Records of hourly trap catches of Helicoverpa armigera (Hübner) in a light trap and two pheromone traps in Andhra Pradesh, India, were used to assess the influence of moonlight and weather on trap performance. The environmental factors that were considered were mean hourly temperature, relative humidity, wind speed and maximum hourly percentage moon illuminance. The mean number of adults caught per hour reached a peak at 03.00 h in the light trap and at 02.00 h in one of the pheromone traps. The environmental factors were not sufficiently severe to produce any marked activity thresholds, although zero catches were recorded in the light and pheromone traps on occasions when the mean hourly temperature was 11°C. Despite there being obvious relationships between hourly light and pheromone trap catches with temperature, relative humidity and wind speed, it was not possible to determine whether these were causally related or merely coincidental relationships. Some of the observed relationships could not be explained in terms of known physiological or behavioural characteristics of the insect. It was evident that the light trap performance was influenced by the level of moon illuminance because this affected both the timing and size of the peak catch.

A description is given of the use of a video camera to estimate light-trap efficiency in the field. This camera relies on the extra light sensitivity provided by the Newvicon detector tube to enable insect track discrimination. Recorded insect flight tracks were classified into three distinct categories, new arrivals, passers by and local flights, the numbers of which were compared to the moth catch in a Robinson mercury vapour light-trap. Calculations of efficiency were made using two methods, the best-estimate efficiency, obtained by comparing the new-arrival tracks to the light-trap catch, and the worst-estimate efficiency, obtained by comparing new-arrival tracks plus passer-by tracks to the light-trap catch. Preliminary results indicate that efficiency varies with windspeed but with a maximum of 39%, obtained in virtually calm conditions, suggesting that some aspect of moth behaviour limits trapping efficiency. It is suggested that the speed of migration of screening pigment from the dark-adapted state to the light-adapted state in superposition eyes may have a bearing on the catching mechanism of a light-trap.

Standard curves for the regression of pteridine fluorescence in the head upon chronological age were constructed for laboratory-reared Glossina adults. Of the five species investigated, the technique was a reliable predictor of age in G. morsitans morsitans Westwood, G. pallidipes Austen, G. palpalis palpalis (Robineau-Desvoidy) and G. tachinoides Westwood, but was not reliable for G. austeni Newstead. Field-caught tenerals of both sexes of G. p. palpalis, field-caught teneral females of G. pallidipes and tenerals of both sexes of G. m. morsitans released on an island in Lake Kariba, Zimbabwe, had significantly higher pteridine fluorescence levels than tenerals hatched in the laboratory. However, the regression of fluorescence on age produced similar slopes for both laboratory-reared and field-caught flies. From this, it is concluded that estimates of the ages of field-caught flies can be corrected by simply subtracting the difference in fluorescence values between field-caught and laboratory-reared tenerals. In practice, this amounts to shifting the frequency distribution of different age categories to bring the youngest age group back to day zero. A comparison of the fluorescence technique and the ovarian dissection method of determining the ages of females showed that over a wide range of ages the former was at least as accurate as the latter and should be the technique of choice for most field investigations.

Survivorship curves for the pre-adult stages of Pieris rapae (L.) on kale in Massachusetts exhibited two patterns. Early season generations showed a linear decline with mortality in all stages, whereas late season generations showed reduced losses in larval instars 2-4 and a concentration of mortality in the fifth instar. Ratios of direct measurement of recruitment of P. rapae and its parasitoid Apanteles glomeratus (L.) to their first larval and egg-plus-larval stages, respectively, indicated that losses to parasitism for five host generations were 86·1, 9·1, 58·O, 71·7 and 40·3% for the 1985 third generation and the 1986 first to fourth generations. Patterns of percentage parasitism within single generations were determined by higher rates of mortality in parasitized than healthy older larvae (instars 3-5) and, in some cases, by higher rates of host than parasitoid recruitment towards the end of the generation.

