Food imprinting and subsequent prey preference in the lynx spider,Oxyopes salticus (Araneae: Oxyopidae)

This object of this study was to determine if early feeding experience can affect subsequent prey choice in lynx spiderlings (Oxyopes salticus), and if so, is it evidence for food/olfactory imprinting. After emergence from the egg sac, three groups of 10 spiderlings were each fed exclusively for a 1-week period on one of three naturally-occurring prey species (crickets): group 1 fed on nymphs of Gryllotalpa hexadactyla; group 2 (Dialeurodes citrifoli); group 3 (Microcentrum rhombifolium). Following this, they were tested for subsequent prey preference in choice tests conducted in a plastic arena. Each spiderling was presented simultaneously with one individual of each prey species in a randomized design. Spiderlings exhibited a significant first preference for the original diet. Thus, experience with certain foods encountered by newly hatched spiderlings can affect subsequent prey preference in this species. Given the primacy of the early experience, the results are best interpreted in terms of imprinting and represent the first demonstration of olfactory imprinting in a spider.     

Drop and swing dispersal behavior of a tropical wandering spider: experiments and numerical model

Summary When exposed to certain air flows spiderlings of the wandering spider Cupiennius getazi (Ctenidae) drop from their dwelling plant and swing in the wind from a gradually lengthening dragline. If body contact is made with a nearby substrate the spiderling detaches. We refer to this form of aerial dispersal as the drop and swing dispersal behavior (DASDB). The dragline being only up to about 70 cm long and only rarely ruptured by the drag forces of the wind, this is a close range type of dispersal as opposed to the ballooning known for many other species of spiders. DASDB is readily elicited in spiderlings at an age of ca. 9 days (outside egg sac). At this age their mass is 1.26 ±0.35 mg and their yolk usually depleted. They then start to catch prey and escape from the unfavorable conditions in the small space around the egg sac where hundreds of spiderlings compete. Air flow rates effectively eliciting DASDB in the laboratory are between 0.2 m/s and 1.5 m/s. The number of spiderlings showing DASDB increases considerably if the air flow is turbulent as opposed to laminar. A numerical model defining the window within which DASDB is supported mechanically was developed from theoretical considerations. Taking the effective wind speeds and the mechanical properties of the dragline, the model accounts very well for the fact that actual rupture of the dragline was observed only rarely in C. Getazi. Other features of the DASDB are also correctly predicted. The model is not only applicable to DASDB but also to the drop and swing preballooning behavior known to occur in several other species of spiders.Abbreviations DASDB drop and swing dispersal behavior     

Variation in group cohesion during the maternal social period of a subsocial spider

During the maternal social period, Amaurobius ferox spiderlings (Araneae: Amaurobiidae) show mutual tolerance, group cohesion and cooperation in prey capturing, which are recognized as the main characteristics in the evolution of spider sociality. Measuring spatial volume occupied by the spiderlings within the maternal web, this study investigated variation in group cohesion over the maternal social period, from emergence to dispersal. The results showed that the spatial volume of spiderlings varied greatly during the maternal social period and was associated with the development of the spiderlings. Strong group cohesion appeared to be related to maternal food provision, trophic egg laying and matriphagy. An increase of the spatial volume was obviously observed after matriphagy. The experiment revealed that group cohesion decreased after the second molt. A compact group of spiderlings should facilitate maternal food production at the prompted time, and reduced group cohesion after the second molt might lead to eventual dispersal of A. ferox spiderlings.     

Costs and Benefits of Maternal Care in a Subsocial Spider,Coelotes terrestris

The maternal social spider Coelotes terrestris demonstrates extended care towards its progeny: the mother guards its egg sac for 3–4 weeks, then stays with its young from the time of their emergence until their dispersal about 1 month later. The present investigation evaluates the adaptiveness of these maternal behaviours by comparing the fitness of females performing them with that of females separated from the egg sac or the spiderlings. By protecting their egg sacs from predation and parasites, and by pursuing this task while supplying the young with food, mothers enhance the survival rate and the development of many of their spiderlings. The costs linked with these activities, estimated by the ability to produce another clutch, appear variable according to the stage in the reproductive cycle. In such terms, the egg sac guarding appears to have a low cost in relation to the care given to the spiderlings.     

