In a rural area of southeastern Tanzania, studies were undertaken on the dispersal and survival of Anopheles funestus Giles and A. gambiae Giles s.l. during the rainy season. Blood fed, resting mosquitoes were collected indoors, marked with fluorescent powder and released on the same day from two different sites in the study area. For two weeks indoor resting mosquitoes were collected from 11 houses in the release area. Additional collections were made with a light trap from a sentinel house in the centre of the study area. Anopheles funestus was more abundant than A. gambiae s.l. Of 4262 A. funestus and 645 A. gambiae s.l. released, 4.3% and 7.4%, respectively, were recaptured. Dispersal of mosquitoes was not random: one of three areas was favoured significantly more than the other areas, as shown by the recapture and movement rates of marked mosquitoes. Based on the regression of the recapture rate, estimated daily survival rates of A. funestus and A. gambiae s.l. were 0.63 and 0.78, respectively. These were significantly different. The differences in dispersal and survival rates between the two species are discussed in view of local topography and species-specific characteristics.

The integrated use of biconical traps, insecticide-impregnated targets and the sterile insect technique was developed for the eradication of Glossina palpalis palpalis (Robineau-Desvoidy) in a 1500-km2 area of central Nigeria. Six weeks or more of continuous removal trapping, using biconical traps, reduced the target tsetse population by more than 90% but failed to eradicate it. Males sterilized by irradiation from a 60Co source that were then released weekly induced significant sterility in target females and were successful in helping to eradicate the target population. A minimum ratio of 10:1 of sterile to wild males was required to achieve eradication in a central area of 300 km2. In marginal habitats, insecticide-impregnated targets were found adequate to control the tsetse population. The targets were also efficient as barriers to prevent reinvasion of the area. The combined effect of removal trapping and sterile male release is expected to eradicate G. p. palpalis from the entire study area.

Using the inverse square law, estimates can be made of the distances at which illumination from a light-trap is equal to that from background sources. From these distances an index of trap radius can be constructed which can be considered as a measure of trap potential. Between new moon and full moon trap radii vary, depending upon the times of the night at which the trap may be operating, in ratios from about 10:1 to 15:1. A comparable index of light-trap catches can be calculated which allows catches to be examined in relation to changing radius of the trap. Analysis of a series of catches in Uganda and Ghana shows that many species are more abundant than expected in periods of moonlight, particularly at and near full moon, the biggest difference between new moon and full moon being about 10:1 for Marasmia trapezalis (Gn.), whereas the Isoptera, Bostrychidae and Spodoptera triturata (Wlk.) are 3–4 times more frequent at full moon. The ratios between catch at new moon and catch at full moon suggest that the primary determinant of catch is the frequency with which insects cross the boundary of a region of influence whose size is determined by a radius of equal energy. Deductions about the pattern of insect activity through a lunation, and nightly, and the general agreement between curves describing the change in radius of the trap and those of trap catches suggest that changes in catch over a lunation can be explained by changes in the effectiveness of the trap. When corrections are made to allow for such changes, all taxa show some increase in numbers in moonlit periods and in many taxa this increase is substantial. Correction of catches should take account of flight periodicity and this periodicity should, if possible, be confirmed by methods independent of light-traps.

Closely spaced stable traps were used to determine the preferences of mosquitoes for 6 vertebrates at Kowanyama, northern Queensland, on 4 occasions during the wet and dry seasons of 1974–75. A total of 44 626 mosquitoes from 35 taxa was collected and compared with 26 215 specimens of 15 taxa trapped at Charleville, south-west Queensland, in February 1976. Host preference was analysed in detail for 11 species; Anopheles bancroftii Giles, An. amictus Edw., An. annulipes Wlk., An. farauti Lav., An. meraukensis Venhuis, Aedes bancroftianus Edw., Ae. normanensis (Tayl.), Ae. vittiger (Skuse), Culex annidirostris Skuse, Cx. quinquefasciatus Say (=fatigans Wied.) and Mansonia uniformis (Theo.). All species in these experiments, including the important vector of arboviruses, Cx. annulirostris, preferred mammalian baits, especially calf, although An. bancroftii and Cx. quinquefasciatus preferred man. Blood-meals of 5802 engorged mosquitoes of 21 taxa collected from natural resting sites at Kowanyama village were analysed by the precipitin test. Mammals, particularly dogs, were the most important hosts. Cx. squamosus (Tayl.) and Cx. quinquefasciatus were the only species to feed extensively on birds (75–6 and 28–7%, respectively). Uranotaenia albescens Tayl. fed almost entirely on amphibia. No seasonal shifts in feeding of An. bancroftii, An. annulipes, Cx. annulirostris or Cx. quinquefasciatus were evident from either host-preference or host-feeding patterns, the latter being evaluated using a ‘ Feeding Index ’. These results are discussed in relation to the transmission of arboviruses, particularly Murray Valley encephalitis virus and pulmonary dirofilariasis of man and dogs in Australia.

