Growth energetics in relation to temperature of the larvae of Rhopaea verreauxi (Coleoptera: Scarabaeidae)

Summary Instantaneous energy budgets were constructed at a range of constant temperatures (7.5°–27.5°C) for the larval stages of the scarabaeid Rhopaea verreauxi. It was found that as larvae increased in size the temperature optima/maxima for the components of the energy budget shifted to lower temperatures. Also, as larvae increased in size the instantaneous assimilation efficiency (A/C) decreased and the temperature range over which energy could be assimilated narrowed. Within this narrowing range, temperature was found to have an increasingly greater influence upon A/C. This was attributed to its influence upon the post-consumption energetics processes rather than upon consumption itself. The instantaneous net production efficiency (P/A) also decreased with increasing body size. Also, the temperature range over which assimilated energy could be partitioned to growth production became narrower as body size increased. These findings are discussed in relation to those of other energy budget studies. Some comment is made on the importance of temperature acclimation in studies such as this, and on the relation of energetics conversion efficiencies to ectothermy and endothermy and to trophic status. It was concluded that in terms of instantaneous conversion efficiences R. verreauxi could be described as a typical ectothermic herbivore, a moderately efficient converter.     

Rearing Costelytra zealandica (Coleoptera: Scarabaeidae)

Interaction between larvae can be a cause of mortality when scarabaeid larvae are concentrated in a confined volume of soil. Larvae of Costelytra zealandica (White), the New Zealand grass grub, were held for 30 days at population densities between 1 and 50 larvae per 200 ml of medium, and the effect of crowding on their survival and weight change was assessed. Larval density had no effect on survival in soil plus chopped sheep dung (3 :1), with up to 10 2nd‐instar larvae or 5 3rd‐instar larvae per 200 ml of medium. Larval survival and weight gain were increased by adding germinating ryegrass seed (Grasslands Ruanui) to the medium base, but the effect of density did not diminish. Weight gain of 3rd‐instar larvae decreased as their density increased. When the amount of germinating ryegrass seed in the medium was varied, there was no significant difference between the survival of larvae held in treatments with 5, 25, and 50 g of seed per litre of medium. Survival was significantly lower with 0 and 100 g of seed per litre of medium. It is concluded that, in rearing conditions, the final density of fully grown 3rd‐instar larvae should be a maximum of about 20 per litre of medium to prevent mortality caused by larval interaction—provided that adequate food is available.     

The biology of a giant dung-beetle (Heliocopris dilloni) (Coleoptera: Scarabaeidae)

Heliocopris dilloni is the largest dung-beetle found in the Tsavo National Park, Kenya, which during the biannual rainy seasons comprises the most important agency of elephant dung removal. The species is shown to exhibit considerable morphological variation. The mode of construction of the brood chamber is described together with details of development from egg to pupa. It is suggested that the depth to which these beetles burrow is related to avoiding the extreme climate near the surface and to predator avoidance.     

Synopsis of Antitrogus Burmeister (Coleoptera: Scarabaeidae: Melolonthini)

Abstract The genus Antitrogus Burmeister is widely distributed in eastern Australia and, because some species are significant pests of sugarcane, pastures and pineapples, it has attracted considerable research interest. This paper reviews the systematics, biology, ecology and management of the genus. The morphology of the 22 known species is described and a further species, A. gubbi sp. n. from south-eastern Queensland which was previously confused with A. robertsi Britton, is described. These species clearly divide into two species-groups: (i) those from south-eastern Queensland, eastern New South Wales and south-eastern Australia, which sometimes have closely related species pairs; and (ii) a more diverse group of species from central and northern Queensland. The latter is linked to A. villosus Allsopp from western Victoria, and this may indicate that further species await discovery in western New South Wales. Known life cycles are of 1 or 2 years. Adults fly for short periods following rain in spring or summer and do not feed. Adult females tend to disperse poorly, and this, coupled with ephemeral and localised rainfall, has probably contributed to speciation. Larvae feed on the roots of grasses and other similar plants. Insecticides are widely used to control them in sugarcane, but are too expensive for use on pastures. Integrating new controls with an emphasis on cultural controls is seen as the best way of managing these pest species.     

Diverse cuticular hydrocarbons from Australian canebeetles (Coleoptera: Scarabaeidae)

Abstract  Cuticular hydrocarbon components in beetles of six Australian melolonthines whose larvae damage sugarcane, Antitrogus parvulus (Britton), A. consanguineus (Blackburn), Lepidiota negatoria (Blackburn), L. picticollis (Lea), L. noxia (Britton) and Dermolepida alborhirtum (Arrow), are identified and compared. These species demonstrate species-specific cuticular hydrocarbon profiles with a number of unprecedented structures. Major components have been identified as polymethylated hydrocarbons, 3-methyl substituted n -alkanes, 9,10-allenes and the corresponding C9 alkenes. The similarity of these compounds shows some correlation with the phylogeny of the beetles, but two polymethylated C₂₂ hydrocarbons are unique to A. parvulus. One C₂₅ allene is shown to have a potential role in mate recognition in A. consanguineus.     