Physiological costs during the first maternal care in the wolf spider Pardosa saltans (Araneae,Lycosidae)

Many arachnids like other terrestrial arthropods, provide extensive maternal care. Few studies have quantified the underlying physiological costs of maternal care. We investigated how maternal care affects the free-moving wolf spider’s (Pardosa saltans) energy requirements. We described in detail their basic reproduction biology (i.e. carrying cocoon and young) and we evaluated the variation in the females’ energy reserves during maternal care. Our results show that mothers guard eggs until hatching and then guard their spiderlings for 27–30 more days. Laboratory observations indicated that spiderlings start leaving the maternal abdomen gradually 5–7 days after hatching. Females carry an egg sac (cocoon) that can weigh up to 77% of their post-reproduction weight and carry young that weigh 87–100% of their body mass. Females lost weight over time despite regular food intake, while carrying cocoon and young; but their weights increased gradually during the dispersal of young. The contributions of proteins, glucose and triglycerides to maintain females’ energy were calculated. Their energetic state varied during maternal care, in particular lipid levels declined, during the care of spiderlings when the females’ predatory behaviour was inhibited. Our results show that the maternal care provided by P. saltans females is particularly costly physiologically, during the 30 days following egg sac formation and development of spiderlings, even when food is available.     

Social Facilitation of Synchronized Molting Behavior in the Spider Amaurobius ferox (Araneae, Amaurobiidae)

During the social period, molting behavior of the young spider, Amaurobius ferox, is highly synchronized within the clutch. Result of the experimental study suggests that social facilitation among group members increased the synchronization. The duration of the molting period of grouped spiderlings was significantly shorter than that of individually isolated spiderlings. Involving the particular maternal strategy in food supply, this phenomenon might have adaptive values in the maintenance of mutual tolerance among the siblings by decreasing the interindividual difference in development and in the avoidance of cannibalism on molting individuals. This probably will also serve to make the peaceful collective behaviors of the spiderlings in matriphagy and cooperative prey capture during their social period.     

Adaptive advantages of maternal care and matriphagy in a foliage spider,Chiracanthium japonicum (Araneae: Coubionidae)

I examined the function of maternal care in a foliage spider,Chiracanthium japonicum. Females of this species make breeding nests with rolled-up grass leaves and provide themselves to spiderlings as food at the end of maternal care. By removing mothers from their offspring at 2 different times, the effects of maternal care on egg and spiderling survival rates were estimated separately. Mother attendance greatly improved survival and development of eggs as well as spiderlings. Detailed observations on the fate of immatures in breeding nests with and without their mothers showed lower hatching and spiderling emergence rates when mothers were removed. Furthermore, spiderlings that fed on their mother’s body showed accelerated growth and quickly molted into the 3rd instar with the delay of dispersal. This suggests that matriphagy, or eating the mother, enables spiderlings of this species to disperse at a later instar. Therefore, I conclude that the maternal care of this spider consists of guarding offspring, supporting offspring development and feeding spiderlings.     

Agonistic behaviour of female Tegenaria atrica in the presence of different aged spiderlings

The agonistic behaviour of adult female T. atrica increases with increasing age of spiderlings until 80 days post-emergence, then decreases. In all cases, cannibalism of spiderlings increases markedly after completion of their pre-dispersal period with a correlation between the switch of behaviour, from tolerance to cannibalism, and a modification of individual’s cuticular compounds. Experiments that compare spiderlings weight and mobility indicate that female agonistic behaviour are always low with spiderlings in pre-dispersal period, and high with spiderlings in post-dispersal period. Female reproductive state and the weight/mobility of spiderlings are not the only factors controlling the adult female’s agonistic behaviour towards spiderlings on her web, as tactochemical information plays an important role in modulating agonistic behaviour after close contact between female spiders and spiderlings. The agonistic behaviour of females appears to correspond with a change in the increase of polar compound levels (methylesters and fatty acids) and the decrease of apolar compound levels (hydrocarbons) in spiderlings of different ages.     

