The sterile insect technique (SIT) is a key element for the integrated management of pest populations of the Mexican fruit fly, Anastrepha ludens, in Mexico. Its success depends on the survival of mass-reared sterile males and their ability to mate with wild females. However, colonization and mass-rearing conditions can adversely affect their ability to avoid predators. To test if colony management strategies could contribute to improve field survival abilities of mass-reared flies, we compared the survival of males exposed to the orb-weaver spider Argiope argentata. Males compared originated from three strains with different colonization strategies: (a) a colony started from field-collected wild flies (replacement), (b) a colony started by hybridizing wild males with mass-reared adapted females (hybrid) and (c) a colony started with mass-reared males selected on the basis of their survival ability and mating competitiveness in field cages (selected). Mass-reared males and wild males were used as controls. Males were exposed to spiders under laboratory cage conditions. Overall, wild males showed better survival ability than mass-reared males. Regarding the colonization approach, wild males survived better than a hybrid, replaced and selected males. We conclude that mass-rearing conditions have a strong negative effect on the ability of males to escape spiders. The colonization systems evaluated did not counter this effect. The lower survival of males from the selected colony suggests that the selection over one generation did not contribute to improve males’ predator avoidance and escape abilities and probably needs to be modified. Possible explanations for this and implications on colonization and colony management for SIT purpose are discussed.

The European cherry fruit fly, Rhagoletis cerasi (Diptera: Tephritidae), is a univoltine species that undergoes obligatory summer–winter diapause at pupal stage in the soil (2–5 cm) beneath host trees. To study the effects of photoperiod and relative humidity on diapause termination and post-winter developmental duration of R. cerasi, pupae collected from Dossenheim (Germany) were exposed to different photoperiod or relative humidity regimes during a chilling period ranging from 2 to 8.5 months. Specifically, pupae were exposed to four photoperiod regimes: (a) light conditions (24L:00D), (b) dark conditions (00L:24D), (c) short photoperiod (08L:16D) and (d) long photoperiod (16L:08D), as well as to three relative humidity regimes: (a) low (40% RH), (b) medium (60% RH) and (c) high (70–80% RH). Data revealed that relative humidity is not a significant predictor of diapause termination, but it affects the post-winter developmental period. Higher relative humidity promotes post-winter pupae development. On the other hand, photoperiod significantly affected both diapause termination and post-winter development of R. cerasi pupae. Light conditions (24L:00D) accelerate adult emergence, particularly for females. Regardless of the photoperiod (24L:00D, 00L:24D, 08L:16D), rates of adult emergence were high (>75%) for chilling intervals longer than 6.5 months. Nonetheless, exposure to a long day photoperiod (16L:08D), during chilling, dramatically reduced the proportion of adult emergence following 6 months exposure to chilling. Our findings broaden the understanding of factors regulating diapause responses in European cherry fruit fly, local adaptation and synchronization of adult emergence with the ripening period of major hosts.

Insect artificial diets are the foundation for mass production of insect predators. Whether there is an influence of long-term rearing with artificial diet on the control ability of predators should be considered. Here, we focused on the effect of nutritional history on the functional response of Geocoris pallidipennis to Myzus persicae. The influence of nutritional history (artificial diet versus natural prey, M. persicae) on the functional response of third to fifth instar nymphs and female G. pallidipennis was examined in the laboratory. The results showed that the functional response curve of both the nymphs and the adult female of G. pallidipennis to M. persicae reflected similar trends on both nutritional histories and confirmed the type II response. Adult female G. pallidipennis reared on either M. persicae or artificial diet produced a significantly better performance than the juvenile stages tested. We estimated that adult female G. pallidipennis can consume 141.6 (artificial diet) or 131.6 (M. persicae) aphids per day, respectively. This indicated that G. pallidipennis reared on both artificial diet and M. persicae displayed high rates of predation.

It is a dictum that Apis mellifera Linnaeus is innocuous in agricultural ecosystems. This study provides the first record of A. mellifera as a significant defoliator of Alnus species. Careful field observations coupled with microscopic examination provided convincing evidence implicating A. mellifera as the cause of leaf perforation on Alnus species in Uganda. Apis mellifera was observed foraging selectively on young Alnus leaves and buds in search of a sticky substance, apparently propolis. In so doing, the bee created wounds that enlarged and caused tattering of Alnus leaves as they matured. Biological surveys indicated that the damage was prevalent and occurred widely, particularly on Alnus acuminata Kunth in Uganda. Incidence of the Apis mellifera damage on Alnus acuminata peaked in the dry season, with up to 90% of leaves emerging per shoot per month damaged, and was lowest in the wet months during peak leaf emergence. Apis mellifera leaf damage was consistently higher on Alnus acuminata than A. nepalensis D. Don., on saplings than mature trees, and on sun exposed than shaded leaves. The activity of honeybees may be detrimental to the productivity of Alnus, yet the substance for which the insect forages on Alnus is a resource with potential economic importance.

