Nest construction and larval behaviour of Onitis belial and Onitis ion (Coleoptera, Scarabaeidae)

Abstract. 1. Female beetles working alone or in cooperation with a male buried dung to make brood masses. O.belial brood masses were packed close together in clusters; each mass was constructed as a horizontal thick-walled tube of dung which was filled with a dung sausage containing two to six eggs. O.ion made vertical sausage-shaped brood masses with one to four eggs.
2. The larvae of both species were able to survive in artificial brood balls as well as in multi-egg brood masses because of their ability to repair larval chambers with their own excrement.
3. The multi-egg brood mass of Onitis has probably evolved from a simple one-egg brood mass. It does not resemble the underground dung mass from which brood balls are made by certain Coprini.     

Nest construction and larval behaviour of Bubas bison (L.) and Bubas bubalus (01.) (Coleoptera, Scarabaeidae)

Abstract.

• 1 Female beetles working alone or in cooperation with a male excavated vertical, tunnel-shaped brood chambers. Each chamber was filled with dung to form a cylindrical brood mass which contained two eggs, one near each pole.
• 2 To examine the possible relationship with other Onitini (which lay either one or several eggs per brood mass) factors that influence the two-egg programme were studied. Brood masses with only a single egg were formed if excavation was resumed prematurely. Conversely, when excavation was suppressed several oviposition programmes fused to produce a multi-egg brood mass.
• 3 The larvae repaired their chambers in the typical Scarabaeine manner by building a self-supporting wall formed from their own excrement. This behaviour also prevented direct contact and fighting between adjacent larvae in the same brood mass, and it allowed the larvae to survive inside artificial brood balls. Similar behaviour was observed in larvae of Onthophagus taunts and Ontho-phagus vacca (which develop in one-egg brood masses). The evolution of nesting habits that involve multi-egg brood masses or free-standing brood balls may depend on the pre-existence of this larval repair behaviour.

     

A comparison of dung beetle (Coleoptera: Scarabaeidae) attraction to native and exotic mammal dung

Although the preference of dung beetles (Coleoptera: Scarabaeidae) for specific types and conditions of dung has been given substantial attention, little has been done to investigate the potential effects of exotic mammal introduction for game farms or rewilding projects. We used pitfall traps baited with various native and exotic herbivore, carnivore, and omnivore dung to evaluate dung beetle preference in the Great Plains of North America. Additionally, we analyzed of the nutrient quality of each dung type. In total, 9,089 dung beetles from 15 species were captured in 2 yr of sampling. We found significant differences (P < 0.05) in mean dung beetle capture among omnivore, herbivore, and carnivore dung, as well as differences in individual species preference for dung type. Omnivore dung was the most attractive with chimpanzee and human dung having the highest mean capture (291.1 ± 27.6 and 287.5 ± 28.5 respectively). Carrion also was highly attractive with a mean of 231.9 ± 20.6 beetles per trap (N = 8). Our results suggest definitive local preference of carrion in Phanaeus vindex Macleay and Onthophagus hecate (Panzer), while the congener, O. pennsylvanicus (Harold), was rarely captured in carrion and highly preferred omnivore dung. Preference for a specific bait type does not appear to be correlated with dung quality, mammalian diet, or origin of mammal. Results suggest niche segregation by dung type among dung beetle species.     

Suspected side effects of a herbicide on dung beetle populations (Coleoptera: Scarabaeidae).

This paper addresses the association between use of a herbicide and anecdotal reports of reduced dung degradation and dung beetle populations. Dung beetles were monthly collected at two adjacent ranches in Mexico. Ranches were similar in area, elevation, exposition, soil, and vegetation, but differed in weed control. Ranch A controlled weeds manually, and ranch B controlled unwanted vegetation with applications of the herbicide Tordon 101M. The main species recovered on each ranch (Ataenius apicalis) was significantly more abundant at ranch A than at ranch B. Conversely, similar numbers of a second species, Ataenius sculptor, were recovered from both ranches. Three lines of evidence support the tentative conclusion that herbicide applications may be causing a decline in populations of A. apicalis on ranch B. First, the greatest reductions of A. apicalis were observed during periods of herbicide application. Second, A. sculptor, apparently little affected by these same herbicide applications, is active primarily during months without herbicide applications. Third, preliminary results of laboratory studies show that exposure to herbicide can impair reproductive function of the dung beetle Canthon cyanellus.     

