Endosulfan resistance in the coffee berry borer Hypothenemus hampei (Ferrari) was discovered in New Caledonia after six years of lindane and 12 years of endosulfan biannual applications. The direct spray technique was used to study cross resistance with lindane and to monitor resistance to both pesticides in 15 regions of New Caledonia. An easier monitoring technique was developed for early detection by field laboratories. Results from this simple method, using twice the LC99 of endosulfan to susceptibles (400 ppm) showed a comparable distribution of resistance to the direct spray method in five regions where resistance was detected. The percentage of surveyed fields containing resistant insects in these areas was: Poindimié, 100%, Ponérihouen, 97%; Touho, 63%; Houailou, 10%; Hienghène, 6%. Resistant insects were significantly more frequent in the new sunny fields than in older shady plantations (P<0.05), and fields with endosulfan used in the preceding year (P<0.001). The possible reasons for the observed distribution of resistance are discussed.

Amblyseius swirskii Athias-Henriot is a well-known predator that is used for controlling the population of two-spotted spider mites (TSSM), Tetranychus urticae Koch, and greenhouse whitefly (GHWF), Trialeurodes vaporariorum Westwood, in strawberry greenhouses. To find the effective factors that influence the efficiency of this predator, the predation rates of A. swirskii fed on (Ι) TSSM in the presence and absence of the pollen, webbing, and GHWF, as well as on (II) GHWF in the presence and absence of the pollen, and GHWF-produced honeydew were determined. Furthermore, developmental time, fecundity, and population growth rate of this predator under the same conditions were measured. Our results showed that A. swirskii was able to reduce TSSM population, while the spider mite webbing had an adverse effect on the performance of the predator. Therefore, the presence of the predator population at the time of the infestation is crucial to the success of biological control. It can be concluded that the alternative food sources such as pollen and GHWF-produced honeydew play an important role in maintaining the predator population in the absence of pests. Moreover, the results indicate that using the pollen and another pest along with the target pest can promote the predator density. A. swirskii consumed lower numbers of TSSM when concurrently offered with GHWF and/or maize pollen, and lower numbers of GHWF in the presence of pollen. On the other hand, in the presence of alternative food or alternative prey, the fecundity of the predator was much higher.

The Rhyzobius (or Lindorus) ventralis frequently referred to in the literature of biological control is shown to be a mixture of two distinct, though similar, species. The origin of the confusion is traced to the nineteenth century searches in Australia for insects to control scale insect infestations on citrus and other crops in California. Adults of the two species are defined and illustrated, and a key is provided for their separation. Lectotypes are designated for R. ventralis (Erichs.), its synonym Scymnus restitutor Sharp and for S. halli Broun, newly synonymised with R. ventralis. A lectotype is designated for Platyomus forestieri Muls., the second species of the complex, here transferred to Rhyzobius, and for S. circularis Sharp, newly synonymised with R. forestieri. Distribution data for both species, based on actual specimens examined, are listed, and their Australian distribution is summarised in a map. Past usages of ‘ R. ventralis’ as a biological control agent are reviewed in the light of the revised taxonomy. The taxonomy and nomenclature of Rhyzobius Stephens is discussed in order to establish the correct generic placement of and binomina for R. ventralis and R. forestieri.

Reactions of 3-day-old first- and fourth-instar hoppers of Schistocerca gregaria (Forsk.) of phase gregaria, to three physical factors, namely to relative humidity, temperature and light have been studied in an alternative chamber apparatus designed to give an enclosed space with gradients of humidity. The responses to each factor independent of the others, and to the interactions of these factors, were considered.

It was found that both the first- and the fourth-instar hoppers respond strongly to humidity. They are agitated by low, and even more by very high, humidities, but become more quiescent within a zone of 60–70 per cent. R.H., where they spend more time. Within this zone they hop and turn less and this decrease in activity appears to be a response which is independent of both temperature and of light intensity. This zone of decreased agitation has been called “the zone of minimum activity”. However, the speed of walking in contrast to the other types of activity, increased progressively with humidity.

