Larval competition for patchy resources in Chrysomya megacephala (Dipt., Calliphoridae): implications of the spatial distribution of immatures

In the present study, a single procedure was established to investigate the effect of the spatial distribution of immatures in patchy resources, on the outcome of larval competition for food. in experimental populations of Chrysomya megacephala. A theoretical model of intraspecific competition was extended and applied to experimental data on survival to adulthood for 20 larval densities, to obtain the theoretical mean number of individuals that will survive, considering a hypothetical previous random adult oviposition in a system of homogeneous patches. The survival curve obtained suggests that the larval competition for food in C. megacephala is of the scramble/exploitative type, which corroborates results from previous studies, although the latter did not consider the correlation between local and global abundances. The present model allows that experimental data could be perfectly applicable, and it incorporates fundamental assumptions about the spatial context of competition for patchy resources in blowflies, and may be applied to the optimization of mass rearing techniques and to the maintenance of insect colonies under experimental conditions.

Insect Venom Peptides

The insects of the order Hymenoptera ( bees, wasps, and ants) are classified in two groups, based on their life history: social and solitary. The venoms of the social Hymenoptera evolved to be used as defensive tools to protect the colonies of these insects from the attacks of predators. Generally they do not cause lethal effects but cause mainly inflammatory and/or immunological reactions in the victims of their stings. However, sometimes it is also possible to observe the occurrence of systemic effects like respiratory and/or kidney failure. Meanwhile, the venoms of solitary Hymenoptera evolved mainly to cause paralysis of the preys in order to permit egg laying on/within the prey's body; thus, some components of these venoms cause permanent/transient paralysis in the preys, while other components seem to act preventing infections of the food and future progenies. The peptide components of venoms from Hymenoptera are spread over the molar mass range of 1400 to 7000 da and together comprise up to 70% of the weight of freeze-dried venoms. Most of these toxins are linear polycationic amphipatic peptides with a high content of alpha-helices in their secondary structures. These peptides generally account for cell lysis, hemolysis, antibiosis, and sometimes promote the delivery of cellular activators/mediators through interaction with the G-protein receptor, and perhaps some of them are even immunogenic components. In addition to these peptides, the Hymenopteran venoms also may contain a few neurotoxins that target Na+ and/or Ca+2 channels or even the nicotinic ACh receptor. This review summarizes current knowledge of the biologically active Hymenoptera venoms.

Neotenic formation in laboratory colonies of the termite Coptotermes gestroi after orphaning

The termite Coptotermes gestroi (Wasmann 1896) ( Rhinotermitidae: Coptotermitinae) is an exotic species in Brazil and information concerning its reproductive developmental biology is scarce. We induced the formation of neotenics in laboratory colonies through orphaning experiments. Orphaning experiments were conducted in three-year old colonies of C. gestroi kept under laboratory conditions. After three months, eight nymphoid neotenics were observed in one colony after queen removal. Histological analysis showed that these neotenics were non-functional. The results suggest that these individuals may have arisen from the first nymphal instar (N1) or from an early N1 instar after one or two larval moults. Neotenics also were recorded on two incipient colonies of C. gestroi that lost the queen naturally.

Immatures of Nesticodes rufipes (Araneae, Theridiidae) Causing Considerable Damage to Ant Colonies in the Laboratory

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Occurrence of different gynandromorphs and ergatandromorphs in laboratory colonies of the urban ant, Monomorium floricola

Colonies of Monomorium floricola (Jerdon) in laboratory conditions showed gynandromorphic and ergatandromorphic specimens, the former with nine different combinations of male and female tissues and the latter with 6 different combinations. Their development from egg to adult was around 74.6 days for gynandromorphs, and 87.5 days for ergantandromorphs.

Dominance hierarchy in different stages of development in colonies of the primitively eusocial wasp Mischocyttarus cerberus styx (Hymenoptera, Vespidae)

In primitively eusocial insect societies, reproductive division of labor is established by dominance-submission interactions which determine a linear dominance hierarchy. As previously observed for other species, in Mischocyttarus cerberus styx (Hymenoptera, Vespidae), the dominant female is the main egg layer. Most of her attacks were to the females directly beneath in the rank establishing a hierarchy. During the pre-emergence stage, the hierarchy was already defined and in the post-emergence stage, pre-male substage, the frequency of dominance interactions were strong but the hierarchy was still maintained by the first-ranked female. In the decline stage there were many neutral individuals which could be the reproductives of a new colony.