Larviposition, Host Cues, and Planidial Behavior in the Sound-Locating Parasitoid Fly Homotrixa alleni (Diptera: Tachinidae)

Some groups of tachinid flies deposit mobile first-instar larvae (or planidia) on or near their host. Flies within one such group, the tribe Ormiini, parasitize singing species of ensiferan Orthoptera and use sound for long distance host location. However, what induces tachinids to larviposit and whether planidia use any cues actively to locate their host remains poorly known. This paper examines the larviposition and planidial behavior of the ormiine Homotrixa alleni in relation to its bushcricket host, Sciarasaga quadrata. Sound alone was sufficient to elicit larviposition in gravid female H. alleni, where females arriving at an arena placed over a speaker broadcasting host song deposited an equal number of planidia in the presence or absence of a silent S. quadrata. Flies were observed to larviposit by forcibly expelling planidia up to 6 cm in a forward direction from the fly, with less than half of the trials with a host present resulting in physical contact between the host and the fly. In the host's absence, flies walked around the arena significantly more often, remained on the arena for the experimental duration (10 min), and changed orientation frequently. In the host's presence, flies generally maintained a position facing the host, stayed in the quadrant of first approach, and typically flew off the arena within 2 min of arrival. When the oncoming fly approached a forward facing host, more planidia were found in the arena's center (i.e., closer to the host) than in the no-host or rearward-facing host treatment. Planidia experimentally placed on a circular arena averaged 1 cm of movement in 15 min but none of the following cues–host song, host song with song-vibration transmission, a silent host, and a silent host with host movement-vibration transmission–significantly affected the direction or distance planidia traveled. At 20 ± 1°C, over half of the planidia died within 1 h and all died within 2 h of deposition. The significance of these results in relation to reproductive strategies and parasitism is discussed.     

Offspring recognition by mother crab spiders with extreme maternal care

Maternal care is provided by several spider species, but there are no reports of mother spiders recognizing their young, which suggests that maternal care can be exploited by unrelated individuals. Diaea ergandros, a crab spider with extreme, sacrificial maternal care, does accept unrelated spiderlings (ca. 43.9% of spiderlings) into its nest in areas of high nest density. However, a field and a laboratory experiment with mother spiders and natural and adoptive spiderlings demonstrated that mothers did recognize their own offspring. Recognition was not expressed in survival as adopted (unrelated) spiderlings had similar survival rate to that of natural offspring. Instead it was displayed in growth; mother D. ergandros caught large prey items for their own offspring, but not for adopted spiderlings, and so natural offspring grew more than adopted spiderlings. Also, mothers produced trophic oocytes, which are important for the sacrificial care that influences spiderling survival, only when they lived with their own offspring.     

Maternal Behavior and Infant Congenital Limb Malformation in a Free-Ranging Group of <Emphasis Type="Italic">Macaca fuscata</Emphasis> on Awaji Island,Japan

We studied the relationship between maternal behavior and infant disability in 12 mother-infant dyads for the first 5 weeks of infant life in the free-ranging Japanese macaque (Macaca fuscata) group on Awaji Island, Japan, from May to September 2001. Congenital limb malformations are prevalent in this population, and as such carry implications for behavior and conservation. We did not detect any differences in maternal activity budgets, mother-infant physical contact, infant holding, and overall nursing and infant transport time between mothers of non-disabled infants, disabled infants that were able to cling to their mothers, and disabled infants whose limb structure prevented clinging. Mothers of infants with limb malformations severe enough to prevent normal clinging behavior manually supported their infants during nursing and locomotion significantly more than other mothers did theirs. Increased support-carrying and support-nursing, and higher frequencies of holding the infant to one's ventrum, suggest that mothers of extensively malformed infants may be investing more to facilitate the survival of their offspring and that infant disability appears to be influencing maternal behaviors in this population.     

