Observations on the developmental biology of Cicindela arenicola Rumpp (Coleoptera: Cicindelidae)

Cicindela arenicola Rumpp is being considered for threatened and endangered status by the U.S. Fish and Wildlife Service. Little is known about the developmental biology of this species. Adults of C. arenicola were active from April through late June and late August through early November, but generally they were not on the surface when temperatures were below 19 C or above 45 C, or when conditions were windy, cloudy, or rainy. Mating and egg-laying occurred only during the spring. Five size classes (1-,2-,3-,4-, and 5-mm diameters) of larval burrow openings were observed. Burrows of 5 mm had a mean depth of 42.23 ± 8.81 cm (1 S.D.). Larvae of C. arenicola were active from April through June and late September through mid-November. Developmental times and larval size were affected by food supplementation. Nearly all food-supplemented, 1-mm, first instars molted to larger second instars of3-mm diameter. Most nonsupplemented larvae spent several months as 2-mm second instars before growing to 3 mm in diameter. Food-supplemented larvae reached the third instar in approximately 13 months, while nonsupplemented larvae took slightly over two years to reach this stage. Development from egg to adult was estimated at two years for food-supplemented larvae and three and one-half to four years for nonsupplemented larvae. Cattle had a significant effect on larval mortality. A high percentage (76-80%) of larval C. arenicola that were stepped on by cattle never reopened their burrows. Only 14% of undisturbed larvae never reopened their burrows. Approximately 15% of 150 larvae marked in 1988 reopened burrows in 1989.     

Relationships of aspen ( Populus tremuloides ) to foraging patterns of beaver ( Castor canadensis ) in the Strawberry Valley of central Utah

Eight study sites were examined in Strawberry Valley, Utah, to assess the response of aspen ( Populus tremuloides Michx.) to cutting activities of beaver ( Castor Canadensis Warren & Hall) and to determine patterns by which the animals utilize aspen stands. Sites utilized by beaver, along with adjacent control plots in mature, uncut aspen stands, were sampled. Age-class profiles of control plots were composed of a broad age distribution with trees ranging from 3 to 108 years old. Age-class profiles for aspen sprouts in areas previously used by beavers were composed of trees averaging seven years of age with a range of 1 to 24 years. Age distribution of sprouts in areas used by beaver show a tendency to be skewed toward younger age classes. Average density of aspen in areas used by beaver was 15,800stems per hectare compared to 2,980 stems per hectare in controls. Stump densities in use areas ranged from 900 to 5,066 stems per hectare. Densities of stumps in the 0-5-cm size class were greater in areas used by beavers than in the corresponding size class in the mature forests. A regression equation describing age versus diameter relationships was calculated using data from 312 aspen trees. Total phenolics and mineral nutrients in the twigs and bark of mature aspen trees and aspen sprouts were also examined to determine if variations could explain foraging patterns of beaver in the valley. Total phenolics were highly variable between sampling groups, and differences were not significant. Twigs from mature aspen and aspen sprouts were significantly higher in nitrogen, phosphorus, and iron. Zinc was significantly higher in the bark of mature aspen trees and twigs of aspen sprouts. Calcium concentrations were significantly higher in mature aspen bark, and magnesium was significantly higher in mature aspen twigs.     

Studies on Alenophalera bronneomixia (Lepidoptera: Notodontidae)—a pest of the West African indigo plant,Lonchocarpus cyanescens (Papilionaceae)

Summary

This paper is concerned with the general biology of the notodontid moth, A. bronneomixia whose larvae are found to be serious defoliators of the West African indigo plant, Lonchocarpus cyanescens.

At temperatures fluctuating between 21°C and 29°C (mean 22·5°C) and humidities between 70 to 95 per cent eggs developed and hatched in a mean of 11·1 days from deposition, mean hatch being 93 per cent.

Under the said environmental conditions, the life cycle from egg to adult entailed six larval instars and a prepupal stage before the real pupa, all lasting 60 to 80 days. Larvae were strongly monophagous, fed communally and in nature pupated in soil/litter very close to the foot of their invaded food plant.

Adults were retiring and in the field deposited clusters of numerous eggs preferably on the abaxial surfaces of their food plants. In nature, this moth's population seemed strongly regulated by high egg and larval parasitization, larval predation and fungal attacks at the pupal stage.     

