Social correlates of testosterone and ornamentation in male mandrills

We investigated relationships between fecal androgen concentrations, facial coloration and behaviour in semi-free-ranging male mandrills. We found that fecal androgen levels were significantly positively related to dominance rank, independent of rank stability and the mating period, suggesting that male mandrills live in a permanently aggressive context in which they must actively maintain their dominance status. Facial red coloration was also significantly related to both fecal androgen levels and rank, with high ranking males having both higher androgen levels and redder faces, although dominant males did not always have the highest androgen levels or the reddest faces. Predictive relationships between androgen levels, coloration and rank were short-term. Androgen concentrations and facial redness both increased in the presence of receptive females, as did the former during periods of rank instability. We conclude that male facial redness is likely to represent an honest signal (to other males) of current androgen status, competitive ability and willingness to engage in fights and that females may also use this to assess male condition. Further, our findings provide support for the “challenge hypothesis” as originally proposed for birds by Wingfield.     

The study of vocal communication of wild mandrills in Cameroon in relation to their social structure

The vocal repertoire of the mandrill (Mandrillus sphinx), a forest living baboon, is described, and their vocal communication analyzed quantitatively. Although the vocal repertoire of mandrills corresponds well to that of savanna living baboons,Papio, some characteristics differed, such as the development of long-distance calls and differentiation of vocalizations between age-sex classes. Vocal communication within a group was closely related to changes in the spatial distribution of group members, and the two most common vocalizations, crowing and 2PG, appear to function as contact calls. Based on the wide dispersion of food trees, a group of mandrills divided into several feeding groups (subgroups). The two types of contact call were given in different and in some senses complementary contexts, and helped to facilitate and maintain group integration. According to their acoustic structure, these calls are long distance calls. Influenced by the high-level of attenuation of vocalization on the forest floor, the mandrill has developed them as contact calls, instead of using the contact “grunt,” which is common to the savanna living baboons. Comparing the patterns of vocal exchanges of mandrills with those of gelada and hamadryas baboons which have a multi-levelled society, the social structure of the mandrill is discussed. From the analysis of the spatial distribution of vocal emission, a number of clusters of vocalizations were obtained. These clusters correspond to subgroups. The frequent female-female and female-male vocal exchange between subgroups of mandrills suggest that the relationships between subgroups are less closed than between the one-male units of gelada and hamadryas baboons. Furthermore some of these clusters include more than two vocalizing adult males, while in other clusters there are no vocalizing adult males. Thus, the social structure of mandrills is suggested to be multi-male rather than a multilevelled type. The absence of contact calls specific for short distance and the functional replacement of the grunting of all group members by persistent emission of a loud call (2PG) by usually just one adult male suggests that the social structure of mandrills is not exactly equivalent to that of the multimale troop of savanna living baboons. Usually the use of 2PG is monopolized by one adult male travelling in the rear part of the group. Such monopolization of 2PG emission and the pattern of 2PG-2PG or 2PG-roar exchanges by adult males in some cases indicate the existence of strong dominance relationships among adult males, and especially the existence of a leader male within a multi-male group of mandrills.     

Aggression and Reconciliation in Two Captive Groups of <Emphasis Type="Italic">Lemur catta</Emphasis>

Kappeler excluded the presence of reconciliation in a free-ranging group of Lemur catta, but a recent study on the same group indicated reconciliation, though with a very long PC duration. We collected data on 2 captive groups of ring-tailed lemurs at the Pistoia Zoo (Italy) in order to shed light on conflict resolution in the species. We investigated the influence of seasonality and of a targeted aggression episode on the occurrence of reconciliation. We collected 164 PC-MC pairs for the A group and 141 for the B group. We performed all analyses at the dyadic level via randomization procedures. Despite the targeting episode, we found no difference in the levels of aggression between the 2 groups. In contrast, just before the onset of the targeting episode, B showed significantly lower rates of affinitive behaviors versus A. Reconciliation occurred in A, whereas it was absent in B. Therefore, we suggest that in B, with the decrease of baseline affinitive interactions associated with the beginning of the targeting episode, the function of postconflict reunions probably stopped working. On the whole, we found that contrasting results were probably related to different seasonal and social conditions (A: breeding/pregnancy season, characterized by higher tolerance rates; B: birth season, characterized by lower tolerance rates). Accordingly, reconciliation should be monitored throughout the different seasonal phases.     

