Sensitivity to perturbations of a cell migration under temporal regulation

Few studies have measured the robustness to perturbations of the final position of a long-range migrating cell. In the nematode Caenorhabditis elegans, the QR neuroblast migrates anteriorly in the young larva, while undergoing three rounds of division. The daughters of QR.pa stop their migration at an anterior body position and acquire a neuronal fate. Previous studies showed that the migration stops upon expression of the Wnt receptor MIG-1, which surprisingly is not induced by positional cues but by a timing mechanism (Mentink et al. 2014). Given this temporal regulation, we wondered 1) how precise QR.pax positioning is when confronted with various challenges, such as stochastic noise, environment or body size variation and 2) whether QR.pax position varies among C. elegans wild isolates. We find that the variance of QR.pax final position is similar to that of other long-range migrating neurons. Its mean position undergoes a slight posterior shift at higher temperature, while its variance is greatly increased following sustained starvation at hatching. We manipulated body size using mutants and tetraploid animals. As expected from the temporal mechanism, smaller mutants display anteriorly shifted QR.pax cells, while longer mutants and tetraploids display posteriorly shifted QR.pax cells. Using a mathematical model, we show however that body size variation is partially compensated. We find that cell speed is indeed altered in body size mutants. Finally, we could detect highly significant variation among C. elegans wild isolates. Overall, this study reveals that the final cell position of QR.pax shows some degree of sensitivity to external perturbations and natural genetic variation.

Disinfestation of Sitophilus zeamais Motschulsky in stored maize using microwave

This study aimed primarily to investigate on disinfestation of maize weevil (Sitophilus zeamais Motschulsky) in maize storage by using microwave method. Specimens of Maize weevils were cultured for 30 days in a maize sample with 17% moisture content (wet basis). Several different life stages of the maize weevil (egg, young larva, old larva, pupa and adult) were then infested in the sample. Next, the maize sample was exposed to 200, 300 and 450 W of microwave power for 60, 120 and 180 s, and the number of weevils were counted after each treatment. Moreover, the sample was kept for another 2 months to see whether the eggs have survived the treatment and grown to be adults. In addition, the effects of the level of microwave power and exposure time on the property of the maize sample were observed. The quality parameters investigated were moisture content, colour and protein and fat contents. It was found that, at 300 W of power for 180 s, the microwave was able to disinfect weevils at all life stages successfully, while the quality of the maize sample did not change significantly at the tested microwave settings and exposure times, except for the protein content. These findings indicate that microwave can be a good alternative to harmful chemical methods for disinfestation of maize weevils.

Insecticidal effect of the ethanol extract of Baccharis dracunculifolia (Asterales: Asteraceae)

Insecticides from plants have been studied as an alternative in agricultural production and in vector control of human diseases. The use of botanical insecticides may cause mortality in different stages, slow growth, infertile adults and decrease in viability of insect eggs. This study aimed to analyze the insecticidal potential of ethanol extract of Baccharis dracunculifolia DC, on Spodoptera frugiperda Smith, 1797 (Noctuidae) and Aedes aegypti L., 1762 (Culicidae). The botanical material was collected and prepared on February 8th, 2011 on the Fazenda Escola Três Barras (20°33’37.44043" S - 54°32'10.3824" W), Campo Grande, MS. The ethanol extract was prepared from dried leaves obtained of adult plants in a vegetative state at the Chemistry Laboratory of Anhanguera University-Uniderp. The experiments of biological activities were conducted at the Entomology Laboratory of the Catholic University Dom Bosco, in a controlled environment with an average temperature of 25 ºC and photoperiod 12 hr. Experiments with S. frugiperda were conducted from August to October 2014. The collection of A. aegypti eggs was made in January 2014 and the treatments were done from March 10th to 17th, 2014. In the development of S. frugiperda the extract caused effect on caterpillars subjected to treatment at one and 10 days. The larval stage proved to be longer at both ages and pupal weight reduced at 10 days, as well as increased mortality at one day, when incorporated concentration 0.2 % into diet. The variables studied were mortality, larval duration, pupal weight, number and viability of the eggs. The bioassay used A. aedes 3º (third) instar, 25 (twenty five) larvae per concentration, at four replicates. Parameters analysed for sublethal doses were pupal and larval, mortality, length larval and young (larva + pupa) the ethanol extract at concentrations 0.5 mg.mL-1 and 0.25 mg.mL-1. The extract resulted in deleterious effect on the development of caterpillars undergoing treatment in larvae of one and 10 days of age, the larval stage stretching, lower pupal weight in caterpillars 10 days and higher mortality in the group with one day of life. It did not interfere with the viability of eggs. In the life cycle of A. aegypti, the extract of B. dracuncufolia at the studied concentrations caused delay in the development of larval and pupal stages, and inhibited the emergence of adults in 85 % and 70 %. In laboratory conditions it can be said that the ethanol extract of B. dracunculifolia has a potential insecticide effect for both species of insects.

