Flightless Females Research Articles

Juvenile hormone titer and morph-specific reproduction in the wing-polymorphic cricket, Gryllus firmus

Juvenile hormone titers and reproductive characteristics were measured in adult wing and flight-muscle morphs of the wing-polymorphic cricket, Gryllus firmus, during the first week of adulthood. This species has three morphs: one flight capable morph with fully-developed wings and fully-developed flight muscles [LW(F)], one flightless morph with fully-developed wings and histolyzed (non-functional) flight muscles [LW(H)], and another flightless morph with underdeveloped (short) wings and underdeveloped flight muscles (SW). Both flightless morphs [LW(H) and SW] had larger ovaries which contained a greater number of postvitellogenic eggs compared with the flight capable [LW(F)] morph. The juvenile hormone titer was significantly higher in SW compared with LW(F) females on days 3–7 of adulthood. On these days, the JH titer also was significantly higher in the other flightless morph, LW(H), compared with flight-capable [LW(F)] females as determined by one statistical test, but did not differ significantly by another test. The JH titer was positively correlated with ovarian mass or terminal oocyte length, but not with the number of post-vitellogenic eggs. This study is the first direct comparison of juvenile hormone titers in adult wing morphs of a wing-polymorphic insect. Results indicate that an elevated juvenile hormone titer may be at least partly responsible for one of the most distinctive features of wing-polymorphic species, the increased early fecundity of flightless females.

The evolution of threshold traits: effects of selection on fecundity and correlated response in wing dimorphism in the sand cricket

Abstract The quantitative genetic basis of traits can be determined using a pedigree analysis or a selection experiment. Each approach is valuable and the combined data can contribute more than either method alone. Analysis using both sib analysis and selection is particularly essential when there are likely to be nonlinearities in the functional relationships among traits. A class of traits for which this occurs is that of threshold traits, which are characterized by a dichotomous phenotype that is determined by a threshold of sensitivity and a continuously distributed underlying trait called the liability. In this case, traits that are correlated with the liability may show a nonlinear relationship due to the dichotomy of expression at the phenotypic level. For example, in wing dimorphic insects fecundity of the macropterous (long-winged) females appears in part to be determined by the allocation of resources to the flight muscles, which are almost invariably small or absent in the micropterous (short-winged, flightless) females. Pedigree analysis of the cricket Gryllus firmus has shown that wing morph, fecundity and the trade-off between the two have additive genetic (co)variance. It has also been shown that selection on proportion macroptery produced an asymmetric correlated response of fecundity. The present paper details the results of direct selection on fecundity and the correlated response in proportion macroptery. Selection for increased fecundity resulted in increased fecundity within both wing morphs and a correlated decrease in proportion macroptery. Similarly, selection for decreased fecundity resulted in a decrease within morphs and a correlated increase in the proportion of macropterous females. This provides additional evidence that the trade-off between fecundity and wing morphology has a genetic basis and will thus modulate the evolution of the two traits.

Biochemical aspects of flight and flightlessness in Gryllus: flight fuels, enzyme activities and electrophoretic profiles of flight muscles from flight-capable and flightless morphs

Female Gryllus assimilis subjected to 4.5–7.7 h continuous tethered flight had significantly lower amounts of total lipid, triglyceride and total soluble carbohydrate compared with unflown controls. A much greater amount of total lipid (6.3 mg) was used during flight compared with carbohydrate (0.14 mg). Flown individuals also had substantially reduced amounts of injected, radiolabeled [ 14C]-oleic acid. Activities of lipid, carbohydrate and amino acid catabolizing enzymes in flight muscles of G. assimilis and its wing-polymorphic congener, G. firmus, were very similar to activities in insects which primarily utilize lipid to power flight. By contrast, enzyme activities were very different from those in insects which primarily or exclusively use carbohydrate or proline as a flight fuel. These results strongly implicate lipid as the major flight fuel in Gryllus. Previous studies have shown that lipid levels are higher in flight-capable (long-winged) G. firmus that have small ovaries compared with flightless (short-winged) females that have large ovaries. Results of the present and previous studies collectively indicate that elevated lipid in long-winged G. firmus represents an energetic cost of flight capability which reduces (trade-offs with) reproduction in Gryllus. In G. firmus, mass-specific activities of nearly all enzymes were considerably reduced in underdeveloped, and to a lesser degree in histolyzed muscle, compared with fully-developed flight muscle. An important exception was alanine aminotransferase, whose activity was the highest in histolyzed muscle, and which may be involved in the catabolism of amino acids derived from muscle degradation. Despite the dramatic differences in enzyme activity, electrophoretic profiles of soluble flight-muscle proteins differed only subtly between fully-developed and underdeveloped or histolyzed flight muscles.