Peaceful Meaning for the Silent Bared-Teeth Displays of Mandrills

We studied the meaning of silent bared-teeth displays in a captive group of mandrills (Mandrillus sphinx). We observed the displays mostly in positive interactions, in which case they could advertise the sender's peaceful intentions, though at times they also occurred as a response to aggression. We found no relationship between the direction of agonistic interactions and the display. Both variants of the display, with closed or open jaws, exhibited mostly symmetrical patterns. The evolutionary convergence of the closed and open bared-teeth displays might be related to the dominance style of mandrills.     

Observation of tool use and modification for apparent hygiene purposes in a mandrill

Tool making or modification to produce a tool of apparent improved functionality has rarely been reported in monkeys, especially when tools are used outside the context of food acquisition. We report on an observation of selection, modification and use of splinters for hygiene purposes in a male mandrill. The zoo-housed animal was video-recorded breaking splinters in sequence to use them underneath his toenails. This record brings forward new evidence that the ability to use and modify tools is not limited to apes and some New World monkeys but is also apparent in Old Word monkeys.     

New record of predatory behavior by the mandrill in Cameroon

The predatory behavior of the mandrill (Mandrillus sphinx,Linnaeus 1758), a forestliving baboon, on the bay duiker (Cephalophus dorsalis,Gray 1864) was observed under natural conditions. In the predatory episode, at least two mandrills (one adult female and one adult male) attacked a bay duiker, but no overt aggressive interactions between the attackers occurred during consumption. The estimated predation pattern based on scars—intensive attacking of the head and pulling of the hind legs to eat the thigh muscles first—resembled the predation patterns of captive mandrills observed experimentally. The findings suggest that the predatory behavior is established in mandrills as a feeding behavior pattern as in savanna-living baboons. New data are thus presented which are relevant to the discussion of the origins of hunting behavior in early hominids.     

Reproductive Parameters and Maternal Investment in Mandrills (Mandrillus sphinx)

We report on 14 years of reproductive data for semifree-ranging mandrills (Mandrillus sphinx) in Gabon, and we explore relationships between female rank, age and parity, and reproductive strategies. Most births (61% of 132) occurred during the wet season in Gabon, between January and March. Female rank and parity were unrelated to the timing of parturition. Gestation lengths average 175 days (SE = ±1 day; N = 61) and were similar irrespective of female rank, parity, or sex of offspring. Birth sex ratio did not differ significantly from unity (52% male), and was unrelated to maternal rank or parity. Stillbirths and neonatal mortality tended to be more common among lower-ranking females than among either mid-ranking or dominant females. Median age at first birth is 4.71 years, at a median body mass of 7.6 kg, ca 5 years before females attain their adult body mass (median 12 kg). Age at first reproduction is significantly correlated with dominance rank, with dominant females giving birth on average 1.3 years earlier than lower-ranking females do. Interbirth intervals (IBI) average 405 days (range 184–1159 days, N = 103), and are independent of the sex of the offspring. Infant death within 6 months shortened IBI to 305 days. Increasing age and parity are also associated with short IBI, as is higher rank. Maternal rank and parity appear to influence reproductive success in female mandrills, but there is no apparent differential maternal investment by sex.     

