Multivariate analysis was used to demonstrate that specimens of Planococcus collected from yams (Dioscorea spp.) in both the West Indies and Africa can be differentiated from the similar P. ficus (Signoret) which occurs on figs, grapevines and pomegranates in the Mediterranean Basin, Pakistan, South Africa and Argentina. The specimens from yams are considered here to be a distinct species, to which the name P. halli Ezzat & McConnell is applied. Examination of material of both species reared on potato tubers at various temperatures showed that the differentiation is not a host-induced effect. Independent canonical variates analysis of the field-collected and reared material each showed clear differentiation of the two groups. However, the coefficients obtained for each character differed markedly between the analysis of the field-collected material and that of the reared material, and thus could not be used to assign individuals to groups. This difference in the values of the coefficients is considered to have been due to the peculiarities of individual populations, as the field-collected material included many genotypes while only three genotypes were represented by the reared material. A key and illustrations are provided for the separation of the two species.

In order to seek at least a partial explanation of the differential occurrence of Cryptolestes turcicus (Grouv.) and C. ferruginous (Steph.), the interaction between different combinations of the larvae of the two species was studied when each newly hatched larva was provided with 12·5 mg. wheatfeed. It was found that the numbers of C. turcicus surviving to the adult stage in the presence of C. ferrugineus was a linear function of its own initial numbers, whereas the survival of C. ferrugineus seemed to be some function of the size of the environment. This conclusion, taken together with other data, suggests that if the two species were to gain access to cereals together, dry conditions, coarse food, low larval density and the availability of refuges for pupation would favour high populations of C. ferrugineus, whereas moist conditions, fine food, moderate to high larval density and the absence of refuges for pupation would favour high populations of C. turcicus.

Coccinellids reported to be feeding on the diaspidid Chrysomphalus aonidum (L.) infesting coconut palms in Gujarat, India, were found to belong to an undescribed species. This is described here as Sukunahi-kona popei sp.n. and is compared with other species of the genus. A key to the species is given. This is the first record of the tribe Sukunahikoni in India.

1. A new species of aphis, Aphis (Doralis) cognatella, found on Euonymus europaeus is described and compared with Aphis (Doralis) fabae, which it closely resembles. This new aphis is brown in colour and has long hairs.

2. Two individuals, intermediate in character between oviparae and sexuparae, are mentioned.

3. Transference experiments, carried out under somewhat artificial conditions, show that although the aphis is normally found on Euonymus sp., it can exist for some time on Rumex obtusifolius, R. crispus, Chenopodium album, Capsella bursapastoris, Arctium lappa, and Beta vulgaris (flower stalks), which are also host plants of A. fabae, but it does not colonise Vicia faba.

4. The sexuparae are apterous and produce males, oviparae and apterae, thus differing from A.fabae, in which there are two sexuparous forms, one an alate gynopara and the other an apterous form found on the summer hosts.

5. Olfactometer experiments give no indication of any olfactory response to the odour of E. europaeus leaves.

The cypress bark beetle, Phloeosinus armatus, is a common element of the dying cypress tree system in East-Mediterranean countries. Adult beetles congregate for breeding on this ephemeral resource. We studied three traits that characterize this beetle's sexual behavior and linked them to its reproductive success: mating system, mate choice, and parental care. We found that the females are the ‘pioneering sex’, excavating the mating chamber. The average female is slightly larger than the male, and female and male body size is correlated, demonstrating size-assortative mating. The time it takes for a male to enter the mating chamber is positively correlated with female size and negatively correlated with its own size, which is perhaps responsible for this assortative mating. Males remain in the gallery during the period of oviposition, gradually leaving soon after the eggs hatch. The number of eggs laid and tunnel length are positively correlated with male body size. Finally, in the presence of both parents, more eggs are laid than when the female alone is present, demonstrating the important contribution of biparental care for reproductive success. We suggest that the interaction between a monogamous mating system, assortative mating, and biparental care contributes to reproductive success.

The importance of Toxoptera species as agricultural pests is briefly discussed, along with the recent discovery in Africa of T. odinae (van der Goot). Banana is recorded as an unusual new host-plant record, and a table of other hosts is presented. The genus Toxoptera is defined and a key to species given.

