The relative costs and benefits of thermal acclimation for manipulating field performance of pest insects depend upon a number of factors including which traits are affected and how persistent any trait changes are in different environments. By assessing plastic trait responses of Ceratitis capitata (Mediterranean fruit fly) across three distinct operational environments (laboratory, semi-field, and field), we examined the influence of different thermal acclimation regimes (cool, intermediate [or handling control], and warm) on thermal tolerance traits (chill-coma recovery, heat-knockdown time, critical thermal minimum and critical thermal maximum) and flight performance (mark-release-recapture). Under laboratory conditions, thermal acclimation altered thermal limits in a relatively predictable manner and there was a generally positive effect across all traits assessed, although some traits responded more strongly. By contrast, dispersal-related performance yielded strongly contrasting results depending on the specific operational environment assessed. In semi-field conditions, warm- or cold-acclimated flies were recaptured more often than the control group at cooler ambient conditions suggesting an overall stimulatory influence of thermal variability on low-temperature dispersal. Under field conditions, a different pattern was identified: colder flies were recaptured more in warmer field conditions relative to other treatment groups. This study highlights the trait- and context-specific nature of how thermal acclimation influences traits of thermal performance and tolerance. Consequently, laboratory and semi-field assessments of dispersal may not provide results that extend into the field setting despite the apparent continuum of environmental complexity among them (laboratory < semi-field < field).

Dryocosmus kuriphilus (Hymenoptera: Cynipidae) is a global invasive gall wasp and a pest of chestnuts (Castanea spp.). A study of the Chalcidoidea parasitoid community of D. kuriphilus was undertaken over two years, from March 2017 to March 2019, at 15 sites in south and northwest Spain (Málaga and Galicia regions). More than 18,000 galls were collected, and 1153 parasitoids belonging to 22 species of seven chalcidoid families, plus two individuals of an inquiline Cynipidae, Synergus facialis, emerged. Richness was higher in the Málaga region, with 20 species, while 17 parasitoids and one inquiline were identified in Galicia. The parasitism rate of native chalcid parasitoid species in both regions was low. Eupelmus urozonus and Mesopolobus lichtensteini were the most abundant native species. Mesopolobus tibialis was a dominant species in south Spain, while Ormyrus pomaceus was a dominant species in northwest Spain. Our results revealed the existence of a sub-community of univoltine, probably host specialized, parasitoids in south Spain, which overwinter in galls, exhibiting a similar life cycle to Torymus sinensis. These species were Torymus notatus, Aulogymnus bicolor, Aulogymnus obscuripes and Aulogymnus balani. Data on the recovery of T. sinensis after release in the south Spain region show it to be well established, but its numbers are still low in northwest Spain.

Many parasitic Hymenoptera are already known to live on lac-insects, and they are of importance either as noxious insects by destroying the Coccid (Tachardia lacca (Kerr)), or as useful insects when parasiting the predators of lac. As a result of the studies of Cameron, Imms, Misra and Mahdihassan, something is already known about them, but the systematic position and the identity of many of the species are still uncertain.

Notes on insects in the Seychelles have appeared from time to time during the last thirty years in the annual reports of Seychelles Department of Agriculture. These records are now mostly lost; it is therefore the object of the present contribution to place on record such minor pests as have been collected during 1936–1939 inclusive, and have been determined by the Imperial Institute of Entomology.

With a view to providing information useful in practical control, the relative susceptibility to pyrethrins, and to pyrethrins plus piperonyl butoxide, of a series of stored product insects has been determined. Adult moths and beetles of 31 species were investigated, together with the larvae of 16 of these, and that of one other.

The insects were treated with 1.3 per cent, pyrethrins, and 0.3 per cent, pyrethrins plus 3.0 per cent, piperonyl butoxide, in a heavy, highly refined mineral oil (Shell Risella 17). Both formulations were applied in two ways: insects were exposed on sprayed filter papers or were directly sprayed. Insects were also treated with the oil alone by both techniques. While confined on films, and after being sprayed, the insects were kept at 25°C. and 70 per cent. R.H.

