Carrion beetles succession in three different habitats in Riyadh,Saudi Arabia

A main objective of the study is the establishment of a forensic entomological database for Riyadh, Saudi Arabia. Decomposition processes and beetle succession were analysed on rabbit carcasses in three different habitats (agricultural, desert and urban) in the period from May to July 2014. Due to the effects of the high temperature at the study sites, carrion reached the dry stage within 12 days in the agricultural habitat, and 6 days in the desert and urban habitats. A total of 125 beetles belonging to eight species and five families were collected during the decaying process, with their abundances increasing from the fresh to decay stages. The prevailing species belonged to the families of Dermestidae and Histeridae. It was not possible to confirm any definitive relationship between the occurrence of a single species and a particular stage of decomposition. The beetle communities were also not distinctively different between desert and urban habitats, but a distinct community was evident in the agriculture habitat. In addition, there were distinct beetle communities between the decay stage and the other stages. The dry stage recorded the lowest number of beetles. This study indicated that, the habitat type had an effect on the decay process and the abundance rate of the beetles.     

Habitat Fragmentation and Burying Beetle Abundance and Success

Four species of burying beetle (Nicrophorus marginatus F., N. tomentosus Weber, N. orbicollis Say and N. defodiens Mannerheim) are attracted to small, fresh mouse carcasses in northern Michigan. The number of burying beetles and their success (burial of a carcass) were greater in woodlands than in edge or field habitats. Species diversity was least in open fields as assessed by two different indices of diversity. Nicrophorus marginatus was the only species captured in large fields (<25ha). This species was never trapped in small fields (>5ha) suggesting that a minimum habitat size might be necessary to maintain local populations. In contrast to previous studies which employed pitfall traps baited with a large quantity of carrion, N. tomentosus was caught exclusively in woodlands at single mouse carcasses. In Connecticut woodlands, burying beetle success, assayed as the proportion of carcasses buried and held for 7 days, was significantly greater in larger as compared to smaller woodlands. The limited success of burying beetles in smaller woodlands was due, in part, to a higher rate of scavenging by vertebrates.     

Delaying insect access alters community composition on small carrion: a quantitative approach

We present a study of interactions in the highly competitive insect communities inhabiting the carrion of small mammals. Via manipulation in a fully quantitative design, we delayed community development by excluding insect colonization in mouse and rat carcasses for 3 days, to study the role of early competitively dominant colonizers [burying beetles (Nicrophorus spp.; Coleoptera: Silphidae) and blowfly larvae (Diptera: Calliphoridae)] in the course of heterotrophic succession on small cadavers. Earlier studies demonstrated that in the case of large mammalian carrion, exclusion of insects’ access to the carcass in the early stages of decomposition altered the successional trajectory and species assemblages. However, the effect of such manipulation in easy monopolizable small vertebrate carrion remained unknown. Our results demonstrate that delaying insect access to carrion significantly lowered blowfly larvae abundances, while it simultaneously had no effect on colonization and carrion burial by burying beetles. Higher abundances of blowfly larvae seem to deter necrophagous beetles, whereas they are not harmful to the larvae of flesh flies, at least in larger rat carcasses. Predatory beetle species preferred the lower abundances of blowfly larvae, presumably due to better accessibility of their prey. Our results therefore suggest that in the course of the entire season, larvae of blowflies are the dominant competitors in small carcasses, and significantly affect the assembly of other insect groups, whereas burying beetles may exhibit a more temporal pattern of dominance.     