Increase in light intensity raises the level of activity at all humidities, i.e., it increases the duration of activity within the limits of experimental time and the speed of walking. With rise in temperature there is an increase in hopping, in klinokinesis and orthokinesis.

These notes are the result of an examination of the literature and are concerned with geographical distribution. The Review of Applied Entomology, Series B, and the Tropical Diseases Bulletin were consulted and many papers were seen in the original; references to a selection of the more important of these is appended herewith. Of the ticks of the genus Ornithodoros occurring in the Old World about 40 names appear in published papers; of these about 20 seem to be valid species and five are well known and readily recognised: erraticus, lahorensis, moubata, savignyi and tholozani.

Parasitoid fitness depends largely on the capability to locate a host in an ecosystem. A parasitoid of a polyphagous host might not be able to find or to access the host in all its feeding niches. This study evaluated the niche selection of Hyssopus pallidus (Askew), a larval parasitoid of Cydia pomonella (Linnaeus), at the plant level with the goal of assessing its potential for biological control on different fruit crops throughout the plant cycle. Parasitoid behaviour during host location and reproduction rate were investigated on host caterpillars actively feeding on apple, pear, apricot or plum, and on caterpillars diapausing under the bark. Under laboratory conditions, the host searching behaviour of H. pallidus varied depending on the fruit species offered and the infestation of the fruits. Parasitoid females searched longer on apples than on other fruit species, and they searched longer on infested than on uninfested apples. Female wasps were able to locate and parasitize host caterpillars under the tree bark, and their behaviour did not vary with host accessibility. The numbers of caterpillars attacked by H. pallidus depended on the fruit species. The highest numbers of caterpillars were parasitized in apples and apricots. Their accessibility (i.e. position) within the fruit or on the branch did not influence parasitism success. Although hosts were parasitized throughout the season, the best results were achieved with early and late releases. Therefore, the host niche selection behaviour of H. pallidus most likely co-evolved with the host C. pomonella on apples, which renders H. pallidus a valuable biocontrol agent for successful release at different times of the season into apple orchards.

A bug identified as Aphanus littoralis, Dist., but believed to be synonymous with A. sordidus, F., was found infesting stored ground-nuts at Yola, Nigeria. It had not hitherto attracted attention in this country, but was found later to be recognised by native farmers as associated with ground-nut plants drying in the fields at harvest.

The nuts concerned were in war emergency mud and thatch stores which were much cooler than the (uninfested) corrugated-iron stores normally used. This difference is believed to have favoured the infestation.

The adults and nymphs cause damage by sucking the oil from the kernels. Loss of weight and germinative power, and development of free fatty acids and rancid and bitter taste follow. It was found, however, that bugs could not penetrate more than three inches or so into the bulked kernels, so damage was not extensive.

The enhancement of bait for the control of grass-cutting ants was investigated using two species of grass-cutting ant, Atta bisphaerica (Forel) and Atta capiguara (Gonçalves) (Hymenoptera: Formicidae). Bait was applied in loose piles to obtain a direct relationship between ant attraction and bait harvest. Enhancement with alarm pheromone compounds significantly increased the attractiveness and harvest of bait under certain conditions. A large proportion of the ants attracted to the enhanced bait were minor workers. These ants rarely transport bait because of their small size, and so it may be possible to increase the effect of bait enhancement by using smaller bait granules. Foragers of A. capiguara were less inclined to transport citrus-pulp bait than were those of Atta laevigata (Fr. Smith), a species that also harvests dicotyledonous plants. This emphasizes the importance of developing a bait matrix that is more acceptable to grass-cutting species. Nevertheless, the results suggest that alarm pheromone compounds have significant potential to improve the efficacy of baits for the control of grass-cutting ants.