Larval growth rates and sexual differences of resource allocation in the cetoniine scarab Mecynorhina polyphemus Fabricius 1781 (Coleoptera: Scarabaeidae: Goliathini)

Larval ontogeny of the scarab Mecynorhina polyphemus was monitored throughout all instars, and larvae were weighed at 7-day intervals. Durations of the prepupal, pupal and postpupal stages were recorded. Larvae increase their body masses over 300 times during ontogeny. Male imagines are larger than females, and this is primarily a function of faster growth rates during instar III, resulting in significantly heavier larvae at the end of this instar. The durations of the three instars are not significantly different in males and females, but the duration of the prepupal and postpupal phases is significantly longer in males. There is a strong correlation in both sexes between maximal larval mass and the mass of the imago, but larval mass–imago mass scales with significantly different slopes in males and females. Male larvae must allocate increasingly more resources into production of cephalic horns with increments in larval mass, requiring differently proportioned pupal chambers.     

Larval instars of the ant Strumigenys solifontis Brown (Hymenoptera: Formicidae): the fallacy of size distribution

Larval instars of the myrmicine ant Strumigenys solifontis Brown were determined by measuring the head width under a stereomicroscope and examining the morphology, especially chaetotaxy, by light microscopy and scanning electron microscopy. This study found that the larval stage consisted of four instars, but the first and second instars were not distinguishable by their head widths. However, the four instars could be discriminated clearly by a combination of size measurement and observations on the chaetotaxy. Within a population, there are few larvae in the first instar because of its short period (only 1–2 days before moulting into the second instar) and the low oviposition rate of the queen. Therefore, the first-instar larva needs to be collected separately from other instars so that it is not missed.     

Intraspecific larval aggression in two species of Hyperini (Coleoptera: Curculionidae)

Two unusual types of behaviour (wandering and intraspecific aggressive behaviour) have been observed when rearing larvae of two species of the tribe Hyperini. Wandering of Hypera postica in search for food was observed in L1, L2 and L3 larvae, as well as in young L4 larvae. L1 larvae also disperse in response to crowding. Wandering of L2 to young L4 instars was a response to food shortage. Wandering of late L4 larva (‘prepupa’) occurs because of searching for a place to spin the cocoon and pupate. Encounters between the larvae may result in agonistic behaviour, and some larvae may die as a consequence of fighting. This aggression increases with food limitation. Agonistic intraspecific behaviour has not been described to date in weevil’s larvae and it probably may not occur under natural conditions when there is a plenty of food and larval densities are decreased by pathogens or parasitoids.     

Developmental stages of Caligus epidemicus Hewitt,a copepod parasite of tilapia cultured in brackish water

The larval development of Caligus epidemicus comprises ten stages: two nauplii, one copepodid, six chalimus, and one preadult (young adult) stages. The morphology of each of these ten instars is described based on material reared from eggs in the laboratory. Addition of fifth and sixth chalimus stages in the ontogeny of C. epidemicus is discussed in the light of the developmental changes in the leg armature. Some peculiarities about the structure of the frontal filament in various chalimus stages are also discussed.     

Emergence, attack densities, and host relationships for the Douglas-fir beetle ( Dendroctonus pseudotsugae Hopkins) in Northern Colorado

Douglas-fir beetle-infested Douglas-fir trees were partially caged to determine the emergence period and beetle production. Beetles began emerging in April, but emergence peaked between 10 and 26 June. In 1987 and 1988 beetle emergence averaged 20 or more per sq. ft. of bark. Annual growth of the infested trees showed a decline prior to the beetle outbreak followed by an increase during the outbreak.     

List of Montana Scolytidae (Coleoptera) and notes on new records

Listed are 96 species of Scolytidae (Coleoptera) from Montana. Eighteen species reported from Montana for the first time are: Scierus pubescens Swaine, Hylastinus obscurus (Marsham), Hylesinus aculeatus Say, Hylesinus californicus (Swaine), Hylesinus criddlei (Swaine), Pseudohylesinus granulatus (LeConte), Dendroctunus punctatus LeConte, Phloeosinus hoferi Blackman, Phloeosinus pini Swaine, Carphoborus pinicolens Wood, Scolytus subscaber LeConte, Ips grandicollis (Eichhoff), Trypodendron betulae Swaine, Trypodendron retusum (LeConte), Trypophloeus populi Hopkins, Procryphalus mucronatus, (LeConte), Pityophthorus alpinensis G. Hopping, and Gnathotrichus denticulatus Blackman.     