Pathogenicity of bacterial isolates to Cyclocephala signaticollis (Coleoptera: Scarabaeidae)

We describe the isolation and identification of pathogenic bacteria obtained from haemolymph of Cyclocephala signaticollis larvae. Two pathogenic bacteria, a Bacillus thuringiensis and an Arthrobacter sp. caused 90–100% mortality to C. signaticollis in 4 days after hemocoel injection, suggesting they might be useful as biological control agents.     

Chemical attractants for larvae of Costelytra zealandica (Coleoptera: Scarabaeidae)

In controlled laboratory tests, using shallow glass chambers containing a coarse river sand substrate between ‘blank’ and ‘test’ sample cages, 3rd‐instar larvae of Costelytra zealandica (White) were attracted to parsnip and carrot root, freshly ground nutmeg, and ß‐pinene (a constituent common to these materials). The terpenol a‐fenchol was strongly attractive to the larvae. Ryegrass root, α‐pinene, and limonene were not significantly attractive, and limonene may indeed have some repellent effect.     

The male reproductive system of Costelytra zealandica (White)(Coleoptera: Scarabaeidae: Melolonthinae)

Abstract

The morphology and histology of the male internal reproductive organs of Costelytra zealandica show many similarities to other Scarabaeoidae, and are particularly close to other Melolonthinae and to Rutelinae. Testes follicles of C. zealandica have the usual structure for Melolonthinae with basal lobes surrounding the ends of the vasa efferentia. Epithelial cells of the vasa efferentia, vasa deferentia, and vesiculae seminales have similar densely basophilic cytoplasm but muscle layers are best developed around the latter. Accessory glands lack muscle and are not differentiated histologically into regions but do differ from their reservoirs. The ejaculatory duct has a cuticular intima and is differentiated into anterior and posterior regions. Both are surrounded by a muscular sheath which expands in the posterior region to enclose fluid. This forms a hydraulic mechanism for everting the internal sac during intromission. The parameres hook into the female’s genital chamber during copulation and have no pincer action. Probable homologies are listed between muscles of the external genitalia and anus of C. zealandica and other Scarabaeoidea.     

The life cycle of Micromalthus debilisLeConte (1878) (Coleoptera: Archostemata: Micromalthidae): historical review and evolutionary perspective

Micromalthus debilis 33 ), has one of the most bizarre life cycles of any metazoan. Reproduction is typically by thelytokous, viviparous, larviform females, but there is also a rare arrhenotokous phase. The active first‐instar (triungulin) larva develops into a legless, feeding (cerambycoid) larva. This form either pupates, leading to a diploid adult female, or develops into any of three subsequent types of reproductive paedogenetic forms: (1) a thelytokous female that produces triungulins via viviparity; (2) an arrhenotokous female that produces a single egg that develops into the short‐legged (curculionoid) larva, eventually devouring its mother and becoming a haploid adult male; or (3) an amphitokous female that can follow either of the two above reproductive pathways. We speculate that Micromalthus is dependent on maternally transmitted bacteria for the ability to digest rotting wood, and that these bacteria are senescent in males, causing males to be obligately cannibalistic. Obligate male cannibalism, in turn, would have dramatically increased the cost of males, and have created a strong selective advantage for cyclic thelytoky and the other features of the Micromalthus life cycle that minimize the role of the male.     

A coleopteran cell line derived fromHeteronychus arator (Coleoptera: Scarabaeidae)

Summary The first continuous coleopteran cell line, designated DSIR-HA-1179, was derived from the scarab beetleHeteronychus arator. Most cells are spindle-shaped, 25 to 40 μm long and 15 to 20 μm wide, adhere strongly to plastic surfaces, and are highly resistant to trypsin and collagenase treatment. The population doubling time of 6 d, at 27° C, is slow compared with most dipteran and lepidopteran cell lines. The cells cross-react in comparative radioimmunoassays withH. arator larval tissue but not other insect cell lines and support the replication ofOryctes baculovirus and at least two nodaviruses, black beetle virus, and Flock House virus.     