Roubaud has recently recorded (cf. Sleeping Sickn. Bull., I l l, p. 419) that in West Africa G. morsitans is intolerant of high temperatures, as he has found that specimens exposed to 40° C. (104° F.) died within an hour. This species is however adapted to withstand such a temperature in the Luangwa Valley; for during the hot months of October and November the shade thermometer frequently registers from 106° to 108° F., seemingly without any ill results to the tsetses.

Rapid determination of the larval species composition and understanding of their genetic structure is important to establish the appropriate management system for multiple species infesting in fruits. We established accurate and rapid diagnostic methods based on multiplex polymerase chain reaction (PCR) diagnostic techniques to discriminate the three major lepidopteran species in orchard, Carposina sasakii, Grapholita dimorpha, and Grapholita molesta. Each species was identified by amplifying species-specific PCR products (375 bp for C. sasakii, 125 and 234 bp for G. dimorpha, and 125 bp for G. molesta). Based on species composition analysis from six types of infested fruits, G. dimorpha constituted the highest proportion (47.8%), followed by 35.2 and 13.5% for G. molesta and C. sasakii, respectively. Interestingly, high prevalence was found in G. dimorpha and G. molesta for plum and peach, respectively. Based on genetic diversity analysis, the three insect species exhibited moderate or high haplotype diversity and low nucleotide diversity, ranging from 0.319 to 0.699 and 0.0006 to 0.0045, respectively. Demographic expansion was not detected according to either a neutrality test or mismatch distribution analysis. Moreover, no significant genetic structure corresponding to province, host plant, fruit type, or collection period was observed. These results suggest that the population of each species would have high dispersal ability following fruit-generating periods via intrinsic host adaptation ability regardless of the spatial and temporal conditions. Determination of larval composition on fruit is valuable for establishing appropriate management systems that take the species into consideration; additionally, population genetic approaches can be utilized to understand the effects of environmental factors (province, host fruit, fruit type, etc.) on population structures.

There is a growing body of evidence to suggest that low density populations of Spodoptera exempta (Walker) in the solitary-phase can persist during the dry season in certain localities in eastern Africa. Moths were caught in simple pheromone traps for several months after the estimated dates of emergence of larval outbreaks in central Tanzania in 1980 and from 1982 to 1984. This provided evidence for the occurrence of a shifting population between the Uluguru Mountains and the swampy coastal areas, in east-central Tanzania, for a large part of the year. Central Tanzania is an important area for the development of the first outbreaks of the season in eastern Africa and for any control strategy. It has been suggested that S. exempta fits the criteria for an r-selected species. However, the low migratory capacity of low-density populations indicates rather that the species spreads out its risks in space and time. A theoretical genetic mechanism controlling the distance flown by moths may enable the species to exhibit both migratory and non-migratory strategies. Thus both ephemeral and continously favourable habitats may be exploited.

In the following pages an attempt is made to deal systematically with a number of Braconids belonging to the subfamily Euphorinae and reared by Dr. T. H. C. Taylor in the course of his investigation into the biology of the Capsid pests of cotton in Uganda. Taylor himself has discussed elsewhere (1945) the importance of the rôle that some of these Braconid parasites are likely to play in the control of their hosts.

Grain losses per unit area in oats following shoot attack by frit fly (Oscinella frit (L.)) were assessed in plots at Rothamsted. Individual plants were marked, and two categories of attacked plants (tillers and both main shoot plus tillers attacked) were distinguished because losses in the former were low or negligible compared with those in the latter. There was no evidence of compensatory growth for lost or damaged plants, so that losses could be assessed by comparing actual yield with yield expected had no plants been attacked. The percentage loss, weighted according to incidence and effect of attack in the two categories, was calculated from hand-harvested samples. The loss per unit area was then estimated from the actual yield obtained by combineharvesting. Estimates of actual yield were affected by the method of harvesting, so that estimates of loss were not precise.