Large differences in susceptibility were encountered. The adult moths and Bruchids were susceptible, the adult Ptinids rather resistant, but otherwise susceptibility showed little correlation with systematic classification. The larva of a given species was usually more resistant than the adult. Among the adults of the different species, susceptibility to pyrethrum appeared to be correlated with high activity of the normal insect.

On the whole, 1.3 per cent, pyrethrins and 0.3 per cent, pyrethrins plus 3.0 per cent, piperonyl butoxide were of about equal toxicity.

Observations were made on the red locust, Nomadacris septemfasciata (Serv.), between October 1957 and February 1958 in an area of grassland, six miles long by one mile wide, marked out by beacons and divided lengthwise by a line of beacons down the centre, in the Rukwa Valley of south-west Tanganyika.

One half of the plot had been burnt off completely in the latter part of the dry season; the other half was unburnt and carried in part a four-year accumulation of growth and in part an area of standing grass that had regenerated after a damaging fire during the previous wet season and then, for the most part, flooded. Vegetation profiles were made along the whole length of the plot, and rain gauges, soil thermometers and soil tensiometers were installed at regular intervals along the three lines of beacons. Assessments of the population and distribution of adult locusts within the plot were made from Land-Rover or on foot in mid-October, mid-December (ten days after the onset of the rains) and early in January. A systematic search was made for egg-pods, starting at the end of December, along furrows ploughed down the middle of each of a number of narrow strips mown in the grass in sets near each beacon and sampling equally the burnt and unburnt halves of the plot. The first hoppers were seen on 3rd January, and assessments of hopper populations were carried out four times during January.

The primary object of the work was to study the effect on choice of oviposition site and on incubation success of the type and condition of the grassland (whether burnt during the previous dry season, at an earlier date, or left unburnt) and its possible bearing on control of the species in an outbreak area. Data were also obtained on the conditions of air temperature, soil moisture, soil temperature and rainfall in which eggs are laid and incubated; and the effect of variations in these factors on oviposition and on incubation success was examined.

It was observed that, in the hot, dry conditions of mid-October, adult locusts were completely absent, from the recently burnt-over ground, and were found almost exclusively in that part of the standing grass that had suffered a wet-season burn. By mid-December, the locusts had spread out from the unburnt into the burnt-over zone, where the grass had put out fresh growth, but many were still to be found hi the former, with a concentration along the line of contact with the latter. By early January, the size of the population had been greatly reduced and it was evenly distributed over the whole plot.

The distribution of egg-pods snowed that the locusts had laid almost exclusively in the burnt-over zone, about 50 per cent. being found within 0·1 mile of the line of contact with the unburnt zone.

The hoppers were likewise almost exclusively confined to the burnt-over zone, and with numbers significantly higher in the ¼-mile band next to the contact line than in the band at ¼–½ mile from it. The numbers of hoppers in the unburnt grass was significantly lower than might have been expected from the results of the egg-pod survey, suggesting that survival was lower there than under fresh grass following a dry-season fire. A subsidiary experiment, in which adult locusts were confined in cages placed on the lately burnt-over zone, the early-burnt and unburnt areas, respectively, suggested that, where there was no choice of oviposition site, the greatest number of surviving egg-pods occurred in the first zone, almost as many in the second and about half as many in the third.

During the incubation period, the soil under the unburnt grass was significantly colder, and tended to be moister, to moisten more slowly and to dry out less rapidly than that which had been burnt over. No significant correlation was found between incubation success in the burnt-over zone and total rainfall, mean recorded soil temperature or soil moisture.

It is concluded that, since these observations show that, for oviposition, adults of N. fasciata exhibit a very significant preference for ground that has been burnt over in the previous dry season, the burning of selected strips should lead to the concentration of oviposition and, consequently, of hoppers, thus making chemical control of the latter easier and cheaper.

There was some evidence, also, that when locusts could not move to bare ground, either oviposition or egg-pod survival (or both) were least successful where the grass cover was thickest.

No method has so far been available for the laboratory culture of Pachydiplosis oryzae Wood-Mason or for the controlled infestation of rice plants with this pest. Suitable techniques for the above have been developed and are described.

