The diel oviposition periodicity of two groups of Aedes aegypti females (Trinidad strain), (i) thoses allowed access to oviposition sites and (ii) females forced to retain-eggs for four days, were studied under laboratory conditions using one female per cage and monitoring by changing substrates every two hours. The individual females which were allowed access to oviposition sites showed peak oviposition between 16.00–18.00 h (50% of eggs), whereas individuals forced to retain eggs for four days showed a similar pattern but with a significantly (P<0.001) larger peak oviposition between 16.00–18.00 h (94% of eggs). However, females forced to retain eggs laid most or all of their eggs in one container (84%), while females given access to oviposition sites distributed their eggs among 2–4 containers. The results of this study are discussed in the context of the strength of the circadian rhythms, oviposition strategies and its impact on vector control activities.

Observations on the taxonomy, distribution and host-plants of scale insects of several taxa in the Middle East are reported. A lectotype is designated for Bodenheimera rachelae (Bodenh.). Coccus capparidis (Green) is recorded for the first time from Israel and the Mediterranean region. C. arens Hodgson is a new synonym of C. capparidis. C. pseudo-magnoliarum (Kuw.) is recorded from Israel and France. The genus Paralecanopsis is regarded as a subjective synonym of Lecanopsis. Archaspis is synonymised with Quadraspidiotus and Archaspis ephedrae Bodenh. with Quadraspidiotus cecconii (Leonardi). The identity of Diaspis capparidis Bodenh. is established, the species is transferred to Rungaspis, and R. trabuti Balachowsky synonymised with it. R. macrolobis Kaussari is redescribed and a lectoype designated; it is recorded from Israel. A key is given to the three species of Rungaspis, and Sinaidiaspis is synonymised with this. Pseudococcus lindingeri Bodenh. is transferred to Planococcus, and Planococcus variabilis (Hall) synonymised with it. Trionymus internodii (Hall) is recorded for the first time from pineapple and from Israel.

Exposure of pregnant females of Glossina morsitans morsitans Westw. to a standard dose of 14·8 ng/fly of endosulfan confirmed that they acquire a higher level of tolerance of this insecticide than young unmated females. The development of tolerance was rapid, from threefold 48 h after larviposition, to eightfold midway through the pregnancy cycle at 4–5 days, and reaching 10- to 14-fold 24–28 h before the next larviposition. The acquisition of substantial tolerance preceded the periods of major growth of the larva in utero and of the developing oocyte, and it is suggested that the development of tolerance is associated with the diversion of insecticide by partitioning into lipid components of the milk as they are synthesised. The level of tolerance attained at equivalent stages of the pregnancy cycle appeared to be largely independent of the age of the fly between the second and fifth cycles, but that reached in the first cycle was lower. Some females survived repeated exposure to endosulfan in successive cycles. The offspring of treated females showed no apparent effects until shortly after adult eclosion, when substantial but variable delayed mortality occurred. However, surviving females and their offspring continued to reproduce normally. It is concluded that tolerance of the insecticide in pregnant flies accounts adequately for the observed survival following non-residual applications of endosulfan, and strategies for preventing this survival, and achieving eradication, are discussed.

Reduction in growth of saplings of Eucalyptus deglupta resulting from die-back caused by Amblypelta cocophaga China was studied in forestry plantations in the Solomon Islands. At a standard spacing of 10 × 3 m, a comparison was made of tree growth and incidence of A. cocophaga attack on saplings planted in strips 2 m wide cut through secondary forest, with those from which all inter-row vegetation was cut back prior to planting. Initially, a greater proportion of trees was infested on the cleared than the uncleared plots, but at the end of the first year, at which time the attack was at its peak, no differences could be detected. From the fifth to the thirteenth month after planting out, uninfested trees on the cleared plots increased in height at an average rate of 60 cm per month. For every week that at least one A. cocophaga was recorded on a tree, this rate was depressed by 1·3 cm. On the uncleared plots, the average rate of increase of uninfested trees was only 42 cm per month and this was reduced by 1·0 cm for every week that an insect was recorded. By the end of the first year, an estimated 37% (in cleared plots) and 41% (in uncleared plots) of the potential stand was rendered useless for future timber production due to A. cocophaga damage. In terms of total stem volume (not log production), about 1 m3/h out of a potential 3 m3/h was lost in the uncleared plots and 0·2 m3/h out of a potential 0·6 m3/h in the uncleared ones. Whilst clearing did not reduce the incidence of A. cocophaga attack, the advantage of clearing in terms of increased tree growth was considerable.

