The four commonest species of Sitona injuring leguminous crops in Israel were found during a survey in 1957–62 to be S. lividipes Fhs., S. hispidulus (F.), S. crinitus (Hbst.) and S. lineatus (L.). Adults of all four were collected in the field in December-January each year, at the termination of diapause, and kept in the laboratory for observations on their bionomics. Larvae and pupae did not survive in the laboratory, and therefore these stages were reared in the soil outside (where suitable food-plants had been grown) from eggs laid by the adults in the laboratory and kept at known temperatures until they were about to hatch. The soil was later examined daily for pupae.

Egg-laying began in December, larvae were found in January–March, pupae in March–April, and adults of the new generation in April–May. These adults fed freely but did not oviposit, and in June–July they sought shelter and entered diapause, which lasted until the close of the year. Feeding was then resumed, oviposition began shortly afterwards, and death occurred up to 250–300 days later.

The eggs of all four species are creamy or yellowish white when laid but soon become glistening black. High humidity was necessary for hatching; no eggs of S. lividipes or S. hispidulus hatched at relative humidities of 76 per cent., or less, and virtually none of S. crinitus or S. lineatus at 56 per cent, or less. In favourable humidities, the percentage hatching was reduced at constant temperatures exceeding 25°C., except in S. lineatus, in which it was not affected up to 29°C. The threshold temperatures for development of eggs of S. lividipes, S. hispidulus, S. crinitus and S. lineatus were 4·8, 4·6, 5·8 and 6·5°C., respectively, and the thermal constants were 180, 211, 166 and 145 day-degrees C. The mean larval and (in brackets) pupal periods outdoors were 52 (23), 58 (34), 36 (25) and 38 (21) days, respectively. The average numbers of eggs laid were 843, 719, 519 and 1,113 per female, and the mean numbers laid per day were 10·2, 8·5, 9·6 and 17·5. These data were obtained by feeding adults on a variety of food-plants throughout their life in the laboratory. In another series of observations, adults were fed on the same type of food-plant throughout. Egg production of S. lividipes and S. hispidulus was greatest on clover (Trifolium alexandrinum) and least on broad bean (Vicia faba) and pea, respectively; that of S. crinitus and S. lineatus was greatest on pea and least on broad bean and clover, respectively.

First instars of the soil-inhabiting whitefringed weevil, Naupactus leucoloma(Boheman), are a particularly good bioassay model for assessing volatile soil fumigants and biofumigants. Eggs are readily obtained and can be stored for long periods with larvae hatched on demand and the first instar is non-feeding, surviving without food or shelter. Longevity varies with temperature, but readily accommodates the period required to conduct bioassays without appreciable mortality of untreated controls. In vitro bioassays of pure methyl isothiocyanate, the active ingredient from metham sodium soil fumigant, and the less volatile 2-phenylethyl isothiocyanate, sensitively detected differences in toxicity and effects of temperature. Bioassay of volatiles emitted from hydrolysed tissue of various isothiocyanate-producing Brassicaplants revealed widely varying toxicity effects, indicating that bioassays with N. leucoloma are a sensitive and relevant indicator of the potential of different plants for biofumigation of soil-borne pest organisms.

Infestations of Dermestes maculatus Deg. in dried fish at Dugbe market, Ibadan, are favoured by traditional packaging and display methods. In laboratory experiments last-instar larvae and adults showed low thigmokinesis and a bias towards the dry end of a 50–100% r.h. gradient; in alternative humidities between 40% and 100% last-instar larvae and adults selected 60–80% r.h., adults having a stronger preference than the larvae for the higher humidity; in a temperature gradient last-instar larvae and adults avoided the 30–45° C zone and showed low thigmokinesis and immobilisation at 19° C. These findings were generally consistent with observations in the market. Heating dried fish in an oven at 60° C for 30 min killed all larvae and adults of D. maculatus present. Two 30-min heat treatments at four-day intervals in a simple charcoal-fired oven and storage in metal containers would control the pest.