For the laboratory culture of P. oryzae, exposure of rice seedlings to gravid females for oviposition and the subsequent maintenance of the plants at a very high humidity in a mist chamber gave high infestation rates but results were not consistent. But this method is suitable for the maintenance of a laboratory culture of this insect.

A special oviposition tube was developed for inducing oviposition on limited areas of muslin, and this permitted easy observation, collection and handling of eggs.

It was found that oviposition tended to occur most frequently between 1900 and 2200 hr. and that the midges most commonly laid 200–285 eggs.

Eggs developed normally and hatched after seventy-two hours when the muslin carrying them was kept on barely moist filter paper in petri dishes.

Sixty-hour-old eggs could be stored for up to five days at 80 ± 2°C. with the percentage hatch decreasing gradually from the first to the fifth day. Low temperature affected development and hatching of thirty-six-hour-old eggs more severely, and hatching was completely inhibited if eggs of this age were exposed to this low temperature for more than two days. Hatching was normal when eggs were maintained at relative humidities of and above 88.8 per cent., but below this level some eggs collapsed as a result of desiccation. At relative humidities below 94.8 per cent., larval movement was initially limited and thereafter inhibited and the larvae were contracted. Such larvae resumed normal activity on immersion in water. These immobilised larvae, obtained by exposure of fully developed eggs to a relative humidity in the range 92.9–94.8 per cent., could be revived by immersion in water and used for infesting paddy plants.

Fully developed eggs, freshly hatched larvae and larvae subjected to relative humidities in the range 92.9–94.8 per cent. and subsequently revived, were transferred to rica plants bt spraying, or by pipetting on the leaf at the ligules or by pipetting on to the soil at the bases of plants. All these mathods proved successful but pipetting on to the soil between rows of plants was the simplest and is to be preferred for controlled infestation of plants.

A very high relative humidity and wet plant surfaces as obtained in the mist chamber used in these studies were essential for successful infestation of rice plants by the gall midge larvae.

The developmental rate of Frankliniella occidentalis (Pergande) was determined on cucumber Cucumis sativus cv. Sandra over a range of constant temperatures. The lower developmental threshold (LDT) and the sum of effective temperatures (SET) for the pre-imaginal development were 10.7°C and 231.1°C, respectively. The rate of population increase was assessed as the sum of effective temperatures above the lower developmental threshold by monitoring the numbers of thrips on individual leaves of cucumber under commercial greenhouse conditions. Population growth was characterized by an early stochastic phase, corresponding to pre-imaginal development of the first generation, and followed by an exponential phase starting with the second generation, the rate of which did not vary between plants. Throughout the exponential phase, the rate of population growth increased with time/age of plant. As significant damage to cucumber may occur during the exponential phase of population increase, the sum of effective temperatures of 231°C can be used to predict when damage is likely to start to occur.

Tetranychus urticae (Acari: Tetranychidae) is one of the most important pests of agricultural crops with worldwide distribution causing considerable damage to different products. Application of chemical acaricides is one of the most important strategies used for the control of this pest. Entomopathogenic fungi, however, have been proposed as alternative control agents. In this study, sub-lethal effects (LC10 = 6.76 × 102, LC20 = 8.74 × 103, and LC30 = 55.38 × 103 conidia ml−1) of Beauveria bassiana strain TV on the life table parameters of T. urticae were evaluated under laboratory conditions. The results demonstrated that by increasing the concentration, a significant decline was observed in adult longevity of both male and female individuals. Total fecundity of T. urticae was calculated as 45.16, 36.28, 23.98, and 18.21 eggs in control, LC10, LC20, and LC30 treatments, respectively. Sub-lethal concentrations drastically affected the population parameters of this mite pest. The intrinsic rate of increase (r) ranged from 0.1983 to 0.1688 day−1 for the mites treated with distilled water and LC20 treatments, respectively. The net reproductive rate (R0) was affected by the sub-lethal concentrations (lower value at LC30 concentration: 11.19 offspring/individual). Considering the detrimental effects of B. bassiana on some biological parameters of T. urticae, it can be concluded that this product can be used to develop targeted interventions aimed at integrated pest management of this pest.