The status of Hemilecanium imbricans (Green) (Homoptera : Coccoidea) in Africa south of the Sahara

Summary

This paper describes the findings from two series of observations on variation in C. austropalpalis L. and R. In Series I the distribution of head capsule lengths of 174 larvae, collected from 11 breeding sites in S.E. Queensland, was polymodal. Polymodality was also shown by the wing lengths of 15♂, 27♀ reared from 7 of the sites. In Series II the head lengths of 302 larvae from 5 sites (one not in Series I) gave the same polymodality, interpreted as representing 3rd and 4th instars of two forms A (smaller) and B (larger). 276 of these larvae, grouped on head length, were reared on agar and small nematodes, producing 62♂, 70♀ C. austropalpalis and 13♂, 5♀ C. narrabeenensis. The latter was not the cause of the polymodality. Adult wing lengths were bimodal in each sex. Form B was longer winged than form A. Within each form there was no significant correlation between larval head length and adult wing length. Only one of the many additional characters (19 in ♀; 22 in ♂) examined, differed between the two forms. Form B had more distinctly patterned wings with the intercalary pale spot more obvious. The results are discussed.     

Biology and defensive secretion of myrmecophilous Thiasophila spp. (Coleoptera: Staphylinidae: Aleocharinae) associated with the Formica rufa species group

Various aspects of the biology of the myrmecophilous Thiasophila angulata and T. szujeckii (Staphylinidae; Aleocharinae), mainly associated with the Formica rufa species group, are studied. The composition of defensive gland secretions from adults of T. angulata has been analysed. The complete development (egg-L_1-3-pupa-adult form), including adult overwintering, of both species takes place solely in ant nests. Under laboratory conditions, this lasts for about 22 days in T. angulata, and the period elapsing between the old and new generations of insects is approximately two months. The mean fecundity of adults of this species (28 eggs) was determined, as well as the duration of its reproductive period (mean 28.5 days), and lifespan (mean 67 days). In natural conditions T. angulata, found within nests of Formica polyctena and F. rufa, produces three generations, and the sibling species T. szujeckii one generation per year. These two species differ in their phenologies and abundance dynamics of adults and larvae, which is linked to the size and temperature regime of the host nest. The results of this study uphold the recent separation of T. angulata and T. szujeckii based on morphological features of adults and selected molecular markers. Adults and larvae of T. angulata forage on both live and dead food items accumulated by the host, as well as on the host’s eggs and larvae. Both the beetle larvae and adults remain unmolested among the host workers. The adults use their defensive gland secretions, which contains substantial quantities of toxic quinones, when necessary. According to the current categories of myrmecophiles, T. angulata (and by analogy, T. szujeckii as well) should be classified as a species wholly integrated with the host.     

Pherbina mediterranea: immature stages,biology, phenology and distribution (Diptera: Sciomyzidae)

The egg, three larval instars, and puparium of Pherbina mediterranea are described. The duration of the various immature stages indicates that this specis is univoltine and spends the winter as quiescent larvae. The biology, phenology and geographical distribution are presented. The main features of the larvae are illustrated with scanning electron micrographs. A key to the adults of genus Pherbina is given.     

Growth ‘rules’ and the larvae of decapod crustaceans

Summary

Statements that have attempted to express the relationship between the sizes of successive arthropodan instars are examined with reference to published data on larval decapod crustaceans.

The conclusions reached are (a) that ‘Brooks's Law’, which simply states that the lengths of successive instars form an exponential series, generally holds good in decapod larvae, (b) that ‘Przibram's Rule’, stating that the weight increase between instars is always by some power of 2, is not supported by the observed length changes, and (c) that Gurney's suggestion that growth factors in decapod larvae do not normally exceed about 1·5 is not applicable to the order as a whole, but may be valid for some sub-groups within it.     

The biology of some Phyllonorycter species (Lepidoptera: Gracillariidae) mining leaves of oak and beech

Summary

The oak leaf miners P. quercifoliella and P. harrisella were encountered at first generation densities of 40 and 48 mines per 1000 leaves in 1968 and 1969 and second generation densities of 179 and 211 mines per 1000 leaves. The 1969 densities for the two generations of P. maestingella on beech were 54 and 118 mines per 1000 leaves. The mines on oak were found to be aggregated on certain trees but the reason for this was not discovered. There was also aggregation on certain leaves within a tree.

The moths had two generations of adults per year at Dunham, the first generation mines appearing on the leaves in June and the second generation mines in August. P. maestingella seemed to be slightly in advance of the oak species.

The sampling data provided estimates of the mortality through 1969. Larval interference and mine damage caused negligible mortality. Death due to unknown factors figured prominently in the early instars but in the later instars, especially during the second generation, parasitism was important. Leaf browning was an added source of mortality in the second generation as was overwintering.

Fifteen species of hymenopterous parasites were bred from Phyllonorycter on oak and eight from P. maestingella on beech. Among these were some new host records. T. ecus was the most common first generation parasite of oak mines and C. nephereus. E. latreillei, S. sericeicornis, C. diallus and C. vittatus figured prominently in the second generation parasite complex. E. cilla was the commonest parasite of both generations of P. maestingella.     