Various aspects were studied of the brood size and sex allocation strategies, and of size-fitness relationships in Parallorhogas pyralophagus (Marsh), a gregarious ectoparasitoid of Eoreuma loftini Dyar. Brood size was significantly correlated with host size; larger hosts were allocated larger broods. Brood sex ratios were fixed precisely at 1 male per 4 females, and eggs were likely to be deposited in that order; differential mortality did not contribute to this precise sex ratio. The sex allocation strategy of P. pyralophagus is likely to conform to strict, i.e. single foundress, local mate competition. Adoption of this strategy is probably influenced by a limited insemination capacity of males; a smaller proportion of females (0.09 vs. 0.21) remained virgin in broods with precise or higher sex ratios (≥0.20 males) relative to broods with lower than precise sex ratios (< 0.20 males). Moreover, all females were inseminated in most broods (60%) with precise or higher sex ratios, whereas this did not occur in broods with lower than precise sex ratios. The hypothesized occurrence of strict local mate competition in P. pyralophagus was supported also by observations that: (i) offspring brood sex ratios were independent of maternal brood sex ratios and number of parental females concurrently allocating offspring to a group of hosts, and; (ii) the rate of superparasitism under no-choice conditions was low (~20%), suggesting that rates of outbreeding in the field are low. Other results suggested that fitness in P. pyralophaguswas correlated with adult size; longevity and reproductive capacity both increased with adult size in males and females. However, adult size may be more important for females than for males because the differences in reproductive capacity between the largest and smallest individuals was up to 7.3 times greater in females versus <2 times in males.

The effects of predators on prey populations can be modified by a number of abiotic factors. Here, we investigated the combined and separate effects of rain and ground-dwelling predators on aphid populations in a microcosm experiment lasting for 21 days, using PCR to analyse the gut content of the predators. Rain significantly dislodged aphids from shoots and ears by 57% and 25%, respectively. The gut content analysis showed that more predators consumed aphids in the rain treatment than without rain, indicating higher availability of aphids to ground-dwelling predators after rain. However, no synergistic effects of rain and ground-dwelling predators on aphid population development could be demonstrated. Rain alone significantly decreased aphid populations by 27%, suggesting that this is a significant mortality factor. Predators alone had no significant effect on aphid numbers, but the gut content analyses showed aphid consumption also in the no-rain treatments, indicating that aphids were available to the predators on the soil surface even without rain. Our results suggest that weather conditions such as rain can modify predator-prey interactions in the field. Employing PCR-based predator gut content analyses proved to be useful as trophic links could be directly verified.

In populations of overwintering pupae of Delia radicum (L.) collected from ten sites in England and Wales, parasitism varied from 0% at Newcastle to 42% at Evesham. Unlike their hosts, few of the parasites were in extended diapause. Irrespective of when collected at Wellesbourne, emergence of 50% of the ichneumonid parasite Phygadeuon trichops Thoms., the eucoilid parasite Trybliographa rapae (Westw.) and the staphylinid parasite Aleochara bilineata Gylh. occurred after 14, 21 and 28 days, respectively, at 20°C. Early-emerging populations of D. radicum were more heavily parasitised than intermediate- or late-emerging populations. During the winters of 1979–80, 1980–81 and 1981–82, T. rapae and A. bilineata emerged in similar numbers from 37% of the field-collected pupae from Wellesbourne. Less than 1% of the pupae were parasitised by P. trichops. D. radicum adults emerged from a further 25% of the pupae, and the remainder, approximately 38%, were dead. Most dead pupae were recovered from heavily parasitised populations. When parasites were present in high numbers, many of their progeny probably died from multiple parasitism and superparasitism. Comparison with earlier studies indicated that parasitism should be expressed as a percentage of the total pupae, and not just as a percentage of the living insects, if the data are subsequently to be of use for studies on the population dynamics of this pest.

Infestations of the sugarcane pest Eldana saccharina Walker have been consistently serious in one part of the cane-growing belt of Natal, South Africa. Mortality in this region over seven years was estimated from moth catches in light traps, checked against population change measured from extensive larval counts, and plotted against climatic indices. The object was to construct a predictive model to illustrate mortality in other regions of the cane belt, to which infestations have spread in recent years. The spread southwards along the coast did not seem to have resulted from a decrease in natural mortality, but the spread to higher altitudes appeared to be due to lower mortality associated with warmer and drier years. The phenology of the insect and the effect of the annual harvesting cycle on phenology are discussed.

