Anopheles subpictus Grassi in Sri Lanka is under selection pressure from both agricultural and public health insecticides. Agricultural selection pressure has produced larval specific carbamate resistance which appears to be correlated with high esterase activity. High esterase activity was found in both larvae and adults, but one of the larval elevated bands was not present in the adult, and two other adult bands were not found in the larvae. Broad spectrum organophosphate resistance was found in both the larvae and the adults and was associated with an increase in mixed-function oxidase activity. There was no evidence of an altered AChE mechanism in this population.

Augmentative biological control is not commonly used in commercial orchards. We used an exclusion system to evaluate the potential of early-season releases of the European earwig (Forficula auricularia L., Dermaptera: Forficulidae) for control of the rosy apple aphid (Dysaphis plantaginea Passerini, Hemiptera: Aphididae) in the spring of 2009 in two pesticide-free apple orchards. In order to conduct this experiment we successfully reared earwigs with a high survival rate of nymphs (more than 96%) which may have commercial application. There were three treatments in the study: (i) a ‘release treatment’ where we confined the released earwigs in the canopy by using a barrier system; (ii) an ‘exclusion treatment’ where we blocked free access of earwigs into the canopy using the same barrier system; and (iii) a ‘control treatment’ that represented the natural situation. Contrary to expectations, earwig releases did not reduce D. plantaginea populations. In general, the abundance of natural enemies and their groups did not differ significantly among treatments, except for earwigs. We observed that the exclusion systems we used successfully kept both earwigs and ants away from tree canopies; total numbers on trees in the ‘exclusion treatment’ were significantly lower than on the other two treatments. Due to the complexity and difficulty of evaluating augmentative releases of natural enemies in open orchard conditions, we conclude that new technical approaches to control site conditions are needed when conducting such studies.

In the field in eastern Australia, adult females of Chortoicetes terminifera (Wlk.) underwent stages of body growth, fat accumulation and then egg maturation. Rainfall, and the resulting condition of the feed, determined the speed of development through the stages. If feed was dry, development was slow and stages could be suppressed; but even with feed that was only ‘dry-green’ locusts grew normally, accumulated fat, and then matured eggs after migration. If lush green pasture occurred following rain on the adults, they persisted and soon began to mature eggs. Thus females oviposit in the area where they hatched only if pastures there are lush green, thus ensuring some food for their offspring.

Spodoptera littoralis (Boisd) is globally recognized as a destructive polyphagous insect pest of various crops in the world. It is commonly managed by chemical pesticides, which can cause deleterious effects such as environmental pollution, toxicity to non-target organisms and the emergence of secondary pests. Hence, investigations into alternative pest control strategies such as the use of resistant host plant cultivar against S. littoralis is important. This study aimed to explore the nutritional performance of S. littoralis larvae in dependence on total anthocyanin, flavonoid, and phenol levels across 11 bean cultivars (Phaseolus and Vigna spp.) under laboratory conditions. The results revealed that the Mashhad cultivar accumulated the highest amount of total phenols (13.59 mg ml−1), whereas Yaghout and Arabi cultivars posed the lowest total phenols contents (1.80 and 1.90 mg ml−1, respectively). Across larval instars (third to sixth), the highest consumption index and relative consumption rate were recorded on the Mashhad cultivar. The lowest values of efficiency of conversion of ingested food and the efficiency of conversion of digested food of total larval instars were detected in the larvae which were reared on the Mashhad cultivar. Likewise, the lowest value of the index of plant quality (IPQ) was obtained in the Mashhad cultivar; however, IPQ was figured out at the highest level in the Arabi cultivar. Our findings show that the differential accumulation of secondary metabolites would change the nutritional quality of plants for S. littoralis. Based on the findings, the Mashhad cultivar may serve as a candidate for either integrated pest management or breeding programs aiming at controlling this pest.

Since 1956, samples of Lucilia cuprina (Wied.) from many parts of New South Wales have been tested annually for signs of resistance to organophosphours insecticides, which are used there to prevent fly-strike in sheep. For tests, 0.1 μg. diazinon per fly was applied topically; this discriminating dose was twice that required to kill 100 per cent. of susceptible flies. In 1965, some of the flies in a sample from Dubbo, in central-western N.S.W., survived the discriminating dose. Sensitivity tests of the progeny of the survivors (DB strain) and of a normal susceptible strain revealed that the LC50 of the DB strain was about three times that of the normal one. Further tests established that a roughly similar change in sensitivity had ocurred to other diethoxy (dichlofenthion, fenthion-ethyl, bromophos-ethyl, parathion) and to dimethoxy (fenchlorphos, parathion-menthyl, bromophos) organophosphors compounds. The change was therefore non-specific and, since it was also small, is regarded as an example of tolerance rather than of resistance.