Field bioassays using three different synthetic sex pheromone blends (Indian, Philippine and Japanese) based on geographic variations of Cnaphalocrocis medinalis Guenée were carried out at 11 sites in Japan and in Hangzhou, China. In all of the tests, only the Japanese pheromone blend attracted a significant number of male moths, while the Indian and Philippine pheromone blends showed no marked activity. The findings in Japan showed no evidence that moths of Philippine or Indian origin were able to migrate to Japan. The results from China also showed that most populations of C. medinalis in the Hangzhou region responded to the Japanese blend. This is consistent with the current hypothesis that most populations of C. medinalis in Japan are migrants from areas to the south of the Yangzhe Valley, including the region surrounding Hangzhou, China. Furthermore, populations in the Hangzhou region can not hibernate, but are considered migrants from the southernmost parts of China and southeast Asian countries such as Vietnam where they breed continuously. Consequently, at least some populations in these areas may respond to the Japanese pheromone blend.

A laboratory colony of Aedes fluviatilis (Lutz) was established in ambient conditions in Brazil in which temperature varied from 22 to 31°C and relative humidity from 61 to 73%. Females laid eggs 3–13 days (mean 5·6 days) after a blood-meal and produced, on average, 64·3 eggs per batch. Eggs were usually deposited directly on the surface of water and preferentially on water that had previously contained fourth-instar larvae. The eggs proved to have little resistance to desiccation, hatching rates being reduced when eggs were kept on dry filter paper for only 1–3 days. Hatching took place following the detachment of a cap-like portion of the anterior end or through an irregular longitudinal split along the side of the egg. In different experiments, about 10–20% of eggs failed to hatch. Eggs usually hatched 2 days after oviposition. The average length of larval life was 10·2 days, and the highest proportion of larvae pupated on day 9. The duration of the successive immature stages increased geometrically with age. Mortality was 1–2% in each of the first 3 larval instars but rose to about 10% in the fourth. In the larval stage, males developed more rapidly than females. Crowding lengthened the duration of the larval stage, reduced the numbers surviving to pupate and resulted in a disparate sex ratio with emergent males much more abundant than females. Pupation occurred throughout the day and night with a slight peak at 05.00–06.00 h. The pupal stage lasted 1–3 days, usually 2 days, and was the same in both sexes.

The direct action of reduced pressures, in the absence of any fumigant, on C. oryzae and C. granaria have been investigated in glass chambers of about 1 litre capacity. C. oryzae is sufficiently sensitive to make the direct effect of reducing the pressure within the range 2 to 10 cm. mercury of some practical importance, but C. granaria is more resistant. Mortality of both species increases for exposure periods of up to 8 hr. and for increased temperatures from 20°C. to 28°C. A large part of the observed mortality must be associated with enhanced water-loss from the insects at reduced pressures, as little response occurs when the atmosphere is kept saturated with water-vapour.

Anthrenus flavipes Lec. (vorax Waterh.), commonly known as the Furniture Carpet Beetle, is a widely occurring species of wool-destroying insect in India. It feeds on woollen materials, feathers, bristles, furs, horse-hair, horny substances and other materials of a keratinous nature. The adult beetles feed on pollen and nectar of flowers in nature and are harmless; and it is the larva which destroys the above materials. The life-history of the pest has been studied at several controlled levels of temperature and humidity, and also in a room where the humidity was controlled at 70–75 per cent. R.H. and the temperature fluctuated between 25 and 31°C. over the year. The results are compared with those of earlier authors. The sex-differentiating characters have also been investigated in the pupa and adult.

Temperature influences the duration of the egg stage and the viability of eggs. The incubation period of eggs at 25, 30, 25 to 31, 35 and 37·5°C. is about 13, 8, 7, 6 and 4 days, respectively. The viability of eggs is greater at 25 to 31, 35 and 37·5°C. than at 25 and 30°C. The fluctuating temperature (25 to 31°C.) has a more favourable effect on the incubation period and viability of eggs than the constant temperatures of 25 and 30°C. Humidity, however, has no effect on either the duration of the egg stage or the viability of eggs.

Temperature has a marked effect on the total larval period and to a lesser extent on the number of larval instars. The larval period is appreciably less at 25 to 31°C. and 35°C. than at 30°C. The number of larval instars is greater at 30 and 35°C. than at 25 to 31°C. though the duration of each instar is less at 35°C. than at 25 to 31 and 30°C. The fluctuating temperature (25 to 31°C.) is more favourable to rapid larval development than the constant temperature of 30°C. and also reduces the number of instars. Humidity has no effect on the number of larval instars and the total larval period.

