of the canes. For every 1% increase in stalk damage there was a corresponding increase of 0.214% in the internode damage. The distribution of larvae inside the internodes was found to depend on the level of infestation. At low field infestation level (below 25 larvae per 100 canes) the distribution was random. As the level of infestation increases, the distribution becomes more aggregated. The distribution of damage in the sugar-cane field was found to depend on the overall stalk damage. The distribution tends to be more contagious when field level of stalk damage was less than 45%. The damage became evenly distributed when stalk damage rose above 60%. An estimation of average loss of sugar caused by stem-borers to the variety NCO 376 (at the field damage rate of 8.6, 10.6 and 3.1% damage for bottom, middle and top parts respectively of the cane) was U.S.S332.10 per ha of field.