Subsequent field surveys in 1965–66 showed that tolerance of L. cuprina to diazinon was widespread in N.S.W. The possibility that resistant strains will be selected out by continued use of organophosphorus insecticides is discussed.

Female Aphidius rhopalosiphi De Stefani Perez reared on Rhopalosiphum padi (Linnaeus) made equal numbers of encounters with another suitable host aphid (Sitobion avenae (Fabricius (both Homoptera: Aphididae))) in arenas where the aphids were on either pieces of wheat leaf or moist filter paper. However, the number of oviposition stabs made in arenas with wheat was far higher than with filter paper, demonstrating the importance of host-plant cues in the acceptance of the aphids by the parasitoid. Diet reared aphids (even if subsequently fed on wheat) appeared to be accepted more readily than totally wheat reared individuals. In another arena experiment, there were more encounters with and more stabs made into both S. avenae and a non-host aphid (Myzus persicae (Sulzer)) on wheat than on Brussels sprouts (a host plant of M. persicae), again showing the over-riding importance of host-plant cues.

Breeding structure of Glossina morsitans submorsitans Newstead was evaluated by using genetic markers in mitochondrial DNA where diversity was scored at two loci in five natural populations from The Gambia and two populations in Ethiopia (form ugandensis Vanderplank), countries separated by c. 5450 km. Twenty six haplotype combinations were found, of which 17 were shared among two or more populations. Nine haplotypes were found in The Gambia and 23 haplotypes in Ethiopia. There were 12 unique haplotypes. Only six haplotypes were shared between the two countries. Populations in The Gambia (he = 0.26 ± 0.04) showed less than a third of the diversity of populations in Ethiopia (he= 0.84 ± 0.03). This suggests recovery from an earlier reduction in population. In a nested analysis of molecular variance of haplotype frequencies, 65%of the variance was due to differences within populations, 34% to differences between populations grouped by country, and only 1% was due to differences among populations within countries. In terms of gene flow, the fixation index FST= 0.35, which leads to an estimate by Wright’s island model of less than one reproducing migrant per generation exchanged between the eastern and western submorsitanspopulations. Nei’s genetic similarity measure showed a deep division between Gambian and Ethiopian populations.

Photoperiod was shown to be the principal factor regulating the induction of a facultative egg-diapause in Chortoicetes terminifera(Wlk.). All developmental stages from first-instar nymphs to immature adults were sensitive to photoperiod. At constant photophases, the insect exhibited a short-day—long-day response, with the upper and lower critical photo-periods for induction approximating to LD 15·5: 8·5 and 11:13, respectively. These correspond to the range of photoperiods experienced by the insect under natural conditions. The maximum inductive response occurred at about the mid-point of this range, i.e. LD 13·5: 10·5. In experiments in which insects experienced a change in photophase at the end of the nymphal stage, the incidence of diapause varied with the direction of change (long to short or short to long) and indicated that diapause induction was prevented by an increase in photophase but enhanced when the photophase was reduced. The size of the inductive response associated with a decrease in photophase appeared to depend less on the size of the decrease than on its position within the inductive range, such that the maximum effects were observed when the sequence of light regimes were close to or spanned the most inductive constant photophase. Temperature was also important in determining the induction of diapause. In the upper portion of the inductive range (15·5 to 12·5 h light), insects subjected to high temperatures or to an increase in temperature during development showed a lower incidence of diapause than those subjected to low temperatures or to a decrease in temperature. In the lower portion of the inductive range, the effects of temperature were reversed, with high temperature or an increase in temperature being more inductive than low temperature or a decrease in temperature.