Phoretic Poecilochirus mites specialize on their burying beetle hosts

Recurring species interactions can cause species to adapt to each other. Specialization will increase the fitness of symbionts in the coevolved association but may reduce the flexibility of symbiont choice as it will often decrease fitness in interactions with other than the main symbiont species. We analyzed the fitness interactions between a complex of two cryptic mite species and their sympatric burying beetle hosts in a European population. Poecilochirus mites (Mesostigmata, Parasitidae) are phoretic on burying beetles and reproduce alongside beetles, while these care for their offspring at vertebrate carcasses. While Poecilochirus carabi is typically found on Nicrophorus vespilloides beetles, P. necrophori is associated with N. vespillo. It has long been known that the mites discriminate between the two beetle species, but the fitness consequences of this choice remained unknown. We experimentally associated both mite species with both beetle species and found that mite fitness suffered when mites reproduced alongside a nonpreferred host. In turn, there is evidence that one of the beetle species is better able to cope with the mite species they are typically associated with. The overall fitness effect of mites on beetles was negative in our laboratory experiments. The Poecilochirus mites studied here are thus specialized competitors or parasites of burying beetles.     

Not all dung beetles feed on dung: Scarabaeinae (Coleoptera: Scarabaeidae) attracted to different carrion types in contrasting habitats at Brazilian Amazon

By understanding how assemblages segregate according to food types, it is possible to depict and understand species distribution and exploitation of similar food resources. Although it is well known that dung beetles may feed on carrion, but the attractiveness of different carrion types for these beetles is still poorly understood. In this study, we compared the dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae) diversity attracted to two carrion types in different habitats in an Amazonian landscape. Dung beetles were captured by using pitfall traps baited with decaying cattle beef and cattle liver in native forest, peach palm plantation, teak plantation and exotic pasture. Overall, we captured 582 dung beetles of 43 species, where Canthidium aff. lentum was classified as a specialist of cattle beef, Deltochilum sp. One was considered specialist of liver carrion, 11 were considered generalists and for the 30 remaining species, it was not possible to determine their carrion preference due to the low number. Abundance, but not species richness, was affected by carrion type, and a higher number of beetles was recorded in beef-baited traps compared to liver-baited traps. According to functional groups, endocoprid beetles were more abundant in traps baited with decaying beef, while paracoprid and telecoprid beetles did not show preference for any carrion type. This study suggests a novel scenario of intra-resource segregation, where species vary their preferences depending to the part of the dead corpse being exploited. The amount of food resource, the maintenance of stable populations and trophic preference mediated by chemical cues are some mechanisms that may explain the segregation of dung beetles among carrion types.     

河西走廊天然固沙植被区地表甲虫多样性及其对沙漠化的指示作用

干旱、半干旱区沙漠化强烈影响动植物分布及多样性,地表甲虫是荒漠中主要的动物类群,它们对沙漠化引起的植被和土壤环境变化响应十分敏感。鉴于此,以河西走廊中部张掖绿洲外围的天然固沙植被区作为研究区,依据沙漠化发育程度选择流动沙丘（ASD）、丘间低地（IL）、半固定（SFSD）和固定沙丘（FSD）4种生境,调查了地表甲虫群落组成及影响甲虫分布的植被和土壤环境。研究发现,4种生境地表甲虫群落组成明显不同并存在季节变异,5月ASD与IL、SFSD和FSD生境地表甲虫群落的相异性大于8月。5月和8月SFSD生境地表甲虫活动密度均显著高于其他生境,8月FSD生境地表甲虫多样性指数显著高于其他生境。不同大小甲虫对沙漠化的响应模式不同,大中型甲虫对沙漠化的响应较小型甲虫敏感,这在5月表现尤为明显。地表甲虫与环境因子的RDA分析结果表明,12个植被和土壤环境因子解释了49.8%的地表甲虫群落变异,其中植被环境解释了甲虫群落变异的16.3%,土壤环境解释了甲虫群落变异的4.2%,植被和土壤环境相互作用解释了甲虫群落变异的29.3%。pRDA分析结果表明,草本物种丰富度、灌木盖度、土壤有机碳含量和粗砂含量是影响地表甲虫分布的主要环境因子,它们解释了43.7%的地表甲虫群落变异。Pearson相关分析表明,草本物种丰富度与地表甲虫活动密度呈显著正相关,而与地表甲虫均匀度呈显著负相关;灌木盖度与地表甲虫多样性呈显著正相关;地表甲虫物种丰富度与灌木盖度和草本物种丰富度均呈显著正相关。此外,研究还发现戈壁琵甲、克氏扁漠甲、中华砚甲和甘肃齿足象可以用于指示FSD生境,东鳖甲属昆虫可以用于指数SFSD生境,谢氏宽漠王可以用于指示IL及ASD生境。     