A mass rearing method for the linyphiid spider species Erigone atra (Blackwall) (Araneae: Linyphiidae)

Abstract:  A mass rearing method for Erigone atra (Blackwall) (Araneae: Linyphiidae) allowing continuous laboratory rearing is described. Twenty 1–2-day old spiderlings were kept together in plastic boxes, which were filled with soil containing a culture of the Collembola species, Lepidocyrtus lanuginosus (Gmelin) (Entomobryidae), and serving the spiders as a continuous available prey source. Once per week vestigial-wing fruit flies of Drosophila melanogaster Meigen (Diptera: Drosophilidae) were provided as additional prey. In addition, the rearing boxes were filled with wood-wool serving spiders as points of contact for their webs. After 3–5 weeks most of the spiderlings developed to adults, which were separated individually into glass tubes filled with soil and Collembola until all of them became adult. To produce a new generation of spiders 20–40 adult/subadult spiders originating from different mass rearing boxes were brought together and kept and fed in the same way as the spiderlings. Within a few days females started to produce eggsacs. The eggsacs were transferred into glass tubes filled with a layer of moist plaster of Paris until the spiderlings hatched, which were then bred as described above. Erigone atra was bred over 12 generations within a period of 2 years. The mean rearing success (from 1 to 2-day-old spiderlings to adults) was 59.3%. Decreasing rearing success, decrease of fecundity or decrease of adult spider size were not observed. Advantages and use of the mass rearing method are discussed in relation to rearing methods for other spiders.     

Survival strategies of the crab spider Thomisus onustus Walckenaer 1806 (Chelicerata,Arachnida, Thomisidae)

Summary The initial energy supply of emerging spiderlings is relatively meagre, so survival without feeding on insects during a spell of bad weather is limited to a period of a few days or weeks. During our investigations, spiderlings of Thomisus onustus (Arachnida, Thomisidae) were kept on different diets. There was a significant difference in survival rate between spiderlings that were starved or fed on pollen, nectar, or Drosophila. The results showed that pollen and nectar can be a source of energy for spiders for an extensive period. This demonstrates another way in which spiders may survive starvation when insect prey is lacking and thus ensure the survival of a whole population.     

Contrasting patch choice behaviour by immature ambush predators, a spider (Misumena vatia) and an insect (Phymata americana)

1. Spiderlings of the crab spider Misumena vatia and nymphs of the ambush bug Phymata americana normally ambush prey in flowers, as do the adults. The immatures of M. vatia are more mobile, by ballooning, than the ambulatory but largely sedentary adult female spiders, but the apterous immatures of P. americana are less mobile than the alate adults. The aim of the work reported here was to investigate how immatures, as compared with adults, select sites from which to ambush their prey. 2. Individual immatures of both species were released in experimental arenas with variously manipulated natural stems: normal, with and without leaves, and with and without flowers of three species of plants. 3. The spiderlings and nymphs showed discriminatory behaviour but not in accordance with optimal foraging in either case. The spiderlings chose more leafy stems than any other kind of stem. For the nymphs, the importance of leaves was less marked, food apparently being more important than shelter. 4. Neither of the predators discriminated among flowering stems of Solidago canadensis, Daucus carota, and Cirsium arvense. 5. In other experiments, in which flowered and deflowered stems were located in two separated groups in the arena and the individual was released in a bare area between the two groups, the spiderlings chose either group as predicted by chance but the nymphs showed a slight preference for the flowered sector. Nevertheless, once in either of the groups, the predators showed similar behaviour in choosing leafy stems more often than other stems. 6. Nymphs of P. americana are much more selective than adults but spiderlings of M. vatia are less selective than adult females. These results appear to accord with the time and energy costs of changing hunting sites, walking being slower than flying or ballooning. 7. The results indicate the need to include other parameters, such as enemy‐free space and time spent in not being able to forage, in the analysis of foraging behaviour.     