Perkembangan dan Kandungan Nutrisi Larva Hermetia illucens (Linnaeus) (Diptera: Stratiomyidae) pada Bungkil Kelapa Sawit

Hermetia illucens, is used as a reducing agent of palm kernel meal (PKM), as well as one of alternative protein sources for aquaculture purposes. Information about biology of H. illucens is absolutely required in mass production. The objectives of these researches were to study the development of H. illucens including the effect of supplementary food to the adult, and nutrient content of the immature stage. The sample of 20 larvae from each 3 replicates were measured and weighed on 0-19th day (larva) and 24th day (pupa) from egg hatching. H. illucens adults were fed by water and honey 5% (v/v). Eggs were collected and counted. Nutrient content of immature stage: 5, 10, 15, 20 days old (larvae), and 25 days old (prepupae) reared on PKM were analyzed proximately. Dry matter was determined by weight loss on drying at 105 oC during overnight. Crude protein was determined by Kjeldahl procedure (N x 6.25), crude fat by soxhlet (ether extract), crude ash by determining the residue after heating at 550 oC for 4–5 h. Data were analyzed descriptively by average from triplicate. The development of H. illucens was shorter than those in previous studies as the differences of abiotical factor. PKM was a suitable medium for development. It was better, however, to fed the adult with honey since it could enhance the fecundity. The young larva certainly contained the best quality of nutrition. To meet the quantity of mass production, however, the use of the elder larva (bigger) was suggested.

Techniques for the In Vitro Production of Queens in Stingless Bees (Apidae, Meliponini)

Considering the ecological importance of stingless bees as caretakers and pollinators of a variety of native plants makes it necessary to improve techniques which increase of colonies’ number in order to preserve these species and the biodiversity associated with them. Thus, our aim was to develop a methodology of in vitro production of stingless bee queens by offering a large quantity of food to the larvae. Our methodology consisted of determining the amount of larval food needed for the development of the queens, collecting and storing the larval food, and feeding the food to the larvae in acrylic plates. We found that the total average amount of larval food in a worker bee cell of F. varia is approximately 26.70 } 3.55 μL. We observed that after the consumption of extra amounts of food (25, 30, 35 and 40 μL) the larvae differentiate into queens (n = 98). Therefore, the average total volume of food needed for the differentiation of a young larva of F. varia queen is approximately 61.70 } 5.00 μL. In other words; the larvae destined to become queens eat 2.31 times more food than the ones destined to become workers. We used the species Frieseomelitta varia as a model, however the methodology can be reproduced for all species of stingless bees whose mechanism of caste differentiation depends on the amount of food ingested by the larvae. Our results demonstrate the effectiveness of the in vitro technique developed herein, pointing to the possibility of its use as a tool to assist the production of queens on a large scale. This would allow for the artificial splitting of colonies and contribute to conservation efforts in native bees.

Biology, immature and adult morphology, and molecular characterization of a new species of the genusEntedon(Hymenoptera: Eulophidae) associated with the invasive pestSpecularius impressithorax(Coleoptera: Chrysomelidae, Bruchinae) onErythrinaplants

Entedon erythrinaesp. n. (Hymenoptera: Eulophidae), a gregarious egg-larval endoparasitoid of the Erythrina bruchineSpecularius impressithorax, an invasive pest of the coral tree seeds (Erythrinaspp.), is described from the Hawaiian Islands and Africa (South Africa, Tanzania and Mozambique). The biology and morphology of preimaginal stages of this new species are described in details.It is remarkable that the early embryo of the parasitoid represents a mass of undifferentiated cells surrounded by a peculiar membrane formed by the peripheral enlarged polygonal cells. The young larva developing inside this membrane corresponds morphologically to the second instar of congeneric species. Various peculiarities of the parasitoid-host relationships in gregarious and solitaryEntedonparasitoids are discussed. The DNA sequences of 28S D2 (nuclear), Cytochrome Oxidase I (COI, mitochondrial) and Cytochrome B (CytB, mitochondrial) genes are provided for this new species and compared with the sequences of some other Afrotropical and Palearctic species of the genus.

