In 1984–1985 insecticide-treated targets were deployed in the 600-km2 Rifa Triangle, Zambezi Valley, Zimbabwe. Trap catches of Glossina pallidipes Austen were modelled using a function combining logistic growth with diffusive movement. A simulation routine was linked to a non-linear least-squares optimization programme and fits optimized with respect to population carrying capacities, rates of growth and movement, and to levels of imposed mortality. In March–September 1984, the overall additional mortality was 2% per day of adult female G. pallidipes, increasing thereafter to 8% per day, due to the deployment of more targets, the onset of the hot, dry season and the ground-spraying of the adjoining Zambezi escarpment with DDT. For G. m. morsitans Westwood the corresponding estimates were 1 and 2% per day. For both species, the deployment of four targets km−2 in a closed population will ensure eradication. For G. m. morsitans a halving of target efficacy would reduce the killing rate to the point where eradication would be unlikely. Estimated daily displacements were c. 200 m for G. m. morsitans and 660 m for G. pallidipes. The lower rate for G. m. morsitans means that, while targets kill this species less effectively, re-invasion of cleared areas is slower. Targets do not markedly affect robust populations outside the deployment area. The Zambian tsetse population adjacent to the Rifa Triangle declined markedly during the experiment, however, suggesting that it is largely maintained by immigration. The methods developed here will be applied to data from other campaigns with the aim of improving the efficiency of tsetse control programmes.

Until 13th March I remained in the Proclaimed Area, then, as the weather condition were very bad, and as moreover the grass had so overgrown all the paths, which are little used, that my movements were very much hampered, I removed to Fort Johnston at the southern extremity of the Lake, and have since been working in its neighbourhood.

1. Methods for laboratory testing of contact insecticides are reviewed, and some of the disadvantages of these methods are discussed. Reasons are given for preferring an immersion to a spraying method, and the necessity for a supply of “ standardised ” insects is stressed.

2. An improved immersion method for laboratory testing of contact insecticides is described, and the rigid technique necessary is detailed.

3. The effect on the resistance of Ahasverus advena to a derris insecticide of varying the time of immersion, the age of the insects, the temperature and the humidity before, during, and after immersion is illustrated and shows the necessity of controlling all these factors.

4. Results with a standard derris insecticide are given to show the great accuracy that can be obtained by the new method ; that the same result with the same insecticide can be repeated from day to day; and that two workers using the same insecticide have obtained identical results.

5. The reaction to starvation is correlated with variations in age, temperature, and humidity, to show that the starvation death rate is a measure of the insects' powers of resistance to an insecticide.

6. Statistical analysis and discussion of methods of expressing mortality is reserved for a later communication.

Diuraphis noxia (Kurdjumov), Russian wheat aphid, is one of the world's most invasive and economically important agricultural pests of wheat and barley. In May 2016, it was found for the first time in Australia, with further sampling confirming it was widespread throughout south-eastern regions. Russian wheat aphid is not yet present in New Zealand. The impacts of this pest if it establishes in New Zealand, could result in serious control problems in wheat- and barley-growing regions. To evaluate whether D. noxia could establish populations in New Zealand we used the climate modelling software CLIMEX to locate where potential viable populations might occur. We re-parameterised the existing CLIMEX model by Hughes and Maywald (1990) by improving the model fit using currently known distribution records of D. noxia, and we also considered the role of irrigation into the potential spread of this invasive insect. The updated model now fits the current known distribution better than the previous Hughes and Maywald CLIMEX model, particularly in temperate and Mediterranean areas in Australia and Europe; and in more semi-arid areas in north-western China and Middle Eastern countries. Our model also highlights new climatically suitable areas for the establishment of D. noxia, not previously reported, including parts of France, the UK and New Zealand. Our results suggest that, when suitable host plants are present, Russian wheat aphid could establish in these regions. The new CLIMEX projections in the present study are useful tools to inform risk assessments and target surveillance and monitoring efforts for identifying susceptible areas to invasion by Russian wheat aphid.

