Week Of Adult Life Research Articles

Early-adult methionine restriction reduces methionine sulfoxide and extends lifespan in Drosophila

Methionine restriction (MetR) extends lifespan in various organisms, but its mechanistic understanding remains incomplete. Whether MetR during a specific period of adulthood increases lifespan is not known. In Drosophila, MetR is reported to extend lifespan only when amino acid levels are low. Here, by using an exome-matched holidic medium, we show that decreasing Met levels to 10% extends Drosophila lifespan with or without decreasing total amino acid levels. MetR during the first four weeks of adult life only robustly extends lifespan. MetR in young flies induces the expression of many longevity-related genes, including Methionine sulfoxide reductase A (MsrA), which reduces oxidatively-damaged Met. MsrA induction is foxo-dependent and persists for two weeks after cessation of the MetR diet. Loss of MsrA attenuates lifespan extension by early-adulthood MetR. Our study highlights the age-dependency of the organismal response to specific nutrients and suggests that nutrient restriction during a particular period of life is sufficient for healthspan extension.

Nymph development and adult feeding on, and damage to, immature siliquae of canola by different species of stink bugs.

Studies were conducted in the laboratory and in the greenhouse with the objective of evaluating nymph development, adult body weight gain, and damage of different species of pentatomids feeding on fruit (hereafter referred to as siliqua) of canola, Brassica napus (L.) var. oleifera. Nymphs of Nezara viridula (L.) were able to reach adulthood feeding on siliquae (93.3% survivorship), while nymphs feeding on siliquae that had their seeds removed showed arrested development, only reaching the 4th instar and did not complete development to adulthood. Adults of N. viridula gained body weight feeding on canola siliquae, particularly during the first two weeks of adult life, dropping weight thereafter. Adults of another species of pentatomid, Diceraeus furcatus (F.), also gained body weight, while adults of Euschistus heros (F.) lost weight. N. viridula adults caused significantly greater damage to seeds (shrunken and with rotten aspect) within siliqua and to the siliqua walls (whitish spots with lesions in the form of starbursts, called rosettes) compared to D. furcatus and to E. heros. The amount of damaged seeds caused by N. viridula adults during the first week of adult life was greater (ca. 60%) compared to those of older females 32days of age (27%). Damage symptons caused by the feeding activity on siliqua walls (commonly known as rosettes) reached up to 10% of the total area with similar injury rates for N. viridula adults of different ages. The majority of N. viridula (70%) caused rosette, while only 20% of E. heros and 5% of D. furcatus produced similar damage.

Worker bees (Apis mellifera) deprived of pollen in the first week of adulthood exhibit signs of premature aging

Pollinator populations, including bees, are in rapid decline in many parts of the world, raising concerns over the future of ecosystems and food production. Among the factors involved in these declines, poor nutrition deserves attention. The diet consumed by adult worker honeybees (Apis mellifera) is crucial for their behavioral maturation, i.e., the progressive division of labor they perform, such as nurse bees initially and later in life as foragers. Poor pollen nutrition is known to reduce the workers’ lifespan, but the underlying physiological and genetic mechanisms are not fully understood. Here we investigate how the lack of pollen in the diet of workers during their first week of adult life can affect age-related phenotypes. During the first seven days of adult life, newly emerged workers were fed either a pollen-deprived (PD) diet mimicking that of an older bee, or a control pollen-rich (PR) diet, as typically consumed by young bees. The PD-fed bees showed alterations in their fat body transcriptome, such as a switch from a protein-lipid based metabolism to a carbohydrate-based metabolism, and a reduced expression of genes involved with immune response. The absence of pollen in the diet also led to an accumulation of oxidative stress markers in fat body tissue and alterations in the cuticular hydrocarbon profiles, which became similar to those of chronologically older bees. Together, our data indicate that the absence of pollen during first week of adulthood triggers the premature onset of an aging-related worker phenotype.

Regulatory Roles of Drosophila Insulin-Like Peptide 1 (DILP1) in Metabolism Differ in Pupal and Adult Stages.