The effects of wind speed, wind direction, strong moonlight and rainfall on hourly light-trap catches of adult Spodoptera exempta (Wlk.) made at Muguga, Kenya, between January and June in 1970 and 1971 were investigated. The highest catches occurred in winds of 2–3 m/s, but generally, fewer moths were caught as wind speed increased. In totally dark hours the geometric mean catch at wind speeds of 5–6 m/s was about one-tenth that at 0–1 m/s. The relationship between catch and wind speed changed between January and June. Wind direction and change in direction were not significantly related to catch. The geometric means of catches made in strong moonlight were about one-tenth those in total darkness at comparable wind speeds. Rainfall was associated with higher catches in seven out of eight months, but the differences were significant in only two months. Recognition of the association between light winds and large numbers of S. exempta should assist forecasting, but a fuller understanding of the relationship between light-trap catch and population requires a method of population assessment that is independent of the effects of weather and moonlight.

The Encyrtidae reported upon in this paper are mostly Coccid-inhabiting species, received by the Imperial Institute of Entomology from various collectors in Africa and forwarded by Dr. C. Ferrière for identification. The species of Microterys, Metaphycus, and Anicetus will be reported upon in separate papers at a later date, All holotypes and allotypes are deposited in the British Museum; paratypes will be deposited in the United States National Museum.

The sandflies of Cyprus have been examined. The following ten species were found: P. papatasii, P. perniciosus var. tobbi, P. chinensis (a local race), P. perfiliewi (rare), P. sergenti, P. alexandri, P. larroussei (rare), P. fallax cypriotica, var. n., P. azizi, sp. n., and P. parroti.

Melanic forms of P. parroti were found. Melanism was associated with a reduction in the teeth of the pharynx in the female in the few specimens collected.

The race of P. chinensis found on the island differs from those hitherto described.

The general composition of the sandfly population of Cyprus is different from that of any other part of the Mediterranean examined.

P. major which is common in Palestine, Syria and the Balkans was not found.

Canine kala-azar is common on the island. P. perniciosus var. tobbi and a race of P. chinensis should be considered as possible carriers but this point must be determined experimentally.

Of the various methods for the eradication of G. palpalis that have been tried in Kenya, hand-catching has the most limited application.

Total and discriminative bush-clearings of the river banks have been used on a considerable scale and progress on the Yala, Magori, and Nyando rivers is reviewed. The decrease in fly-populations caused by these clearings is gradual, but complete eradication may be achieved. Maintenance of the clearings is however difficult, the initial cost varied from £200 to £300 per mile and labour was often difficult to obtain in sufficient numbers.

The use of 5 per cent. DDT sprays on the fringing vegetation along 20 miles of the Mbogo river gave dramatic results and G. palpalis was eradicated at a cost of £42 per mile. The rate of application was 15 to 20 lbs. of DDT per acre and the residual effect lasted for at least 14 days during dry weather, but was rapidly lost during the rains.

Spraying along the Ainamotua gave equally promising results.

Areas under treatment, either by hand-catching, bush-clearing or spraying with DDT, must be properly isolated from other tsetse-infested areas if quick results are to be achieved.

(1) Previous records of natural enemies of the cacao thrips, Selenothrips rubrocinctus, Giard, are reviewed.

(2) An account is given of the following natural enemies in Trinidad, B.W.I. :—Dasyscapus parvipennis, Franklinothrips tenuicornis, F. vespiformis, Chrysopids, Ninyas torvus, Termatophylidea maculata and Wasmannia auropunctata.

(3) The Eulophid parasite, Dasyscapus parvipennis, was introduced into the West Indies from the Gold Coast in 1935. It is now successfully established in Trinidad, Puerto Rico and Jamaica, but has so far given no indication of economic control of the cacao thrips.

(4) The importance of natural enemies is discussed. Observations are made on the feeding propensities of some of the predators in the laboratory. Chrysopids are regarded as the most important predators and probably exercise some measure of control.

(5) Population counts of the cacao thrips and Chrysopid and Franklinothrips larvae are given.

Adults of the dung fly Neomyia cornicina (Fabricius) (Diptera: Muscidae) were allowed to feed on cattle dung containing known quantities of ivermectin for a single period of 24 hours. The concentrations required to kill 50% and 95% of the population, within one week of feeding, were calculated to be 0.139 and 0.393 μg/g (wet weight), respectively. Ingested ivermectin was found to reduce significantly the proportion of females ovipositing and delay significantly the onset of first oviposition. For those females which did oviposit, there was no effect of ivermectin ingestion on the number of eggs laid, but the eggs of females fed dung containing ivermectin at 0.15 μg/g showed a significant reduction in percentage egg hatch.

