Hidden Diversity—A New Speciose Gall Midge Genus (Diptera: Cecidomyiidae) Associated with Succulent Aizoaceae in South Africa

Aizoaceae (Caryophyllales) constitute one of the major floral components of the unique Greater Cape Floristic Region (GCFR), with more than 1700 species and 70% endemism. Within succulent Aizoaceae, the subfamily Ruschioideae is the most speciose and rapidly diversifying clade, offering potential niches for the diversification of specialized herbivorous insects. Nevertheless, insect diversity on these plants has not been studied to date, and knowledge of gall-inducing insects in the Afrotropics is generally scarce. Our recent observations indicate that succulent Aizoaceae in the GCFR support a rich and largely unstudied community of gall midges (Diptera: Cecidomyiidae). Here, we provide a first report of their diversity with a description of a new genus, Ruschiola Dorchin, and ten new species, based on morphological and molecular analyses of material collected during a three-year targeted survey across major GCFR vegetation types. A high degree of morphological uniformity in Ruschiola suggests recent diversification and necessitated the use of molecular data and laboratory rearing from host plants to verify species boundaries and host ranges.

Notes on the biological development of the darkling beetle Blaps nefrauensis nefrauensis Seidlitz, 1893 (Coleoptera: Tenebrionidae)

Several endemic species of Blaps occur in Tunisia, and the species Blaps nefrauensis nefrauensis has been reported in Moulares (urban zone in west-central Tunisia), where it lives and reproduces in home gardens and old buildings. The aim of this work is to study the life cycle of the darkling beetle, considering both field and laboratory rearing conditions. As a result, the beetle species has different developmental stages (egg, larva, prepupa, pupa, and adult) that last about 15 months. Each year during the same period, adults emerge (early summer) and expire (late autumn), larvae hatch (late summer) and pupate (early summer). There is only one generation per year. Females began laying eggs in late July. The eggs were ovoid, white, and about 2.7 mm in length and 1.5 mm in width. Embryogenesis took an average of nine days. The first instar larvae were at initially only 4.5 mm long and ivory white in color. A brief description of the newly egg hatched larva was provided; thus, the nerve fibers innervating the apical setae in the antennae and ligula were detected. Further light microscopic examination of the embryo before hatching from the egg pointed out that the antennal sensilla are protected during the embryogenesis stage.

Parasitism, seasonality, and diversity of trombiculid mites (Trombidiformes: Parasitengona, Trombiculidae) infesting bats (Chiroptera) in Poland

The study aims to ascertain the diversity of trombiculid species associated with Chiroptera in Poland, and for the first time in the case of research on Central European Trombiculidae, we use both DNA and morphology in an integrative taxonomic approach to determine species identities of trombiculids. The research was carried out from 2015 to 2019. In total, 2725 larvae were collected from 300 specimens of bats belonging to 11 species. Deutonymphs were obtained through laboratory rearing of larvae; few larvae and deutonymphs were collected also from bats' daily roosts. The presence of trombiculid larvae on hosts was observed between July and April of the following year, with the highest numbers recorded in autumn, during bat swarming. Male bats were infested more often than females (16.4 vs. 6.6%). The highest infestation rate was recorded for Barbastella barbastellus, Myotis nattereri and Plecotus auritus, and the highest prevalence of chiggers (> 30%) for Myotis bechsteinii and P. auritus. The larvae found on bats occupied the areas with free access to the host’s skin: auricles, tragus, and snout. Morphological identification of specimens to the species level was hindered by the mosaic distribution of diagnostic traits. Morphological analyses indicated the presence of Leptotrombidium russicum and Leptotrombidium spp. in the examined material, whereas molecular analyses additionally suggested three other potential species assigned to the same genus based on the assessed scope of intrageneric variation (ASAP method). We argue that the identification of the parasitic larvae (chiggers) using morphological characters does not address the question of actual species boundaries, which, in turn, affects the inferences about host specificity and host range.

Larval culture and settlement of the intertidal gastropod Siphonaria australis

<p>Laboratory rearing studies on the larvae of benthic marine invertebrates are important in providing information on the development of marine species, particularly those with complex life history cycles. Intertidal gastropods of the genus Siphonaria have been well studied in aspects of their physiology, behaviour, ecology, and reproduction. However, to our current knowledge, there are no cases on the successful laboratory rearing, from hatching through to metamorphosis, of larvae within this genus. Siphonariids are a primitive family of basommatophoran limpets in which the majority produce encapsulated embryos that hatch into feeding, planktonic veliger larvae. For such larvae, the quality and quantity of phytoplankton food can strongly affect larval growth, survival, and the ability to settle and metamorphose successfully. The primary aim of this study was to identify the optimal algal feeding diet for culturing the larvae of Siphonaria australis to competence in laboratory conditions, with a focus on algal composition and quantity. Once having defined the preferred feeding conditions, a secondary aim was to successfully culture larvae through to metamorphosis, by identifying the required settlement cue(s). First, I exposed newly hatched larvae to diets of three different algal compositions (all at a high concentration of 20,000 cells/mL): two unialgal diets of Isochrysis galbana and Pavlova lutheri, and a mixed diet consisting of a 1:1 ratio of both species. The results revealed that, although they grew in all diets, S. australis larvae exhibited highest growth and survival when fed the unialgal I.galbana diet. In a second experiment, I exposed newly hatched larvae to three different food concentrations of the unialgal I. galbana diet; low (1,000 cells/mL), medium (10,000 cells/mL) and high (20,000 cells/mL). Larval growth and survival were highest when fed a high food concentration, with development and survival severely reduced in low food treatments. At the end of this experiment it was discovered that once larvae grew to ~350µm in length, at an age of approximately one month post-hatching, they began to demonstrate signs of competence and growth rates plateaued. Finally, I exposed newly hatched larvae to optimum feeding conditions in an attempt to achieve larval settlement using different potential cues. Once larvae began to show signs of competence, they were exposed to five settlement cues: (1) live adults in filtered seawater (FSW), (2) adult-conditioned FSW, (3) rocks in adult-conditioned FSW, (4) rocks in regular FSW, and (5) crustose coralline algae-covered rocks in FSW. Larvae only successfully metamorphosed (i.e. exhibited loss of the larval velum) in treatments containing live adults. In total, my results provide a successful method in culturing Siphonaria australis larvae in laboratory conditions, as well as determines the cue required to induce settlement and metamorphosis. Not only can this method aid in providing more information on the development of this species, but it may also be applied to other members in this genus as well, and further our knowledge on the overall biology of Siphonariid limpets.</p>