A survey for ticks on livestock with emphasis on ticks parasitizing cattle was conducted below 16°N lat. in Mali. Seventeen species of ixodid ticks were recovered from cattle, 12 from sheep, five from goat, four from horse, one from donkey and four from camel. Amblyomma variegatum (F.), Boophilus geigyi Aeschlimann & Morel, Hyalomma marginatum rufipes Koch and H. truncatum Koch were widespread, and could each be collected as adults from cattle throughout the year in certain regions. A. variegatum was most numerous from the tropical woodlands to the Sahelo-Sudanian steppe. The prevalence of B. geigyi in Mali confirms an extended distribution of this species in West Africa. B. annulatus (Say) and B. decoloratus (Koch) were prevalent in the inland delta area and in south-western Mali. H. m. rufipes and H. truncatum were most numerous in the Sudanian and Sahelo-Sudanian steppe. H. dromedarii Koch, H. impeltatum Schulze & Schlottke and H. impressum Koch were collected in the steppeland areas. H. nitidum Schulze was collected for the first time in Mali. This comparatively more hydrophilic species was prevalent in the North Guinean forest and Sudano-Guinean vegetation zones. Of eight Rhipicephalus species from livestock, seven were collected from cattle: R. cuspidatus Neumann, R. evertsi evertsi Neumann, R. guilhoni Morel & Vassiliades, R. muhsamae Morel & Vassiliades, R. sanguineus (Latreille), R. senegalensis Koch and R. lunulatus Neumann. R. sulcatus Neumann was obtained only from sheep. The distribution and phytoclimatic associations of these species are discussed.

A total of 134 species of Coleoptera (100 of staphylinids, 13 of hydrophilids and 21 of histerids) was extracted from pads of cattle dung placed in four contrasting habitats in both Hluhluwe Game Reserve, Natal, South Africa, and the surrounding pastoral regions. Pads were exposed to colonists for 24 h on eight occasions over one year. Forty-six species and species complexes were captured in numbers sufficient to permit analysis of their distribution patterns. Of 27 species significantly influenced by vegetation type, 22 were more abundant in unshaded situations and five more abundant in situations shaded by high profile vegetation. The total numbers of individual predatory staphylinids were evenly distributed between vegetation types, but members of coprophagous staphylinid and other predatory taxa were more numerous in unshaded situations. Of 13 species significantly influenced by soil type, six were more abundant on clay and seven more abundant on deep sand. The total numbers of individual coprophagous oxyteline staphylinids were greater on clay than on sand, but the members of predatory taxa, including staphylinids, were evenly distributed across soil types. Of 14 species showing significant seasonal changes in abundance, 13 were more abundant in hot wet months and one in cool dry months. The total numbers of hydrophilid individuals were greater in the cool dry season, but the other taxa were active predominantly in the rainy season. Most species were present in similar numbers in both the game reserve and pastoral regions. Enclosure of dung pads within wiremesh cones to exclude large dung-burying beetles resulted in reduced colonization by most beetle species regardless of their size.

In the ecologically sensitive Sahel of West Africa, two major crop pests, Helicoverpa armigera (Hübner) and Heliocheilus albipunctella (de Joannis), are attacked by Cardiochiles variegatus Szépligeti and C. sahelensis sp. n., respectively. The twelve Cardiochiles species present in the Sahel are revised, and a key is given for their identification. Five of these species (C. calvus sp. n., C. coelofrons sp. n., C. exiguurus sp. n., C. nixoni sp. n. and C. sahelensis sp. n.) are described, and C. striatus Brues is made a synonym of C. punctatus Szépligeti. Host relationships of the genus worldwide are discussed and the host records, principally involving Pyralidae and Noctuidae, collated. The known biology is summarized from the literature on the North American species C. nigriceps Viereck, and a comprehensive bibliography on the genus is given.