Crops transformed to express Bacillus thuringiensis (Bt) toxins can cause close to 100% mortality of certain target pest species. This study assessed the effect of target pest reduction on the predatory insect Chrysoperla carnea (Stephens) in the presence of alternative prey. Numbers of lacewings recovered from Bt oilseed rape (cultivar Oscar, event O52) did not differ significantly from numbers of lacewings recovered from conventional oilseed rape in cage experiments with the target pest Plutella xylostella (Linnaeus) and the non-target pest Myzus persicae (Sulzer) when aphid densities were high. However, significantly fewer lacewings were recovered from Bt plants as aphid densities were lowered. Lacewing weights were not affected by plant type.

1. Ecological studies on aphides attacking potatoes were commenced in 1928 with a view to elucidating certain problems of entomological interest and also the role of these insects as vectors of disease. The species include, Myzus persicae, Sulz., Macrosiphum gei, Koch, and Myzus pseudosolani, Theo.

2. The present study is confined mainly to the infestation of aphides on potatoes at a selected centre which is described.

3. Solitary apterous viviparous females were in a majority on potatoes during the period of initial infestation in early June. Their presence is explained by (1) the overwintering of aphides on weeds and field plants, (2) the first few alatae depositing single nymphs and then migrating, (3) infection from infested seed.

4. The maximum infestation was reached during mid-July, when 86 per cent. of the leaves were infested and there was an average of 2·8 aphides to a leaf. The infestation was below that of the previous three years. Macrosiphum gei bred up rapidly, at first on the flower-heads, and was the predominant species, its decline in numbers being equally rapid. Myzus persicae increased more slowly and did not reach such numbers, but the maximum was maintained longer and the disappearance of the species was delayed. Myzus pseudosolani was only taken in August and then in small numbers.

5. An estimate of the intensity of the aphis population is attempted, and in the present moderate infestation of 2·8 aphides to a leaf it was of the order of 2,000,000 aphides to an acre of potatoes.

6. A technique was established to ascertain the movement of aphides within the crop. Weekly records on observational leaves revealed that 100 per cent. of the aphides moved their site and at least 84 per cent. of each species moved from leaf to leaf within the weekly period. Daily records during the period of maximum infestation showed that 84 per cent. of Macrosiphum gei and 73 per cent. of Myzus persicae changed site within 24 hours, and of these at least 50 per cent. moved from the leaves upon which they had been observed.

7. It was noted that no attempt was made to maintain large local colonies, for the movement of both adults and nymphs was frequent, and observed colonies soon dispersed. The extended infestation of Myzus persicae is discussed with reference to its establishment on field plants, other than potatoes, during the autumn and winter.

The short- and long-term consequences of monogamy and promiscuity in an aphidophagous ladybird, Propylea dissecta (Mulsant) in terms of reproductive performance and offspring fitness were investigated. Promiscuous females were more fecund and laid more viable eggs than monogamous ones. Amongst promiscuous females, those mated with multiple males (freedom for mate choice) had significantly higher reproductive output than those mated daily with a new unmated male. The increased reproductive output of females mated with an unmated male each day in comparison to monogamous ones might possibly be a result of their increased ejaculate size. The further increase in reproductive output, when a female was allowed to choose a mate, may be because of repeated preferential mating with the fitter males. Results on long-term consequences of promiscuity revealed faster development and increased survival in offspring of promiscuous females at 25, 27 and 30%C. The percent adult emergence was more strongly influenced than development by the mating regime. There were no statistically significant differences in survival of offspring of promiscuous females (mate choice) at the three temperatures, while the percent survival of offspring of monogamous females differed significantly. Offspring of promiscuous females (mate choice) were fittest in terms of development and survival, which indicates their probable better genetic constitution and subsequently that of chosen mates. Thus, promiscuity has both short- and long-term benefits and is advantageous to ladybirds. The presence of long-term benefits in terms of fitter offspring probably indicates the evolutionary rationale behind the prevalence of promiscuity in ladybirds.