Social Influence on Early Foraging of Domestic Chicks (Gallus gallus) in a Near-to-Nature Procedure

The aim of this study was to investigate the social influence of single chicks with different foraging experience on the behaviour of their group members during the first days after hatching. In contrast to the duplicate cage procedure normally used in social learning studies, four naïve group members could freely interact with a tutor or a control chick in an enriched 20-m² test arena. This arena contained two types of food caches with differently coloured food. The tutor was 3 d older than its group members and was trained to feed from one of the two food cache types, whereas the control chick was not familiar with the characteristics of the test arena and was either of the same age or 3 d older than its group members. During the first 9 d after hatching, the foraging activity of 32 chick groups was tested in 15 trials per group. Groups with a 3 d older but inexperienced control chick had the least foraging success whilst groups with a naïve control chick of the same age compared more favourably with the groups with experienced tutors than with groups that included older control chicks. In a second experiment, a tutor compartment was introduced into the test arena in order to compare a situation of unrestricted contact possibilities with the duplicate cage procedure in which tutor and bystanders are separated by a Perspex divider. The tutor compartment was opened for some test groups, allowing free interaction between tutor and naïve chicks. Those chicks which could only watch the tutor through the Perspex developed a preference for the tutor’s food type and discovered this food type as fast as the chicks of groups with unrestricted interactions. However, a relatively large proportion of groups (3 out of 8) did not develop successful foraging behaviour at all, whereas the successful groups showed longer feeding latencies during the subsequent trials than groups which had unrestricted contact with their tutor. This indicates an inhibiting effect of the duplicate cage procedure. It is concluded that when testing chicks of a few days of age, a distinction should be made between (i) the social influence on food particle preferences and (ii) the social influence on learning where to find food. This is important for generalizations taken from duplicate cage procedures without any environmental enrichment, as this restrictive setting only allows detection of food particle preferences.     

Maternal Care and Infanticide by Males in Helvibis longicauda (Araneae: Theridiidae)

Maternal care in spiders varies from just the construction of a protective silken structure for the eggs and the selection of a safe site to place them, to a long period of association between the mother and spiderlings. Such extended care may involve the active protection from predators and parasitoids, food regurgitation, the production of trophic eggs and even matriphagy. In this study, we describe extended maternal care in Helvibis longicauda (Theridiidae) and evaluate the effectiveness of maternal protection against predators of eggs and spiderlings. We conducted experiments comparing the frequency of egg sac destruction and mortality of spiderlings in the presence and absence of mothers. We also observed the behaviour of the mother and spiderlings during prey capture events and interactions with possible predators. Helvibis longicauda females guard their egg sacs until the emergence of the young and guard the spiderlings for several instar stages, fighting possible predators, including conspecifics. We found that aggressive behaviour by females increased the survival of both eggs and spiderlings in our experiments. Intruder males were the main source of mortality in the absence of females. The benefits of maternal care for the young also include the acquisition of prey items that are captured, immobilized and pre‐digested by the mother. Effective maternal protection and the extended period of supplying food to juveniles probably contribute to the late dispersal of offspring in H. longicauda.     

Side-effects of insecticides on two erigonid spider species

The current rearing technique forErigone atra (Blackwall) andOedothorax apicatus (Blackwall) (Araneae, Erigonidae) was improved. To reduce time spent rearing on live fruit flies the spiders were kept on a culture of the Collembola speciesLepidocyrtus lanuginosus (Gmelin) (Entomobryidae). Side-effects on spiders of two pyrethroid insecticides (fenvalerate and lambda-cyhalothrin) and one carbamate insecticide (pirimicarb) were tested. Sensitivity of adults of both sexes and juveniles to insecticides and their influence on the rate of emergence of spiderlings from cocoons were investigated using topical application, spraying or residual contact. LD₅₀ values for adults ranged from 0.49 to 2.52 ng a.i./spider for lambda-cyhalothrin and from 5.75 to 98.20 ng a.i./spider for fenvalerate. Topical application also resulted in up to a week's delay of web-building. A moving laboratory spraying equipment was used to spray spiders with different insecticide dosages and water volumes. Pyrethroids sprayed onto adults in webs had stronger effects than pyrethroids sprayed onto sitting or walking spiders on the soil surface. Residual contamination caused higher mortality of spiders after contact with lambda-cyhalothrin than fenvalerate. In all tests, males were more susceptible to pyrethroids than females; this difference was related to body weight. Mortality rate was higher forE. atra than forO. apicatus. Both pyrethroids were also toxic to spiderlings. Lambda-cyhalothrin inhibited emergence ofE. atra spiderlings from cocoons. Pirimicarb was harmless to both spider species.     