Conservation of Drill Populations in Bakossiland,Cameroon: Historical Trends and Current Status

Very little information is available on the current status of drill populations in Cameroon. We report on drill group sizes and status in Bakossiland, a mountainous area spanning 2000 km² in the Littoral and South West Provinces of southwestern Cameroon. Between 1970 and 2002 direct visual counts of drill groups (n = 105) yielded group size estimates ranging from 5 to 400 (mean ± S.E.M.; 93.1 ± 8.4). We encountered solitary adult male drills on 8 occasions. Groups were at all elevations (150–2000 m) in 5 habitat types: lowland, premontane, submontane and montane forests and montane savannah at 2000 m). Group sizes did not vary with respect to elevation, habitat type or season (wet and dry mo). However, over the past decade drills have been virtually hunted out of the Mwenzekong Mountains (Banyang Mbo Wildlife Sanctuary), and they are greatly reduced in the southern Bakossi forests of Mwendolengo, Edib Hills and Mungo River. The species became extinct in the Loum Forest Reserve in the late 1970s, and until recently was thought to have become extinct on Mount Mwanenguba. Since 1994 on Mount Kupe, the drill population has begun to recover, largely due to protection afforded by the Bakossi traditional chiefs. Traditional powers and values are still influential in the region. A new national park—Bakossi Mountains National Park— and associated Protected Areas are currently under gazettment. We discuss the effectiveness of conservation strategies in relation to the survival of drills in the area.     

The role of natural enemy guilds in Aphis glycines suppression

Generalist natural enemy guilds are increasingly recognized as important sources of mortality for invasive agricultural pests. However, the net contribution of different species to pest suppression is conditioned by their biology and interspecific interactions. The soybean aphid, Aphis glycines (Hemiptera: Aphididae), is widely attacked by generalist predators, but the relative impacts of different natural enemy guilds remains poorly understood. Moreover, low levels of A. glycines parasitism suggest that resident parasitoids may be limited through intraguild predation. During 2004 and 2005, we conducted field experiments to test the impact of different guilds of natural enemies on A. glycines. We contrasted aphid abundance on field cages with ambient levels of small predators (primarily Orius insidiosus) and parasitoids (primarily Braconidae), sham cages and open controls exposed to large predators (primarily coccinellids), and cages excluding all natural enemies. We observed strong aphid suppression (86- to 36-fold reduction) in treatments exposed to coccinellids, but only minor reduction due to small predators and parasitoids, with aphids reaching rapidly economic injury levels when coccinellids were excluded. Three species of resident parasitoids were found attacking A. glycines at very low levels (<1% parasitism), with no evidence that intraguild predation by coccinellids attenuated parasitoid impacts. At the plant level, coccinellid impacts resulted in a trophic cascade that restored soybean biomass and yield, whereas small natural enemies provided only minor protection against yield loss. Our results indicate that within the assemblage of A. glycines natural enemies in Michigan, coccinellids are critical to maintain aphids below economic injury levels.     

Hymenopteran parasitoids and dipteran predators of the invasive aphid Diuraphis noxia after enemy introductions: Temporal variation and implication for future aphid invasions

Shifts in prevalence and abundance of hymenopteran parasitoids and dipteran predators, Diuraphis noxia, and other aphids were measured in the west-central Great Plains of North America, April–September, in 2001 and 2002, corresponding to over a decade after first detection of D. noxia and first release of D. noxia enemies. Significant temporal shifts in enemy species prevalence and diversity were detected in this study and more broadly during an 11 year time span. At any given time, some species were relatively common. One parasitoid had been predominant throughout (Aphelinus albipodus), two had shifted in dominance (Lysiphlebus testaceipes and Diaeretiella rapae), three parasitoids had been detected infrequently (Aphidius avenaphis, Aphidius matricariae, and Aphelinus asychis), one parasitoid was detected in the 1990s but not during 2001 and 2002 (Aphelinus varipes), two predatory flies occurred at occasional significant levels (Leucopis gaimarii and Eupeodes volucris), and two parasitoids may have been minor members of the fauna (Aphidius ervi and Praon yakimanum). Aphid populations detected were usually very low or not detected, precluding estimation of percent parasitism. The best evidence of suppression was observations of parasitoids in the rare case of D. noxia exceeding economic thresholds, which complemented past studies using high aphid densities. The D. noxia enemies detected were primarily endemic or long-time residents derived from previous introductions. This enemy community may provide flexibility in responding to a future aphid invasion, allowing more strategic use of biological control and other pest management approaches.     