Conservation strategies for poorly surveyed taxa: a dung beetle (Coleoptera, Scarabaeidae) case study from southern Africa

Despite being the focus of an international research effort spanning decades, the spatial distribution of southern African scarab beetles remains poorly documented. As well as reinforcing the magnitude of the challenge facing biodiversity scientists, this raises real concerns about best practice conservation strategies in the absence of detailed distribution information. However, dung beetles appear to be well represented in established conservation areas. This apparent contradiction could be ascribed to anthropogenic transformation, successful conservation efforts, the presence of dung generalists and reserve-biased or mesic-biased dung beetle collection efforts. It is suggested that all of the above contribute to the observed pattern to varying degrees. The implications of selecting areas that are either rich in species, contain rare species or contain taxonomically distinct species from a group whose taxonomy is well known but for which inadequate distribution data exist are explored. Best practice, in the face of inadequate data, appears to revolve around a subtle interplay between advantages and disadvantages associated with data interpolation techniques, reserve selection algorithms that use criteria more robust than database rarity (such as taxonomic distinctiveness) and the long-term economic costs of proceeding with the data at hand versus investing in biological surveys.     

Duration and benefits of biparental brood care in the dung beetle Onthophagus vacca (Coleoptera: Scarabaeidae)

Abstract.

• 1 Single males, single females or pairs of dung beetles, Onthophagus vacca, were released on artificial small (100 g) or large (1000 g) dung pats in the laboratory. Emigrating beetles were trapped at 12 h intervals, and the number and size of the brood chambers were recorded after each replicate.
• 2 Emigration of males was delayed if females were present in the same dung pats, whereas emigration times of females were independent of the presence or absence of males.
• 3 A residency of 60 h proved to be a threshold value. Females emigrating before this time did not breed, whereas those emigrating later had built at least two brood chambers.
• 4 Females paired with males built more brood chambers than single females.
• 5 The reproductive success of pairs was not influenced by the size of the dung pats.

     

Horn polyphenism and related head shape variation in a single-horned dung beetle: Onthophagus (Palaeonthophagus) fracticornis (Coleoptera: Scarabaeidae)

Horns of Onthophagus beetles are typical examples of phenotypically plastic traits: they are expressed as a function of environmental (nutritional) stimuli, and their reaction norm (i.e. the full set of horn lengths expressed as a response to different degrees of nutritional states) can be either linear or threshold-dependent. Horned males of Onthophagus ( Palaeonthophagus ) fracticornis (Preyssler, 1790) bear a single triangular cephalic protrusion of vertex carina, which has received phylogenetic support as the most primitive horn shape in the genus. Inter- and intra-sexual patterns of horn expression were studied in O. fracticornis by means of static allometries while associated variations in head shape were assessed using geometric morphometric techniques. The relation between log-transformed measurements of body size and vertex carina supported an isometric scaling in females. On the contrary, a sigmoidal model described better the horn length-body size allometry in males, with a switch point between alternative morphs at a pronotum width of 3.88 mm. Sigmoidal static allometries of horns in Onthophagus populations arise from a threshold-dependent developmental process of horn growth. This process underlies the expression of both plesiomorphic and apomorphic horn shapes in the genus. Given that the single-horn model has been identified as primitive, we propose that such a developmental process giving rise to it may be evolutionarily ancient as well. Horn expression was accompanied by a deformation of the head which makes minor and major morphs appear even more different. Therefore, in this species both horn and head shape expression contribute to male dimorphism.     

Food availability controls the onset of metamorphosis in the dung beetle Onthophagus taurus (Coleoptera: Scarabaeidae)

In nature, larvae of the dung beetle Onthophagus taurus (Schreber 1759) are confronted with significant variation in the availability of food without the option of locating new resources. Here we explore how variation in feeding conditions during the final larval instar affects larval growth and the timing of pupation. We found that larvae respond to food deprivation with a reduction in the length of the instar and premature pupation, leading to the early eclosion of a small adult. To achieve pupation, larvae required access to food for at least the first 5 days of the final instar (= 30% of mean third‐instar duration in control individuals), and had to exceed a weight of 0.08 g (= 58% of mean peak weight in control individuals). Larvae that were allowed to feed longer exhibited higher pupation success, but increased larval weight at the time of food deprivation did not result in increased pupation success except for larvae weighing > 0.14 g. Larvae responded to food deprivation by initiating and undergoing the same sequence of developmental events, requiring the same amount of time, as ad libitum‐fed larvae once those had reached their natural peak weight. Our results reveal a striking degree of flexibility in the dynamics and timing of larval development in O. taurus. They also suggest that premature exhaustion of a larva's food supply can serve as a cue for the initiation of metamorphosis. Premature metamorphosis in response to food deprivation has been documented in amphibians, but this is, to the best of our knowledge, the first time such a behaviour has been documented for a holometabolous insect. We discuss our findings in the context of the natural history and behavioural ecology of onthophagine beetles.     