Mobile Parasitoids may Restrict the Spatial Spread of an Insect Outbreak

1. The western tussock moth Orgyia vetusta, a defoliator with flightless adult females, forms localized outbreaks within larger areas of its habitat. These outbreaks may persist for several (> 10) years with little tendency to spread. 2. According to reaction-diffusion models, spatial patterns in population density may arise from the interaction between a mobile predator and a less-mobile prey. This occurs because predators 'spill over' around the edges of prey populations, creating zones in which ratios of predators to prey are elevated. 3. To test this 'predator diffusion' hypothesis for tussock moths, we placed their eggs and larvae along a 500-m transect leading away from the edge of a tussock moth outbreak. through suitable but sparsely occupied habitat. We measured attack rates by a wasp egg parasitoid and four species of tachinid fly larval-to-pupal parasitoids on these experimental immature moths. 4. As predicted rates of parasitism were elevated in the zone surrounding the outbreak. For some parasitoid species, the relationship between parasitism and distance from the outbreak was linear; for others it was parabolic. 5. These results are compatible with several explanations, including the predator diffusion hypothesis. Whatever the mechanism, the results suggest that parasitism restricts the spatial distribution and therefore the global abundance of the host insect in this system.

Physiology and ecology of dispersal polymorphism in insects.

Studies of dispersal polymorphism in insects have played a pivotal role in advancing our understanding of population dynamics, life history evolution, and the physiological basis of adaptation. Comparative data on wing-dimorphic insects provide the most definitive evidence to date that habitat persistence selects for reduced dispersal capability. The increased fecundity of flightless females documents that a fitness trade-off exists between flight capability and reproduction. However, only recently have studies of nutrient consumption and allocation provided unequivocal evidence that this fitness trade-off results from a trade-off of internal resources. Recent studies involving wing-dimorphic insects document that flight capability imposes reproductive penalties in males as well as females. Direct information on hormone titers and their regulation implicates juvenile hormone and ecdysone in the control of wing-morph determination. However, detailed information is available for only one species, and the physiological regulation of wing-morph production remains poorly understood. Establishing a link between the ecological factors that influence dispersal and the proximate physiological mechanisms regulating dispersal ability in the same taxon remains as a key challenge for future research.

Location and ultrastructure of sex pheromone glands in female Callosobruchus maculatus (Fabricius) (Coleoptera : Bruchidae)

The ultrastructure of the female sex pheromone glands in Callosobruchus maculatus (Coleoptera : Bruchidae) were localized using a masking technique, combined with eiectro-antennography and by a comparison of the glandular cells of sexually active (flightless) females and non-sexually active (flight-form) females. Each unicellular gland is an invagination of the integumental membrane capped by a single secretory cell. These glands are situated on the fine intersegmental membrane, which joins the pygidium to the ovipositor. The secretory cells of the glands of active females are characterized by well-developed microvilli, with many elongated mitochondria among the latter. The high metabolic activity of these cells is revealed by the presence of heterogeneous secretion vesicles, some of which contain abundant crystallized material. Deep basal invaginations indicate the uptake of substances from the haemolymph. The receptor canal is a network of fine cuticular filaments which have the same structure regardless of the female's sexual status. Cells from the glands of non-sexually active females are underdeveloped and show no invaginations of the basal membrane and very few microvilli. The localization of these glands was made possible by the use of SEM, TEM and EAG as well as by masking the suspected zones and by comparing females in different physiological states: flightless females, which were sexually active and producing pheromones; and flight-form females, non-sexually active and producing no sex pheromones. Only by adopting such a stringent method was it possible to confirm the function of the glands whose ultrastructure was studied.