Dans la région écologiquement difficile du Sahel de l'Afrique de l'Ouest, on a découvert que deux importantes variétés d'insectes nuisibles à la culture, Helicoverpa armigera (Hübner) et Heliocheilus albipunctella (de Joannis), sont attaquées respectivement par Cardiochiles variegatus Szépligeti et C. sahelensis sp. n. Les douze espèces de Cardiochiles qui se trouvent dans la région du Sahel sont réétudiés, et une clé est formulée afin de les identifier. Cinq de ces espèces (C. calvus sp. n., C. coelofrons sp. n., C. exiguurus sp. n., C. nixoni sp. n. et C. sahelensis sp. n.) sont décrites, et C. striatus Brues devient synonyme du C. punctatus Szépligeti. Les rapports universels de ces genres d'hôtes sont discutés ainsi que la comparaison des rapports d'observation, principalement en ce qui concerne les pyralides et les noctuides. La biologie actuelle est resumée de la littérature sur l'espèce C. nigriceps Viereck nord américain et une vaste bibliographie du genre est présentée.

The synthetic attractant pheromone 6-acetoxy-5-hexadecanolide in a formulation of 20 mg containing 5 mg of the active (−)-(5R,6S)-isomer in an effervescent tablet produced a high, positive overall response by gravid females of Culex quinquefasciatus Say when the mosquitoes were exposed to the pheromone in established breeding sites in western Kenya. Significantly more females (82%) oviposited around the pheromone source compared to a control. The activity of the pheromone persisted in the established breeding place for four days after application. The addition of the insect growth regulator S-31183 (2-[1-methyl-2-(4-phenoxyphenoxy)ethoxy]pyridine) to the formulation did not affect the activity of the pheromone. Newly-made breeding sites exposed domestically were not attractive initially for oviposition by gravid females but, after 18 days, they became more attractive. Trays treated with synthetic pheromone diverted females from similar unbaited trays exposed within 10 m. A sample of larvae taken from a site treated with pheromone and insect growth regulator showed 100% mortality by the pupal stage. Thus, the efficacy of the pheromone has been demonstrated for the first time in the field and the possibility of using this material in combination with a ‘safe’ insecticide confirmed.

Treatment of rice fields in Sri Lanka with monocrotophos at 10 mg/litre or pirimiphos-methyl at 0·1 mg/litre gave a selective advantage to larvae of Anopheles subpictus Grassi and A. nigerrimus Giles carrying the oxidase- and acetylcholinesterase-based resistance genes, respectively. However, this selective advantage was apparent for less than ten days after spraying. There was no mortality of any larval instar with monocrotophos 12 days after spraying, and no fourth-instar larval mortality with pirimiphos-methyl 17 days after spraying. The chemical degredation curves for these compounds indicated that this short duration of efficacy was due to the instability of the compounds in water under field conditions. In contrast, the new growth regulator S-31183 (2-[1-methy1-2-(4-phenoxyphenoxy)ethoxy]pyridine) sprayed at 0·1 mg/litre conferred no selective advantage to larvae with either resistance mechanism and had a total efficacy period of at least 71 days. This difference can be attributed to the greater toxicity of the growth regulator and its slower chemical degradation under field conditions when compared to the organophosphates.

Opisina arenosella Walker is a defoliating pest of coconut in Sri Lanka. A first attempt was made to understand its population dynamics. Analysis of records of population outbreaks throughout the country from 1965 to 1985 revealed cycles in the population of approximately one generation period, giving the population the appearance of partially discrete generations. There was also evidence for longer cycles of six-month period. Outbreaks occurred throughout the coconut-growing regions of Sri Lanka, and the numbers of outbreaks per year in different provinces were sometimes correlated, indicating a common, probably climatic, triggering mechanism. Parasitism remained high throughout the outbreaks and there was some evidence that pupal parasitism increased towards the end of an outbreak. A working hypothesis that explains the population dynamics of O. arenosella and the origin of outbreaks is presented.