Isolation of Bacillus thuringiensis strains that contain Dipteran-specific cry genes from Ilha Bela (São Paulo, Brazil) soil samples

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A non-invasive method for silencing gene transcription in honeybees maintained under natural conditions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A novel system for large-scale gene expression analysis: bacterial colonies array

In the present work, we report the use of bacterial colonies to optimize macroarray technique. The devised system is significantly cheaper than other methods available to detect large-scale differential gene expression. Recombinant Escherichia coli clones containing plasmid-encoded copies of 4,608 individual expressed sequence tag (ESTs) were robotically spotted onto nylon membranes that were incubated for 6 and 12 h to allow the bacteria to grow and, consequently, amplify the cloned ESTs. The membranes were then hybridized with a beta-lactamase gene specific probe from the recombinant plasmid and, subsequently, phosphorimaged to quantify the microbial cells. Variance analysis demonstrated that the spot hybridization signal intensity was similar for 3,954 ESTs (85.8%) after 6 h of bacterial growth. Membranes spotted with bacteria colonies grown for 12 h had 4,017 ESTs (87.2%) with comparable signal intensity but the signal to noise ratio was fivefold higher. Taken together, the results of this study indicate that it is possible to investigate large-scale gene expression using macroarrays based on bacterial colonies grown for 6 h onto membranes.

Worker laying in leafcutter ant Acromyrmex subterraneus brunneus (Formicidae, Attini)

We studied the process of offspring production in queenless colonies of Acromyrmex subterraneus brunneus, and particularly evaluated the ovary development of workers as a function of their age. For this, subcolonies were set up and evaluated at different periods of isolation from the queen (2, 4 and 6 months), besides individually labeled age groups. The subcolonies were assessed according to offspring production and ovaries containing oocytes or not. The evaluations showed worker oviposition and development of males originating from worker-laid eggs. At 2 months'absence of the queen, eggs and larvae were found, with eggs in a higher proportion than larvae. After 4 months, the proportion of eggs had reduced while larvae had increased, and a pupa was found in one subcolony. At 6 months, besides a higher share of larvae, one pupa and one adult male were found. Dissection of workers revealed ovaries containing oocytes during the periods of evaluation. Only a group of medium-sized and large workers, 23.3%, 20.9% and 37.5% of the population from each period assessed in queenless subcolonies respectively, presented developed oocytes in the ovary. The same was observed in colonies with a queen, with 17.6%, 19.6% and 7.8% of the group of dissected workers from each time period, respectively. With respect to worker age, we observed by dissection of the ovary, that the greatest percentage of individuals with ovarioles containing oocytes occurred at 45 days (6 weeks) up to 90 days (12 weeks). These results probably are associated with the workers reproduction and the laying of trophic and reproductive eggs in colonies with and without a queen; these eggs have distinct functions in each situation.

Patogenicidade de Steinernema carpocapsae (Rhabditida: Steinernematidae) ao Cupim de Montículo Cornitermes cumulans (Isoptera: Termitidae)

Cornitermes cumulans is a termite species often found in pastures of Brazil, mainly in the most degraded ones. Chemical control has been the most recommended method against this insect pest, but control measures are usually avoided by farmers. Biocontrol of termites with entomopathogenic fungi and possibly with entomopathogenic nematodes have been considered promising techniques, being recommended for use in several countries. This study aimed to evaluate the pathogenicity of Steinernema carpocapsae (an unidentified isolate) against C cumulans castes (workers and soldiers). Three experiments were done, one using Petri dishes, with daily evaluations, and two others in artificial colonies (with workers and soldiers). For one of the experiments in artificial colonies, nematode suspensions (167 and 333 infective juveniles (IJ) per insect) were applied over the food supplied to the termites. For the other experiment, nematode suspensions (133, 267 and 533 IJ per insect) were applied directly over the artificial termite colonies. In these two experiments evaluations were done 1, 5 and 9 days after nematode application. Each dead insect was dissected for nematode verification. S. carpocapsae was highly pathogenic to both castes of C cumulans in all experiments.

Relationship Between Population Size and Symbiont Fungus Culture Volume in Colonies of Acromyrmex balzani (Hymenoptera: Formicidae)

In order to quantify the population of Acromyrmex balzani Emery, 1890 nests and to verify whether the population dynamic of the colony is correlated with the symbiont fungus volume, the principal energy source of the colony, five nests located in grassland areas were evaluated. The nests were sprayed with neutral talcum powder to improve visualization and digging. The symbiont fungus and the entire population existent in the chambers were collected. The mean fungus volume and total nest population in excavated nests were, respectively, 74.76 ml and 1,095 individuals. Simple linear correlation analysis verified that the fungus volume grew proportionally to the number of individuals. Despite the correlation between fungus volume and population dynamic of colonies, the factors that determine this relationship are little known since other microorganisms live in association with the colony.

Ocorrência de Dictyla monotropidia Stål (Hemiptera: Tingidae) em Cordia verbenacea Al. DC no Brasil

Recently, Dictyla monotropidia Stal was observed feeding on plants of black sage (Cordia verbenacea Al. DC). The colonies of this insect were observed on abaxial surface of leaves, with nymphs and adults sucking the phloem sieve, causing spot, yellow aspect and leaf fall. D. monotropidia was already related as pest in other Cordia species in countries of Central and South America. Although, this is the first report of this insect attacking plants of C. verbenacea in Brazil.

Mating system parameters at hierarchical levels of fruits, individuals and populations in the Brazilian insect-pollinated tropical tree, Tabebuia roseo-alba (Bignoniaceae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Clinical and histopathological aspects of the insect bite hypersensitivity in horses

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)