Resources and dispersal as factors limiting a population of the tussock moth (Orgyia vetusta), a flightless defoliator.

The western tussock moth (Orgyia vetusta) is very abundant on one stand of bush lupine (Lupinus arboreus) at the Bodega Marine Reserve (Sonoma Co, Calif., USA), but is sparse or absent on nearby stands. To determine what controls its abundance, both within the outbreak area and more globally, I performed experimental manipulations of resource availability and dispersal. To measure resource limitation, I inoculated 30 caged and 30 uncaged bushes with a realistic range of numbers of tussock moth eggs. On caged bushes, starvation led to density-dependent reductions in survival, pupal weight and fecundity. Larvae on uncaged bushes experienced density-independent ant predation on early instars and density-dependent emigration by late instars. From the results of this experiment, I predicted the density of a resource-limited tussock moth population. The predictions agreed fairly well with data from the outbreak area in 1992. To measure dispersal by the moth, which has flightless adult females, I released 30,000 tussock moth eggs at a central point in each of two uninfested lupine stands, and censused larvae weekly in a circle of radius 16 m until pupation. Median displacement over one entire generation was only 2 m, or about 2 bush radii. Rearing experiments indicated that bushes outside the out-break area are fully nutritionally suitable for the moth. I conclude that two major factors limiting the population are resources (within the outbreak area) and inefficient dispersal (more globally).

A review of the biology and control of the vine weevil, Otiorhynchus sulcatus (Coleoptera: Curculionidae)

SummaryAt the turn of the century, damage by Otiorhynchus sulcatus was sporadic and limited to small areas. Increasing horticultural intensification and the adoption of husbandry techniques favourable to the weevil, such as the use of polythene mulches, increased its pest status. The development of the early inorganic pesticides reduced the number of serious outbreaks of this pest and weevil control was further improved by the development of the persistent organochlorine insecticides in the 1940's. The banning of a number of the more persistent insecticides over recent years has now left the horticultural industry in a very vulnerable position. O. sulcatus is now a pest on a range of horticultural crops throughout the temperate regions of the world. Infestations are most common in Europe (where it originated) and the USA, and nearly 150 plants species have been identified as potential hosts to O. sulcatus. Damage is most frequently caused by the root feeding larval stage. Populations as low as one larva plant can kill sensitive species such as Cyclamen. Severe damage by the leaf feeding adults is less common, although low levels of damage or contamination by adults may be unacceptable in certain situations. There is one generation a year. Oviposition by the flightless parthenogenetic females occurs over the summer months with oviposition rates of c. 500 and 1200 eggs adult‐1for outdoor and laboratory populations, respectively. O. sulcatus mainly overwinters as larvae, although significant numbers of adults may survive in areas where winter temperatures are not too severe.A number of natural enemies, such as hedgehogs, frogs and predatory beetles, help to maintain O. sulcatus populations at a low level in natural environments, but they are less successful in intensive horticultural systems where persistent chemicals have been heavily relied on to maintain the population below the economic threshold level. Increasing environmental concern is now forcing growers to consider new pest control strategies. Controlled release formulations of non‐persistent products, such as fonofos and chlorpyrifos, have shown potential as control agents for O. sulcatus larvae. Biological control agents, such as insect parasitic nematodes, have been developed commercially and new microbial control agents are in the process of development. Most of the new control products are directed towards control of O. sulcatus larvae. Adult vine weevils are nocturnal and a much more difficult target for the new control agents. It is likely that an integrated approach to pest control will be required to maintain O. sulcatus populations below their economic threshold level.

Reproductive isolation inProkelisia planthoppers (Homoptera: Delphacidae): Acoustic differentiation and hybridization failure