Diet is a critical component of the mass-rearing of biological control agents, but the impacts of diet are not always immediately obvious and can take several generations to manifest, resulting in poor survival, reproduction, and ability to kill prey under natural conditions. Our present study aimed to investigate the performance of a commercially-reared phytoseiid mite, Amblyseius swirskii, after four (G4) and six (G6) consecutive generations on pollen grains of two plant species, as well as its ability to find and kill its natural prey, Tetranychus urticae, after long-term rearing on each diet. We found no significant difference between the two diets in intrinsic and finite rates in G4. However, both diet and generation exerted a significant influence on the fecundity of A. swirskii. By G6, females reared on almond pollen had greater net reproductive and intrinsic rate compared to those reared on maize pollen. Conversely, A. swirskii fed on maize pollen consumed fewer prey than those reared on other diets, especially at higher prey densities. The findings have important implications for developing the mass-rearing program of A. swirskii on non-prey diets. Further research must explore the suitability of almond pollen in the large-scale culture of A. swirskii.

Phorodon humuli (Schr.) was obtained from both wild and cultivated hop plants, cultured, and bioassayed using seven different foliar spray insecticides, and the results were assesssed by probit analysis to determine LC50s and LC95s. The wild aphids and their progeny were highly susceptible to the insecticides, whereas those from cultivated hops were generally resistant to them. The level of resistance was related to the source of the original aphid population and the insecticide used. Clones of insecticide-resistant and susceptible aphids were maintained under identical conditions, and individual adult apterae were assayed for total esterase and esterase isoenzyme activities. Total esterase activity was appreciably higher in resistant aphids than in susceptible ones. Resistant aphids were associated with high esterase isoenzyme activity of complex bands II–V, while in susceptible aphids these bands were virtually missing. An insecticide-resistant clone of P. humuli was selected for low esterase activity and a susceptible clone was selected for high esterase activity, over eight generations. Selection pressure was then reversed for a further eight generations. The resistant clone lost its esterase activity by generation six and it remained low thereafter, whereas that of the control stock remained high. By contrast, the esterase activity of the susceptible clone remained unaltered by selection. The resistant clone also lost its resistance to both methomyl and methidathion.

We report the occurrence of Lysiphlebus orientalis in Serbia, an aphid parasitoid from the Far East that is new to Europe and has the potential to become invasive. Our finding based on morphological characters is confirmed by analyses of mitochondrial cytochrome oxidase subunit I sequences. An increase in number and an expansion of the host range were observed during field studies over the past two years, and it is determined that the current host range encompasses nine aphid hosts on 12 different host plants, forming 13 tri-trophic associations. A host range determined for European populations of L. orientalis appears wider compared with that in its Far Eastern native habitats where Aphis glycines Mats. is the sole known host. Moreover, it overlaps considerably with the host ranges of European parasitoids that play an important role in the natural control of pest aphids.

The tobacco cutworm Spodoptera litura (Lepidoptera: Noctuidae) is a polyphagous pest with a highly selective and sensitive chemosensory system involved in complex physiological behaviors such as searching for food sources, feeding, courtship, and oviposition. However, effective management strategies for controlling the insect pest populations under threshold levels are lacking. Therefore, there is an urgent need to formulate eco-friendly pest control strategies based on the disruption of the insect chemosensory system. In this study, we identified 158 putative chemosensory genes based on transcriptomic and genomic data for S. litura, including 45 odorant-binding proteins (OBPs, nine were new), 23 chemosensory proteins (CSPs), 60 odorant receptors (ORs, three were new), and 30 gustatory receptors (GRs, three were new), a number higher than those reported by previous transcriptome studies. Subsequently, we constructed phylogenetic trees based on these genes in moths and analyzed the dynamic expression of various genes in head capsules across larval instars using quantitative real-time polymerase chain reaction. Nine genes–SlitOBP8, SlitOBP9, SlitOBP25, SlitCSP1, SlitCSP7, SlitCSP18, SlitOR34, SlitGR240, and SlitGR242–were highly expressed in the heads of 3- to 5-day-old S. litura larvae. The genes differentially expressed in olfactory organs during larval development might play crucial roles in the chemosensory system of S. litura larvae. Our findings substantially expand the gene inventory for S. litura and present potential target genes for further studies on larval feeding in S. litura.