Most of the early stages described below were previously unknown, and as Aëdes variegatus, Dol. (Stegomyia pseudoscutellaris, Theo.) is of great importance in preventive medicine, it seems best to publish these notes and figures at once.

During a general survey of malaria in Transjordan, which was carried out in the summer and autumn of 1942, the Anopheline here discussed was found to be widely distributed and often common. It was first seen as an adult female, then considered to be Anopheles (Myzomyia) turkhudi, Liston, 1901, brought from Amman, Transjordan, in May 1942 by Capt. H. F. West, R.A.M.C. It is of value to describe the present material and compare it with such descriptions of the other members of the turkhudi group as are available to me at the moment, though it is considered that in no respect does it differ widely enough from A. (M.) hispaniola, Theobald, 1903, to be accorded more than varietal rank within that species.

1. From a block of country of four square miles, infested by Glossina swynner-toni and a few G. pallidipes, grass-fires have been excluded for three years in succession. The tsetse-population has decreased in that time by nearly nine-tenths (from 9.4 to 1.0 flies per 1,000 yards of transect). In a block of two square miles it has decreased in two years without burning to the same average of one fly per thousand yards of transect from a high previous figure unmeasured. Two “barrier” strips following roads that previously were highly infested have also been unburned for three and four years respectively and have become similarly inhospitable to the flies.

2. In a control block of only 1¾ square miles, the grass has been burned in the ordinary native fashion annually during the same period. The average fly-catch per thousand yards of transect has increased since this was done from 4.2 to 13.1.

3. In each of these blocks game is about as plentiful as it was at the first. The 4-square-mile block shows a slight gain.

4. In the four experimental blocks and strips, but not in the controls, extensive thicket is growing up everywhere in the grass as a result of the exclusion of the fires. Thus the previous marked difference, both spatial and seasonal, between the respective densities of the different vegetational communities is commencing to disappear. Much grass-country remains but its average condition is one of long grass rising from a mulch, thick or thin and sometimes absent, of the previous year's grass that keeps the soil damp after rain—the more so since run-off is checked. Longer and denser grass is encroaching into the previously very open concentration sites of G. swynnertoni, which are also being invaded by thicket.

5. The contrasts between burned and unburned country are especially strong in the short wet season. At this time in burned country the flies have just gone through a period of intense desiccation, short hunger cycle and hardship, and the population is at its annual minimum. The ground, however, is very open and visibility of the other sex and of food animals and breeding-places is unimpeded. Conditions are suddenly made ideal by the advent of the rains. Humidity is added to temperature; the hunger cycle is lengthened; the openness and insolation of the ground now probably play a further beneficent part by preventing an excess of humidity. The flies are active, they breed freely, the shade conditions enable them to spread, and the density curve soars upward.

On the unburned ground the water-content of the soil is increased in the early rains, dampness is retained between showers, the temperature is lowered, evaporation is reduced, and light intensity in the grass becomes less (Scott, 1934). The activity and breeding of the flies is quite likely affected. The striking increase in the population that characterised unburned country in the early rams and short dry season is absent, and the density, having failed to rise at this time, continues low or falls further.

6. In two cases (G. morsitans, Nash 1933, at Kandaga; G. swynnertoni in Block 11 at Shinyanga) the second annual impetus to breeding, associated normally with the advent of the long dry season, duly produced its usual effect on the tsetse-populations of country that was in its first year of no burning. In the case of the block that has been unburned for three years this effect has been slight.

7. That the conditions, though deteriorating, are as yet not lethal through hunger, due to poor visibility or otherwise, is suggested by the fact that the very small fly populations referred to maintain a nearly stationary balance in at least the larger experimental block and do not show special hunger or other sign of distress. It is possible that most of the diminution hitherto has been caused merely by emigration to better conditions, for the blocks are not yet fully isolated. On the other hand, were the main effect on the breeding, distress would not be detected and the result might take place independently of any emigration. Reduced visibility of food animals may become operative later.

8. It is suggested by the results so far on the tsetse and by the present appearance of the country in these four experiments that with the further advance of the vegetational succession towards its natural climax the remaining fly population will probably dwindle further and disappear—at least if the areas are isolated; the growing homogeneity in the density of the whole vegetation will reach a point at which it is unlikely to satisfy the daily and seasonal needs of an insect which for food, breeding and regulation of moisture and temperature, has a separate and vital use for each of the three densities furnished by thicket, savannah wooding and nearly open hard-pan and vlei.