Experimental huts similar in construction to the dwellings commonly used in East Africa, but with exit window traps, were sprayed with various formulations of the three residual insecticides, DDT, BHC, and dieldrin, and the effect on the A. gambiae and A. funestus entering them was observed.

The almost complete absence of kill recorded by Muirhead Thomson (1950) in experiments in similar huts in Tanganyika treated with DDT Ditreen was not confirmed by these experiments.

A significant proportion of the A. gambiae and A. funestus entering huts treated with DDT did, however, escape unharmed, even immediately after treatment, whereas with the other insecticides, BHC and dieldrin, none of these mosquitos escaped the effect at least in the first month after treatment.

In preliminary experiments in which observations were carried on for nine months after treatments, BHC P.530 still showed some effect after seven months. This was almost certainly due to the fumigant effect of the small amount of insecticide still remaining below the wall surface. The irritant properties of the two DDT formulations, Ditreen and the oil-bound suspension “Supona” D, still existed after nine months.

In a second group of experiments, dosages of less than 80 mg. DDT and less than 60 mg. BHC (8 mg. of the gamma isomer) per sq. ft. gave over 50 per cent. kills of A. gambiae and A. funestus for only one month.

In a third group of experiments, using two formulations of BHC, five of DDT, one of a mixture of DDT and BHC and one of dieldrin:—

(a) Dieldrin was by far the most efficient insecticide and gave very high kills for over seven months.

(b) The DDT formulations, Murphy paste, Murphy wettable powder, suspensions of DDT crystals <30 μ and 30–70 μ in diameter, when applied to the whole internal surface of the huts, produced fairly high kills over the period of the observations (six to seven months), but significant proportions of the mosquitos escaped their action even immediately after treatment.

(c) The BHC formulations, P.520 and the oil-bound suspension “Supona” B, gave high kills for three to four months only.

(d) The mixture of BHC and DDT in oil-bound suspension “Supona” DB gave the high initial kill of BHC and the long-lasting moderately high kill of DDT.

(e) Against C. fatigans all the DDT formulations used in the third group of experiments gave very low kills, the BHC formulations high initial kills and dieldrin high long-lasting kills.

BHC has marked fumigant and particulate properties lasting for three to four months. Dieldrin has a remarkable particulate action, which produces for the whole six-month period of the experiment, very high kills among mosquitos suspended without actual contact with the insecticidal surfaces; DDT only shows this particulate effect to a slight extent.

It is probable that the differences in the toxicities to mosquitos of the insecticides used in these experiments is due partly to differences in the irritant properties of the insecticides. In the case of DDT many of the mosquitos having contact with this insecticide are irritated and escape from the treated surface before acquiring a lethal dose.

Molecular species identification is becoming more wide-spread in diagnostics and ecological studies, particularly with regard to insects for which morphological identification is difficult or time-consuming. In this study, we describe the development and application of a single-step multiplex PCR for the identification of three mealybug species (Hemiptera: Pseudococcidae) associated with grapevine in South Africa: Planococcus ficus (vine mealybug), Planococcus citri (citrus mealybug) and Pseudococcus longispinus (longtailed mealybug). Mealybugs are pests on many commercial crops, including grapevine, in which they transmit viral diseases. Morphological identification of mealybug species is usually time-consuming, requires a high level of taxonomic expertise and usually only adult females can be identified. The single-step multiplex PCR developed here, based on the mitochondrial cytochrome c oxidase subunit 1 (CO I) gene, is rapid, reliable, sensitive, accurate and simple. The entire identification protocol (including DNA extraction, PCR and electrophoresis) can be completed in approximately four hours. Successful DNA extraction from laboratory and unparasitized field-collected individuals stored in absolute ethanol was 97%. Specimens from which DNA could be extracted were always correctly identified (100% accuracy). The technique developed is simple enough to be implemented in any molecular laboratory. The principles described here can be extended to any organism for which rapid, reliable identification is needed.