The insulin/IGF-signaling pathway is central in control of nutrient-dependent growth during development, and in adult physiology and longevity. Eight insulin-like peptides (DILP1–8) have been identified in Drosophila, and several of these are known to regulate growth, metabolism, reproduction, stress responses, and lifespan. However, the functional role of DILP1 is far from understood. Previous work has shown that dilp1/DILP1 is transiently expressed mainly during the pupal stage and the first days of adult life. Here, we study the role of dilp1 in the pupa, as well as in the first week of adult life, and make some comparisons to dilp6 that displays a similar pupal expression profile, but is expressed in fat body rather than brain neurosecretory cells. We show that mutation of dilp1 diminishes organismal weight during pupal development, whereas overexpression increases it, similar to dilp6 manipulations. No growth effects of dilp1 or dilp6 manipulations were detected during larval development. We next show that dilp1 and dilp6 increase metabolic rate in the late pupa and promote lipids as the primary source of catabolic energy. Effects of dilp1 manipulations can also be seen in the adult fly. In newly eclosed female flies, survival during starvation is strongly diminished in dilp1 mutants, but not in dilp2 and dilp1/dilp2 mutants, whereas in older flies, only the double mutants display reduced starvation resistance. Starvation resistance is not affected in male dilp1 mutant flies, suggesting a sex dimorphism in dilp1 function. Overexpression of dilp1 also decreases survival during starvation in female flies and increases egg laying and decreases egg to pupal viability. In conclusion, dilp1 and dilp6 overexpression promotes metabolism and growth of adult tissues during the pupal stage, likely by utilization of stored lipids. Some of the effects of the dilp1 manipulations may carry over from the pupa to affect physiology in young adults, but our data also suggest that dilp1 signaling is important in metabolism and stress resistance in the adult stage.

The septate junction protein Tetraspanin 2A is critical to the structure and function of Malpighian tubules in Drosophila melanogaster.

Tetraspanin-2A (Tsp2A) is an integral membrane protein of smooth septate junctions in Drosophila melanogaster. To elucidate its structural and functional roles in Malpighian tubules, we used the c42-GAL4/UAS system to selectively knock down Tsp2A in principal cells of the tubule. Tsp2A localizes to smooth septate junctions (sSJ) in Malpighian tubules in a complex shared with partner proteins Snakeskin (Ssk), Mesh, and Discs large (Dlg). Knockdown of Tsp2A led to the intracellular retention of Tsp2A, Ssk, Mesh, and Dlg, gaps and widening spaces in remaining sSJ, and tumorous and cystic tubules. Elevated protein levels together with diminished V-type H+-ATPase activity in Tsp2A knockdown tubules are consistent with cell proliferation and reduced transport activity. Indeed, Malpighian tubules isolated from Tsp2A knockdown flies failed to secrete fluid in vitro. The absence of significant transepithelial voltages and resistances manifests an extremely leaky epithelium that allows secreted solutes and water to leak back to the peritubular side. The tubular failure to excrete fluid leads to extracellular volume expansion in the fly and to death within the first week of adult life. Expression of the c42-GAL4 driver begins in Malpighian tubules in the late embryo and progresses upstream to distal tubules in third instar larvae, which can explain why larvae survive Tsp2A knockdown and adults do not. Uncontrolled cell proliferation upon Tsp2A knockdown confirms the role of Tsp2A as tumor suppressor in addition to its role in sSJ structure and transepithelial transport.

Biology of a Neotropical Harlequin Stink Bug, Runibia perspicua (F.).

Laboratory and field studies were conducted with nymphs and adults of the Neotropical stink bug Runibia perspicua (F.) to evaluate their biology on plants. Total nymph mortality was ca. 13% on immature fruits of Brunfelsia australis Benth. (IFBA) and 90% on raw shelled peanuts, Arachis hypogaea L. (RSP); no nymphs survived on immature pods of green bean, Phaseolus vulgaris L., or on immature fruits of privet, Ligustrum lucidum Ait. Nymph developmental time was ca. 36 on IFBA and 55days on RSP. Body weight was significantly greater when nymphs were raised isolated compared to those raised in groups. Adult feeding activity was greater than third instars on IFBA. Adult longevity on IFBA + cherry tomato, Solanum lycopersicum L. fruit, reached ca. 150days. On IFBA, fecundity was 2.5 egg masses/female and 48.3 eggs/female; 25.6% of the eggs hatched. Adults did not reproduce on tomato. Body weight gain did not increase significantly for both sexes during the first four weeks of adult life on IFBA. In the field, plants of B. australis were surveyed in Passo Fundo, RS (28°15'S; 52°24'W). The majority of egg masses were deposited on the lower (abaxial) surface of leaves. Nymphs aggregated on immature fruits, and adults were seldom found on the plants. These are the first data on the performance of R. perspicua on B. australis indicating that this plant species is suitable to the bug's biology.