Spatial separation of Afrotropical dung beetle guilds: a trade-off between competitive superiority and energetic constraints (Coleoptera: Scarabaeidae)

In the forest-savanna mosaic of Côte d'Ivoire (Parc National de la Comoé), we studied the guild structure of dung beetle assemblages of fresh buffalo faeces (60 samples, 19 626 specimens) in three adjacent habitats: savanna parkland, gallery forest, grassland of the river valley. We found clear patterns at the guild level determined by the habitat type and time of day: in the savanna parkland during the day, telecoprids (rollers) and their kleptoparasites are dominant. At night, paracoprids (tunnelers) and endocoprids (dwellers) dominate the dung beetle assemblages. In the river valley during the day and the gallery forest all day and night, the abundance of dung beetles is very low and does not reach a competitive level. In the river valley at night, endocoprids are quite abundant. Abundances of kleptoparasites and their hosts are positively correlated. The telecoprids are the most competitively superior guild since they use the resource most rapidly, but their abundance is correlated with temperature of faeces and soil. This is probably because their mode of resource utilization is energetically costly, so they require higher temperatures in order to maximize their competitiveness. Their ecological tolerance is therefore narrow and they are only present in the savanna parkland during the day. The endocoprids are the least competitive guild, since they do not relocate the resource and so are not able to monopolize parts of it. However, their mode of resource utilization is less energetically costly. They seem to be more tolerant of temperature fluctuation and more able to cross barriers such as the gallery forest. Spatial separation of Afrotropical dung beetle guilds is likely to be due to a trade-off between competitive superiority and energetic constraints.     

Residual effects of imidacloprid on Japanese beetle (Coleoptera: Scarabaeidae) oviposition, egg hatch, and larval viability in turfgrass

Preventive control of turf-infesting scarabaeid grubs by neonicotinoid insecticides is presumed to mainly result from residues killing first instars in the soil. The extent to which sublethal behavioral effects or intoxication of other life stages contribute to such control is poorly known. We tested whether Japanese beetle, Popillia japonica Newman, females lay fewer eggs in turf treated with imidacloprid (Merit 75 WP) or an imidacloprid-bifenthrin combination (Allectus GC SC), and whether exposure to those residues in thatch and soil reduces their survival and subsequent ability to feed or take flight. Effects of imidacloprid residues on egg hatch and viability of successive larval instars also were studied. In two sets of choice tests, 68 and 82% fewer eggs were laid in Kentucky bluegrass with Allectus residues than in controls. When females were confined in treated turf, however, neither insecticide consistently reduced their fecundity or affected depth at which eggs were laid, although exposure to fresh Allectus residues reduced the beetles' subsequent viability. Imidacloprid residues up to 2 ppm in soil did not affect egg viability or days to hatch, but they killed neonates soon after eclosion. Imidacloprid curatively applied at label rate (0.34 kg active ingredient/ha) reduced weight gain, burrowing capability, frass production, and survival of second and third instars in turfgrass cores, with high mortality within 30 d. Intoxication and behavioral impairment of third instars also occurred in autumn field trials. Our data suggest that imidacloprid has greater activity against late instars than is generally appreciated.     

Intraspecific patterns of mitochondrial variation in natural population fragments of a localized desert dung beetle species, Pachysoma gariepinum (Coleoptera: Scarabaeidae)

Phylogenetic, population, and coalescent methods were used to examine the genetic structuring of Pachysoma gariepinum, a flightless dung beetle species endemic to the arid west coast of southern Africa that exhibits interrupted south to north morphological clinal variation along a distributional gradient. Mitochondrial cytochrome oxidase I sequence data of 67 individuals from 5 localities revealed the presence of 3 geographically distinct evolutionary lineages (with an overall nucleotide divergence of 5.7% and a per-locality divergence of 1.9-3.8%) which display significant levels of genetic structuring. The separation of the lineages was estimated to have occurred between 2.2 and 5.7 million years ago--which is the late Miocene, early Plio-Pleistocene era--possibly in response to the ebb and flow of the Orange and Holgat River systems as well as the interactions between the moving and stable sand dune systems. Moreover the species' current range appears to have been influenced by the formation of advective fog resulting in a constant source of water in an area with low precipitation thereby allowing for the beetles to radiate to areas that were previously inhospitable. Fu's F-statistics and population parameters based on recent mutations indicated that little to no recent population growth has occurred. This together with changing anthropogenic factors and the recovery of 3 geographically discrete management units, points to a need for census data in order to monitor and conserve the genetic diversity of this species.     