What factors influence the diversity of saproxylic beetles? A multiscaled study from a spruce forest in southern Norway

The diversity in different groups of obligate saproxylic beetles was related to ecological variables at three levels of spatial scale in mature spruce-dominated forest. The variables were connected to: (i) decaying wood, (ii) wood-inhabiting fungi, (iii) the level of disturbance, (iv) landscape ecology, and (v) vegetational structure. Several strong relationships were found at medium (1 km²) and large scales (4 km²), while only weak relationships were found at a small scale (0.16 ha; 1 ha=10⁴ m²). This may be explained by the local variations in habitat parameters and the high mobilities of many beetle species. Factors connected to decaying wood and wood-inhabiting fungi were clearly the most important factors at all scale levels. In particular, the variables diversity of dead tree parts, number of dead trees of large diameter and number of polypore fungi species increased the species richness of many groups and increased the abundance of many species. Eight species were absent below a certain density of decaying wood per 1 or 4 km². Former extensive cutting was a negative factor at large scale, probably because of decreasing recolonization with increasing distance to the source habitats. Thinning reduced the diversity of species associated with birch. The development of guidelines favouring the diversity of saproxylic beetles are discussed below.     

Response of rove beetles (Staphylinidae) to various habitat types and change in Southern Mexico

We evaluated changes in levels of diversity of copro-necrophilous staphylinids attracted to piles of cattle dung and rat carrion in four contrasting habitats (continuous oak forest, oak forest patches, savannah and ravines) in southeastern Mexico during 2005 and 2006. In total, 181 morpho-species (N = 9,875 individuals) of Staphylinidae were recorded, of which 40 were coprophiles, 98 were necrophiles, and 43 were present in both substrates. Ten species accounted for 65% of the total number of individuals, 68 species were represented by singletons, whereas 103 species registered intermediate abundances. Less disturbed habitats recorded higher levels of beetle diversity. A strong seasonality effect was recorded for necrophiles, but not for coprophiles. A beta diversity analysis suggested that continuous oak forest registered the lowest fauna similarity when contrasted to other habitats; yet beetle composition among oak forest patches, savannah and ravine remained comparable. Staphylinidae body size and trophic guilds differed significantly among habitats. The results of this study suggest that key habitats such as ravines may represent a more permanent and predictable habitat for beetles in highly seasonal landscapes, even at early stages, because this habitat is characterized by a slower turnover of Staphylinidae species than in the case of tropical oak patches or savannah habitats.     

Does natural reforestation represent a potential threat to dung beetle diversity in the Alps?

Traditional agro-pastoral practices are in decline over much of the Alps, resulting in the complete elimination of livestock grazing in some areas. Natural reforestation following pastoral abandonment may represent a significant threat to alpine biodiversity, especially that associated with open habitats. This study presents the first assessment of the potential effects of natural reforestation on dung beetles by exploring the relationships between the beetle community (abundance, diversity, species turnover and assemblage structure) and the vegetation stages of ecological succession following pastoral abandonment. A hierarchical sampling design was used in the montane belt of the Sessera Valley (north-western Italian Alps). Dung beetles were sampled across 16 sampling sites set in four habitat types corresponding to four different successional stages (pasture, shrub, pioneer forest and beech forest) at two altitudinal levels. The two habitats at the extremes of the ecological succession, i.e. pasture and beech forest, had the greatest effect on the structure of local dung beetle assemblages. Overall, dung beetle abundance was greater in beech forest, whereas species richness, Shannon diversity and taxonomic diversity were significantly higher in pasture, hence suggesting this latter habitat can be considered as a key conservation habitat. Forests and pastures shared a lower number of species than the other pairs of habitats (i.e. species turnover between these two habitats was the highest). The two intermediate seral stages, i.e. shrub and pioneer forest, showed low dung beetle abundance and diversity values. Local dung beetle assemblages were also dependent on season and altitude; early-arriving species were typical of pastures of high elevation, whereas late-arriving species were typical of beech forests. It is likely that grazing in the Alps will continue to decrease in the future leading to replacement of open habitats by forest. This study suggests therefore that, at least in the montane belt, reforestation may have potentially profound and negative effects on dung beetle diversity. Maintaining traditional pastoral activities appears to be the most promising approach to preserve open habitats and adjacent beech forests, resulting in the conservation of species of both habitats.     