My breeding experiments on Locusta migratoria, L., in 1913−14 enabled me to establish that the progeny of this species sometimes belongs to the form which was previously regarded as a distinct species, L. danica, L., and in the same way, the latter insect may give rise to progeny that is typical of L. migratoria. These results have been used by B. P. Uvarov in developing his theory that the periodicity of locusts is due to a kind of irregular alternation of two phases, swarming (ph. migratoria) and solitary (ph. danica), respectively. I shall not dwell here on that theory or on the differences between the two phases, referring those interested in the subject to Uvarov's paper, but will describe further breeding experiments conducted during the year 1923 with a view to obtaining an idea as to what may be the factors that cause the variation in the species.

Isolates of Serratia marinorubra and S. liquefaciens pathogenic for Costelytra zealandica (White) were artificially cultured and applied to field populations of larvae of C. zealandica in New Zealand in the late summer and autumn of 1984. In four trials, when bacteria were applied from February to late March, high levels of disease transmission were recorded. Three months after application, significant (P<0·05) reductions of 30–59% in the larval populations were obtained, and 47% of the remaining larvae in the treated plots were diseased, suggesting the long-term effect would be greater. Treatment resulted in a 30% increase in dry matter production in the pastures. There was no consistent difference between the bacterial isolates tested. Application of the bacteria in May had no effect on the larvae, suggesting that they were no longer susceptible. It is concluded that these pathogenic isolates should be developed further as microbial insecticides for control of C. zealandica.

Fruit-piercing Lepidoptera constitute an important problem in some parts of the world, such as Africa, Australia and India; they also occur in Ceylon, Fiji, Dutch East Indies, Indo-China, Japan, Malaya, Samoa, and South America.

In Sierra Leone, grape-fruit, orange (sweet), mandarine, tangerine and sweet lime, are affected in addition to cashew, mango, bread-fruit and jak-fruit; whilst in other countries apple, apricot, banana, fig, grape, guava, litchi, nectarine, peach, pear and pomegranate, have been recorded as other adult food-plants; it is noteworthy that in South Africa grape-fruit does not appear to be attacked. Available information regarding fruit-piercing species and their biology is meagre compared with that of many other groups of economic insects, and it is considered desirable to place on record observations made in Sierra Leone.

Difficulties in the way of the study of these insects are the lack of knowledge regarding (a) larval food-plants; (b) characters and habits of the larvae; (c) the breeding areas and possible migratory habits of the larvae; (d) the breeding areas and possible migratory habits of the adults of some species.

Unless otherwise stated this account applies to Njala, where there is a plot of budded citrus; the trees were planted in 1925-1927 and mainly consist of Late Valentia and Washington Navel orange, and Marsh and Foster grape-fruit. The sweet lime, mandarine and tangerine are about ten years older.

Better performance of generalist predators, as well as an increase in their density, may be an incentive factor in the ability of the predators to exploit more than one food item or mixed diets. In this study, the effects of four pollen grains (cedar, pear, apricot, and pistachio) when provided to Neoseiulus californicus in mixed diets with prey, Tetranychus urticae, were evaluated. The result indicated that the fastest female developmental time was observed on pistachio pollen + T. urticae, together with apricot pollen + T. urticae. Females reared on the mixed diet comprising pistachio pollen reflected the longest total life span duration, while the shortest total life span was observed in those on the diet that included pear pollen. Furthermore, the lowest fecundity, as well as the shortest reproduction period, was determined on the diets that included pear pollen, while the highest fecundity and the longest reproduction period were observed in pistachio pollen + T. urticae. In addition, the intrinsic (r) and finite rate of increase (λ), net (R0) and gross (GRR) reproductive rates were highest in pistachio pollen + T. urticae. These findings have important implications for developing a comprehensive biological control program of T. urticae, which will be discussed.

Descriptions are given of Orasema asscctator sp.n. and O. initiator sp.n. (Hym., Eucharitidae) from India, causing damage to the leaves of tea. For purpose of comparison, two species of the same genus are redescribed. The genus Semora Cameron is shown to be synonymous.