Drench treatments for management of larval Japanese beetle (Coleoptera: Scarabaeidae) in field-grown balled and burlapped nursery plants

Insecticide drenches were applied to postharvest field-grown nursery plants harvested as 60-cm-diameter balled and burlapped (B&B) root balls for controlling third instars of Japanese beetle, Popillia japonica Newman (Coleoptera: Scarabaeidae). Bifenthrin, chlorpyrifos, lambda-cyhalothrin, and thiamethoxam were drench-applied in fall and spring tests at volumes of runoff (1X; approximately equal 2.57 liters per drench per root ball) or twice runoff (2X). Tests also examined consecutive drenches (two, four, or six) and B&B rotation between drenches. Fall-applied drenches did not meet the Domestic Japanese Beetle Harmonization Plan (DJHP) standards of < or =1 grub and ranged from 0 to 90% control. However, most fall-applied drenches significantly reduced grub numbers relative to the untreated root balls. Spring-applied drenches were more effective than fall drenches: chlorpyrifos treatments gave 94-100% control, whereas other spring-applied treatments were less consistent, including thiamethoxam (83-100% control) and bifenthrin (61-100% control). Lambda-cyhalothrin was not effective. A higher drench volume (2X) did not significantly improve treatment efficacy; however, grub numbers decreased as the number of drenches increased for fall-applied chlorpyrifos and thiamethoxam and spring-applied bifenthrin. Rotation of root balls significantly reduced grub numbers compared with nonrotated treatments for fall-applied chlorpyrifos (six drenches) and bifenthrin (two or six drenches), but these treatments did not meet DJHP standards. The study indicates chlorpyrifos, bifenthrin, and thiamethoxam drenches can control Japanese beetle in the spring and may provide a new postharvest option to certify B&B plants for Japanese beetle.     

Copro-necrophagous beetle (Coleoptera: Scarabaeidae) diversity in an agroecosystem in Yucatan, Mexico

Scarabaeinae are sensitive to structural habitat changes caused by disturbance. We compared copronecrophagous beetle (Scarabaeinae) community structure in three differently managed zones within an agroeco-system of the northern Yucatan Peninsula, Mexico. We placed dung and carrion traps once a month from June 2004 through May 2005. The beetle community included 17 species from the genera Canthon, Canthidium, Deltochilum, Pseudocanthon, Malagoniella, Onthophagus, Phanaeus, Copris, Uroxys, Sisyphus and Ateuchus. The secondary vegetation had a higher beetle diversity than the other two zones. Species richness was highest in the Brosimum alicastrum plantation. The pasture had the lowest species diversity and richness, but exhibited the highest abundance of Scarabaeinae in the dry season. The two zones with extensive tree cover were the most diverse. Roller beetles were dominant over burrower species and small-sized species outnumbered large species. Our data show two important issues: beetle species in the pasture extended their activity to the beginning of the dry season, while abundances dropped in the other, unirrigated zones; and the possibility that the Scarabaeinae living in neotropical forests are opportunistic saprophages and have specialized habits for resources other than dung. The B. alicastrum plantation is beneficial to the entire ranch production system because it functions as a dispersion and development area for stenotopic species limited to tree cover.     