Age‐related and light‐induced plasticity in opsin gene expression and in primary and secondary visual centers of the nectar‐feeding ant Camponotus rufipes

Camponotus rufipes workers are characterized by an age-related polyethism. In the initial weeks of adult life, young workers perform tasks inside the nest before they switch to multimodal foraging tasks outside. We tested the hypothesis that this transition is accompanied by profound adaptations in the peripheral and central visual systems. Our results show that C. rufipes workers of all tested ages (between 1 and 42 days) express three genes encoding for ultraviolet (UV), blue (BL), and long-wavelength (LW1) sensitive opsins in their retina, which are likely to provide the substrate for trichromatic color vision. Expression levels of all three opsin genes increased significantly within the first two weeks of adulthood and following light exposure. Interestingly, the volumes of all three optic neuropils (lamina, medulla, and lobula) showed corresponding volume increases. Tracing of connections to higher visual centers in the mushroom bodies (MBs) revealed only one optic pathway, the anterior superior optic tract, emerging from the medulla and sending segregated input to the MB-calyx collar. The MB collar volumes and densities of synaptic complexes (microglomeruli, MGs) increased with age. Exposure to light for 4 days induced a decrease in MG densities followed by an increase after extended light exposure. This shows that plasticity in retinal opsin gene expression and structural neuroplasticity in primary and secondary visual centers comprise both "experience-independent" and "experience-dependent" elements. We conclude that both sources of plasticity in the visual system represent important components promoting optimal timing of the interior-forager transition and flexibility of age-related division of labor. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 76: 1041-1057, 2016.

Neuronal plasticity in the mushroom body calyx during adult maturation in the honeybee and possible pheromonal influences.

Honeybee workers express a pronounced age-dependent polyethism switching from various indoor duties to foraging outside the hive. This transition is accompanied by tremendous changes in the sensory environment that sensory systems and higher brain centers have to cope with. Foraging and age have earlier been shown to be associated with volume changes in the mushroom bodies (MBs). Using age- and task-controlled bees this study provides a detailed framework of neuronal maturation processes in the MB calyx during the course of natural behavioral maturation. We show that the MB calyx volume already increases during the first week of adult life. This process is mainly driven by broadening of the Kenyon cell dendritic branching pattern and then followed by pruning of projection neuron axonal boutons during the actual transition from indoor to outdoor duties. To further investigate the flexible regulation of division of labor and its neuronal correlates in a honeybee colony, we studied the modulation of the nurse-forager transition via a chemical communication system, the primer pheromone ethyl oleate (EO). EO is found at high concentrations on foragers in contrast to nurse bees and was shown to delay the onset of foraging. In this study, EO effects on colony behavior were not as robust as expected, and we found no direct correlation between EO treatment and synaptic maturation in the MB calyx. In general, we assume that the primer pheromone EO rather acts in concert with other factors influencing the onset of foraging with its effect being highly adaptive.

Sublethal effects of insecticide seed treatments on two nearctic lady beetles (Coleoptera: Coccinellidae).