Development of epipods and gills in some pagurids and brachyurans

Sepedon trichrooscelis is a semiaquatic, multivoltine species whose larvae feed on snails of the genus Succinea. The duration of the various developmental periods and larval biology are presented. The egg, three larval instars, and puparium of Sepedon trichrooscelis are described and illustrated. The distribution of the cuticular sensorial receptors, the shape of the hydrofuge setae on the posterior disc, and the details of the egg are illustrated by scanning electron micrographs.     

Bionomics and control of the walnut spanworm, Phigalia plumogeraria (Hulst), on bitterbrush in Utah

In 1979, the walnut spanworm defoliated a 1 ha bitterbrush seed orchard near Nephi, Utah. No seed was produced for two years thereafter due to feeding damage. Life stages were described and illustrated. The female is brachypterous and incapable of flight. First instar larvae readily drop on their silk threads and probably are dispersed by wind. The insect has one annual generation. Moths laid an average of 159 eggs per cluster in April; larvae began to appear in early May and matured by the first week of June. The pupal period extended from June until mid-April. The parasitic bombyliid, Villa faustina (Osten Sacken), was reared from pupae. In April 1980, shrubs contained an estimated average of 1044 eggs each. On 19 May, larvae averaged 1.9 per 7.5 cm of twig and were in the first and second instar. On 20 May the population was controlled by spraying with Sevimol-4. Other potential host plants, as determined from greenhouse tests, are rose, ceanothus, mountain mahogany, serviceberry, and willow.     

On the life-habits and developmental stages of Nidomyia cana Papp (Diptera,Borboropsidae)

Eggs, second and third instar larvae of the enigmatic species Nidomyia cana, which was discovered most recently from the nests of raptorial birds in southern Hungary, are described. Both egg and larvae show peculiarities among the so-called heleomyzoid flies. Larvae were found in wet vegetable material (mostly pieces of poplar bark) of a buzzard nest and their shape is of a saprophagous type. Females are macro-oviparous, with a maximum of 15 to 17 eggs laid in one batch. Adults live mostly on the surface the of the nest, they copulate there, and they find shelter in the nest itself. No direct contact with adults or nestlings within the nest was observed. It is suggested that overwintering occurs as pupae (pharate adults) underground, beneath the nest. However, if N. cana lives exclusively in the nests of raptors, adults would have difficulties in finding a new nest, and it is probable that they are transferred to new nests attached to the birds.     

Morphology and larval development of Polydora cf. websteri (Polychaeta: Spionidae) in a tropical region of north-eastern Brazil

Polydora websteri belongs to a group of the Spionidae known as the Polydora complex, members of which are known for building tubes within the shells of mussels and for their ability to infest commercially valuable bivalves, which causes serious losses for malacoculture. P. websteri is a species subjected to increasing research due to the global scale at which these infestations occur. In this paper, we describe the larval development of P.cf. websteri associated with the oyster Crassostrea cf. brasiliana in a tropical region of north-east Brazil. The main structures of all stages of development were analysed and compared to other populations of P. websteri. Ovigerous capsules of P.cf. websteri were cultured in the laboratory and the larval stages were analysed until metamorphosis. Ovigerous capsules were present in all sampling intervals, indicating that this population exhibits continuous reproduction. Up to 21 capsules per tube were found, and the number of eggs per capsule varied from 20 to 40. All observed eggs developed into larvae. Larval development from egg to recruitment stage did not exceed 13 days. Metamorphosis occurred when larvae attained 17 chaetigers, at which stage important diagnostic characteristics were revealed, such as the spines on chaetiger 5. The developmental stages of P.cf. websteri larvae, and the morphological features found at each stage, are in accordance with what has been recorded for temperate populations. In our study, the planktonic stage was found to be of shorter duration than elsewhere, which might be associated with the higher temperatures at which larvae were cultured compared to previous studies.     

Natural history and ecological niche modelling of coastal Atyphella Olliff Larvae (Lampyridae: Luciolinae) in Vanuatu

ABSTRACT

The genus Atyphella Olliff includes several coastal species with larvae that were collected on coastal rock within the intertidal zone. Recent fieldwork in Vanuatu has expanded the distribution of these insects and begun to provide insight into how they are able to survive in such a unique environment. An ecological niche model is produced using Maxent to predict additional locations of coastal Atyphella in the South Pacific. Larval instars for the two species of Atyphella in Vanuatu are estimated using protergum shield width measurements. Additionally, submersion tests were performed on larvae to determine survivability in saltwater and freshwater environments. These data provide evidence for previously unknown aspects of their natural history that strongly suggest the species are multivoltine and spend a large portion of their larval stage in the intertidal zone.