Males and females of Prokelisia marginata (Van Duzee) and Prokelisia dolusWilson communicate through substrate-transmitted vibrations. The acoustic signals (attraction and courtship calls) of these planthoppers are effective in mate location, attraction, and mate choice. Attraction calls are structurally distinct for both species and differ in pulse type, pulse repetition rate, and pulse duration. Using playback of prerecorded calls, individuals discriminated between conspecific and heterospecific signals. Depending on the sex and species, response calls were produced three to eight times more frequently to conspecifics than to heterospecifics. However, acoustic signals alone did not explain reproductive isolation and hybridization failure in these two congeners. Some heterospecific pairs called, courted, and attempted to join genitalia, but no connections were successful and no progeny were produced. Thus, acoustic behavior is not a guaranteed premating isolating mechanism in no-choice situations. Other courtship behaviors and possibly morphological differences in genitalia also contributed to their isolation. Females displayed a variety of rejection behaviors to conspecific and heterospecific males, suggesting that sexual selection (female choice), in addition to species recognition, may be an important force in the evolution of the acoustic signals of planthoppers. Although signal structure was not dependent on wing form (planthoppers exhibit wing dimorphism), the age when females first began to call was related to wing form. Brachypterous (flightless) females of both species began calling early in adult life (day 2), whereas macropterous (migratory) females began calling later in adult life (day 6). This pattern is consistent with the oogenesis-flight syndrome, in which reproductive maturity is delayed until after migration occurs.

Phenotypic Plasticity in Reproductive Behaviour of Waterstriders: Trade-Offs Between Reproduction and Longevity During Food Stress

This paper addresses the question of how plasticity of reproductive behaviour varies between and within waterstrider species. I focus especially on how females differ in trade-offs between longevity and reproductive investment as the food availability changes. I reared long-winged waterstriders in high and low food levels. The trade-off between reproductive investment and longevity was measured as changes in life-span and fecundity at a low food level compared to that at an abundant food level. The direction of trade-off was compared (1) between morphs that differ in flight ability, (2) between Finnish and Hungarian populations of Gerris thoracicus Schummel, and (3) among Finnish G. thoracicus, G. odontogaster (Zett.) and G. lacustris (L.) populations. Results show differences in phenotypic plasticity at all levels. When the environment was relatively permanent or as the number of generations increased, females maintained relatively high reproductive investment when food was scarce even at the cost of reduced life-span. In unpredictable environments, females reduced reproduction during food stress so that they maintained long reproductive life-spans. The cost of being able to fly differed between populations of G. thoracicus. In the Finnish population females that could fly had shorter life-spans during food stress than flightless females. In the Hungarian population flightless females had higher fecundity than flyers. Hence phenotypic plasticity in reproductive behaviour is an important life-history trait. The direction of trade-off between reproduction and longevity may vary between two females that have * Present address: A. Kaitala, University of Stockholm, Department of Zoology, S-106 91 Stockholm, Sweden. the same reproductive potential in optimal food conditions. Hence the two females have totally different reproductive tactics in response to variation in resources. Key-words: Flight-muscle histolysis, food stress, longevity, phenotypic plasticity, reproduction, trade-off, waterstriders