Potential resistance of crape myrtle cultivars to flea beetle (Coleoptera: Chrysomelidae) and Japanese beetle (Coleoptera: Scarabaeidae) damage

Field and laboratory studies were conducted to identify potential resistance among crape myrtles, Lagerstroemia spp., to Japanese beetle, Popillia japonica Newman and to flea beetles, Altica spp. Damage ratings revealed variation among cultivars in susceptibility to beetle feeding. Cultivars with Lagerstroemia fauriei Koehne in their parentage exhibited the least amount of damage in choice and no-choice experiments, with few exceptions. The data indicate that both beetle species cause more feeding damage on certain cultivars of Lagerstroemia indica L., such as 'Country Red', 'Twilight', and 'Carolina Beauty' than interspecific cultivars with L. fauriei in their parentage, such as 'Natchez', 'Tonto', and 'Muskogee'. When comparing the effect of parentage on all of the major pests of crape myrtle, L. faurei confers resistance to all pests except crape myrtle aphid. No correlation was found between leaf toughness, leaf color, and leaf nutrients in estimating flea beetle cultivar preference. With this information, growers can more effectively target scouting measures to the most susceptible cultivars. and breeders can select plants that will require the fewest chemical inputs.     

An Iridovirus from the black beetle,Heteronychus arator (Coleoptera : Scarabaeidae)

Abstract

Iridescent virus type 23 from the black beetle (Heteronychus arator) replicated in Spodoptera frugiperda cells, producing some cell vacuolation after 3 days and extensive vacuolation and detachment of cells 7 days after infection. The virus also replicated in Aedes albopictus cells, and in the larvae and pupae of Galleria mellonella.     

Effect of population density on reproduction of two sympatric dung beetle species,Aphodius haroldianus andA. Elegans (Coleoptera: Scarabaeidae)

The effect of population density on reproduction as well as the oviposition modes of two sympatric dung beetle species, Aphodius haroldianus (a low fecundity/high parental effort species) and A. elegans (a high fecundity/low parental effort species) was studied at a pasture in central Japan from 1982 to 1986.

1. The adult population density of A. haroldianus was high (>40 per dung pat). The density of A. elegans was low (<5 per dung pat). Oviposition of A. haroldianus was suppressed above the density of about 10 adults of conspecifics but not affected by the density of other species. The intra- and interspecific density effects on oviposition were not detected in A. elegans.
2. The number of A. haroldianus adults per pat decreased with dung age, while that of A. elegans increased until sixth day after deposition and then decreased. The number of eggs laid per pat was not different between 1-day-and 3-day-old pats for A. haroldianus. However, more eggs of A. elegans were found in 3-day-old pats than in 1-day-old ones.
3. In the both species, the amplitude of population fluctuations was not remarkable; the maximum/minimum ratio for five years being 2.3 for A. haroldianus and 2.9 for A. elegans. Different density dependent processes were suggested to function for the small fluctuation of population density between the two species, i.e. intraspecific density effect on oviposition for A. haroldianus and contest type competition for food among larvae of A. elegans.

     

Trophic associations of a dung beetle assemblage (Scarabaeidae: Scarabaeinae) in a woodland savanna of Botswana

Species richness and abundance of dung beetles were assessed across a range of bait types that acted as surrogates for the food resources available in Chobe National Park, Botswana. These bait types were comprised of the dung of pig (omnivore), cattle (ruminant herbivore dropping fine-fiberd pads), sheep (pellet-dropping ruminant herbivore), and elephant (monogastric, nonruminant herbivore producing coarse-fibered droppings), and chicken livers (carrion). Species richness was similar between traps baited with pig, cattle, and elephant dung but was relatively lower in those baited with sheep dung and carrion. In traps baited with pig dung, abundance was relatively greater than in all other bait types. A cluster analysis of species abundance distributions for the 30 most abundant species identified four different patterns of bait type association at a 60% level of similarity. All but 1 of the 15 species in cluster A were attracted primarily to the dung of omnivores and pad-dropping ruminant herbivores (pig and cattle). All seven species of cluster B were attracted primarily to coarse-fibered, nonruminant herbivore dung (elephant). All four species of cluster C were primarily carrion and pig dung associated, whereas all four species of cluster D were carrion specialists. In conclusion, the most abundant species were attracted to all bait types, but most species were largely specialized to different dung types or carrion, with dung attracting the majority of the fauna in terms of both species richness and abundance.     

Diversity and seasonal fluctuations in dung beetle (Coleoptera) community in Kurukshetra,India

Five pitfall traps baited with 150–200 g of fresh cattle dung were installed for 24 h at weekly intervals. A total of 991 dung beetles from 11 genera, 31 species and three subfamilies was obtained. The community was dominated by Oniticellus spinipes individuals by 32.3%. Ten species appeared only once during the collection period and species composition and dominance changed throughout the period. The overall pattern we detected in the organization of the dung beetle community is that the species richness, abundance and diversity rise in September and the 2^nd week of October. The dung beetle community was found to be affected by season.