Whitefly, Bemisia tabaci, is one of the most important pests of tomato, Solanum lycopersicum L. The Mi-1 gene mediates tomato resistance to the Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED) species of B. tabaci, three species of root-knot nematodes, Meloidogyne spp., and the potato aphid, Macrosiphum euphorbiae. Tomato seedlings bearing the Mi-1 gene are resistant to nematodes soon after germination but resistance to aphids is developmentally regulated; a reliable conclusion about Mi-1 resistance to B. tabaci was not available to date. In the present work, 3-, 5- and 8-week-old plants of the tomato cultivars Motelle and Moneymaker (bearing and lacking the Mi-1 gene, respectively) were simultaneously tested under free-choice (antixenosis) and no-choice (antibiosis) conditions, to assess the real influence of plant age on the Mi-1-mediated resistance to the MED species of B. tabaci. Subsequently, plants of the same age but with different level of development were compared to check whether the plant size can also affect this tomato resistance. Obtained results demonstrated that Mi-1-mediated resistance to B. tabaci is developmentally regulated, as variations in the age of bearing-Mi-1 plants affects most infestation parameters tested. Differences between cultivars with and without the Mi-1 gene were significant for 8- but not for 3-week-old plants. For 5-week-old plants, differences between cultivars were less pronounced than in older plants, expressing an intermediate level of resistance in Motelle. Plant size also influenced whitefly infestation and reproductive activity on the resistant cultivar. However, plant age has more impact than plant size on the Mi-1-mediated resistance of tomato to B. tabaci.

The Citrus Leaf-miner (Phyllocnistis citrella) has been recorded from plants belonging to several widely differing botanical families.

It is shown that the true food-plants of this pest are the various species of Citrus and Aegle marmelos.

Elephant lemon (Citrus medica), which has comparatively succulent leaves, is the most susceptible species of Citrus, whilst lime (C. aurantiifolia), with its comparatively thick and coarse leaves, is the least susceptible. Aegle marmelos is not of any importance as the attack in this case is negligible.

C. medica should be excluded from citrus orchards as it is of least economic importance, and is highly susceptible to attack. C. limonia, which is usually grown as a hedge around gardens, provides an undisturbed breeding ground for the pest and should as far as possible not be planted around citrus plantations.

In March 1920 my attention was called by Dr. F. W. Dootson, University Lecturer in Chemistry, to the fact that a beetle was breeding in numbers in a jar of argol in the Chemical Laboratory of Cambridge University. The insect proved on examination to be the introduced Ptinid, Trigonogenius globulum, Solier, a form related to the household insect, Niptus hololeucus, to which it bears at first sight a slight resemblance.

Tsetse flies (Glossina morsitans Westw.) were marked and released at Daga-Iloi, in Tanganyika on four or, usually, six days weekly for over 15 months, at 75 catching points situated 100 yards apart on an “octagonal spiral” whose successive rings were separated by 250 yards. Outer “spirals” were also traversed occasionally.

The country was hilly and dominated by woodland of Brachystegia tamarindoides, broken by more open grassland with Combretum on the one hand and by thicketed ravines on the other. The ungulate animals included zebra, buffalo, bushbuck, roan antelope, hartebeest, reedbuck, duiker, wart-hog and bushpig, with very occasional elephant, rhinoceros, waterbuck and klipspringer. Baboons and Cercopithecus monkeys were also present. Spoors of the ungulates were recorded on the daily rounds: bushbuck were most common about the ravines, but in general the ungulates tended to be most common in the open grassland with Combretum.

G. morsitans was most numerous in tall Brachystegia woodland where the slope was moderate, and where open grasslands were not too far away. Thicketed ravines were avoided. The highest apparent densities were observed on the outer “spirals”, perhaps because of disturbance on the inner one traversed almost every day.

During the rains, well-marked concentrations of flies occurred in certain parts of the Brachystegia woodland, and these re-formed in the second year. The hungriest flies were always found outside the Brachystegia, and hunger was higher in the dry season. Hunger was measured objectively by the proportion of non-teneral males alighting head-upwards on members of the catching party, which hungry flies mostly do.

There was a negative correlation between numbers of flies and numbers of ungulates, and a positive correlation between the numbers of ungulates and hunger of the flies. This is in accordance with the feeding-ground theory, and is very generally observed with G. morsitans in East Africa. Certain movements of individual flies also accorded with the theory, against which, however, the suggestion has now been made that flies caught in the putative feeding grounds have not ventured out into them until attracted there by the sight of the catching party. This suggestion is to some extent countered by quotations from previous work, but it deserves further thought, and carefully planned experiments.

Passage of large herds of buffalo through portions of the “spiral” were not apparently accompanied by mass movements of flies, even when the animals passed by day and many flies fed on them.

In crossing experiments with Gryon triatomae Masner, reared from the eggs of Triatoma rubrofasciata (De Geer) from Singapore and India, and G. linshcostei Masner, from eggs of Linshcosteus sp. from India, only the females of G. linshcostei yielded hybrids (3.9%). G. linshcostei accepted both hosts offered separately but preferred Linshcosteus when the two were provided together; G. triatomae showed poor acceptance of Linshcosteus eggs under both sets of conditions. In view of their reproductive isolation and these and other observed differences in their behaviour, these two sibling species could be selectively introduced into other areas for biological control of Triatominae.