Diamides have been used worldwide to manage the diamondback moth (DBM), Plutella xylostella L. (Lepidoptera: Plutellidae), however some strains showed resistance to these molecules. Also, pheromone traps could be used to manage this pest, hence reducing the use of insecticides in the field. Resistant DBM strains may have biological disadvantages in comparison to susceptible strains in areas without sprays, including reduction in fitness or behavioral changes. Therefore, the aim of this study was to investigate whether DBM strains resistant to chlorantraniliprole showed adaptive costs that could alter male attraction to the sex pheromone, in comparison to susceptible strains in the laboratory and semi-field conditions. First, the LC1, LC10, LC25, and LC50 of DBM to chlorantraniliprole were established, which were 0.003, 0.005, 0.007, and 0.011 mg a.i. liter−1, and 5.88, 24.80, 57.22, and 144.87 mg a.i. liter−1 for the susceptible and resistant strains, respectively. Development and reproduction of DBM strains subjected to those concentrations were compared. Later, male response to the sex pheromone was investigated in a Y-tube in the laboratory and in a greenhouse to pheromone traps. Resistant DBM strain showed an adaptive cost in comparison to the susceptible strain that can result in a delay in population growth in the field when selection pressure is absent. Conversely, resistant males have no olfactory response alteration in comparison to susceptible males, consistently at 3 (P = 0.6848) and 7 days (P = 0.9140) after release, suggesting that pheromone traps continue to be a viable alternative to manage DBM in an IPM system.

The persistence and toxicity of DDT crystals on thin layers of plant wax were studied. Deposits of crystalline DDT at rates of 2 to 8 microgm. per sq. cm. were applied to glass plates, plain or coated with a 0·5 μ layer of wax obtained from leaves of sisal or cabbage. The plates were stored for various periods at 18°C. and at 43°C. (representing temperature and tropical leaf-temperatures). DDT remaining after storage was estimated biologically by means of its contact action on adult Tribolium castaneum (Hbst.), and chemically by a modification of the Schechter-Haller method. At 18°C, there was no significant change in any of the deposits when estimated chemically. But biological estimation showed that, although the toxicity of the deposits on waxed plates was unchanged, that on glass plates was doubled after storage for eight days. The reason for this change was not discovered. At 43°C., the amount of DDT, estimated both chemically and biologically, diminished rapidly and was negligible after 26 days. The loss of toxicity at 43°C. was shown to be accompanied by loss of weight of the deposits. Loss at 43°C. from plain glass plates could be much reduced by storing them in an atmosphere saturated with DDT vapour. It appeared, therefore, that loss of toxicity at the higher temperature was due to volatilisation of DDT and not to decomposition.

European farms at Abercorn had been suffering from bovine trypanosomiasis carried by Glossina morsitans Westw., and the Tanganyika Department of Tsetse Research were asked in 1935 to advise.

Fly-pickets were established in 1936 to prevent carriage of flies on to the farms, and a belt of country was protected from fire, with the object of thickening the woody vegetation so as to make it unfavourable to G. morsitans. The fire-protected area was extended and continued until 1946; serious escape fires occurred in 1938 and 1941. During these first five years the reduction in catches at the pickets was only about one-third.

An intensive survey of the area was made in 1941, as the result of which concentrations of flies were identified in certain shallow valleys forming the headwaters of small tributary streams. Several of these were cleared of trees, with the result that the apparent density of G. morsitans was at once depressed not only in the valleys themselves but over wide areas of untouched woodland round about.

In 1942 and the following years these clearings were extended to new valley sites as they were discovered, both inside and outside the fire-excluded area, and always with striking effects. The last clearing of all was done in 1952.

Field studies on the biting habits of Culicoides barbosai Wirth & Blanton were made near Montego Bay, Jamaica, during 1959 and 1960. Females of C. barbosai were collected in sufficient numbers for analysis in. seven experiments, six from Florida beach and one from Beading. Four positions were marked out on each site. Begular meteorological observations were made in the middle of the catching positions. An experiment consisted of four trials held on different days, each trial being composed of four collecting periods of 15 min. separated by 5-min. intervals. In each period four individuals collected, two exposing an arm each and two a leg. Individuals collected in a different position in each period of a trial.