天然和人工固沙灌木林蜘蛛和甲虫分布与环境因子的关系

干旱区人工植被恢复驱动的土地利用变化强烈影响了地表和土栖的节肢动物群落结构及多样性。然而,我们对地表节肢动物群落关键类群-蜘蛛和甲虫对固沙植被恢复的响应及与环境变化关系的认识还很有限。以天然固沙灌木林和2种人工固沙灌木林为研究对象,运用方差分析和多变量分析等方法定量研究了干旱区天然和人工固沙植被区地表蜘蛛和甲虫分布特征及影响要素。结果表明,天然灌木林与人工梭梭、柽柳林地表蜘蛛和甲虫群落组成明显不同,人工梭梭、柽柳林地表蜘蛛活动密度和甲虫多样性均显著高于天然灌木林,而地表甲虫密度和蜘蛛多样性变化与之相反。两种人工固沙灌木林之间蜘蛛和甲虫群落组成也存在一定差异,人工柽柳林地表蜘蛛活动密度、多样性和甲虫物种丰富度均显著高于人工梭梭林。进一步分析发现,蜘蛛群落中狼蛛科、平腹蛛科、皿蛛亚科和球蛛科与甲虫群落中拟步甲科、步甲科和象甲科等一些甲虫种属对3种生境的选择模式不同决定了蜘蛛和甲虫群落聚集结构。植被、土壤环境因子与蜘蛛和甲虫pRDA和pCCA结果表明,草本生物量、凋落物量、土壤含砂量、电导率和灌木盖度是影响蜘蛛分布的主要环境因子,它们解释了82.1%的蜘蛛群落变异;灌木盖度、草本生物量、土壤...     

First Quantitative Study of Rove Beetles in Oklahoma Winter Wheat Fields

Adult rove beetles (Staphylinidae) were sampled every 7–14 days from one winter wheat field located in each of the four major wheat growing regions of Oklahoma during the 1999–2000 and 2000–2001 growing seasons. The number of cereal aphids per tiller, wheat plant growth stage, and wheat tiller density also were estimated. A total of 12 genera representing 13 species of beetles were collected from the field. The density of rove beetles was generally low, ranging from 0.003 beetles per m² in fall to 0.106 beetles per m² in spring. Rove beetle communities differed among seasons. After accounting for the effect of season, there was no statistically significant association between rove beetle community structure and field location, aphid density, wheat plant growth stage, or wheat plant density. Most rove beetle species showed no association with a particular season, however, Aleochara notula Erichson, Lathrobium sp., and Oxypoda sp. were present predominantly in fall, while Bisnius inquitus Erichson was associated with winter. Oxypoda sp. was the most abundant rove beetle in winter wheat fields in spring and was relatively abundant in winter, but was not collected from wheat fields in fall. Tachyporus jocosus Say was present in wheat fields during all seasons. T. jocosus was the most abundant rove beetle species in the winter wheat fields in fall and winter and was the second most abundant species during spring.     