Cocoon-spinning larvae of the codling moth, Cydia pomonella, emit a pheromone that mediates aggregation by pupation site-seeking fifth-instar larvae. It was unknown and, thus, we tested whether the aggregation pheromone induces arrestment or attraction responses. In paired straight-tube experiment 1, fifth-instars moved faster and farther upwind toward cospecific cocoons compared to blank controls. In still-air cage experiment 2, fifth-instars selected more often as first and final choices of pupation sites those with cocooning conspecifics than those without. Finally, in Y-tube olfactometer experiment 3, fifth-instars anemotactically responded to, and preferred, side arms with cocooning conspecifics to those without. Our data provide evidence that codling moth larvae are attracted to, rather than merely arrested by, larval aggregation pheromone. These results help explain reported aggregations or clumped distributions of larvae on tree trunks, which would likely not occur if they were based merely on chance encounter of cocoon-spinning larvae by foraging larvae.

Carbon dioxide, carbon monoxide, chloroform, hydrogen, methane and nitrous oxide emissions were collected from within several mound colonies of the subterranean termite Coptotermes lacteus (Fgottatt) and the surrounding habitat of a dry sclerophyll forest in central Gippsland, Australia, following treatment of the termite mounds with mirex-treated bait blocks. All the mirex-treated colonies died within two weeks of commencing active feeding on the bait blocks. The flux measurements of the gaseous emissions were calculated before, during and after treatment with the mirex-treated decayed wood bait blocks. Carbon dioxide, methane and hydrogen all declined after colony death.

One gynandromorph and six intersexes of Austrosimulium bancrofti (Tayl.) are described from specimens caught in Queensland. All of the intersexes, as well as some normal flies, were infected with mermithid larvae. The infected flies rest preferentially on trees near the river's edge which would facilitate deposition of mermithids in the river. Except for a few with mature eggs, infected females had little internal abdominal structure, and most lacked ovaries.

Two toxic baits, one containing aldrin and the other containing mirex, were compared for their effectiveness in killing field colonies of Atta cephalotes (L.) and Acromyrmex octospinosus (Reich) in Trinidad, West Indies. The fate of these two toxicants within tie nests was followed by using radiolabelled bait. Of the two baits, mirex appeared to be more acceptable to both species of ant. With Acromyrmex, the ratio of living to dead fungus gardens was not affected by the bait used, whereas with Atta there was a significant difference, aldrin killing many more gardens than mirex. For both species the proportion of medium-sized workers radiolabelled was significantly greater than for the other castes, and mirex marked greater numbers of all castes than did aldrin. Greatly different proportions of Atta workers were radiolabelled in the different fungus gardens of a nest with both baits. More radioactivity was detected in the fungus gardens treated with mirex, the difference being significant for Atta but not for Acromyrmex. Mirex bait particles incorporated into the fungus gardens were significantly smaller than aldrin bait particles, indicating different degrees of comminution by the ants.

The pear thrips Taeniothrips inconsequens (Uzel) was sampled for four years in a small sugar maple Acer saccharum plantation in Centre County, Pennsylvania, USA. The life cycle of T. inconsequens was univoltine with the main period of emergence and flight from late March to mid May. Adults, eggs, and first and second instar larvae were associated with sugar maple budburst and early leaf development from late April to late May. Larval drop occurred from mid to late May. Mature second instar larvae, propupae, pupae and adults spent from June to March in the ground; development from larva to adult occurred between September and November. From March to May most (usually >90%) thrips adults and larvae sampled were T. inconsequens. No T. inconsequens males were found. In soil samples taken in spring, summer and autumn T. inconsequens were found to a depth of 50 cm but over 87% were in the top 20 cm. Almost no T. inconsequens were found in the litter layer. Large variations in T. inconsequens adult emergence and larval drop were recorded. The most important contributing factors in fluctuations of T. inconsequens populations were the length of sugar maple budburst, the degree of synchrony between thrips emergence and sugar maple budburst, and the occurence of sugar maple flowering.

It has been found that the size of adults of the parasites Mutilla glossinae Turner and Thyridanthrax abruptus (Lw.) reared from puparia of Glossina differ with the size of the host, the puparia of the larger tsetse species, G. pallidipes Aust., producing larger parasite than the puparia of the smaller species, G. morsitans Westw. A significant relationship has been found between size of puparium (measured by puparial width) of G. morsitans and size of the parasite (measured by thoracic area and dry weight) for males of T. abruptus and males and females of M. glossinae, and it is suggested that this relationship may extend also to other species of Thyridanthrax and Mutilla that parasitise Glossina. Evidence, both from other workers and this laboratory, indicates that it is the different quantities of food supply in the hosts that affects the size of the adult parasite.