Larval culture and settlement of the intertidal gastropod Siphonaria australis

<p>Laboratory rearing studies on the larvae of benthic marine invertebrates are important in providing information on the development of marine species, particularly those with complex life history cycles. Intertidal gastropods of the genus Siphonaria have been well studied in aspects of their physiology, behaviour, ecology, and reproduction. However, to our current knowledge, there are no cases on the successful laboratory rearing, from hatching through to metamorphosis, of larvae within this genus. Siphonariids are a primitive family of basommatophoran limpets in which the majority produce encapsulated embryos that hatch into feeding, planktonic veliger larvae. For such larvae, the quality and quantity of phytoplankton food can strongly affect larval growth, survival, and the ability to settle and metamorphose successfully. The primary aim of this study was to identify the optimal algal feeding diet for culturing the larvae of Siphonaria australis to competence in laboratory conditions, with a focus on algal composition and quantity. Once having defined the preferred feeding conditions, a secondary aim was to successfully culture larvae through to metamorphosis, by identifying the required settlement cue(s). First, I exposed newly hatched larvae to diets of three different algal compositions (all at a high concentration of 20,000 cells/mL): two unialgal diets of Isochrysis galbana and Pavlova lutheri, and a mixed diet consisting of a 1:1 ratio of both species. The results revealed that, although they grew in all diets, S. australis larvae exhibited highest growth and survival when fed the unialgal I.galbana diet. In a second experiment, I exposed newly hatched larvae to three different food concentrations of the unialgal I. galbana diet; low (1,000 cells/mL), medium (10,000 cells/mL) and high (20,000 cells/mL). Larval growth and survival were highest when fed a high food concentration, with development and survival severely reduced in low food treatments. At the end of this experiment it was discovered that once larvae grew to ~350µm in length, at an age of approximately one month post-hatching, they began to demonstrate signs of competence and growth rates plateaued. Finally, I exposed newly hatched larvae to optimum feeding conditions in an attempt to achieve larval settlement using different potential cues. Once larvae began to show signs of competence, they were exposed to five settlement cues: (1) live adults in filtered seawater (FSW), (2) adult-conditioned FSW, (3) rocks in adult-conditioned FSW, (4) rocks in regular FSW, and (5) crustose coralline algae-covered rocks in FSW. Larvae only successfully metamorphosed (i.e. exhibited loss of the larval velum) in treatments containing live adults. In total, my results provide a successful method in culturing Siphonaria australis larvae in laboratory conditions, as well as determines the cue required to induce settlement and metamorphosis. Not only can this method aid in providing more information on the development of this species, but it may also be applied to other members in this genus as well, and further our knowledge on the overall biology of Siphonariid limpets.</p>

Development of a nondiapausing strain of northern corn rootworm with rearing techniques for both diapausing and nondiapausing strains

The northern corn rootworm, Diabrotica barberi Smith & Lawrence, has a univoltine life cycle that typically produces one generation a year. When rearing the northern corn rootworm in the laboratory, in order to break diapause, it is necessary to expose eggs to a five month cold period before raising the temperature. By selective breeding of the small fraction of eggs that hatched without cold within 19–32 days post oviposition, we were able to develop a non-diapausing colony of the northern corn rootworm within five generations of selection. Through selection, the percentages of adult emergence from egg hatch without exposure to cold treatment significantly increased from 0.52% ± 0.07 at generation zero to 29.0% ± 2.47 at generation eight. During this process, we developed an improved method for laboratory rearing of both the newly developed non-diapausing strain as well as the diapausing strain. The development of the non-diapausing colony along with the improvements to the rearing system will allow researchers to produce up to six generations of the northern corn rootworm per year, which would facilitate research and advance our knowledge of this pest at an accelerated rate.

Optimizing Laboratory Rearing of a Key Pollinator, Bombus impatiens

Bumble bees are key pollinators for wild and managed plants and serve as a model system in various research fields, largely due to their commercial availability. Despite their extensive use, laboratory rearing of bumble bees is often challenging, particularly during the solitary phase queens undergo before founding a colony. Using a literature survey, we demonstrate that most studies rely on commercially available species that are provided during the colony’s social phase, limiting study on early phases of the life cycle and the ability to control for colony age and relatedness. Laboratory rearing is challenging since the queen solitary phase is less understood compared to the social phase. To overcome this barrier, we examined several aspects related to the queen solitary phase: the effect of age on likelihood of mating, how the timing of CO2 narcosis post-mating (a technique to bypass diapause) affects egg-laying, and whether different social cues affect the success of colony initiation. Our data show an optimum age for mating in both sexuals and decreased egg-laying latency in the presence of workers and pupae. The timing of CO2 narcosis did not significantly affect egg laying in queens. These findings can be incorporated to improve bumble bee rearing for research purposes.