Body water content and desiccation resistance in some arthropods from subantarctic South Georgia

Summary The body water content and resistance to desiccation were studied in two perimylopid beetles, Perimylops antarcticus and Hydromedion sparsutum, a chironomid midge, Eretmoptera murphyi, and two spiders, Notiomaso australis and Perimaso grytvikensis from the subantarctic island of South Georgia. Comparisons were made between different species, different life stages and, where possible, between a high and a low altitude. Perimylops is abundant at higher elevations and in more exposed habitats (fellfields). This may be accounted for by its feeding behaviour, high body water content (relative to Hydromedion) and low rate of water loss under desiccating conditions, particularly in the larval stages. Hydromedion is more abundant at the lower collection site. It is a more robust beetle than Perimylops and its feeding preference is for plants such as grasses and Acaena. Nevertheless, at the upper site adult Hydromedion are able to withstand desiccation to an even greater degree than Perimylops. Water loss rates for both beetles are significantly higher than those reported for related beetles from arid and semi-arid regions. The ability to regulate water loss is not as apparent in the polar perimylopids Perimylops and Hydromedion as in related species from other xeric habitats. These two species, in fact, resemble more closely carabid beetles in xeric habitats in rates of water loss under controlled conditions. Increased temperatures elevate the rate of water loss significantly. South Georgia spiders have a similar rate of water loss to several species of spiders that have been studied in the temperate zone. Eretmoptera is restricted to moist conditions and cannot survive desiccating conditions even for brief periods. It has the highest body water content (78% of fresh weight) of all of the South Georgian arthropods studied. Among the spiders, sufficient information could be obtained only for Notiomaso. This species is much less resistant to desiccation than the perimylopid beetles, and it has a relatively high body water content. It is quite numerous in the lower, warmer habitats where its insect prey is more abundant and diverse.     

人工柠条-荒漠草地交错带拟步甲昆虫群落多样性

选取宁夏东部盐池县人工柠条灌丛-荒漠草地交错带为研究样地,以距离梯度形式,利用巴氏诱罐法对拟步甲科昆虫群落多样性进行了调查,研究了边缘效应对拟步甲昆虫群落多样性的影响。共采集拟步甲昆虫1405只,分属8属13种。结果表明,克小鳖甲和弯齿琵甲个体数量分别占总个体数的32.74%和43.27%,为该地区的优势种类。拟步甲昆虫在人工柠条灌丛-荒漠草地交错带的分布可分为3种类型,优势种克小鳖甲和弯齿琵甲属于栖息地广布型,但二者并没有表现出十分均匀的适应性,而且他们在各样带的分布呈显著负相关,克小鳖甲的分布趋向于沙生荒漠环境,弯齿琵甲的分布趋向于柠条灌丛;常见种蒙古漠王、小皮鳖甲的分布偏向于喜好荒漠草地;异距琵甲、奥氏真土甲、网目土甲和淡红毛隐甲的分布则偏向于喜好柠条灌丛。拟步甲昆虫丰富度与Shannon-Wiener多样性沿边缘分别向柠条灌丛和荒漠草地内部降低,个体数量总体上沿柠条灌丛、交错带向荒漠草地内部降低,但各样带差异不显著。从季节动态看,荒漠草地和柠条灌丛物种多样性季节变化相似,3种生境拟步甲活动密度季节变化相似。边缘效应强度分析呈现边缘正效应。CCA排序图显示分类地位相近的物种在生态适应上具有趋同性。多元回归分析表明,植被密度影响拟步甲昆虫群落的优势种和个体数量,植被盖度和高度分别影响拟步甲群落的均匀度和丰富度。主坐标分析(PCo A)排序表明人工柠条灌丛-荒漠草地交错带的拟步甲昆虫群落组成与柠条灌丛内部没有明显分化,但趋于向柠条灌丛生境演替。     

Factors affecting overwinter survival of the American burying beetle, <Emphasis Type="Italic">Nicrophorus americanus</Emphasis> (Coleoptera: Silphidae)