Larvae thrive most satisfactorily on woollen fabric treated with 10 to 20 per cent, commercial yeast.

The duration of the pupal period and the number of adults emerging are dependent on temperature. The pupal period is about 14, 12, 9 and 7 days at 25, 25 to 31, 30 and 35°C. and is nearly the same for the male and the female. Humidity has no effect on the pupal period. These results are discussed in relation to those of earlier workers.

The pre-emergence (quiescent) period extends over 7 to 9, 7 to 8, 6 to 8 and 5 to 6 days at 25, 25 to 31, 30 and 35°C., respectively, irrespective of sex. Humidity has no appreciable effect on this period. These results are at variance with those reported by earlier workers.

The length of life of the adults is dependent on temperature but humidity has no appreciable effect on this period. The nature of food influences the length of life of the adults. A female starts laying eggs 4 to 10 days after emergence, depending upon temperature and humidity, and lays 12 to 41 eggs. The sex ratio between male and female was found to be 0·8:1.

The entire life-cycle is shortest at 35°C. Under conditions similar to those of the experiments described, there are one to one-and-a-half generations of the insect in a year depending upon the temperature conditions.

Phenoloxidase (PO) plays a key role in melanin biosynthesis during insect development. Here, we isolated the 2310-bp full-length cDNA of PPO1 from Zeugodacus tau, a destructive horticultural pest. qRT-polymerase chain reaction showed that the ZtPPO1 transcripts were highly expressed during larval–prepupal transition and in the haemolymph. When the larvae were fed a 1.66% kojic acid (KA)-containing diet, the levels of the ZtPPO1 transcripts significantly increased by 2.79- and 3.39-fold in the whole larvae and cuticles, respectively, while the corresponding PO activity was significantly reduced; in addition, the larval and pupal durations were significantly prolonged; pupal weights were lowered; and abnormal phenotypes were observed. An in vitro inhibition experiment indicated that KA was an effective competitive inhibitor of PO in Z. tau. Additionally, the functional analysis showed that 20E could significantly up-regulate the expression of ZtPPO1, induce lower pupal weight, and advance pupation. Knockdown of the ZtPPO1 gene by RNAi significantly decreased mRNA levels after 24 h and led to low pupation rates and incomplete pupae with abnormal phenotypes during the larval-pupal interim period. These results proved that PO is important for the normal growth of Z. tau and that KA can disrupt the development of this pest insect.

Field experiments were conducted to investigate the mechanism underlying patterns of the rove beetle populations in apple and pear orchards (1998–2002) and winter wheat (2006–2007) in Hungary following treatment with broad-spectrum insecticide. The capacity of predatory staphylinid species to feed on cereal pests was measured, with six species tested in petri dishes, in the laboratory at room temperature. Almost 23% of the Hungarian and 13% of the European staphylinid fauna are represented in the investigated agro-ecosystems. In orchards, 5236 individuals, belonging to 253 species, were collected. The most widely occurring were Omalium caesum Gravenhorst, Drusilla canaliculata (F.), Dinaraea angustula (Gyllenhal), Palporus nitidulus (F.), Xantholinus. longiventris (Olivier), X. linearis (Olivier) and Aleochara bipustulata (L.). In winter wheat, 798 individuals and 20 species were collected, the most frequent were Staphylinus caesareus Cederh, Tachyporus hypnorum (F.), Philonthus cognatus (Stephens), Aloconota gregaria (Erichson), Tachyporus chrysomelinus (L.) and T. obtusus (L.). Species composition differed by crop (apple, pear and wheat), soil composition and surrounding habitat. Species diversity was also influenced by these parameters. In wheat, one acute change in species composition was observed with the decline of Tachyporus spp., which occurred equally across all farms. The consumption rate of prey by the dominant species occurring in wheat ecosystems was relatively high; however, we did not offer any fungal food to compare with insects' prey.