9. The concentration sites of G. swynnertoni combine in a small space the types of vegetation the flies need, both the denser and the more open. They are important at all times but especially as refuges from unfavourable conditions elsewhere and as meeting-grounds of the sexes when the population is reduced. They are operative all the year round, and an effective change in these refuges alone in either the wet season or dry should be a shrewd blow at the fly. In experiments elsewhere in Shinyanga the clearing of the thickets at these places has quickly brought down the fly-population through its dry-season effect. In Blocks 4A and 10A the cessation of grass-burning is apparently already affecting these sites by hemming them in with areas presenting unfavourable conditions—probably mainly through excessive shade and over-humidity in the rains. The cessation of burning might even suffice if confined to these concentration sites and their neighbourhood.

10. As regards the probable effect of not burning the grass on other species of tsetse, it is considered that the method may prove useful against G. morsitans under moderately extensive vegetational conditions, though it may in this case take much longer and may not apply to large areas. Berlinia-Brachystegia wooding went to thicket in the writer's early experiments in a specially high rainfall area in Rhodesia, and (under lower rainfall) the exclusion of fire for five years at Itundwe (Central Province, Tanganyika) has produced strong densification in the Berlinia. In the Kikore plots (5 years protected) savannah type seedlings are being suppressed by the new conditions, but the flourishing state of the few shade-tolerating thicket plants suggests that all that is wanted is the introduction of a suitable seed-supply. This will be necessary in any case in all places without natural regeneration.

11. In an observation by Nash (Kandaga, Central Province) G. morsitans reacted initially in much the same way as G. swynnertoni, but the experiment was interrupted. In Itundwe G. morsitans and its pupae are much less numerous in the unburned Berlinia than in the burned.

12. The reaction of G. pallidipes, as distinguished from that of its habitat, is uncertain but so far has been promising under Shinyanga conditions; but the new conditions at Itundwe look as though they might favour this fly. G. brevipalpis is definitely likely to be favoured by the effect of not burning the grass.

13. The increase in humidity and lowering of the temperature produced by not burning the grass may be expected to be specially effective towards the wet side of a tsetse-fly's range. Towards the dry side it might even at first assist the fly.

14. Experiments to test the possibility of success against morsitans are being taken in hand, as are experiments on larger pieces of country infested by swynnertoni and pallidipes.

15. The control of grass-fires offers difficulties, but our experience over a wide area and many years shows that with determination and organisation it is quite possible, though an occasional minor set-back must be expected. The advantages of this measure from other points of view than that of tsetse extirpation, and the means of restoring the pasture, are referred to on p. 425.

Male mating success depends on various traits and factors, and correctly identifying these traits can be key in the context of pest management. For tephritid pests, controlled through the sterile insect technique (SIT) traits, such as male size, can be manipulated through mass-rearing procedures. Thus, it is particularly important to understand whether male size can favor mating success. Here, we evaluated mating success of males of different sizes in Anastrepha ludens and Anastrepha obliqua, two species controlled through SIT. For both species, a morphometric analysis was performed of mated and unmated mass-reared and wild males in field cages. In both A. ludens and A. obliqua, wild females did not discriminate their mates based on male size and mated more frequently with wild males regardless of size. For mass-reared males, we found no evidence of an advantage of the large males compared to small males in mating success. However, we did find differences between the morphometric traits of mass-reared and wild males. In A. ludens, traits associated to mating success were Face Width (FW), Head Width (HW), Thorax Length (TL) and Wing Length (WL), and for A. obliqua were FW, HW, WL and WW (Wing Width). Overall, FW and TL were more consistent predictors of mating success. In conclusion, female choice seems to suggest multivariate selection, confirming that overall body size (expressed as pupal diameter, which is highly correlated with weight) is not a decisive factor in male mating success in these two species. However, morphological traits such as FW, HW, TL, WL and WW may be relevant in mating preference of wild female.

During the past summer Mr. F. W. Urich, Government Entomologist, Trinidad, B.W.I., succeeded in rearing a number of small Chalcids from larvae of a thrips in the prepupal stage. The following description is based on part of this material.

When I assumed duty in the Nile Province of the Uganda Protectorate, it was known to me that Dr. Shircore had taken a tsetse-fly near Nimule, which he considered to be nearly allied to, but distinct from, G. palpalis. I had been asked to take an early opportunity of examining the haunt of these insects and capturing further specimens. On several occasions I therefore repaired to the site of Dr. Shircore's find, and along some two miles of the bank succeeded in taking a large number of Glossina. These did not appear to differ in any noticeable degree from those one had seen on Lake Victoria, or on the smaller rivers of this Province, and as Dr. Shircore had reported that he had frequently seen the fly in question with the larger palpalis, especially near Nimule, I came to the conclusion that I had been very unfortunate in not taking a single specimen.