The majority of sorghum in Northern Nigeria is stored unthreshed in farmers' granaries made of dried mud or plant materials such as grass matting and cereal stems. During the course of survey work and insecticide trials in 1959–61 it was possible to examine many samples of unthreshed sorghum from granaries throughout Northern Nigeria. It was found that the distribution of insect species within the Region is not uniform. Sitophilus oryzae (L.) and Sitotroga cerealella (Ol.) are the major pests. Sitophilus zeamais Motsch. was found only in the southernmost area. Heavy infestations of Rhyzopertha dominica (F.), Lasioderma serricorne (F.), Cryptolestes ugandae Steel & Howe, Oryzaephilus mercator (Fauv.), Tribolium castaneum (Hbst.) and T. confusum Duv. usually occur. Attagenus gloriosae (F.), Ahasverus advena (Waltl), Palorus ficicola (Woll.), P. ratzeburgi (Wissm.) and P. subdcpressus (Woll.) are occasionally important.

R. dominica, Bruchidius sp., G. ugandae, Planolestes cornutus (Grouv.), S. oryzae, Brachypeplus sp., T. castaneum, Sitotroga cerealella (all of which occurred on the standing crop), L. serricorne, Typhaea stercorea (L.), O. mercator, Palorus spp. and Tribolium confusum were found in sorghum sampled before storage. Insects from infested stores were found to infest sorghum growing nearby. Prestorage infestation alone can result in subsequent heavy populations of insects in the store. Cross-infestation between granaries almost certainly occurs.

Under Samaru conditions, where sorghum is harvested in November–December, insect populations remain at a low level in granary-stored unthreshed sorghum until after June, when the moisture content rises in the rainy season. In sorghum stored for nine months in provincial trials, more damage occurred during the last three months than during the previous six months of storage.

Sorghum heads stored in granaries made of plant materials such as grass matting and cereal stems are more severely damaged by insects than those stored in dried-mud granaries. This is probably due to a higher rate of immigration in the former.

In threshed grain stored in a mud granary, moisture content and damage by the most abundant insect, Sitophilus oryzae, decreased with depth. The insect population rose to a peak in November, two months after the maximum moisture content. The numbers fell rapidly during the following dry season. The annual cycle of insect damage was also assessed by taking fortnightly samples of threshed grain from a local market. S. oryzae was the most numerous insect, but even this species was uncommon from December to May, during the dry season.

Contarinia sorghicola was discovered in Uganda in 1951, the only previous African record being from the Sudan. The infestation started in September in early varieties of sorghum grown in observation plots and reached a peak onlate varieties and ratoons in early March, thereafter declining as parasitism, chiefly by Tetrastichus sp. and Aprostocetus sp., increased to reach 100 per cent. in April.

The life-cycle was normally 19–25 days, but between December and April diapause larvae were found; these all produced adults in early August, following a period of high humidity.

Midges morphologically indistinguishable from C. sorghicola have been bred from Eleusine coracana and from wild Sorghum verticilliflorum in Uganda, and the midge may well be endemic wherever wild sorghums grow. Enquiries show that midge damage to sorghum occurs in Kenya, Tanganyika and Nyasaland, and it is likely that all the mainsorghum growing areas of Africa will prove to be infested.

The possible occurrence of resistance is discussed.

A total of 4418 mosquitoes caught by three collection methods at two levels in the forest near Belém, Brazil, were dissected to determine the proportion of parous individuals. About two-thirds of the mosquitoes belonged to Culex (Melanoconion) portesi Senevet & Abonnenc and C. (M.) taeniopus D. & K. The dissection technique entailed dissecting out the ovaries for examination of the tracheoles, whilst preserving the rest of the mosquito for later processing for virus recovery. Analysis of the results showed that, although significant differences were found in the parous rates from samples caught off human bait, and from mouse-baited Trinidad no. 17 and blower traps, these differences were unlikely to be of practical value when compared to differences in catching ability and ease of operation of the methods. In all, 2771 mosquitoes were classed as parous, and these when inoculated into baby mice in 142 pools yielded 14 isolations. It was concluded that the technique used did not reduce the likelihood of isolating viruses from the dissected mosquitoes.

Catches of Musca vetustissima Wlk. in West Australian blowfly traps containing week-old baits were consistently greater (4·5–24·1 times higher) than in traps with fresh baits. Recovery of marked flies within 26·5h of release showed mean dispersal distances of 1·5 ± 0·7 km for males and 1·6 ± 0·6 km for females under favourable weather conditions (mean air temperature 28·8°C and mean wind speed 5·5 m/s). The recovery rate of males (1·3%) and females (1·0%) over this period indicates the feasibility of using single mark-release experiments to estimate absolute fly densities. It is shown that estimates having a 95% probability of being within ± 10% of the true population density could be achieved by the release of 39 000 marked flies.