The role of the host plant in the development of larval diapause in the millet stem borer, Coniesta ignefusalis (Hampson) was investigated in northern Ghana in 1996 and 1997. Surveys conducted in farmers' fields in the Guinea and Sudan savannah revealed that of all the upland cereals grown, the insect survived the dry season only in stalks and stubble of pearl millet, Pennisetum glaucum and late sorghum, Sorghum bicolor. This observation was confirmed by results from field trials conducted at the Manga Research Station. In these studies, C. ignefusalis larvae entered diapause only in late millet and late sorghum, with a higher incidence in the former. The insect neither attacked nor entered diapause in maize planted during the same period as the other crops. Results from controlled experiments showed that diapause incidence in the preferred host, millet, was higher in older than in younger plants, suggesting that host plant maturation is a key factor influencing the development of larval diapause in C. ignefusalis.

Light-trap catches of Heliothis armigera (Hb.) reach peaks during the wet seasons, April and November–January. Initial infestation of seed beans by H. armigera occurs in April–May at the time of flowering of the early-sown crop, the adults probably originating from an earlier generation on maize. Two generations are completed during the main seed bean season, the first on early-sown beans and the second on later beans, and the dry period July–October may be passed in pupal diapause. Damage, caused by the older larvae eating the seeds in the pod, is prevented by spraying the young larvae with DDT (25% e.c. at 3 pt/2 gal spray/acre) (the standard treatment) or endosulfan (35% e.c. at 1½ pt/2 gal spray/acre) at about six weeks after the beans emerge.

Adults of the Pentatomid Nezara viridula (L.) invade bean fields from alternative host-plants at the same time as H. armigera. This species, even in small numbers, causes the loss of young pods and also damages or kills the developing seed. It is not controlled by the standard DDT treatment for H. armigera, but the following insecticides were found to be effective: γBHC 20% e.c. (1¼ pt), dieldrin 18% e.c. (2 pt) and endosulfan 35% e.c. (1½ pt) in 2 gal spray/acre. Where N. viridula and H. armigera are found together, the standard recommendation is endosulfan 35% e.c. (1½ pt/2 gal spray/acre).

The Coreids Acanthomia horrida (Germ.) and A. tomentosicollis (Stål) cause damage similar to that of N. viridula, but are serious only when infestations are heavy. They were found to be controlled by DDT, dieldrin or endosulfan at the rates given above.

Alatae of the bean aphis Aphis fabae Scop, invade bean fields mainly during the first two weeks of the crop, producing apterae which concentrate on the tip of the plants. Damage (stunting, and loss of flowers and pods) is serious only when large populations of apterae are produced on a high proportion of the young plants. The early infestation demands control measures separate from those for the other pests, the most effective being methyl-demeton 50% e.c. (½ pt/2 gal spray/acre) applied 3–4 weeks after emergence. Endosulfan, although promising and far less toxic than methyl-demeton to larvae of the predator Cheilomenes lunata (F.), was discarded on grounds of cost, as was dimethoate. Aphid populations reached a peak during July and August and decreased with the warmer weather in September. A large number of alternative host-plants is listed, but the source of the primary flight into beans is not known.

Melanagromyza phaseoli (Tryon), the life-cycle of which is completed in 23 days, is unimportant on seed beans as it is least abundant during the growing period of the main crop, but may damage plants suffering from water stress. Tunnelling in stems by larvae was controlled by seed dressings of aldrin or heptachlor (both 40% wettable powders mixed with seed at 1:200 w/w).

Leaving the Government post on the Amala river, at an altitude of 5,500 feet, on 25th July, I moved down the west bank of the river and camped at a spring known as Ol-otu-lomot, at an altitude of 5,200 feet (see accompanying sketch-map). The next day I moved further down the river in search of an old Masai native, by name Ol-botor-ol-joni, who was reported to be familiar with the places in which tsetse-fly (Endorobo of the Masai) was to be found. I found this old man at the place marked on the map and camped there at an altitude of 5,100 feet.