Evidence from observing resistance in decline in fourth instar larvae of the multiple resistant MUHEZA strain of Culex quinquefasciatus Say from Tanzania (MUHEZA), showed that the major mechanisms for chlorpyrifos and propoxur resistance were different. Resistance to chlorpyrifos declined more than 400-fold (from an initial resistance ratio (RR) of 14285) while resistance to propoxur remained stable for at least 30 generations of laboratory culture. Significant synergism was found between propoxur and piperonyl butoxide (PB), propoxur and s,s,s-tributyl trithiophosphate (DEF), and permethrin and PB, but antagonism occurred between chlorpyrifos and PB, and no synergism between chlorpyrifos and DEF. Nine esterase isozymes active against naphthyl acetates on polyacrylamide gel electrophoresis (PAGE), were identified, four (A2, A3, B2, B3) showing polymorphism in activity, with very intense expression at one or other position in more than 32% of larvae, and null expression in less than 30%. The frequency of intense bands and of nulls both declined as resistance declined. A selected substrain (MUHEZA-fb), breeding true for A2, A3, B2 and B3 at the standard level of activity, showed almost stable chlorpyrifos resistance (RR=1428–1785) for approximately 35 generations. In mass larval assays of in vitro sensitivity of acetylcholinesterase (AChE) to propoxur, the I50 in MUHEZA was 950-fold greater than in a reverted resistant strain (RANGOON). Single larval assays indicated an AChE resistance allele (AceR) at frequency 0.43. PAGE of AChE revealed nine isozymes in MUHEZA and five in RANGOON, three of which were in common. It is concluded that propoxur resistance was due principally to AceR with a minor influence from oxidases and non-specific esterases, while chlorpyrifos resistance was due to an interaction between AceR and non-specific esterases, the latter exerting the dominant effect.

A laboratory study was carried out to assess the potential prey-mediated effects of Cry3Bb1-expressing Bt maize on the fitness and predatory ability of Atheta coriaria Kraatz (Coleoptera: Staphylinidae), using Tetranychus urticae Koch (Acari: Tetranychidae) as prey. The concentration of Cry3Bb1 toxin through the trophic chain significantly decreased from Bt maize (21.7 μg g−1 FW) to mites (5.6 μg g−1 FW) and then to A. coriaria adults (1.4 μg g−1 FW), but not from mites to A. coriaria L1–L3 larvae (4.1–4.6 μg g−1 FW). Interestingly, the toxin levels detected in A. coriaria larvae represent more than 20% of the concentration found in Bt maize, and the toxin was detected up to 48 h after exposure. To our knowledge, this is the highest level of exposure ever reported in a predatory beetle to the Cry3Bb1 protein. When A. coriaria larvae were reared on Bt-fed mites, Bt-free mites or rearing food, no significant differences among treatments were observed in development, morphological measurements of sclerotized structures and body weight. Moreover, no negative effects on reproductive parameters were reported in adults feeding on Bt-fed prey after 30 days of treatment, and survival was not affected after 60 days of exposure. Similarly, predatory ability and prey consumption of A. coriaria larvae and adults were not affected by exposure to the toxin. All together, these results indicate a lack of adverse effects on A. coriaria, a species commonly used as a biological control agent. The use of A. coriaria as a surrogate species for risk assessment of GM crops that express insecticidal proteins is discussed.

The root-feeding flea beetle Longitarsus bethae Savini & Escalona, was introduced into South Africa as a candidate biological control agent for the noxious and invasive weed, Lantana camara L. As part of the study to predict the beetles' survival in its new range, the influence of climatic conditions on its egg development and reproductive performance were investigated in the laboratory. The threshold temperature (T°) and degree-days (DD) required for egg hatch were determined after exposing the eggs to various constant temperatures (12, 17, 22, 27 and 32°C) in separate growth chambers. The DD required for egg hatch was 178.6, and the temperature threshold required for egg hatch was 11.3°C. Survival of eggs varied from 27 to 56% at 32 and 17°C, respectively, and was optimum between 17 and 25°C. Oviposition was examined under high and low relative humidity (RH) regimes while egg hatch was determined at six RH levels, each maintained in a separate controlled growth chamber set at a constant temperature (25°C). Whilst RH had no influence on oviposition, eggs were highly susceptible to aridity, and continuous exposure to relative humidity below 63% for more than three days was wholly lethal at 25°C. Optimum egg hatch occurred at RH between 85 and 95% for up to 12 days. The effect of day length on oviposition and subsequent egg hatch was investigated under two photoperiod regimes. Neither oviposition nor subsequent egg hatch was influenced by photoperiod. The knowledge obtained will be useful for mass rearing as well as field release programmes for L. bethae.