The effect of increasing mating delay on the reproductive performance and population growth rates of the vine mealybug, Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae), was investigated under laboratory conditions. Virgin females were mated at 1, 3, 5, 7, 14, 21 and 28 days after emergence and reproductive and life table parameters were estimated. The pre-oviposition period (number of days between mating and the onset of oviposition) significantly decreased in females mated within 7 days, whereas females mated at older ages showed equivalent pre-oviposition periods (<4 days). The length of the oviposition period did not vary with increasing age at mating. Female longevity significantly increased in females mated at 21 and 28 days, as a consequence of a longer pre-reproductive period. Fecundity and sex ratio were not affected by the female age at mating, whereas fertility was higher in mealybugs mated at older ages. Additional field observations highlighted that young and old virgin females were equally able to attract males, as both mated on the same day as the field release. Mating delay also affected the life table parameters of P. ficus, as the intrinsic and finite rates of increase did not differ in mealybugs mated within 7 days and significantly decreased in females mated at older ages. The mean generation time and the population doubling time were overall similar in females mated at 1–7 days, and increased significantly in females that experienced longer mating delays. In terms of the mating disruption control of P. ficus, our findings indicate that this method would be effective if mating is delayed >7 days, as shorter delays in mating did not reduce the population growth rates.

We, herein, report evidence that wing fanning by the aphid parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae) constitutes a courtship song. Complete removal of the forewings or only the distal half of them reduced male copulation success in comparison to intact males. Males that achieved copulation within the observation period produced wing fanning at a higher rate than males that did not copulate. Playback of wing fanning sound altered the behaviour of virgin females, increasing the time they devoted to grooming, as compared with subjects that were exposed to silence or white noise. Our findings contribute to the understanding of the acoustic dimension of the sensory modalities employed by this aphid parasitoid in sexual signalling.

Invasive plants have been shown to negatively affect the diversity of plant communities. However, little is known about the effect of invasive plants on the diversity at other trophic levels. In this study, we examine the per capita effects of two invasive plants, purple loosestrife (Lythrum salicaria) and reed canary grass (Phalaris arundinacea), on moth diversity in wetland communities at 20 sites in the Pacific Northwest, USA. Prior studies document that increasing abundance of these two plant species decreases the diversity of plant communities. We predicted that this reduction in plant diversity would result in reduced herbivore diversity. Four measurements were used to quantify diversity: species richness (S), community evenness (J), Brillouin's index (H) and Simpson's index (D). We identified 162 plant species and 156 moth species across the 20 wetland sites. The number of moth species was positively correlated with the number of plant species. In addition, invasive plant abundance was negatively correlated with species richness of the moth community (linear relationship), and the effect was similar for both invasive plant species. However, no relationship was found between invasive plant abundance and the three other measures of moth diversity (J, H, D) which included moth abundance in their calculation. We conclude that species richness within, and among, trophic levels is adversely affected by these two invasive wetland plant species.

The life cycle of Strobilomyia anthracina (Czerny) which exploits Norway spruce seed cones was investigated in 1992 and 1993 in the Alps at c. 1800 m at Torgnon (Valle d'Aosta, Italy) and Lac de Tseuzier (Valais, Switzerland) by sampling cones at fortnightly intervals. Oviposition occurred primarily singly in the basal third of cones at the beginning of June when cone scales were open for pollination. Infestation rates were higher when cone crops were poor. Most larvae left the cones in August to pupate in the litter beneath trees, usually at a depth of 1–4 cm. Prolonged diapause of pupae coincided with failed or poor cone crops. Parasitism was investigated at these two and 27 additional sites in the Swiss, French and Italian Alps. Among several hundred host eggs only one was parasitized by Trichogramma sp. (Trichogrammatidae). Among the larval-pupal endoparasitoids, the figitid Sarothrus areolatus Hartig was more common than an ichneumonid, Atractodes sp., but parasitism by both was commonly below 10%. Parasitism by an ichneumonid larval ectoparasitoid, Scambus sp., also rarely exceeded 10%. Puparia of S. anthracina that were buried in the litter to detect pupal parasitoids revealed the gregarious pteromalid Tritneptis sp. near lophyrorum (Rushka). This is the first record of a pupal parasitoid of Strobilomyia species. Information on the biology of the three larval parasitoids is presented. The potential for biological control of North American Strobilomyia neanthracina Michelsen and S. appalachensis Michelsen by importation of natural enemies of S. anthracina appears limited.