Insects and mites associated with each species in the Salvinia auriculata complex were recorded in Trinidad, Venezuela, Guyana, Brazil, Uruguay, Paraguay and Argentina. There was a consistent pattern of herbivore-plant association throughout the range of the complex. Field studies showed that three insects, the curculionid Cyrtobagous sp., the pyralid Samea multiplicalis Gn. and the pauliniid Paulinia acuminata (Deg.), together contained Salvinia molesta at a density slightly below the carrying capacity of the environment in coastal areas of Brazil.

Thirty Reticulitermes flavipes (Kollar) colonies established by alates collected from two separate field sites were raised in the laboratory for eight years. Twenty-one of the colonies were founded by alates from one field source and nine from another, providing demographic data from two unrelated parental lineages. Colony totals ranged from 3620 to 11641 individuals, with no significant difference in size between lineages. Soldier caste proportion of the colony total and mean wet weights for workers, soldiers and kings were significantly different between the two lineages. This suggests that at least a portion of the variability observed in caste ratios and body size may be heritable. One founding reproductive had died in five of the colonies (17%); none lost both parents. The queenless colonies contained exclusively female replacement reproductives (neotenics); the kingless colony contained a female-skewed mixture of male and female neotenics. All the nests that lost a founding parent contained significantly more pre-alate nymphs than the nests with both a king and a queen. Comparisons with published reports of ontogenetic patterns in other termites and social insects are discussed.

The Sugar Industry of Mauritius is suffering heavily from damage by stem-borers, especially the “Spotted Borer,” Diatraea mauriciella, Wlk. It has been estimated (Moutia, 1934) that this species alone is responsible for an average reduction of 15 per cent, in the field, per arpent, and that the loss in sugar averages 2-3 per cent., i.e. 16 per cent, of the sugar in cane. This means a gross loss of about 1£ million rupees per annum for the whole island, or a net loss of approximately 125,000 rupees.

The effects of avermectin exposure on natural populations of the yellow dung fly, Scathophaga stercoraria Linnaeus, were investigated at the field scale on farms in south-west Scotland. Pastures forming the focus of the study were grazed with either untreated cattle or cattle receiving standard, manufacturer-recommended treatment regimes of an avermectin product. Flies were sampled between April and July in 2002 and 2003 using dung-baited pitfall traps. Abundance and wing asymmetry in S. stercoraria populations were examined in relation to a range of environmental and management variables (including avermectin exposure, pasture management intensity, weather and season). Data used for abundance analyses were collected in fields where treated cattle had been dosed with either doramectin or ivermectin, while the data for the asymmetry analyses were from a subset of fields where treated cattle had been dosed with doramectin only. While abundance of S. stercoraria varied significantly between years and with season, there was no difference in their abundance between fields grazed by avermectin-treated or untreated cattle. Asymmetry was significantly higher in fly populations in fields grazed by doramectin-treated cattle, suggesting that exposure to doramectin during development could have imposed some degree of environmental stress. While these results suggest that exposure to doramectin residues in dung on grazed pastures may have sublethal effects on the insects developing in that dung, there was no evident avermectin effect on the abundance of adult S. stercoraria occurring in the pastures.

Vertical polythene exclusion barriers combined with trapping out using pitfall traps have been used to create enclosures within which arthropod numbers can be manipulated. This technique has been primarily used to investigate the impact of ground-dwelling polyphagous arthropods on cereal pests. Arthropod numbers in a total of 42 enclosed areas were compared to adjacent unenclosed areas over three years in Hampshire, UK. A range of arthropod monitoring techniques was used, including pitfall traps, fenced pitfall traps and D-vac suction samples. The enclosures were effective in reducing most species of Carabidae, Linyphiidae and Lycosidae encountered and numbers in pitfall traps were reduced by an average of 74%, 62% and 77% respectively. Similar reductions in densities of these taxa were found. Staphylinidae were less effected with an average reduction of only 32% in pitfall traps, although Philonthus species were reduced by 82%. Results were compared to previous studies.