Nanophyes sp. nr. nigritulus Boh. infests the aquatic weed, Jussieua repens (Onagraceae) in India, its larvae feeing and developing inside the fruits. Adults feed on the leaves and also on the pollen and nectar of flowers. Eggs are laid singly in the interior ovaries of flower buds or blossoms. The ovaries hypertrophy and develop into deformed fruits which, when severely infested, are also completely seedles. The number of eggs laid by six females was found to vary from 89 to 410. The female that laid 410eggs distributed them in as many as 167 flowers, 7 being the maximum number of flwers in which eggs were laid and 13 the maximum number of eggs laid per day. In the laboratory, one of the females lived for 207 days and one of the males for 93 days. The period hatched in 4–8 days, the larval period occupied 7–16 days and teh pupal period, 3–6 days. The larvae moulter three times and pupated in separate chambers that they formed before pupating. Adults emerged by biting holes in the wall of the fruit. The egg and immature stages of the weevil are briefly described. Three species of Pteromalid wasps belonging to Habrocytus, Trichomalopsis and an unidentifies genus, and a species of Eupelmus (Eupelmidae) attacked the larvae.

Visual and olfactory responses of Glossina fuscipes fuscipes Newstead to the monitor lizard, Varanus niloticus niloticus Laurenti were studied using various catching devices near Lake Victoria, Kenya. Electric nets baited with visible lizards caught more males (×2.1) and significantly more females (×2.0) than unbaited nets. Lizards concealed in electrified black PVC pipe models, simulating the shape and size of a monitor lizard, increased significantly the catches of tsetse by 2.1 times. Fresh lizard urine dispensed at an evaporation rate of 500 to 1000 mg/h also increased significantly the catches of flies at biconical traps, electrified models and electric nets. Identification of chemical constituents of the odour could improve monitoring and control strategies for G. f. fuscipes, and possibly for other palpalis tsetse species.

A laboratory technique is described which enables large numbers of Simulium larvae from field sources to be established in a narrow 12-in. long experimental channel in the laboratory where they can be maintained in a continuous flow of water. The apparatus was primarily designed for a critical study of the reactions of larvae exposed to various time/concentrations of larvicides and other chemicals. By exposing dense aggregations of many hundred larvae at a time, significant figures can be obtained regarding the number of larvae detached at various intervals during and after exposure to larvicide, and also regarding the subsequent survival or mortality of the different detached fractions.

An inexpensive and versatile method for maintaining age-structured Musca domestica L. populations for studies on the evolution of insecticide resistance is described. Adult flies are kept in spacious aluminium cages in which age-structuring is maintained by the thrice-weekly addition of pupae bred from eggs collected from within the cages. The population size is regulated in a density-independent manner by constraining the input of pupae to that necessary to maintain the required equilibrium density of adults within a cage. Adult numbers are monitored by photographing from outside the cage flies settled on a grid etched on the rear wall, and by converting this grid count to an estimate of population size using a calculated regression line. Observed changes in fly numbers in a cage accorded well with those predicted by a computer model using empirical data on larval productivity, and the emergence and survivorship schedules of adult flies. Since a variety of insecticide control regimes can be applied within the cage, this system enables an adequate yet tractable simulation of selection for resistance by insecticides under field conditions.

The most favourable areas for the cultivation of grape-vines in Ukraine are the sands of the lower reaches of the Dnieper in the district of Kherson, the shore of the Black Sea, the Kherson-Odessa districts, and along the Sea of Asov, chiefly in the district of Mariupol. Moreover, as is well known, vines do not suffer from Phylloxera when grown on pure sand. For these reasons, numerous State Departments, and also many private individuals, have spent a great deal of money in utilising this enormous extent of shifting sands for growing grapes.

The unexpected appearance of the larvae of various Scarabaeid beetles, especially Polyphylla fullo, L. (fig. 1), has been a great obstacle to the successful exploitation of these barren spaces. The larvae in the soil generally average about 10–12 to the square metre, and they often completely destroy the newly planted vines in one summer. Many enterprising persons have thus been ruined in their endeavours to form vineyards on the sands. It was stated officially in pre-war times that these pioneers had spent over £2,000,000 sterling without any result.