The embryonic development of Dysdercus fasciatus Sign. is described in terms of 15 arbitrary stages based on external morphological characters. The effects of treating eggs early in development with juvenile hormone and a mimic (JH) are then described in terms of the stages at which embryonic development is arrested and the resulting morphological aberrations are summarised. The effects of the treatment of two strains of D. fasciatus with two JH (Law's mimic and Ayerst synthetic juvenile hormone) are described and compared in terms of both the hatchability of the eggs and the stage distributions of the arrested embryos. Law's mimic was more effective than Ayerst SJH in preventing egg hatch, and the Malawi strain was less susceptible than the Reading strain. Embryonic development was never arrested earlier than the commencement of blastokinesis (Stage VIII). After treatment with Ayerst SJH most embryos of both strains were arrested during dorsal closure (Stages XI-XII) or at the time of eclosion (Stages XHI-XIV). Treatment of the Reading strain with Law's mimic resulted in the majority of embryos being arrested during blastokinesis (Stages VIII-X) at all doses. Examination of the timetable of development in both control and treated eggs reveals a dramatic reduction in developmental rate in treated eggs at the commencement of blastokinesis. It is suggested that JH may act on eggs of D. fasciatus in three ways: interference with eclosion, differentiation and the embryonic movements during blastokinesis.

Evidence gained using blowflies (Calliphora vicina R.-D., Lucilia sericata (Mg.), L. cuprina (Wied.) and Protophormia terraenovae (R.-D.) ), fleshflies (Sarcophaga spp.) and tsetse flies (Glossina spp.) in ligaturing experiments and by the injection of prepupal haemolymph (with added ecdysone) suggests that factors other than ecdysone, released in the posterior segments, may initiate pupariation. They could act as synergists for ecdysone. Puparium formation is reduced from 77·5±3·1% to 35·7±2·8% (P<0·001) if 50 ng α-ecdysone is injected through the anterior knot into the middle region of twice-ligatured Sarcophaga argyrostoma (R.-D.) larvae instead of into the abdomens of singly tied larvae. The pupariation score is increased to 57·2±4·8% if haemolymph from rounded-off prepupae is injected into the middle region of isolated abdomens. The uninjected posterior region sometimes darkens alone. Ligature of the abdomens of S. peregrina R.-D. and S. argyrostoma prepupae which have just reached the orange-peritreme stage before rounding-off confines the pupariation to the posterior segments.

The effects of retarding puparium formation for 12–24 h by the use of dopa decarboxylase inhibitors or by means of a loose constriction (‘ cummerbund‘) are reported because the location of the patches of cuticle which stabilise and darken as the inhibition slowly wears off implicates certain areas under the integument as the sites of production or secretion of puparial tanning hormone or ‘ posterior darkening factor ’. Retardation of pupariation results from the pressure stimulus applied to rounded-off prepupae because either a hormone is held back or an inhibitor is released as a consequence of the distortion of the cuticle by the cummerbund. When fleshfly larvae are tightly ligatured every hour in front of or behind the brain for 18 h after removal from a moist environment which inhibits pupariation, the percentage of larvae which pupariate in both situations suggests that the CNS itself can inhibit pupariation of the anterior region because of the presence of the stricture. This inhibition, which is not due to lack of oxygen, can be reversed by the presence of factors produced in the abdomen.

Many aphid species have life cycles which alternate between asexual reproduction during spring and summer and sexual reproduction in autumn. This paper describes the sequences of morphs produced by clones of Rhopalosiphum padi (Linnaeus) in response to a range of photoperiods and temperatures in the laboratory, and under semi-natural conditions at the time of year when the transition from parthenogenetic to sexual reproduction occurs. By using similarities in the order in which the various morphs were born, clones of R. padi were found to produce eight progeny sequence types. A clone of R. padi will produce these sequence types sequentially as it changes from parthenogenetic to fully sexual reproduction. The progeny sequence produced by clones under conditions corresponding to those of spring and summer consist of parthenogenetic females only. During late summer, production of parthenogenetic females is followed by males. Later in the year, a clone produces progeny sequences consisting of parthenogenetic females, gynoparae and males. The asexual phase of reproduction is terminated in late autumn when only gynoparae and males are born. A minority of clones terminate parthenogenetic reproduction by producing only gynoparae. The function of these changes in progeny sequence in maximizing the reproductive success of a clone of R. padi is discussed.