The is insufficient knowledge of arthropod communities occurring in specific microhabitats. In this study, we characterize the arthropod assemblages inhabiting burrows of the common hamster (Cricetus cricetus L.) and factors that determine their diversity and abundance. We tested the following hypotheses: (1) arthropod assemblages are associated with a particular dominant vegetation occurring in the vicinity of burrows; (2) a correlation exists between fine-scale geographic distances among burrows and assemblage dissimilarity; and (3) the type of trap influences the sampling success of captured arthropods. We found 73 morphospecies belonging to 16 families in 109 burrows, most of which were in the families Staphylinidae (Coleoptera) and Parasitidae (Arachnida: Acari: Mesostigmata). The most abundant families were Staphylinidae, Cryptophagidae (Coleoptera), Parasitidae, and Macrochelidae (Mesostigmata) (78.89%). Among the identified species, we found Aleochara irmgardis (Staphylinidae) and Poecilochirus sexclavatus (Parasitidae) which had not yet been reported in Poland, and several other rare species. Meat-baited traps captured 64.34% more individuals, which were more diverse and species-rich than the non-baited control traps, but the former was more selective for saprophages, necrophages, and coprophages. The burrows located in areas overgrown by triticale (a hybrid of wheat and rye) were inhabited by 69.86% of the identified arthropod species, and these also had the highest abundance (64.07%) in comparison with other habitats. However, differences in sample size biased our results toward and overestimate arthropods associated with this vegetation. This study underlines that the species composition detected in burrows was affected by the methods used and hamster preferences for a specific habitat rather than the geographic proximity of the burrows. More extensive sampling across multiple habitats will be necessary to confirm our findings.

Nectar is a main resource harvested by foraging honeybees: their ability in selecting among flowers is the key to optimize resource collection. This ability is expected to be the result of co-evolutionary traits between the plant and the pollinator visiting it; notwithstanding, novel interactions may occur between native and invasive species. Analysing foraging efforts, flexibility and individual constrains has to be taken into account. The foraging pattern of the ubiquitous honeybee on Robinia pseudoacacia, a North-American species widely naturalized in European countries, grounds a perfect case study. The plant shows papilionate flowers especially reach in nectar, but their tripping mechanism is difficult for the small/light-weight honeybee. Yet Apis mellifera is known to pay frequent and constant visits to them: in fact, one of the most appreciated unifloral honey is produced out of R. pseudoacacia. The aim of this study was to understand when and how the bees overcome physical constraints to succeed in flower visits, and to what extent this flexibility extend from the individual to the species. Data were collected in Italy, through focal observations of foraging individuals, nectar content measurements and experiments with manipulated inflorescences. Results clearly indicate that nectar content changes accordingly to the state of flowers (visited or unvisited), which also show slight changes in appearance. Foraging individuals, able to detect these differences, perform active choices preferentially selecting already-visited flowers: lower in nectar content but easier to manipulate. Even if the choice is primarily driven by handling constraints, individual experience and strength of stimuli are prompting visits also to unvisited flowers, notwithstanding a higher risk of failure in resource collection. Behavioural plasticity matching a satisfactory compromise grounds the decision that maximizes the intake of resource balanced with the effort to gain it.

A steady supply of hosts at the susceptible stage for parasitism is a major component of mass rearing parasitoids for biological control programs. Here we describe the effects of storing 5th instar Plodia interpunctella larvae in dormancy on subsequent host development in the context of host colony maintenance and effects of the duration of host dormancy on the development of Habrobracon hebetor parasitoids reared from dormant hosts. We induced dormancy with a combination of short daylength (12L:12D) and lower temperature (15°C), conditions known to induce diapause in this species, and held 5th instar larvae of P. interpunctella for a series of dormancy durations ranging from 15 to 105 days. Extended storage of dormant 5th instar larvae had no significant impacts on survival, development, or reproductive potential of P. interpunctella, reinforcing that dormant hosts have a substantial shelf life. This ability to store hosts in dormancy for more than 3 months at a time without strong negative consequences reinforces the promise of using dormancy to maintain host colonies. The proportion of hosts parasitized by H. hebetor did not vary significantly between non-dormant host larvae and dormant host larvae stored for periods as long as 105 days. Concordant with a prior study, H. hebetor adult progeny production from dormant host larvae was higher than the number of progeny produced on non-dormant host larvae. There were no differences in size, sex ratio, or reproductive output of parasitoids reared on dormant hosts compared to non-dormant hosts stored for up to 105 days. Larval development times of H. hebetor were however longer when reared on dormant hosts compared to non-dormant hosts. Our results agree with other studies showing using dormant hosts can improve parasitoid mass rearing, and we show benefits for parasitoid rearing even after 3 months of host dormancy.