A revision of Dichotomius (Homocanthonides) Luederwaldt, 1929 (Coleoptera: Scarabaeidae: Scarabaeinae)

The monospecific subgenus Dichotomius (Homocanthonides) is revised and its single species, Dichotomius (H.) smaragdinus (Perty, 1830) is redescribed and distinguished from other Dichotomius species. Dichotomius (H.) smaragdinus is a polymorphic species and its distribution comprises the Brazilian Cerrado. For the first time, morphological variation and male genital organ are described and illustrated. We believe that this species might be endangered due to extensive deforestation of Brazilian Cerrado by agricultural and pasture expansion. Thus, we highlight the importance of preserving this very unusual Dichotomius species.     

Male dimorphism in three sympatric species of Onthophagus (Coleoptera: Scarabaeidae)

Onthophagus trituber, O. taurinus, and O. proletarius, three sympatric dung beetle species native to southern Taiwan, exhibit normally distributed body size (pronotum width) but non-normally distributed horn length due to the presence of horned and hornless morphs. The scaling relationships between horn length and body size were established by using sigmoidal and segmented linear estimation, and the horned/hornless ratio in each of the species was estimated. The ratios estimated by sigmoidal curves showed that all three species were biased toward the hornless morph, whereas the ratios from segmented lines showed that only one species (O. taurinus) was biased toward the hornless morph. Nevertheless, the results of the two methods of estimation were concordant in ranking the horned morph proportions among the three species; O. proletarius had the largest proportion of horned morphs, whereas O. taurinus had the smallest, suggesting that the fewer horned morph in O. taurinus likely resulted from both intra- and inter-specific competition.     

Impact of Japanese beetle (Coleoptera: Scarabaeidae) feeding on seashore paspalum

Ten cultivars of seashore paspalum, Paspalum vaginatum Swartz, were compared for their response to Japanese beetle, Popillia japonica Newman, larval root feeding. Cultivars of Bermuda grass, Cynodon sp., and zoysiagrass, Zoysia sp., also were included for comparison. Turf grown in pots in the greenhouse was infested with second and third instars in this 2-yr study. Grub survival and weight gain, foliar growth, and root loss were compared among turfgrass species and cultivars. Few species-related differences were identified. Differences in grub tolerance were, however, observed to be a function of turfgrass cultivar. Some turf types demonstrating tolerance to grub feeding had rapid root growth and high root mass in control pots, but this was not consistent for all cultivars showing enhanced ability to maintain foliar growth despite grub feeding. The paspalum cultivars that seemed most tolerant of grub feeding were '561-79', 'Sea Isle 2000', 'Durban', 'HI-10', 'Kim-1', 'Sea Dwarf', and 'Sea Spray'.     

The evolution of parental behaviour in Scarabaeinae (Coleoptera, Scarabaeidae): an experimental approach

ABSTRACT.

• 1 Dung beetle lifestyles are reviewed. Most Scarabaeinae lay their eggs in dung masses that are packed into underground chambers, but Coprini and Scarabaeini typically lay their eggs in free-standing brood balls and it is in these tribes that parental care of the brood has evolved.
• 2 Brood balls are constructed by aggregating fragments of dung. This technique is derived from the method of gathering dung at the surface. Larvae developing in brood balls are better protected against dehydration and parasite attack. The repair technique of Scarabaeine larvae preadapts them to life in brood balls.
• 3 Parental care by Copris lunaris depends on appropriate responses by the female to the brood, and it has the selective advantage of protecting the brood against parasites. Preadaptations for parental care in‘non-brooding’Coprini are discussed.
• 4 Variations in the basic Copris nesting behaviour are summarized. Similar variations can occur spontaneously in C.lunaris and can also be released by unusual circumstances.
• 5 C.lunaris females could in principle cooperate but certain factors have prevented this social evolution. The significance of the transient cooperation with the male beetle is discussed.

     

Sexual and male horn dimorphism in Copris ochus (Coleoptera: Scarabaeidae)

Copris ochus (Coleoptera: Scarabaeidae), an endangered species, is the largest dung beetle in Japan. In C. ochus, males have a long head horn, while females lack this long horn (sexual dimorphism). Very large males of C. ochus have disproportionately longer head horns than small males, suggesting male horn dimorphism, although the dimorphism has not been investigated quantitatively. To clarify sexual and male horn dimorphism in C. ochus quantitatively, we examined the scaling relationship between body size (prothorax width) and head horn length in 94 females and 76 males. These beetles were captured during July 1978 from a natural population on Mt. Aso in southwestern Japan using a light trap. Although the horn length of the females and males scaled with prothorax width, the scaling relationship differed between the sexes, i.e., the relationship was linear in females and nonlinear in males. Statistical tests for dimorphism in male horn length showed a significant discontinuous relationship, thus indicating distinct sexual and male dimorphism in head horns. Long- and short-horned C. ochus males may have different reproductive behaviors, as described in other horned dung beetles.     

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.