One of the most remarkable features of the locust season during the summer and autumn of 1930 in the Sudan was the unexpected and widespread occurrence of Locusta migratorioides, R. & F. Swarms, which laid eggs over a large extent of the country, entered from the west and south-west during July and August. There is no evidence of any of these swarms having been produced within the Sudan, and the place of origin of all the early swarms was without doubt situated outside its boundaries. There is evidence that breeding continued later in the southern portions of the country, particularly in the upper reaches of the White Nile (N. Lat. 5°), and movements of swarms were reported during the winter, but no reliable observations were made on the nature or extent of these activities. Only one brood was produced in the northern and central Sudan (probably north of N. Lat. 11°), and by October all locusts bred in these parts had either migrated away in swarms or had scattered. Migration took place in the case of the gregarious phase produced by large bands of hoppers. Where, however, bands of hoppers had been broken up by poisoning, or in cases where the bands were very small, the adults did not migrate. The absence of further breeding in the northern Sudan must be connected with the absence of winter rains and suitable vegetation.

Population genetics of invading pests can be informative for understanding their ecology. In this study, we investigated population genetics of the invasive alfalfa weevil Hypera postica in Fukuoka Prefecture, Japan. We analyzed mitochondrial tRNALeu-COII, nuclear EF-1α gene fragments, and Wolbachia infection in relation to three leguminous host plants: Vicia angustifolia, Vicia villosa, and a new host Astragalus sinicus cultivated as a honey source and green manure crop. A parsimony network generated from mitochondrial gene sequences uncovered two major haplotypic groups, Western and Egyptian. In contrast to reported Wolbachia infection of the Western strain in the United States, none of our analyzed individuals were infected. The absence of Wolbachia may contribute to the stable coexistence of mitochondrial strains through inter-strain reproductive compatibility. Hypera postica genetic variants for the mitochondrial and nuclear genes were associated neither with host plant species nor with two geographic regions (Hisayama and Kama) within Fukuoka. Mitochondrial haplogroups were incongruent with nuclear genetic variants. Genetic diversity at the nuclear locus was the highest for the populations feeding on V. angustifolia. The nuclear data for A. sinicus-feeding populations indicated past sudden population growth and extended Bayesian skyline plot analysis based on the mitochondrial and nuclear data showed that the growth of A. sinicus-feeding population took place within the past 1000 years. These results suggest a shorter history of A. sinicus as a host plant compared with V. angustifolia and a recent rapid growth of H. postica population using the new host A. sinicus.

Heliothis viriplaca (Hüfnagel) (Lepidoptera: Noctuidae) is an important polyphagous pest of beans, cotton, maize, and alfalfa worldwide. H. viriplaca is a long-distance migrant, and if so, what pattern of seasonal migration this species exhibits in northern China remains unknown. In this study, in order to determine the seasonal migration of H. viriplaca in northern China, the combination of searchlight trapping and ovarian dissection was carried out on an isolated small island in the center of the Bohai Strait during 2003–2014. The results confirmed that H. viriplaca undertakes long-distance migration on the prevailing winds of the East Asian monsoon airflows. This species exhibited a regular pattern of seasonal migration across the sea from May to October, but there was considerable yearly and monthly variation in the trapped numbers, with the majority being trapped in summer (67.99 ± 6.54%). The mean period when migration was detectable at the island was 116.5 ± 5.6 days from 2003 to 2014, with the shortest time span of 74 days in 2013 and the longest of 144 days in 2005. Trapped females in May and June showed a relatively higher mating rates and some degree of ovarian development when compared with July, August and September, suggesting the migration of this species is not completely bound by the ‘oogenesis-flight syndrome’. These findings will be helpful to improve the forecasting system and managing strategies of H. viriplaca.

An experiment is described where applications of a coarse aerosol were made to savannah woodland containing the tsetse flies, Glossina moritans Westw., G. swynnertoni Aust. and G. pallidipes Aust.

Seven applications were made, each at a nominal dosage of 0·25 lb. of technical DDT per acre and 0·25 gallons of solution per acre. The applications in any particular part of the treaed woodland covered an interval of 90 days, or rather more than two pupal periods.

The coarse aerosol was produced by emitting the insecticidal solution under pressure through fine nozzles fitted to a boom. It had a mass median diameter of approximately 60 microns, and droplet dismeters varied from a few microns to approximately 200 microns.

The population of G. pallidipes was so drastically reduced that it has subsequently dies out. The reduction of G. morsitans was approximately 95 per cent. The differences between the reductions are attributed mainly to differences between the ease with which the three species can be killed. It is pointed out that this is not necessarily equivalent to differences in susceptibility.

Comparisons are made with previous experiments, and the different results of the various experiments are difficult to explian satisfactory. The increased cover in savannah areas during the leafy period may have reduced the effectiveness of the applications, and the total periods covered by the various series of applications were probably also important. Random effects, leading to ineffective treatments, may also be important.

Costs are discussed.