Remex Growth and Body Mass of Mallards during Wing Molt

-We captured, banded (n = 4,129), and weighed (n = 809) Mallards (Anas platyrhynchos) during wing molt in western Poland. The condition of remex development was assessed (n = 3,421). We recaptured and remeasured 248 birds. The rate of remex growth in males (calculated by two methods) was 6.7 and 5.5 mm/day (P < 0.02). Males regained flight capability in 22-29 days, when remiges had reached 75-83% of final length. During the flightless period, males and females lost 12% of body mass. Birds whose flightless period was extended to replace only a few damaged quills continued to decline in body mass, which indicates that rate of mass loss was unrelated to costs of feather synthesis. We conclude that decrease of body mass is related to constraints on foraging time. We think this is a response to high exposure to predation during foraging. Reduction of flightlessness seems to be realized by a high growth rate of remiges, which was almost constant and independent of body mass. Received 24 August 1988, accepted 25 September 1989. LIKE other waterfowl, Mallards shed all their primaries and secondaries simultaneously, and are flightless during the period of wing molt. Flightless birds are more susceptible to predation, and movements are constrained. This situation influences habitat selection, antipredator behavior, foraging, and energy budget. Body mass decreases and body composition changes during flightlessness. Several hypotheses attempt to account for the changes in body mass. Hanson (1962) concluded that remex molt is a period of great nutritional stress for Canada Geese, and birds must catabolize body tissues to build feathers. Ankney (1979) argued that flightless geese can meet their nutrient requirements from the diet, and that maintenance of a superfluous reserve would be a waste of energy. Decreased body mass during molt may be adaptive, because it enabled birds to fly before completing growth of remiges, and this reduced the flightless period (Douthwaite 1976, Dean and Skead 1979, Owen and Ogilvie 1979, Bailey 1985, Austin and Fredrickson 1987, Sjoberg 1988). Young and Boag (1982) suggested that ducks may lose feeding opportunities as a result of secretive behavior. Douthwaite (1976) suggested that reserves accumulated before the molt make birds less vulnerable to food shortages where they would be exposed to predators. These hypotheses are not mutually exclusive, and Pehrsson (1987) suggested that limitation of foraging and use of body reserves minimalize exposure to predation and simultaneously shorten flightlessness. STUDY AREA AND METHODS This study was conducted in the floodplain of the River Warta at its confluence with the Odra River, western Poland (Majewski 1986). Flightless ducks concentrate in willow bushes (Salix spp.) surrounded by shallow water. The number of male Mallards that molt here reaches 25,000, many times greater than the number of local breeders. In 1981-1982 flightless Mallards were surrounded and driven into a net enclosure (Majewski 1981). Birds were banded (3,788 males and 341 females), weighed to the nearest 20 g (640 males and 169 females), and the ninth primary was measured to the nearest 1.0 mm (3,143 males and 278 females). The birds were then released. We recaptured 337 males and 13 females, typically after 3-9 days. Each was remeasured. Because most females were trapped late in the season, there were relatively few recaptures. We calculated the rate of remex growth from differences between lengths of the remiges divided by number of days between capture and recapture of each individual (n = 237). Birds with broken or pulled remiges were excluded, but some damage to remiges might have been overlooked. When caught for the first time, some birds shed their remiges, but regrowth was not yet visible. Recapture of these birds (n = 12) provided remex growth rates from the beginning of feather replacement. The remex length required to resume flight was established from the longest primaries among captured birds. We assumed that birds capable of flying could not be captured. We measured final length of the ninth primary in 18 males and 50 females caught or shot in other seasons. We estimated duration of flightlessness from the growth rate of remiges. Changes in body mass during molt were calculated 255 The Auk 107: 255-259. April 1990 This content downloaded from 207.46.13.101 on Sat, 08 Oct 2016 05:49:11 UTC All use subject to http://about.jstor.org/terms 256 PANEK AND MAJEWSKI [Auk, Vol. 107

Life-history Traits of Forest-inhabiting Flightless Lepidoptera

-Some species of forest-inhabiting Lepidoptera possess a set of life-history traits including flightless females, larval dispersal by ballooning, polyphagy, univoltinism and overwintering larvae or eggs. Convergence in these life-history traits occurs in species from the Geometridae, Lymantriidae and Psychidae. Ecological factors in the forest habitat which probably contribute to this convergence include habitat stability, resource persistence, convergence in tree chemical defense and phenological variability in bud-break. These lifehistory traits contribute to the ability of these species to reach high population density during years favorable to larval growth and survival resulting in the economic importance of these species. Increased fecundity may be associated with flightlessness, although nutritional studies comparing number of eggs produced in relation to female pupal weight for species with flighted and flightless females must be performed to evaluate this assertion.

The habitat templet and life history strategies of pond skaters (Heteroptera: Gerridae): reproductive potential, phenology, and wing dimorphism