In Southern Rhodesia conditions are better than in most other parts of Africa for gathering information concerning the distribution of tsetse in the past, and perhaps even in the present. This is due to a combination of two factors, namely, that only one species of tsetse, Glossina morsitans, is found within our borders, and that the territory, in comparison with the Central African States, contains and has contained a relatively large European population. The first factor eliminates the possibility of confusion of species in connexion with the evidence forthcoming, at least in the case of those able to distinguish tsetse from other species of bloodsucking flies, whilst the second provides a more reliable source of information than the native.

Carabid beetles are important predators in agricultural landscapes feeding on a range of prey items. However, their role as predators of the olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), one of the most serious pests of olives, is unknown. In this context, the feeding preferences and the functional responses of two carabid beetle species, Calathus granatensis (Vuillefroy) and Pterostichus globosus (Fabricius), were studied under laboratory conditions. Feeding preference assays involved exposing carabid beetles to different ratios of B. oleae pupae and an alternative prey, the Mediterranean fruit fly, Ceratitis capitata (Wiedemann). Both species fed on B. oleae pupae however, C. granatensis always showed a significant preference for that prey whereas P. globosus switched to C. capitata pupae when the offered ratio was below 0.5. The total prey biomass consumed was significantly higher for P. globosus than for C. granatensis. Functional response curves were estimated based on different densities of B. oleae pupae and both carabid beetle species exhibited a type II functional response using Rogers’ random-predator equation. P. globosus showed shorter handling time (1.223 ± 0.118 h) on B. oleae pupae than C. granatensis (3.230 ± 0.627 h). Our results suggest that both species can be important in reducing the densities of B. oleae in olive groves, although P. globosus was more efficient than C. granatensis.

A number of observations were made on parasites of certain Pentatomoids (sunn pest) attacking wheat in Middle East countries, during the course of other work on these pests. The principal host species studied were Eurygaster integriceps Put., E. maura (L.) and Aelia rostrata Boh. The data concern both Dipterous (Tachinid) endoparasites of the adult bugs, and also Hymenopterous (Scelionid) egg-parasites; the observations were made principally in central Turkey, and in the Varamine district of Iran. A few observations on predators were made also.

The data concerning Tachinids consist of host records for six species of parasites. In no case observed by the author did these parasites appear to be of great importance in reducing the numbers of sunn pest; the same is true of the few instances of predators recorded.

Observations were made on six species of Scelionid egg-parasites (five species of Asolcus and one of Hadronotus), five of which were bred from eggs of four species of Pentatomoid hosts collected in the field. The species concerning which the most comprehensive data were obtained were Asolcus rufiventris (Mayr), A. semistriatus (Nees) and A. vassilievi (Mayr). Egg-parasites are well known to be more efficacious in reducing sunn-pest populations, and A. semistriatus has been extensively used in Iran as a biological control agent. The data obtained enabled some ideas which are of importance for the use of egg-parasites in biological control to be formed and discussed. These concern principally (a) the susceptibilities of different hosts to parasitisation; (b) host selection by parasites; (c) the selection of a species of parasite most suitable for biological control in a particular area.

1. A selected stock bred on middlings and not diapausing at 25°C. was used in these experiments. None of the larvae reared on Manitoba wheat diapaused at 25°C., 70 per cent. R.H.; some diapaused at 21°C. and 17°C., 70 per cent. R.H. At these lower temperatures development was slower, more food by weight was eaten, and the moths were heavier.

2. More larval substance by weight was needed to produce a male than a female adult.

3. It was possible to subdivide natural foods into 3 groups: (i) Those on which no larvae diapaused at 25°C., 70 per cent. R.H. (ii) Foods on which a fairly low percentage of larvae diapaused at 25°C. 70 per cent. R.H. (iii) Foods on which most, or all of the larvae diapaused at 25°C., 70 per cent. R.H.; these foods were all characterised by a high content of starch. The possible cause is discussed.

4. Larvae moult 4 or 5 times on Manitoba wheat at 25°C. 70 per cent. R.H. Most of the larvae developing on this food under warehouse conditions could be allocated to 6 instars. At 25°C., 35·5 per cent. R.H. the number of larval instars is increased— one larva died in 12th instar.

5. The growth curves, obtained by measuring head capsules of successive instars roughly follow Dyar's law, although the ratio of increase falls off in the last 2 instars.