Predatory insects often feed on plants or use plant products to supplement their diet, creating a potential route of exposure to systemic insecticides used as seed treatments. This study examined whether chlorantraniliprole or thiamethoxam might negatively impact Coleomegilla maculata and Hippodamia convergens when the beetles consumed the extrafloral nectar of sunflowers grown from treated seed. We reared both species on eggs of Ephestia kuehniella and then switched adult H. convergens to a diet of greenbugs, Schizaphis graminum, in order to induce oviposition in this species. Excised sunflower stems, either treated or control and refreshed every 48 h, were provided throughout larval development, or for the first week of adult life. Exposure of C. maculata larvae to chlorantraniliprole and thiamethoxam applied as seed treatments delayed adult emergence by prolonging the pupal period. When adults were exposed, thiamethoxam reduced the preoviposition period compared to chlorantraniliprole, whereas the latter treatment cause females to produce fewer clutches during the observation period. Larvae of C. maculata did not appear to obtain sufficient hydration from the sunflower stems and their subsequent fecundity and fertility were compromised in comparison to the adult exposure experiment where larvae received supplemental water during development. Exposure of H. convergens larvae to thiamethoxam skewed the sex ratio in favor of females; both materials reduced the egg viability of resulting adults and increased the period required for eclosion. Exposure of H. convergens adults to chlorantraniliprole reduced egg eclosion times compared to thiamethoxam and exposure to both insecticides reduced pupation times in progeny. The results indicate that both insecticides have negative, sublethal impacts on the biology of these predators when they feed on extrafloral nectar of sunflower plants grown from treated seed.

Dynamic haematopoietic cell contribution to the developing and adult epicardium.

The epicardium is a cellular source with the potential to reconstitute lost cardiovascular tissue following myocardial infarction. Here we show that the adult epicardium contains a population of CD45+ haematopoietic cells (HCs), which are located proximal to coronary vessels and encased by extracellular matrix (ECM). This complex tertiary structure is established during the regenerative window between post-natal days 1 and 7. We show that these HCs proliferate within the first 24 h and are released between days 2 and 7 after myocardial infarction. The ECM subsequently reforms to encapsulate HCs after 21 days. Vav1-tdTomato labelling reveals an integral contribution of CD45+ HCs to the developing epicardium, which is not derived from the proepicardial organ. Transplantation experiments with either whole bone marrow or a Vav1+ subpopulation of cells confirm a contribution of HCs to the intact adult epicardium, which is elevated during the first 24 weeks of adult life but depleted in aged mice.

Development and plasticity of mitochondria and electrical properties of the cell membrane in blowfly photoreceptors.

Blowfly photoreceptors are highly energy demanding sensory systems. Their information processing efficiency is enabled by the high temporal resolution of the cell membrane, requiring heavy metabolic support by the mitochondria. We studied the developmental changes of the mitochondrial apparatus and electrical properties of the photoreceptor membrane in the white eyed Calliphora vicina Chalky. Using in vivo microspectrophotometry and Western blot analysis, we found an age-dependent increase in the concentration of mitochondrial pigments. The maximal change occurred during the first week. The age-related changes were smaller in dark-bred than in light-bred flies. The mitochondrial pigment content increased after the switch from dark to light rearing and decreased after the switch from light to dark rearing. The electrical parameters of the photoreceptors were investigated with intracellular recordings. The resting membrane resistance and time constant decreased significantly after eclosion. The decrease was again most significant during the first week of adult life, paralleled with changes in the Na/K pump-dependent hyperpolarizing afterpotential. We conclude that the photoreceptor mitochondria exhibit remarkable ontogenetic and phenotypic plasticity, because the quantity of mitochondrial pigments tightly follows the development of the cell membrane as well as the energy demands of the photoreceptors under different rearing conditions.

Heterogeneity's ruses: How hidden variation affects population trajectories of age-dependent fecundity in Drosophila melanogaster