Reproductive traits, diapause, and wing dimorphism of four pond skater species occurring in central Alberta, Canada, are explained as adaptive responses to a complex of habitat features. Species using temporary habitats had greater fecundity, but habitat permanence alone was a poor predictor of reproductive longevity, preoviposition period, or reproductive rate. Fecundity and longevity were significantly lower and more variable in direct than in diapaused breeders. There was no geographical or annual variation in fecundity, suggesting that values observed are good measures of reproductive potential. Overwintered females of species from temporary habitats (Gerris buenoi and Limnoporus dissortis) lived longer than those from more permanent habitats (G. comatus and G. pingreensis), and, concomitantly, are able to spread reproduction over several ponds. Proportion of summer-generation bugs breeding without diapause was inversely related to habitat permanence for the Gerris species, but few nondiapause breeders occurred in L. dissortis. Diapause was not averted consistently by exposure to increasing long-day photoperiods, and sensitive stage for diapause induction varied within all species. In G. pingreensis and L. dissortis many individuals reaching the adult and fifth instar by the solstice diapaused. Diapause and wing morphism were associated only loosely in the dimorphic species. Many apterous G. pingreensis entered diapause despite early emergence. Wing morph in G. pingreensis is determined genetically but is not based in simple Mendelian inheritance. Flightless bugs occur mainly among direct breeders in G. buenoi and G. comatus but many direct breeders were macropterous. Wing morph is influenced by a photoperiod switch in G. buenoi, but there is also genetic variation. There was no significant difference in total fecundity, longevity, or juvenile development time between wing morphs of the same generation in either G. buenoi or G. pingreensis. However, flightless females had shorter preoviposition periods, leading to greater egg production over the first 20 days of reproductive life. Gerrid life histories are adaptions to a complex of factors, including but not confined to habitat stability. Other aspects of the habitat templet such as the impact of natural enemies and food input should be considered.

Reproductive cost of flight capability: a comparison of life history traits in wing dimorphic planthoppers

Abstract. 1. Reproductive costs associated with flight capability were evaluated in the wing dimorphic planthopper, Prokelisia dolus Wilson, by comparing the life history of traits of winged (macropterous) and flightless (brachypterous) females under controlled laboratory conditions.2. Macropters with large thoraces and fully developed wings maintain a greater investment in flight apparatus than brachypters with small thoraces and reduced wings.3. Associated with greater flight capability in the macropter of P.dolus are shorter adult life, decreased total fecundity, and delayed age at first reproduction compared to brachypterous females.4. Under field conditions where mortality is high, the difference in realized fecundity between the two wing forms living on similar resources is further exaggerated with the brachypter having the greater advantage.5. When the life history traits of the wing forms of P. dolus are compared with traits for nine other species of planthoppers, two similarities emerge. First, the preoviposition period of the macropterous wing form is always longer than that for the brachypter resulting in a reproductive delay. Second, most studies show that macropters are less fecund than brachypters.6. There is no general tendency among planthopper species for macropterous adults to live fewer days or develop more slowly as nymphs compared to their flightless counterparts.7. The reproductive delay and reduced fecundity of the volent wing form of planthoppers supports the notion that flight capability is costly and that phenotypic trade‐offs between flight and reproduction exist.

Auditory characteristics and sexual dimorphism in the gypsy moth

ABSTRACT. The auditory characteristics of two populations (laboratory reared and wild) of North American gypsy moths (Lymantriidae: Lymantria dispar L.) were sampled and the neurally derived thresholds of wild males and females to frequencies from 5 to 150 kHz compared. The noctuoid auditory receptors, Al and A2‐cell, and putative proprioceptor, B‐cell, were identified. Both sexes possess neurally responsive ears but females exhibit median best frequencies significantly lower than those of males. Audiogram comparisons reveal significantly different thresholds at 5–15 kHz, 30–120 kHz and 130–140 kHz, with females less sensitive to all but the lowest frequencies. Wild male populations reveal less audiogram variability than laboratory‐reared individuals, while females' tuning curves appear more similar. The high variability present in colony moths warrants caution in the use of laboratory‐reared insects for studies that assume natural levels of selection pressure. We suggest that male L. dispar possess adaptively functional ears tuned to the frequencies in the echo‐location signals of bats but that the flightless females of this species are not exposed to bat predation and therefore possess ears in a state of evolutionary degeneration.

The biology of Physcus seminotus Silv. and P. subflavus Annecke &amp; Insley (Aphelinidae), parasites of the sugar-cane scale insect Aulacaspis tegalensis (Zhnt.) (Diaspididae)