Aerial sampling for Nysius vinitor Bergroth was undertaken in the surface and upper air, at altitudes of 2 and 100-300 m, respectively, at Trangie in central New South Wales and at Corny Point, Yorke Peninsula, South Australia. Insects were sampled for 15 periods, each of 3-11 days, between October 1979 and February 1984, covering all months except January, March and May. N. vinitor was one of the most abundant insects caught in the upper air during the day and night (mean density of 652/106 m3), while the congeneric N. clevelandensis Evans was rarely caught at any time. N. vinitor was caught in all months sampled except for the winter months of July and August, and the largest daily catches occurred in September. Females were generally less common than males, although the relative incidence in the upper air catches frequently increased significantly from day to night. Fewer mature females were caught in the upper air (0-16·8%) than at the surface (0-48·4%). Densities were generally much greater in the surface air than in the upper air, although during the major flights of spring, there was less than a two-fold difference, indicating increased migratory activity. Migration occurred in a range of synoptic conditions resulting in the displacement of individuals in a variety of directions and distances depending on synoptic flow at the time of flight. Major migrations occurred at night, following dusk take-off, in disturbed weather associated with prefrontal airflows. These resulted in net southward displacements of ca 200-300 km depending on flight duration. It is suggested that major immigration flights into central-western New South Wales and regions to the south regularly occur in early spring (September-October) and probably arise from breeding areas in subtropical latitudes.

In southern Brazil, adults and larvae of the halticine beetle Alagoasa parana Samuelson fed on the foliage and flowers of Lantana tiliaefolia and L. glutinosa (Verbenaceae). The life-cycle of this univoltine species from egg to adult emergence took 80-90 days between October and April. The abundance varied seasonally from four to eight adults per 100 branches. Larvae remained on the foliage during development and pupated in moist, loose, friable soil within a cocoon at the base of the host-plant. Adults overwintered and oviposited in litter at the base of the host-plant. In multiple-choice host- specificity studies in Australia, adults fed lightly on Verbena bonariensis and Clerodendrum speciosissimum (Verbenaceae) and produced minute scars on leaves on unrelated passion fruit (Passiflora edulis) and sunflower (Helianthus annuus). However, A. parana completed immature development only on L. camara among the 55 plants tested. The potential of A. parana as a biological control agent for L. camara in Australia is discussed.

The species of the cixiid genus Myndus occurring in the Solomon Islands and Vanuatu are reviewed. M. macfarlanei sp. n. is described from Santa Cruz Islands. It is distinguished from M. mavors Fennah and M. taffini Bonfils, both of which are redescribed and illustrated. All species have been collected from coconut palms, and M. macfarlanei also from areca palm (Areca catechu). M. taffini has been previously confirmed as the vector of foliar decay of coconut palms in Vanuatu.

Densities of four herbivorous insect species were compared on field beans (Phaseolus vulgaris) grown in monoculture and those grown in relay intercropping with winter wheat. In three years of study in New York State, population densities of Empoasca fabae (Harris) and Aphis fabae Scopoli were significantly less in plots intercropped with winter wheat than in those grown in monoculture. In contrast, intercropping was associated with greater densities of Lygus lineolaris (Palisot de Beauvois) and Systena frontalis (F.). An increased density of L. lineolaris may be an economic risk factor in beans intercropped with wheat because only this species of the four studied feeds exclusively on the flowers and developing seed pods.

A rapid technique is described for characterizing and monitoring, in single insects, the insensitivity of acetylcholinesterase (AChE) to organophosphorus and carbamate insecticides. Ninety-six insects are homogenized simultaneously in a microtitre plate and portions (e.g. 0·05 for Musca domestica L.) assayed colorimetrically with acetylthiocholine in the presence and absence of diagnostic concentrations of insecticide. Reactions are monitored by a kinetic microplate reader linked to a microcomputer that determines mean AChE activities automatically by linear regressions of absorbance-time data. Mean inhibited activity is then expressed as a percentage of uninhibited activity. Several inhibitors can be tested against the same insect to yield an ‘insensitivity profile‘ of individuals and strains. In tests on M. domestica adults of known AChE genotype, the assay clearly distinguished not only between a sensitive and two slightly (3-15-fold) insensitive AChE variants but between all six genotypic combinations of these three alleles.

Tamarixia leucaenae sp. n. is described from Trinidad as a parasitoid of Heteropsylla cubana Crawford. The psyllid is a serious pest of Leucaena leucocephala, which is used as a shade tree in plantations of various crops in the tropics.