Keys are provided for the larvae of 32 species of TINEIDAE, and detailed descriptions are given of 31 species. These include most of the species known to be of any economic importance. What is known of the biology of each is briefly summarised, but no attempt has been made to collate the available information on control measures.

No larvae have been available of four species of some economic importance nor of twelve others of doubtful status as pests. The literature on each of these species is noted.

The larvae of a few species of no known economic importance are described and are included in the keys. Most of these are very closely related to species known to be pests.

The keys and descriptions include 21 species which are indigenous to Britain or are established here, so that keys and descriptions are now provided for half of the British species of Tineidae.

Researchers and regulatory agencies often make statistical inferences from insect count data using modelling approaches that assume homogeneous variance. Such models do not allow for formal appraisal of variability which in its different forms is the subject of interest in ecology. Therefore, the objectives of this paper were to (i) compare models suitable for handling variance heterogeneity and (ii) select optimal models to ensure valid statistical inferences from insect count data. The log-normal, standard Poisson, Poisson corrected for overdispersion, zero-inflated Poisson, the negative binomial distribution and zero-inflated negative binomial models were compared using six count datasets on foliage-dwelling insects and five families of soil-dwelling insects. Akaike's and Schwarz Bayesian information criteria were used for comparing the various models. Over 50% of the counts were zeros even in locally abundant species such as Ootheca bennigseni Weise, Mesoplatys ochroptera Stål and Diaecoderus spp. The Poisson model after correction for overdispersion and the standard negative binomial distribution model provided better description of the probability distribution of seven out of the 11 insects than the log-normal, standard Poisson, zero-inflated Poisson or zero-inflated negative binomial models. It is concluded that excess zeros and variance heterogeneity are common data phenomena in insect counts. If not properly modelled, these properties can invalidate the normal distribution assumptions resulting in biased estimation of ecological effects and jeopardizing the integrity of the scientific inferences. Therefore, it is recommended that statistical models appropriate for handling these data properties be selected using objective criteria to ensure efficient statistical inference.

The thermal preference of adults of the reduviid bug Triatoma infestans (Klug) was investigated along a temperature gradient by means of video recording. The preferred temperature varied with a daily rhythm, reaching the highest value at the onset and the lowest at the end of the dark phase. The daily range of preferred temperatures depended on the starvation level. After feeding it was about 28–29°C, and after 12 days of starvation 25–26°C. The number of eggs laid showed a bimodal pattern, with maxima at 29°C and 26°C. Along a gradient of relative humidity, the bugs were always found around 40% r.h.

A description is given of a verandah-trap hut designed to assess the egress and survival of mosquitos escaping through the eaves of the type of window-trap hut used in insecticide testing in East Africa.

Fifty-one per cent. of females of Anopheles gambiae Giles in all gonotrophic stages and 19 per cent. of those recently fed left the hut each night, with 15 and 30 per cent., respectively, of the egress occurring through the eaves.

Ninety per cent of females of Mansonia uniformis (Theo.) in all gonotrophic stages and 91 per cent. of those recently fed left the hut each night, with 69 and 66 per cent., respectively, of the egress occurring through the eaves.

It was concluded that, owing to the high proportion of individuals of M. uniformis that leaves by the eaves, the verandah-trap hut was of a more suitable design for studying the house-frequenting habits of this species, and of other species with similar habits, than the simple window-trap hut.

Targets of black cloth with or without flanking netting panels (ca. 1 m tall × 1.7 m) baited with acetone (130 mg/h) and 1-octen-3-ol (0.5 mg/h), coated with deltamethrin suspension concentrate and deployed at 4/km2, produced a decline of 3% per day in the apparent density of the tsetse fly Glossina morsitans centralis Machado in 500 km2 of the Western Province of Zambia. Flies were eradicated in a year as evidenced by the absence of catches from flyrounds and traps and the elimination of the transmission of trypanosomiasis. The promise of the target technique is confirmed but the need for its further development is emphasized.