Haltung und Zucht der Geißelspinne (Damon variegatus) (Phrynichidae) (Chelicerata: Amblypygi)

In the temporary carboniferous hall of „GONDWANA – Das Prähistorium“ in Germany, whip spiders (Damon variegatus) were kept and bred. 3,3 were purchased from a dealer in summer 2007. The night active spiders were kept together in a terrarium. No aggresions were observed. The animals were fed little locusts, young hissing cockroaches, and crickets. In 2008 courtship display and mating could be observed. The biggest male was the only active one. After 7 days after the intake of the spermatophores all females carried eggsacs under the ophistosoma. Each egg sack contained approximately 25–30 eggs. During the carrying phase only one female feasted on a cricket. 98 days after the egg sack was produced the young spiderlings hatched. The coloration of the spiderlings was completely different from the coloration of the adults. The spiderlings were carried by the female for the next 9 days. Then, the spiderlings moulted and left the female immediately. The adults were now separated from their young. The three groups of spiderlings stayed together in a smaller terrarium. However, each group from each female stayed separate from the others for weeks. The second moulting took place 41 days after the first one. No cannibalism was observed. Obviously Damon variegatus seems to be a spider with a social touch. If the terrarium and the climate conditions inside are adapted to the needs of the whip spiders keeping and breeding is possible. The species is highly attractive to visitors.     

Mother-infant interactions of wild-born,individually-caged cynomolgus monkeys (Macaca fascicularis) during the first 14 weeks of infant life

This study documents age-related changes in the interactions of wild-born cynomolgus macaque mothers and their infants living in individual cages during the first 14 weeks of infant life. Body contact between mother and infant, maternal holding, and infant sucking were found to decrease, and the mothers showed an increased frequency of aggression toward their infants with age. These results were broadly similar to those reported for mother-infant interactions in other macaques living in social groups. Nevertheless, a clear difference between the present cynomolgus macaques and other macaques in social groups was apparent. The cynomolgus macaque mothers tended to permit their infants to move about freely without displaying maternal protectiveness such as restraint or retrieval, unlike other macaque mothers in social groups. Such maternal behaviors might derive from the experience of living in individual cages for many years and the relative safety of living in individual cages. The lack of maternal restraint and retrieval could be responsible for the observed sex differences in behavior: male infants moved more actively, and broke, and made contact with their mothers more frequently than did female infants. Moreover, mothers of female infants held and groomed them more frequently and were less aggressive toward them.     

The emergence and maintenance of interdyad differences in the mother-infant relationships of rhesus macaques: A correlational study

The role of the mother in promoting infant independence, reflected in the time spent out of contact with her by the infant, was addressed with a simple correlational approach to scores of time out of contact (Off) and frequencies of acts of maternal rejection and restriction through the infants’ first 16 weeks of life. Correlations of the extents of age changes from week to week were also examined. Infants differed consistently in the times they spent off from their fourth through their eighth weeks, while rates of maternal restriction and rejection were consistent from week 4 until at least week 8 in both sexes and from week 2 in females. The correlations were consistent with the view that time off was set at its week-4 and possibly later levels by maternal rejection, while some further changes in time off, resulting in a loss of consistency from week to week, reflected the extents to which mothers of daughters decreased their restrictive behavior. Weeks in which individual differences in maternal restriction and rejection were correlated with differences in time spent off were generally weeks in which changes in group means of these mean measures were correlated. In daughters, age changes of individual dyad’s scores of time off and maternal rejection were correlated between week 2 and week 4, supporting the view that in these early weeks age changes and individual differences were produced by the same processes. Findings from comparative and experimental studies, and the limitations of correlational approaches now available, are discussed.