Blattisocius keegani (Fox) is a predatory mite in the family Ascidae (Acari), noted for potential biological control of Coleopteran stored product pests. Performance of B. keegani on eggs of navel orangeworm, Amyelois transitella Walker (Lepidoptera: Pyralidae), was investigated. Mites completed development from egg to adult in 9.2±0.22 days at 25°C and 50–60% relative humidity, and in 6.33±0.29 days at 32.2°C, 30% relative humidity. Mites provisioned with three or five eggs consumed a median of 1.25 to 1.5 eggs, with a maximum of three eggs consumed over 24 h. Regression analyses indicated egg-laying by B. keegani was significantly correlated with the number of A. transitella eggs consumed, and female mites laid an average of 5.82±0.44 eggs over 72 h. Blattisocius keegani, developed on fresh and frozen eggs, laid significantly more eggs when provided with fresh eggs (F3,26=6.16, P=0.0026) and were able to develop on frozen Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs as an alternative host. Mites were equally fecund when fed eggs stored at 0° or −20°C. Provisioning of adult moth bodies in addition to egg prey items increased mite fecundity, although it was demonstrated that B. keegani are phoretic on adult moths as well. The results are the first experimental evidence of B. keegani as a predator of Lepidopteran eggs, as a phoretic species, and of their potential for biological control of navel orangeworm.

The onion thrips (Thrips tabaci Lindeman, 1889) is a key pest of a wide range of crops because of its ecological attributes such as polyphagy, high reproduction rate, ability to transmit tospoviruses and resistance to insecticides. Recent studies revealed that T. tabaci is a cryptic species complex and it has three lineages (leek-associated arrhenotokous L1-biotype, leek-associated thelytokous L2-biotype and tobacco-associated arrhenotokous T-biotype), however, the adults remain indistinguishable. T. tabaci individuals were collected from different locations of Hungary to create laboratory colonies from each biotypes. Mitochondrial COI (mtCOI) region was sequenced from morphologically identified individuals. After sequence analysis SNPs were identified and used for CAPS marker development, which were suitable for distinguishing the three T. tabaci lineages. Genetic analysis of the T. tabaci species complex based on mtCOI gene confirmed the three well-known biotypes (L1, L2, T) and a new biotype because the new molecular evidence presented in this study suggests T-biotype of T. tabaci forming two distinct (sub)clades (T1 and T2). This genetic finding indicates that the genetic variability of T. tabaci populations is still not fully mapped. We validated our developed marker on thrips individuals from our thrips colonies. The results demonstrated that the new marker effectively identifies the different T. tabaci biotypes. We believe that our reliable genotyping method will be useful in further studies focusing on T. tabaci biotypes and in pest management by scanning the composition of sympatric T. tabaci populations.

Fungus-growing termites (Macrotermitinae) are important pests in tropical countries. They are difficult to control with existing baiting methods, as chitin synthesis inhibitors are not effectual as active ingredients. We tested two neurotoxins, fipronil and imidacloprid, as potential bait active ingredients against Macrotermes gilvus (Hagen) in Singapore. In laboratory bioassays, M. gilvus showed no preference for doses of 0–64 ppm fipronil, or for doses of 0–250 ppm imidacloprid, indicating no repellence. We tested each insecticide in toilet paper as a bait matrix in a field experiment. After 28 days, termites had eaten 5–13% of the fipronil treated toilet paper, abandoned bait and monitoring stations, contacted no new stations, and repaired poorly their experimentally damaged mounds. Termites ate no imidacloprid treated toilet paper, abandoned bait stations although contacted new stations, and repaired fully their damaged mounds. Termites ate 60–70% of the control toilet paper, remained in bait stations, and fully repaired damaged mounds. After 56 days, all five fipronil colonies were eliminated, whereas all of the imidacloprid and control colonies were healthy. The results suggest that fipronil could be an effective active ingredient in bait systems for fungus-growing termites in tropical countries.

The identity of Phenacoccus gossypii Townsend & Cockerell is established as a local species in Mexico and southern USA. Although P. madeirensis Green was described from Madeira and is recorded from much of the African mainland, it was probably introduced from tropical America. It is now known to be common on many crop and ornamental plants in North and South America where it has often been mistaken for P. gossypii. Both species are redescribed and illustrated, and their range of variation is discussed. P. grenadensis Green & Laing and P. harbisoni Peterson are synonymized with P. madeirensis. A related species, P. baccharidis sp. n., is described from Brazil, and P. sphaeralceae sp. n. is described from Arizona. P. hurdi McKenzie is redescribed and is now recorded from an extensive area in southern USA and Mexico. All five species have numerous dorsal multilocular pores and are included in a key to 15 related species in North and South America.