The principal object of this work was to elucidate the swarming behaviour of Aëdes cantans and other mosquitos, Chaoborus crystallinus and certain Chironomids. In addition, ancillary studies were made of the general ecology of these species. The swarms were found to consist entirely of males and to bear no direct relationship to mating or to the search for food. There was no noticeable difference between the swarming habits of the different species of mosquitos and even the differences between the Culicids and Chironomids were very slight. Swarming was observed to take place at about sunset in the evening and sunrise in the morning. The evening swarms appeared to be formed in response to decreasing light intensity and to disperse at a light intensity of about 7 Lux. Low temperatures may delay the start of swarming. The morning swarms started at about the same threshold of light intensity and at this time also their duration was reduced by low temperatures. Below about 50°F. they were not formed at all. Atmospheric humidity appeared to be of minor importance.

The distribution of termites in north-eastern Tanganyika is discussed in relation to eight zones delimited by contours and vegetation types. Some termites show very definite limits to their distribution; Hodotermes mossambicus (Hagen) and Amitermes lonnbergianus (Sjöstedt) are examples. The significance of this is discussed.

There is a greater variety of Termitinae near the coast, while the subterranean termites are the more abundant in dry bushland. Some species are able to extend their distribution where gallery forest is found along the larger rivers. Two types of mountain forest are included in the region and extremely few termites are to be found within these.

The distribution of termites observed on descending from the mountains to the plains is discussed and illustrated by a diagram. In addition, two methods of indicating the relative abundance of termites in the soil is described.

The effect of quantitative and qualitative differences in maize leaf fed to larvae of Spodoptera exempta (Walker), and of larval density, on flight duration in female moths was investigated using a tethered-flight technique. Neither food deprivation nor diets of water-stressed maize influenced the proportion of moths flying for long periods. However, a significant increase in the incidence of long flights was recorded in moths from larvae reared at high densities. Significant differences were observed in the weights and sizes of moths from the different larval treatments. Wing-loading was shown to be a function of moth weight, with lighter moths having lower wing-loadings. However, wing-loadings of long-flying moths and those of short-fliers were similar, and it is concluded that the migratory potential of females of S. exempta cannot be predicted from moth weight or morphometric data. A feature of the results was the variable proportion of long-flying moths in the test and control groups, irrespective of larval treatment. Re-examination of the data showed that a high incidence of long flights was evident in the experimental insects at approximately one-generation intervals, and it is suggested that there is a major genetic component in the determination of flight capacity in this species.

Two commercial cultivars of tomato, Alta and Peto 95, the accession line number LA716 of Lycopersicon pennellii and lines 94GH-006 and 94GH-033 (backcrosses between Peto 95 and LA716), with different leaf acyl sugar contents were screened for resistance to Bemisia argentifolii Bellows & Perring (corresponding to the Spanish B-biotype of Bemisia tabaci (Gennadius)), in greenhouse- and field-no-choice experiments. There was no oviposition on LA716 (with the highest acyl sugar content) while the greatest fecundity and fertility values were observed on the cultivar Alta (no acyl sugar content). However, no clear relationship was found between the low acyl sugar content in the other tomato cultivars tested and whitefly reproduction. Thus, resistance to B. tabaci did not appear to correlate with acyl sugar content below a threshold level of 37.8 μg cm-2leaf. In a greenhouse choice-assay, B. tabaci exhibited reduced host preference and reproduction on the commercial tomato cultivars Motelle, VFN8 and Ronita all of which carry the Mi gene resistance to Meloidogyne nematodes and the aphid Macrosiphum euphorbiae (Thomas), than on the Mi-lacking cultivars Moneymaker, Rio Fuego and Roma. When data of Mi-bearing plants were pooled, the mean values for daily infestation and pupal production of B. tabaci were significantly lower than those of Mi-lacking plants. This reflected a level of antixenosis- and antibiosis-based resistance in commercial tomato and indicated that Mi, or another closely linked gene, might be implicated in a partial resistance which was not associated either with the presence of glandular trichomes or their exudates. These findings support the general hypothesis for the existence of similarities among the resistance mechanisms to whiteflies, aphids and nematodes in commercial tomato plants.