AbstractBACKGROUNDProgress in understanding senescence requires information about age-dependent changes in individual organisms. However, for experimental systems such as Drosophila melanogaster we usually do not know whether population trajectories are an accurate guide to patterns of individual aging, or are artifacts of population heterogeneity.OBJECTIVEIn experimental cohorts of D. melanogaster, population trajectories of age-specific fecundity typically plateau in old age. Here we ask whether fecundity plateaus can be explained by hidden heterogeneity in reproductive life spans (RLS).METHODSUsing published and original data from five experimental populations, we examined fecundity trajectories in subpopulations stratified by RLS, and in total populations with age expressed relative to RLS for each individual fly. We also executed computer simulations of reproductive senescence in which individuals vary in RLS, and show linear decline in fecundity with increasing age.RESULTSIn subgroups of flies with similar RLS, the senescent decline of fecundity is generally linear. Population trajectories in which age is expressed relative to individual RLS also exhibit linear or slightly accelerated decline. Simulations demonstrate that observed levels of variation in RLS are sufficient to produce plateaus in the mixture trajectories that are very much like those observed in experiments, even though fecundity declines linearly in individuals.CONCLUSIONSLate-life fecundity plateaus in D. melanogaster are artifacts of population heterogeneity in RLS. This conclusion applies to both inbred and outbred populations, and both wild and lab-adapted stocks. For reproductive senescence in this model system, population trajectories are not an accurate guide to individual senescence.1. IntroductionOne goal of biodemography is to understand the forces that shape trajectories of survival and reproduction in laboratory populations of experimental organisms. Here we examine original and published life history data from five populations of the fruit fly Drosophila melanogaster. Our objective is to determine whether population trajectories of age-specific fecundity, which plateau late in life, accurately reflect the pattern of reproductive senescence in individual flies, or whether plateaus are artifacts of population heterogeneity.Examples of population fecundity trajectories are shown in Figure 1. The reproductive chronology starts when females mate, store sperm, and begin laying eggs, one or two days after emergence from the puparium. Flies typically reach peak daily fecundity within the first two weeks of adult life, and then exhibit declining fecundity in old age. At some point in mid- to late-life, the decline moderates and population trajectories inflect upward, producing fecundity plateaus. The plateaus could reflect real biological change in individuals, or they could be an example of heterogeneity's ruses (Vaupel and Yashin 1985). The alternative explanations are analogous to discussions surrounding mortality plateaus, which are well documented in this species (Curtsinger et al. 1992; Vaupel et al. 1998, Khazaeli, Pletcher, and Curtsinger 1998; Wachter 1999; Drapeau et al. 2000; Service 2000; Curtsinger, Gavrilov, and Gavrilova 2006).1.1 The argument for late-life fecundity plateausBased on study of three genetically heterogeneous, lab-adapted populations of D. melanogaster, Rauser et al. (2003; 2005a, 2005b; 2006) argued that reproductive senescence is best understood as a two-stage process: rapid linear decline until a breakday age, followed by a fecundity plateau with low, relatively constant levels late in life. The evidence came primarily from fitting two-stage regression models to complete data on survival and reproduction of individual flies, and also from testing and rejecting a heterogeneity model that involved trade-offs between survival and reproduction (Rauser et al. …

Effect of Photoperiod and Temperature on Nymphal Development and Adult Reproduction ofPiezodorus guildinii(Heteroptera: Pentatomidae)

The effect of photoperiod and temperature on the biology of nymphs and adults of Piezodorus guildinii (Westwood) was studied in the laboratory. Four different conditions were tested (14:10, 12:12 and 10:14 h L:D at 25 °C, and 10:14 h L:D at 20 °C), at 80 ± 10% RH. The shortest nymph development time was recorded at 14:10 h L:D (25 °C) (21.5 days) and the longest at 10:14 h L:D (20 °C) (42 days). The highest nymph mortality rate was recorded at 10:14 h L:D (20 °C) and the lowest at 14:10 h L:D (25 °C) (84.5 vs. 24.2%). Newly emerged females reared at 14:10 h L:D (25 °C) were heavier than those of the remaining treatments. Fresh body weight gain (mg) occurred only during the 1st week of adult life. Adult survivorship was highest at 10:14 h L:D (20 °C) and lowest at 14:10 h L:D (25 °C). Total longevity was shortest when adults were held at 14:10 h L:D (25 °C) and longest at 10:14 h L:D (20 °C) (38.6 vs. 98.8 days). The maximum percentage of ovipositing females occurred at 14:10 h L:D (25 °C) and the minimum at 10:14 h L:D (20 °C). Females maintained at 14:10 h L:D (25 °C) and 12:12 h L:D (25 °C) produced similar and greater number of egg masses than females at 10:14 h L:D (25 °C) and 10:14 h L:D (20 °C). The number of eggs/female was the greatest at 14:10 h L:D (25 °C) and the lowest at 10:14 h L:D (20 °C) (196.2 vs. 21.7 eggs/♀). Egg viability was similar under different photophases at 25 °C, while significantly reduced at 10:14 h L:D (20 °C) (54 vs. 4.1%). The longest egg incubation period was recorded at 10:14 h L:D (20 °C) and the shortest at 14:10 h L:D (25 °C) (7 vs. 4.1 days). These laboratory results suggest that P. guildinii does not reproduce during the time its preferred host soybean is unavailable at latitude 30°–35° S, which corresponds approximately to the conditions tested at 10:14 h L:D (20 °C).