Wolbachia is an intracellular symbiotic bacterium that infects various spider mite species and is associated with alterations in host reproduction, which indicates the potential role in mite evolution. However, studies of Wolbachia infections in the spider mite Tetranychus pueraricola, a major agricultural pest, are limited. Here, we used multilocus sequence typing to determine Wolbachia infection status and examined the relationship between Wolbachia infection status and mitochondrial diversity in T. pueraricola from 12 populations in China. The prevalence of Wolbachia ranged from 2.8 to 50%, and three strains (wTpue1, wTpue2, and wTpue3) were identified. We also found double infections (wTpue1 + wTpue3) within the same individuals. Furthermore, the wTpue1 strain caused weak cytoplasmic incompatibility (CI) (egg hatchability ~55%), whereas another widespread strain, wTpue3, did not induce CI. There was no reduction in mitochondrial DNA (mtDNA) or nuclear DNA diversity among infected individuals, and mtDNA haplotypes did not correspond to specific Wolbachia strains. Phylogenetic analysis and analysis of molecular variance revealed that the distribution of mtDNA and nuclear DNA haplotypes were significantly associated with geography. These findings indicate that Wolbachia infection in T. pueraricola is complex, but T. pueraricola genetic differentiation likely resulted from substantial geographic isolation.

Desiccation resistance was examined in pre-diapause, diapause and post-diapause larvae of the spruce budworm, Choristoneura fumiferana (Clemens), in terms of passive water evaporation under three desiccation conditions: freeze-drying, desiccant-drying at 2°C and desiccant-drying 18°C. Diapausing second instar larvae and post-diapause non-feeding second instar larvae showed strongest desiccation resistance: a significant amount of water was retained after repeated drying under desiccating conditions, while pre-diapause first instar larvae and post-diapause feeding instar larvae lost almost all their water content after one or two drying cycles. A hibernaculum covering had no effect on water evaporation. While dead larvae tended to lose significantly more water than their living counterparts, particularly among first instar larvae, such an impact much weaker among diapausing second instar larvae. Desiccation resistance was lost when post-diapause second instar larvae were allowed access to water while the level of desiccation resistance was maintained or enhanced when the larvae did not have access to water. These results are discussed the context of overwintering ecology of the species and possible mechanisms for the desiccation resistance are also discussed.

An attempt has been made to assemble the important factors concerned with the atomisation of a kerosene spray and to consider the behaviour of the spray alone, and in its relation with an insect flying through it.

The degree of atomisation attained by the spray gun is dependent upon nozzle design, the spraying pressure, the relative rate of liquid and air flow through the nozzle and such physical properties of the spray fluid as viscosity and surface tension.

All atomisers produce droplets of a variety of sizes which leave the gun with a considerable velocity and are carried along by the air current. At this stage they are at their maximum size and possess their maximum velocity so that the chance of impacting with an insect is great. Later on when the droplets have lost much of their velocity and volume (if they contained a non-volatile insecticide they will have become much more concentrated), they are much less likely to impact. It can thus be seen that a non-toxic carrier can increase apparent toxicity of a spray mist by assisting in the production of the momentum necessary for impaction (David and Bracey, 1944). On the other hand a reduction in the size of the droplet decreases the rate of loss from the air space by precipitation. In connection with evaporation the enormous change in concentration which occurs should be borne in mind. Within a few minutes the smallest droplets will have entirely evaporated, leaving only the non-volatile solute and before this stage is reached the droplet will have become super-saturated. Finally this non-volatile solute will exist as minute nuclei which, when they result from a fairly typical insecticidal formula containing up to say 5 per cent. nonvolatile material, may be so small as to settle only very slowly.

Regarding the response of the insect to the spray mist, it may be said that this depends upon the resistance of the insect and the dose of insecticide picked up. Since the spray mist takes some time to distribute evenly and since it is more easily picked up during or immediately after spraying and by insects in flight, it can be seen that the dose received by individual insects will vary a good deal unless the insects behave identically so that under these conditions there is little correlation between the comparative effect recorded on individuals and their relative innate resistance.

To the above remarks arising out of the theoretical discussion which formed the first part of this paper must be added the following conclusions from the experimental work.