The endangered American burying beetle (Nicrophorus americanus) is relatively abundant at Fort Chaffee Maneuver Training Center in northwestern Arkansas. There is a paucity of basic life-history information available, particularly with respect to factors affecting overwintering success. In a field experiment we: (1) captured beetles at Fort Chaffee; (2) bred them in captivity; (3) in the fall on Fort Chaffee placed offspring individually in well-ventilated, lidded 21.1-l buckets containing original soil plugs in grassland or woodland, either provisioned or not with a rat carcass as potential food; (4) overwintered the beetles; (5) checked in the spring to determine survival; and (6) released surviving beetles. Overall, 59.6% of 104 beetles survived the winter, with 77.1% and 44.6% survival in provisioned and nonprovisioned buckets, respectively. No differences were evident between habitats. Beetle age was an important survival predictor, with older beetles having a higher survival probability, but only if nonprovisioned. Gender and body size were not predictive of survival. Many surviving beetles were at or near the surface; depth averaged 6.0 cm, with some as deep as 20 cm. Our findings suggest that American burying beetles will have a higher probability of overwinter survival if carcasses are readily available as winter approaches.     

Real‐time PCR identification of the ambrosia beetles,Trypodendron domesticum (L.) and Trypodendron lineatum (Olivier) (Coleoptera: Scolytidae)

The European hardwood ambrosia beetle (Trypodendron domesticum) and the striped ambrosia beetle (Trypodendron lineatum) are wood‐boring pests that can cause serious damage to lumber, resulting in a need for management of these pests in logging and lumber industries. Natural populations of ambrosia beetles exist throughout the world, but movement of ambrosia beetles into new habitats, particularly via international trade, can result in the establishment of invasive species that have the potential to spread into new territory. Efforts to monitor ambrosia beetle populations are time‐consuming and could be greatly enhanced by the use of molecular methods, which would provide accurate and rapid identification of potentially problematic species. Here, we present new real‐time PCR assays for the detection and identification of T. domesticum and T. lineatum. The methods described herein can be used with a variety of sampling strategies to enable timely and well‐informed decision‐making in efforts to control these ambrosia beetles.     

Non-native plantation forests as alternative habitat for native forest beetles in a heavily modified landscape

The once extensive native forests of New Zealand’s central North Island are heavily fragmented, and the scattered remnants are now surrounded by a matrix of exotic pastoral grasslands and Pinus radiata plantation forests. The importance of these exotic habitats for native biodiversity is poorly understood. This study examines the utilisation of exotic plantation forests by native beetles in a heavily modified landscape. The diversity of selected beetle taxa was compared at multiple distances across edge gradients between each of the six possible combinations of adjacent pastoral, plantation, clearfell and native forest land-use types. Estimated species richness (Michaelis–Menten) was greater in production habitats than native forest; however this was largely due to the absence of exotic species in native forest. Beetle relative abundance was highest in clearfell-harvested areas, mainly due to colonisation by open-habitat, disturbance-adapted species. More importantly, though, of all the non-native habitats sampled, beetle species composition in mature P. radiata was most similar to native forest. Understanding the influence of key environmental factors and stand level management is important for enhancing biodiversity values within the landscape. Native habitat proximity was the most significant environmental correlate of beetle community composition, highlighting the importance of retaining native remnants within plantation landscapes. The proportion of exotic beetles was consistently low in mature plantation stands, however it increased in pasture sites at increasing distances from native forest. These results suggest that exotic plantation forests may provide important alternative habitat for native forest beetles in landscapes with a low proportion of native forest cover.     

Different effects of coarse woody material on the species diversity of three saproxylic beetle families (Cerambycidae, Melandryidae, and Curculionidae)

The relationships between coarse woody material (CWM) and the diversity of three saproxylic beetle families (Cerambycidae, Melandryidae, and Curculionidae) were investigated. These three families responded differently toward the quality and quantity of CWM. The species richness of cerambycid beetles increased in forests with more CWM in the early stage of decomposition. The richness of saproxylic curculionids increased in stands with more tree species. No clear trend was evident for melandryid diversity. The CWM differed in quality and quantity among three forest types [middle-aged larch (Larix kaempferi [Lamb.] Carrière) plantation, secondary forest, and old-growth forest] and between two forest-management practices (thinning and long rotation). Forest type and management practices affected CWM and the number of tree species, and CWM and the number of tree species influenced the diversity of saproxylic families differently. Because each decomposition stage is considered to be important for saproxylic beetles at the species level, a constant supply of CWM is necessary to maintain a suitable balance of CWM through these decomposition stages in forests to maintain the diversity of saproxylic beetles.     