Physcus seminotus Silv. (properly P. sp. nr. seminotus Silv.) and P. subflavus Annecke &amp; Insley (Aphelinidae) are parasites of the sugar-cane scale insect Aulacaspis tegalensis (Zhnt.) (Diaspididae) in East Africa and they have been purposely introduced into Mauritius where A. tegalensis is an important pest. P. seminotus has brachypterous, flightless females and P. subflavus winged females but their biology is essentially similar. The parasites are arrhenotokous and fertilised and unfertilised eggs are deposited in different sites concomitant with development of female and male larvae on different primary hosts. Female larvae develop endoparasitically in A. tegalensis from fertilised eggs deposited in the host's body cavity. Male larvae develop ectoparasitically on immature Hymenoptera in A. tegalensis from unfertilised eggs deposited in the air-filled cavity of the latter's integumentary remnant. The males of the two Physcus spp. are therefore hyperparasitic and they frequently develop on the immature stages, both male and female, of their own kind (autoparasitism). Unfertilised eggs are laid by virgin females and also by mated females, the latter being able to deposit fertilised and unfertilised eggs at will, depending on the egg site encountered. Sexual dimorphism occurs at all stages, including the deposited egg. The preovipositional adult is the preferred stage of A. tegalensis for deposition of fertilised eggs and development of females is most rapid in such hosts. Development in young hosts is arrested until the hosts have grown to virtually their full size. The host of a male is apparently a matter of chance in so far as evelopment will occur on larval and pupal Hymenoptera of various species found in the empty, inflated, brittle integument of parasitised A. tegalensis. Only one individual, whether male or female, develops per host. Oviposition behaviour of mated females is such that superparasitism is largely avoided but it is liable to occur frequently when virgin females oviposit. Adult females will feed on the body fluids of A. tegalensis that are released by insertion of the ovipositor and also on sugary fluids. They live a month or more, ovipositing continually at a gradually decreasing rate, and laying usually 50–100 eggs.

New and little known species of Azotus Howard, Ablerus Howard and Physcus Howard (Hym., Aphelinidae) from Africa and Mauritius

Descriptions are given of five new species of Azotus Howard from the Ethiopian region, including one from Mauritius. These bring the total number of Azotus species known from this region to eight. Two described species, A. capensis Howard and A. elegantulus Silvestri, are annotated and figured, and a key to the species is given. The related genus, Ablerus Howard, is recorded from Africa for the first time on the basis of a new species from the eastern Cape Province, and a new East African species of Physcus Howard, is described. A second East African species of the latter genus, one with flightless females, is characterised but not named to species.

Ectosynibiosis Between Phorid Flies1 and Army Ants23

Minute phorid flies are the most abundant myrmecophilous insects living in colonies of army ants and their refuse deposits. More than 300 colonies of army ants (Dorylinae: Ecitonini) were sampled, and 3900 female and 469 male phorids were collected. The phorids were active constantly but were most commonly seen from 5:00 to 7:00 PM. They were abundant in refuse deposits and at the ends of emigration and raid columns after most or all of the ants had passed. The number of phorids with 1 colony varied greatly and sometimes exceeded 4000. Most species considered to be myrmecophiles were found with more than 1 ant species. The phorids are scavengers that feed on booty refuse and dead workers discarded by army ants, but may feed also on booty and live brood within bivouacs. Eggs laid near the beginning of a statary phase of the ants can develop into adults before the colony emigrates. Flightless females also emerged before the large-winged males, an adaptation that would increase cross mating by keeping females in the colony and forcing some males to fly to other bivouacs.

CONTROL OF DASYSTOMA SALICELLUM, A NEW PEST OF BLUEBERRIES IN BRITISH COLUMBIA

A leafroller, Dasystoma salicellum Hbn. (Lepidoptera:Oecophoridae), recorded on this continent only from Lulu Island, B.C., in 1955, became a pest m 1962 when the larvae were found infesting the early berries, and mechanical pickers dislodged large numbers into the crates. This univoltine, phytophagous, photopositive insect overwinters as the pupa in the litter under the bushes. Flightless females emerge in mid-March, mate, and lay eggs under the blossom scales and loose bark of the canes. The eggs hatch in 2 weeks beginning in mid-May and the larvae destroy flower buds, invade or scar the berries, and sometimes defoliate the bushes.Preblossom sprays were not effective because plots were reinfested by first-instar larvae blown in from wild hosts nearby. Single postblossom sprays of phosphamidon, TDE, mevinphos, malathion, carbaryl, and Perthane and three sprays of Thuricide (Bacillus thuringiensis Berliner) were all effective. Malathion is recommended. Several non-chemical methods of control are discussed.