Catches were logarithmically transformed for analysis and tests of significance. The experiments were designed to provide correction factors for limbs, positions on Florida beach, and collectors, for use in other experiments. Correction factors are given as logarithms for application to transformed catches.

More C. barbosai were collected from arms than legs, and catches in position IV were significantly higher than those in positions I, II and III. Five collectors (C, D, K, L and S) were compared. The ratio between leg/arm catches from D, who collected in only two experiments, was significantly different from those of C, L and S. The differences between the catches of C, K and L were insignificant, but all three caught significantly more than S. The catches from L were smaller after sea bathing and, compared to C and S, L’s catches increased significantly immediately after sunset. For this reason and to avoid inhibiting winds, quantitative studies on females of C. barbosai are best conducted in the early morning (dawn + 40 min.).

The experimental errors (residual variances) were homogeneous with probabilities of 0.1 (C. barbosai—7 experiments) and 0.4 (C. furens (Poey)—8 experiments).

Larvae of aphidophagous ladybirds leave a cue in their tracks that deters oviposition. The influence of relatedness on this behaviour is for the first time explored in this paper. Two-spot ladybird females (Adalia bipunctata L.) under different conditions (young and naive, young and experienced, and old and naive) were exposed either to (i) clean filter paper, (ii) filter paper contaminated with unrelated larval tracks or (iii) filter paper contaminated with related larval tracks from their offspring. Oviposition time was recorded during nine hours. Oviposition was inhibited by larval tracks, and was more so by related than unrelated ones. Experienced females showed the same behaviour but with lower intensity. With old females, response was not significant with any type of larval tracks. This is the first report of the effect of relatedness on a ladybird's response to larval tracks.

Plant-derived compounds can be an environmentally friendly alternative to synthetic pesticide use for pest management. Essential oils (EOs) in several plant families have been found to be toxic to various pest species of insects through topical application, ingestion, and as fumigants. Previous studies revealed that, among various environmentally friendly insecticides, the EOs of Baccharis dracunculifolia and Pinus elliottii and an ethanol extract of Solanum granulosoleprosum plus Ricinus communis, were toxic to Ceratitis capitata and Anastrepha fraterculus (Diptera: Tephritidae) when applied topically to pupae or when ingested by adults. Here, we aimed to examine the potentially toxic effects of these plant-derived compounds when these two pestiferous fruit fly species were exposed to their vapors. We also examined their fumigant effect on female fecundity and fertility and compared it with water and ethanol controls. Exposure of C. capitata and A. fraterculus sexually mature adults to volatiles and vapors of both B. dracunculifolia and P. elliottii EOs resulted in lower longevity (half-life), survivorship, and female fecundity than the water vapor control. Toxicity of C. capitata was greater for P. elliottii than for B. dracunculifolia while the reverse was true for A. fraterculus. Exposure to vapors of S. granulosoleprosum + R. communis (S + R) had no effect on longevity but reduced survivorship of adults of both species. Interestingly, exposure to vapors of S + R, 50% (v/v) and pure ethanol resulted in greater fecundity of females of both frugivorous fly species than the water control. By contrast, fertility (% egg hatch) was in all cases high (>85%) and not different than the water control. Exposure to ethanol vapors appears to have similar effects on frugivorous tephritids as those reported on saprophagous and frugivorous species of Drosophila, a novel finding that may have important practical implications.

Five sampling methods were evaluated for efficiency in estimating field populations of Megalurothrips sjostedti (Trybom) on cowpeas in Nigeria. The methods (sticky traps, water traps, sweep netting, shaking plants and the collection of whole plant samples) were judged on the basis of low sample variance, low cost and fidelity to absolute population trends. Shaking plants and water traps were the best sampling techniques on the basis of sample variance and cost. Shaking plants also showed the closest correlation with absolute population trends and is therefore recommended for rapid estimation of field populations of thrips. The performance of the usual alcohol method of sampling M. sjostedti on cowpeas (collecting racemes and flowers in alcohol) was not comparable with those of shaking plants and water traps, but was considered important because it sampled the infested structures, eliminating more transient visitors which might also be sampled by shaking plants.