Assessment of three techniques for measuring natural enemy inflicted mortality of leafroller larvae in commercial orchards

Measuring natural enemy (NE) inflicted mortality presents a serious challenge in managed habitats, such as apple orchards, where the crop-plant is frequently treated with a wide range of insecticides. Toxic residues keep natural populations of pests at too low levels to sample and prevent the use of techniques in which laboratory reared insects are released directly on foliage and used to measure NE activity. Three methods to implant obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae) larvae were tested: (1) larvae placed on potted apple trees, (2) larvae placed on excised leaves inserted in florists’ waterpicks and (3) larvae placed on branches placed into water filled Polyvinyl chloride (PVC) pipes. Use of potted trees allowed accurate estimation of NE inflicted mortality; however, this method was very labor intensive. The waterpick method required less labor, but it underestimated larval mortality caused by NEs. The use of PVC pipes to hold infested branches combined the benefits of the other two methods tested. This technique was simple to use and provided accurate estimates of NE inflicted mortality.     

Spatial and temporal patterns of morel fruiting

The biotic and abiotic factors conditioning morel fruit body production are incompletely known. We examined spatial and temporal patterns of Morchella esculenta fruiting over five years in a wooded site in Missouri, USA. Fruiting onset was inversely correlated with spring air and soil temperatures, whereas abundance was positively correlated with rain events (>10 mm) during the 30 d preceding fruiting. The two years with the greatest fruiting had the shortest fruiting seasons (6–7 d). Fruiting season length was positively correlated with soil warming, suggesting that a narrow range of optimum soil temperatures favour the explosive production of fruit bodies. All woody stems of at least 1 cm diam were mapped and stem diameter and crown condition were noted. Morel fruit bodies were significantly closer to stems of Carya spp., Tilia americana and Ulmus americana than predicted by the frequencies of these woody species or their contribution to the total basal area on the site. Although intra-annual clustering of fruit bodies was often observed, inter-annual clustering was not. The spatial pattern of M. esculenta fruiting appears to be associated with vegetation pattern, whereas the onset and abundance of fruiting are determined by the interaction of spring temperatures with availability of supporting precipitation.     

Diurnal and spatial patterns of Phytoseiidae in the citrus canopy

Phytoseiid mites were sampled in a grapefruit orchard at various times of the day to study their diurnal and seasonal distributions in the tree canopy. Samples were collected on 14, 20 and 28 October 1999 at 2 h intervals from 0600 to 2200 h. Similar samples were collected in a grapefruit orchard at 3 h intervals from 0600 to 2100 h on 9 and 16 March and on 17 and 24 August 2000 for phytoseiid mites. No differences in numbers of phytoseiid motiles were observed among the hours sampled in any of the three months. However, significant differences were observed in the number of phytoseiids per leaf based on location within the tree (eastern, western sides of the canopy or interior). Interior leaves collected in March and August 2000 had higher numbers of phytoseiids than exterior leaves taken from either the eastern or western sides of the tree canopy. Phytoseiids were more abundant in the March 2000 samples (mean = 1.10 phytoseiids/leaf) than in either October 1999 or August 2000 samples (mean = 0.16 and 0.19 phytoseiids/leaf, respectively). Prevalent phytoseiid species were Typhlodromalus peregrinus (Muma) (42.1%) and Iphiseiodes quadripilis (Banks) (50.4%) in October 1999, Typhlodromalus peregrinus (Muma) (76.2%) in March 2000, and Euseius mesembrinus (Dean) (54%) in August 2000.