A seed-feeding curculionid, Rhyssomatus marginatus Fåhraeus, was introduced into South Africa for biological control of a perennial leguminous weed, Sesbania punicea, from South America. R. marginatus has become established even though its larval food source, seeds in ripening pods, is severely depleted by another biological control agent, an apionid, Trichapion lativentre (Beguin Billecocq), which destroys nearly all the flower-buds produced by the plants and reduces seed-set by 98% on average. In spite of this indirect competition, R. marginatus destroys up to 88% of the remaining seeds that develop on S. punicea, regardless of host plant location. Detrimental intraspecific interactions between larvae of R. marginatus are minimized, and the utilization of a depleted food source is optimized, through meticulous selection of oviposition sites by the female weevils. Although numerically inferior, R. marginatus is an important supplementary agent to T. lativentre and together the two species of weevils have almost arrested the reproductive potential of S. punicea.

The nature, frequency and causes of reproductive loss were investigated in populations of Glossina pallidipes Aust. in western and coastal localities in Kenya. Daily collections from biconical traps in which females were trapped for varying periods up to 30 h were followed by a series of hourly captures which gave less biased data. Ovarian abnormalities and insemination failure were rare, and abortion was the only major source of loss of fecundity. Total reproductive loss was within the range 1·60–1·97% (0·23% ovarian loss plus 1·37% abortions or 1·74% total empty uteri) in western Kenya (Lambwe Valley) and 0·99–1·71% from less comprehensive data at the coast. The incidence of empty uteri was higher in daily than in hourly collections, due mainly to premature parturitions brought about by the stressful effects of prolonged confinement in traps and handling. Abortions were significantly more frequent in females which had ovulated but were not yet parous than in older, parous flies. No relationship between the frequency of abortion and climate, tsetse density or pathogen or parasite infection could be demonstrated.

A study has been made of the development of Cryptolestes pusillus (Schönh.) at various combinations of high temperatures and humidities. Larval development is much quicker at 90 than at 70 per cent. R.H., and the optimal temperature is probably about 37°C. Under optimal conditions the developmental period is less than has so far been recorded for other species of Cryptolestes, the mean duration of the larval stage being as little as 8½ days at 33°C. and 90 per cent. R.H. The oviposition rate is similarly much increased at both high temperatures and high humidities. There is evidence that middle-aged females lay more rapidly than either younger or older individuals. Under optimal conditions the average oviposition rate can exceed 7 eggs/ ♀ /day, about 17 per cent. of the weight of the adult.

In cultures of adults on flour, there was no clear indication of a reduction of the oviposition rate or of a juvenile mortality at densities ranging from 1·5 g. per adult down to 0·03 per adult, but there were signs that the latter density was near a critical value.

Eggs of C. pusillus were cultured on whole English grain with the germs in poor condition, at humidities ranging from 50 to 90 per cent. The endosperm rather than the germ was attacked in almost all cases. At 50 per cent. R.H., only one individual out of 21 completed its development whereas at 90 per cent. R.H. few failed to do so. Humidity had a considerable effect on the rate of development in the larval stage. At 90 per cent. R.H. it was only slightly slower on grain than on flour.

Latrophilin (LPH) is known as an adhesion G-protein-coupled receptor which involved in multiple physiological processes in organisms. Previous studies showed that lph not only involved the susceptibility to anticholinesterase insecticides but also affected fecundity in Tribolium castaneum. However, its regulatory mechanisms in these biological processes are still not clear. Here, we identified two potential downstream carboxylesterase (cce) genes of Tclph, esterase4 and esterase6, and further characterized their interactions with Tclph. After treatment of T. castaneum larvae with carbofuran or dichlorvos insecticides, the transcript levels of Tcest4 and Tcest6 were significantly induced from 12 to 72 h. RNAi against Tcest4 or Tcest6 led to the higher mortality compared with the controls after the insecticides treatment, suggesting that these two genes play a vital role in detoxification of insecticides in T. castaneum. Furthermore, with insecticides exposure to Tclph knockdown beetles, the expression of Tcest4 was upregulated but Tcest6 was downregulated, indicating that beetles existed a compensatory response against the insecticides. Additionally, RNAi of Tcest6 resulted in 43% reductions in female egg laying and completely inhibited egg hatching, which showed the similar phenotype as that of Tclph knockdown. These results indicated that Tclph affected fecundity by positively regulating Tcest6 expression. Our findings will provide a new insight into the molecular mechanisms of Tclph involved in physiological functions in T. castaneum.