The immature stages of Elachista zonulae (Sruoga, 1992) (Lepidoptera: Elachistidae)

The morphology of larva and pupa, as well as larval mines of Elachista zonulae (Sruoga, 1992) are described and illustrated for the first time. Carex firma Host is reported as a new host plant ofthe species; previously only Carex sempervirens Vill. was known to be host plant of E. zonulae. Some information on life history of this elachistid moth is also provided. The mature larva is 4.5—5.5 mm long. Pupation takes place usually at base of leaf blade of the food plant. The species is univoltine and hibernates as young larva.

The nervous system of amphioxus: structure, development, and evolutionary significance

Amphioxus neuroanatomy is important not just in its own right but also for the insights it provides regarding the evolutionary origin and basic organization of the vertebrate nervous system. This review summarizes the overall layout of the central nervous system (CNS), peripheral nerves, and nerve plexuses in amphioxus, and what is currently known of their histology and cell types, with special attention to new information on the anterior nerve cord. The intercalated region (IR) is of special functional and evolutionary interest. It extends caudally to the end of somite 4, traditionally considered the limit of the brain-like region of the amphioxus CNS, and is notable for the presence of a number of migrated cell groups. Unlike most other neurons in the cord, these migrated cells detach from the ventricular lumen and move into the adjacent neuropile, much as developing neurons do in vertebrates. The larval nervous system is also considered, as there is a wealth of new data on the organization and cell types of the anterior nerve cord in young larvae, based on detailed electron microscopical analyses and nerve tracing studies, and an emerging consensus regarding how this region relates to the vertebrate brain. Much less is known about the intervening period of the life history, i.e., the period between the young larva and the adult, but a great deal of neural development must occur during this time to generate a fully mature nervous system. It is especially interesting that the vertebrate counterparts of at least some postembryonic events of amphioxus neurogenesis occur, in vertebrates, in the embryo. The implication is that the whole of the postembryonic phase of neural development in amphioxus needs to be considered when making phylogenetic comparisons. Yet this is a period about which almost nothing is known. Considering this, plus the number of new molecular and immunocytochemical techniques now available to researchers, there is no shortage of worthwhile research topics using amphioxus, of whatever stage, as a subject.

The Reproduction of the Entozoic Nemertean Gononemertes australiensis Gibson (Nemertea: Hoplonemertea : Monostylifera) - Gonads, Gametes, Embryonic Development and Larval Development

G. australiensis is an entozoic nemertean found in the atrium of the ascidian Pyura pachydermatina (Herdman) var. intermedia Herdman. The host is common in the low intertidal and shallow sublittoral waters of the Sydney region of New South Wales. The nemertean is dioecious and possesses numerous gonads. In mature female worms, oocytes at different stages of maturity are always found throughout the body. The more mature oocytes lie close to the gut. Each temporary gonad produces several oocytes. The mature male worms contain ripe testes close packed within the parenchymal tissue along the body. The spermatozoon of G. australiensis has a head 6.5 µm long and a tail 38 µm in length. The head is rod- shaped with a blunt simple acrosome. The base of the head is surrounded by a mitochondria1 bulge which also encloses the connecting piece. A close apposition between the nucleus and the mitochondrion occurs in this area. The sperm is intermediate in type between primitive and modified nemertean spermatozoa. The egg of G. australiensis is spherical, yolky, 0.18mm in diameter and surrounded by a glutinous membrane. Fertilization is external. Cleavage, gastrulation and later embryonic development are similar to those of other hoplonemerteans and the resulting larva is of the hoplonemertean type. The larva is free- swimming for 3-5 days before invading a host. Some features of larval structure and behaviour are specializations associated with the entozoic habit of the nemertean. The development of the larval ocelli, lost soon after host invasion, is one of these. The young larva is photopositive, but after the ocelli have formed it becomes photonegative. Older larvae respond to a water current by an attachment response. No stomodaeum is formed during embryonic or larval development and completion of the differentiation of the proboscis is delayed until host invasion takes place. The larva exists on yolk until this time. The resources of the larva are concentrated on host location rather than on the feeding, growth and continued development typical of the larvae of other free-living hoplonemerteans.