A controlled technique is described, whereby the comparative protective values of various dips and sprays used in sheep maggot fly control can be accurately assessed.

In order to determine the exact mode of action of the agents under test, each is examined from the point of view of its power to inhibit oviposition by the adult fly and also for its larvicidal properties.

The “anti-adult” test involves the weekly exposure of treated groups of sheep to an active and dense fly population, maintained in a closed chamber under controlled conditions of temperature and light.

The larvicide test is a modification of a former method of larval implantation, and is applied to the sheep when the “anti-adult” protection, indicated by the previous test, is found to have failed.

In the second part of the paper, a number of results are presented which serve to illustrate the working of the technique, and demonstrate the comparative value of several methods of maggot fly control which are in current use.

A dip containing 0·5 per cent. DDT in water suspension was found to give the most satisfactory protection, and to achieve this result purely by its action against the adult fly. A 0·5 per cent. DDT benzene emulsion dip was less satisfactory, as alsowas spraying as a method of applying the insecticide. In general, spraying has given about half the protection of dipping, whilst on sheep in full fleece, the application of half a gallon of spray was found to be inadequate. Protection was again found to be poor when the fleece was carefully dressed with half a pound of a dry powder containing 5 per cent. DDT.

In contrast to DDT, BHC and arsenic were shown to possess virtually no “antiadult” properties at the concentrations tested. BHC and arsenic both acted as efficient larvicides and provided a valuable and similar degree of protection against the sheep maggot fly, as an incidental effect, when they were tested at the concentrations normally used for their primary function of sheep scab control.

The seasonal abundance, biting cycle, age composition and survival of females of Aedes polynesiensis Marks and A. samoanus (Grünberg), the major vectors of subperiodic bancroftian filariasis, were studied in Samoa. A. polynesiensis density was low during the high rainfall months and increased immediately following them. A. samoanus density showed no clear relation to rainfall. A. polynesiensis was active throughout the day, with peaks indoors and out at 08.00–09.00 h and 16.00–18.00 h. The nulliparous and parous populations showed similar patterns of activity. The biting cycles of 2-parous and 3- plus 4-parous females were asymmetric with time. A. samoanus was active throughout the night, with highest activity at 23.00– 01.00 h. A minor peak at 19.00–20.00 h was more pronounced among older females than among younger ones. Night biting by A. polynesiensis and day biting by A. samoanus were rare. The parous proportion of A. polynesiensis ranged from 36·3 to 59·5% and the epidemiologically significant 3- plus 4-parous proportion ranged from 1·0 to 6·7%. The parous proportion of A. samoanus was 37·9–49·7% and the 3- plus 4-parous proportion 1·4–2·6%. The proportions found to be parous in both vectors were generally higher in the cool than the warm season, suggesting higher daily survival during that period.

The males of Heliothrips haemorrhoidalis (Bouché) are very rare and the species is thelytokous. Mutation of genes controlling male characteristics will therefore not be subject to selection, and so structural variation in these males is of no taxonomic significance. It is concluded that haemorrhoidalis and ceylonicus Schmutz represent one species in which the females vary in size, sculpture and colour throughout the tropics.

Examination of the polytene chromosomes and cross-breeding data confirmed the specific status of Anopheles dirusPeyton & Harrison within the complex of A. balabacensis Baisas. The data also strongly suggested that A. dirus itself is a complex of at least two species, one of which, a hitherto unrecognized species, provisionally designated A. dirus species B, previously known as the Perlis form, occurs in northern Peninsular Malaysia. A distinct population from Thailand was designated A. dirus species A. The mosquitoes studied also include material from natural populations in Sabah, here provisionally designated A. balabacensis s.s., and may represent the first genetic analysis of this species. The Sabah material is distinct from either of the A. dirus forms. Hybrid males from crosses of A. balabacensis × A. dirus species A and of A. dirus species B females × A. dirus species A males were sterile. Chromosome studies also showed that reproductive isolation was accompanied by genetic changes in both the autosomesand X chromosome in the hybrid larvae.