Estimated density of four carabid beetle species in Mongolian oak and Korean red pine forest ecosystems on Baekdudaegan mountain range (Mt. Oade and Mt. Guryong) of South Korea

The estimation of animal population size is a primary field of interest for wildlife biologists, and such numerical estimation of wild animals is a very important factor in establishing national policy towards nature. Therefore, we performed this study to estimate the population density of carabid beetles preying on soil biota at the Mongolian oak (Quercus mongolica) forests and Korean red pine (Pinus densiflora) forests of two mountains, Mt. Odae and Mt. Guryong. We used the trapping web method with pitfall traps to collect the beetles. We calculated the estimated density of a total of four carabid beetle species in two specific regions and converted them to an estimated beetle population size within a certain area by using the study area. From our estimates, one beetle species, Leptocarabus seishinensis seishinensis L., displayed statistically significant results. Although there was no appreciable difference in the makeup of different carabid beetle species between the two forest communities, the population size of the beetle species was larger in Mongolian oak forests than in Korean red pine forests. The spatial distribution of carabid beetles by forest type did not show any preference for particular spots. Our results showed that carabid beetles did not have specific home ranges and that they were not density dependent. We expect to use the raw data to recognize the response of soil organisms to changes in the habitat environment and to track the patterns of change more accurately over long passages of time.     

Stage‐dependent responses to emergent habitat heterogeneity: consequences for a predatory insect population in a coffee agroecosystem

Interactions among members of biological communities can create spatial patterns that effectively generate habitat heterogeneity for other members in the community, and this heterogeneity might be crucial for their persistence. For example, stage‐dependent vulnerability of a predatory lady beetle to aggression of the ant, Azteca instabilis, creates two habitat types that are utilized differently by the immature and adult life stages of the beetle. Due to a mutualistic association between A. instabilis and the hemipteran Coccus viridis – which is A. orbigera main prey in the area – only plants around ant nests have high C. viridis populations. Here, we report on a series of surveys at three different scales aimed at detecting how the presence and clustered distribution of ant nests affect the distribution of the different life stages of this predatory lady beetle in a coffee farm in Chiapas, Mexico. Both beetle adults and larvae were more abundant in areas with ant nests, but adults were restricted to the peripheries of highest ant activity and outside the reach of coffee bushes containing the highest densities of lady beetle larvae. The abundance of adult beetles located around trees with ants increased with the size of the ant nest clusters but the relationship is not significant for larvae. Thus, we suggest that A. orbigera undergoes an ontogenetic niche shift, not through shifting prey species, but through stage‐specific vulnerability differences against a competitor that renders areas of abundant prey populations inaccessible for adults but not for larvae. Together with evidence presented elsewhere, this study shows how an important predator is not only dependent on the existence of two qualitatively distinct habitat types, but also on the spatial distribution of these habitats. We suggest that this dependency arises due to the different responses that the predator's life stages have to this emergent spatial pattern.     

Interspecific interactions change the outcome of sexual conflict over prehatching parental investment in the burying beetle Nicrophorus vespilloides

Sexual conflict arises when the optimal reproductive strategy differs for males and females. It is associated with every reproductive stage, yet few studies have considered how the outcome may be changed by interactions with other species. Here, we show that phoretic mites Poecilochirus carabi change the outcome of sexual conflict over the supply of prehatching parental investment in the burying beetle Nicrophorus vespilloides. Burying beetles require a small dead vertebrate for reproduction, which they prepare by shaving it, rolling up the flesh, and burying it. When pairs were given a medium‐sized mouse to prepare (13–16 g), mites changed how the costs of reproduction were divided between the sexes, with males then sustaining greater costs than females. We found no equivalent difference when pairs prepared larger or smaller carcasses. Thus, our experiment shows that the outcome of sexual conflict over prehatching parental investment is changed by interactions with other species during reproduction.