6. The prepupal stage in E. elutella can be subdivided into five stages, on the basis of withdrawal of ocellar pigment, described in E. kühniella by Kühn and Piepho. Only those prepupae which have reached stages four and five attempt to pupate after the head is ligatured, the other stages remain as “permanent larvae”.

Pheromone-binding proteins (PBPs) are believed to be involved in the recognition of semiochemicals. In the present study, western blot analysis, fluorescence-binding characteristics and immunolocalization of CmedPBP4 from the rice leaffolder, Cnaphalocrocis medinalis, were investigated. Western blot analysis revealed that CmedPBP4 showed obvious antenna-specific expression patterns in female and male antenna, and made a clearly different sex-biased expression. Immunocytochemical labeling revealed that CmedPBP4 showed specific expression in the trichoid sensilla. Competitive fluorescence binding assays indicated that CmedPBP4 could selectively recognize three sex pheromone components (Z13-18:Ac, Z11-16:Al and Z13-18:OH) and eleven rice plant volatiles, including cyclohexanol, nerolidol, cedrol, dodecanal, ionone, (−)-α-cedrene, (Z)-farnesene, β-myrcene, R-(+)-limonene, (−)-limonene, and (+)-3-carene. Meanwhile the CmedPBP4 detection of sex pheromones and host odorants was pH-dependent. Our results, for the first time, provide further evidence that trichoid sensilla might be play an important role in detecting sex pheromones and host plant volatiles in the C. medinalis moth. Our systematic studies provided further detailed evidence for the function of trichoid sensilla in insect semiochemical perception.

Experiments were designed to determine the criteria by which an ovipositing female of Spalangia drosophilae Ashm. is attracted to an environment where suitable hosts may be found, and by which these hosts are selected.

The results obtained indicate that ovipositing female Spalangia are attracted to and maintained in areas where suitable host puparia may occur by their reaction to sensory impressions. Thus females tend to be attracted to dampness and to soil level where, in grasses, host material is likely to be found. In such an area searching for hosts appears to be at random, but once an object that is a possible host is located there follows a careful examination and, if the object is “ considered ” a suitable host, oviposition follows. It appears that there are several definite criteria by which an object is accepted as a host suitable for oviposition. In general the hosts selected by the parasite are those which are suitable for the development of her progeny.

Various instances of the formation of a chitinous capsule around parasites in mosquitos have been described in literature. Worms as well as Protozoa, Hyphomycetes and bacilli have been seen encapsuled in this way.

Quantitative measurements of the sorption of γ BHC and dieldrin in Uganda mud blocks have been made. Gamma BHC diffused more rapidly than dieldrin, and within a few weeks had achieved an almost uniform concentration throughout the sprayed blocks. Only when the uniform concentration had been reached did loss by evaporation from the blocks become marked. Increased dosages of γ BHC gave increases in biological activity which were roughly proportional to the dosages used. Sorption on to mud greatly prolonged the residual life of γ BHC as compared with similar deposits on glass.

Dieldrin behaved in the same way as γ BHC although because of its slower rate of diffusion the distribution in the blocks had only reached in 48 weeks the stage reached by γ BHC in eight weeks. There was no appreciable loss of dieldrin during this time, whereas about 90 per cent. of the deposit on glass plates had been lost.

Gamma BHC, dieldrin and DDT were recovered from the adsorbed state on mud and identified. Any decomposition is therefore likely to be negligible. Dieldrin was also recovered from two soils which had much higher “surface acidities” than the standard.

Active mud can only sorb the portion of insecticide vapour from an evaporating deposit which happens to diffuse in its direction. This is to be expected, but the system has some peculiarities because the evaporation of γ BHC from filter papers over mud blocks is much faster than in the absence of the mud.

Measurements of the distribution of DDT and dieldrin in soils less active than the standard Uganda one showed that both the initial adsorption and subsequent diffusion were very much slower.

The activity of Uganda soil was not reduced by removal of material soluble in organic solvents, and was only partly reduced by complete extraction of iron compounds.

Variation in temperature over the range 20 to 30°C. had only small effects on the diffusion of DDT and dieldrin within mud blocks.

Repeated applications of DDT and dieldrin to the same blocks did not result in any observable slowing in the rate of disappearance. The concentration of insecticide in the successive layers of mud, did, of course, increase with successive sprayings.