Age- and behaviour-related changes in the expression of biogenic amine receptor genes in the antennae of honey bees (Apis mellifera)

We recently identified changes in amine-receptor gene expression in the antennae of the honey bee that correlate with shifts in the behavioural responsiveness of worker bees towards queen mandibular pheromone. Here we examine whether variations in expression of amine-receptor genes are related to age and/or to behavioural state. Colonies with a normal age structure were used to collect bees of different ages, as well as pollen foragers of unknown age. Single- and double-cohort colonies were established also to generate nurses and pollen foragers of the same age. Amdop1 was the only gene examined that showed no significant change in expression levels across the age groups tested. However, expression of this gene was significantly higher in 6-day-old nurses than in pollen foragers of the same age. Levels of expression of Amdop2 were very variable, particularly during the first week of adult life, and showed no correlation with nursing or foraging behaviour. Amdop3 and Amtyr1 expression levels changed dramatically with age. Interestingly, Amtyr1 expression was significantly higher in 15-day-old pollen foragers than in same-age nurses, whereas the opposite was true for Amoa1. While Amoa1 expression in the antennae was lower in 6- and 15-day-old pollen foragers than in nurses of the same age, differences in gene expression levels between nurses and pollen foragers could not be detected in 22-day-old bees. Our data show dynamic modulation of gene expression in the antennae of worker bees and suggest a peripheral role for biogenic amines in regulating behavioural plasticity in the honey bee.

Floral scents learned inside the honeybee hive have a long-lasting effect on recruitment

Floral scents learned during the waggle dance, a signal through which honeybees provide nestmates with spatial information on foraging sites, are an important component of recruitment. Forager bees can be reactivated to go to previously exploited food sources by perceiving scents they learned at the flowers within the dance context. Here, we tested whether floral scents experienced not at the foraging site, but via scented nectar inside the nest, can influence subsequent recruitment. We determined that bees that were exposed to scented food while in the hive tended to follow dances in which the recruiting bee presented the same odour experienced 8 days earlier. Moreover, a higher proportion of bees with in-hive experience were successfully recruited to the feeding sites scented with the experienced odours than to the feeding sites scented with novel odours. This bias in recruitment was independent of the time that the bees spent following dances. These findings suggest that associative memories acquired even as early as the first week of adult life were responsible for a variation in recruitment. We discuss our results in terms of the adaptive value of the long-term olfactory memories acquired inside the nest as a facilitator to decode the spatial information transmitted in the honeybee dance.

Patterns of male fitness conform to predictions of evolutionary models of late life

We studied lifetime male virility, a male fitness component, in five populations of Drosophila melanogaster. Virility was measured as the number of females, of eight total, that a male could fertilize in 24 h. Individual males were measured at weekly intervals until they died. Virility declined in an approximately linear fashion for the first 3 weeks of adult life. It then stayed low but relatively constant for another 3 weeks, exhibiting a clear plateau. These observations are consistent with the evolutionary theories of late life. The results were not consistent with a simple heterogeneity theory of late life. This is the first demonstration of a late-life plateau for a male fitness component. We also found that the virility of males that were within 7 days of death was significantly lower than that of similarly aged males that were not about to die. This rapid deterioration of virility prior to death, or death spiral, is similar to a decline in fecundity that we had previously documented.

Comparative performance of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) across populations, resource types and structural forms of those resources

The significance of Tribolium castaneum (Herbst) as a pest of stored grains will likely be influenced by the relative availability of different resources regionally and the beetles’ ability to utilize each of them. Therefore the performance across the life cycle of laboratory and field populations of T. castaneum on commonly available structural forms of wheat and sorghum, as conventional resources, was quantified and compared to that on cotton seed. The latter is not usually associated with T. castaneum, but large beetle infestations have been recorded commonly in cotton gins in Australia. The highest number of individuals of each stage (from a given number of eggs) developed on wheat and sorghum flour and kibbled seeds. Cotton seed did not support the development of laboratory population beetles and all neonate larvae died before pupation. In contrast, some of the field population larvae did develop on cotton flour, but their number was significantly lower in comparison to development on wheat and sorghum. Field population beetles produced significantly more eggs than did laboratory population beetles, on both the whole seed and flour. Field population females had a consistently higher fecundity (∼78% more eggs) than the laboratory population females, at least over the first three weeks of adult life. These results suggest that field populations of T. castaneum should be used in experiments if we are to develop a more realistic understanding of the field ecology of this species. The relative rate at which these insects infest available resources in the field also warrants further investigation.