In small-scale experiments, the predatory mites, Hypoaspis aculeifer (Canestrini) and H. miles Berlese, applied at 700 mites m−2, and the entomopathogenic nematode, Steinernema feltiae (Filipjev) applied at 3 × 10−6 nematodes m−2 controlled sciarids and phorids in mushroom compost and casing substrates. For both mite species, earliest application to the growing substrate following sciarid infestation reduced sciarid emergence. In contrast, later application of each biological control agent provided more effective control of phorid emergence. The behaviour of adult mites suggested that H. aculeifer were more positively geotactic than H. miles although both species could penetrate compost and casing substrates to a depth of 2–12 cm. A majority of S. feltiae nematodes resided at a depth of 2–4 cm in both substrate types. Independent application of H. aculeifer provided more comprehensive control of sciarids and phorids than the other biological agents studied, owing to its better dispersal within compost and casing, and ability to attack larvae of differing ages.

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.

The behaviour of Anopheles gambiae Giles and A. funestus Giles was studied under natural conditions in a lowland area of Tanganyika.

Studies on the outside resting population were carried out by direct searching for natural resting sites, and by the use of artificial box shelters partly buried in the ground in shaded localities. Catches in these give a valid sample when set up at some distance from houses.

Fed and gravid females comprised 67 per cent. of the outside resting gambiae population, the latter group being between 12 and 4·5 times as numerous as the former. Rather less than half the funestus females caught were unfed, the remainder of the population being mainly composed of gravid females.

Precipitin tests on the small numbers of fed females caught outside were nearly all positive for man.

The identification of gravid funestus females was confirmed by periodic examination of the eggs.

Entry of females into outside shelters did not occur solely in the period around sunrise. An appreciable number of funestus females did not enter before 07.00 hours and this was particularly so in shaded shelters.

The building of a hut in the vicinity of a box shelter caused a drastic reduction in the numbers of mosquitos resting in the latter.

Outside biting activity in these two species is of negligible importance as a source of females resting outside.

The performance of Nzi traps for tabanids (Tabanus similis Macquart, T. quinquevittatus Wiedemann, Chrysops aberrans Philip, C. univittatus Macquart, C. cincticornis Walker, Hybomitra lasiophthalma (Macquart)), stable flies (Stomoxys calcitrans Linnaeus) (Diptera: Muscidae) and mosquitoes (Aedes) (Diptera: Culicidae) was investigated at various sites in Canada (Ontario, Alberta) and USA (Iowa, Florida, Louisiana). Traps made from selected fabrics, insect nettings and hand-dyed blue cotton were compared to the African design to provide practical recommendations for temperate environments. Comparisons of substituted materials showed that trap performance was optimal only when traps were made from appropriate fabrics in the colours produced by either copper phthalocyanine (phthalogen blue), or its sulphonated forms (turquoise). Fabrics dyed with other blue chromophores were not as effective (anthraquinone, disazo, formazan, indanthrone, triphenodioxazine). An appropriate texture as well as an appropriate colour was critical for optimal performance. Smooth, shiny synthetic fabrics (polyester, nylon) and polyester blends reduced catches. Low catches occurred even for nominal phthalogen blue, but slightly-shiny, polyester fabrics in widespread use for tsetse. The most suitable retail fabric in place of phthalogen blue cotton was Sunbrella Pacific Blue acrylic awning/marine fabric. It was both attractive and durable, and had a matching colour-fast black. Nzi traps caught grossly similar numbers of biting flies as canopy, Vavoua, and Alsynite cylinder traps, but with differences in relative performance among species or locations.

The climbing behaviour of newly hatched larvae of Chilo partellus (Swinh.) on sorghum plants was studied in the laboratory and in the field in India. The upward movement is directed by light, while the final downwards movement into the whorl is probably a response to the contrast of light above and dark below. Many larvae fail to reach the whorl, and success is reduced by high winds and rain, and by some physical features of the plants. Two sorghum cultivars, IS 1151 and IS 2205, differed in the extent to which larvae successfully reached their whorls, and their relative susceptibilities altered with age.