Population Growth Potential of the Bed Bug, Cimex lectularius L.: A Life Table Analysis.

Experimental life tables were constructed and analyzed for three strains of the common bed bug: a pyrethroid-susceptible laboratory strain (HS), a highly resistant field strain (RR), and a field strain with a declining level of resistance (KR). Egg to adult survival in the RR strain was 94% compared with 79% and 69% in the HS and KR strains, respectively. The RR strain also developed significantly faster from egg to adult (∼35 days) than the other two strains (∼40 days). Analysis of a survivorship and fecundity life table for the RR strain produced the following results. The average life expectancy for a newly laid egg was ∼143 days, and that of a newly molted adult was ∼127 days. Females produced an average of 0.64 daughter eggs/day with the highest weekly production during the fifth week of adult life. Analysis of daily reproductive parity showed that females produced 1–3 and 4–6 eggs on 79 and 21% of the days, respectively, when egg laying occurred. The net reproductive rate (R0) of the RR strain was ∼35, which represents a 35-fold increase in the population per generation (∼92 days). The intrinsic rate of increase, r, was 0.054 indicating that the population multiplies 1.1 times/female/day (λ) and doubles in size every 13 days. The stable age distribution (cx) was dominated by nymphs (54%), followed by eggs (34%) and adults (12%). Reproductive values (vx) for the strain increased from egg to the adult stage.

A general model for mortality in adult tsetse (Glossina spp.)

Tsetse exhibit a U-shaped age-mortality curve, with high losses after eclosion and a well-marked ageing process, which is particularly dramatic in males. A three-parameter (k(1) -k(3) ) model for age-dependent adult instantaneous mortality rates was constructed using mark-recapture data for the tsetse fly Glossina morsitans morsitans Westwood (Diptera: Glossinidae). Mortality changed linearly with k(1) over all ages; k(2) affected only losses in roughly the first week of adult life, and k(3) controlled the ageing rate. Mortality pooled over age was twice as sensitive to changes in k(3) as in k(1) . Population growth rate was, however, similarly affected by these two parameters, reflecting the disproportionate effect of k(3) on mortality in the oldest flies that contribute least to the growth rate. Pooled-age mortality and growth rate were insensitive to changes in k(2) . The same model also provided good fits to data for laboratory colonies of female G. m. morsitans and Glossina austeni Newstead and should be applicable to all tsetse of both sexes. The new model for tsetse mortality should be incorporated into models of tsetse and trypanosome population dynamics; it will also inform the estimation of adult female mortality from ovarian dissection data.

Variation in and Responses to Brood Pheromone of the Honey Bee (APIS mellifera L.)

The 10 fatty acid ester components of brood pheromone were extracted from larvae of different populations of USA and South African honey bees and subjected to gas chromatography-mass spectrometry quantitative analysis. Extractable amounts of brood pheromone were not significantly different by larval population; however, differences in the proportions of components enabled us to classify larval population of 77% of samples correctly by discriminant analysis. Honeybee releaser and primer pheromone responses to USA, Africanized and-European pheromone blends were tested. Texas-Africanized and Georgia-European colonies responded with a significantly greater ratio of returning pollen foragers when treated with a blend from the same population than from a different population. There was a significant interaction of pheromone blend by adult population source among Georgia-European bees for modulation of sucrose response threshold, a primer response. Brood pheromone blend variation interacted with population for pollen foraging response of colonies, suggesting a self recognition cue for this pheromone releaser behavior. An interaction of pheromone blend and population for priming sucrose response thresholds among workers within the first week of adult life suggested a more complex interplay of genotype, ontogeny, and pheromone blend.