The mothematics of female pheromone signaling: strategies for aging virgins

Although females rarely experience strong mate limitation, delays or lifelong problems of mate acquisition are detrimental to female fitness. In systems where males search for females via pheromone plumes, it is often difficult to assess whether female signaling is costly. Direct costs include the energetics of pheromone production and attention from unwanted eavesdroppers, such as parasites, parasitoids, and predators. Suboptimal outcomes are also possible from too many or too few mating events or near-simultaneous arrival of males who make unwanted mating attempts (even if successfully thwarted). We show that, in theory, even small costs can lead to a scenario where young females signal less intensely (lower pheromone concentration and/or shorter time spent signaling) and increase signaling effort only as they age and gather evidence (while still virgin) on whether sperm limitation threatens their reproductive success. Our synthesis of the empirical data available on Lepidoptera supports this prediction for one frequently reported component of signaling-time spent calling (often reported as the time of onset of calling at night)-but not for another, pheromone titer. This difference is explicable under the plausible but currently untested assumption that signaling earlier than other females each night is a more reliable way of increasing the probability of acquiring at least one mate than producing a more concentrated pheromone plume.

Análise do comportamento e crescimento do camarão branco Litopenaeus vannamei (Boone, 1931) em diferentes substratos inconsolidados

The aim of this study was to test the sediment preference of L. vannamei shrimp. It was observed shrimp visit frequency, swimming and burying behaviour at different sediment compositions for 24h. Juvenile (0.93 ± 0.29g) and sub-adult shrimps (10.0 ± 1.18g) were obtained from the aquaculture station at Universidade Federal Rural do Semi-Árido UFERSA, and held in a plastic tank (water volume 500 L) supplied with aerated water and kept at constant temperature, pH, and salinity. Shrimp was fed by commercial shrimp dry food. The experimental substrates were composed by A: medium sand + thick sand + very thick sand + gravel; B: very fine sand + fine sand; and C: silt + clay. Thus, six different substrate combinations were tested: A, B, C, A+B, A+C, B+C. To test preference, it was used a cylindrical tank (40 l) divided into six differently substrate compartments. A single shrimp was introduced each tank and the frequency at which this shrimp visited each compartment was recorded over a 24h study period. It was tested 54 shrimp (18 sub-adult males, 18 subadult females and 18 juveniles). For each trial, sediment and water were changed to avoid pheromones and residues influence. Shrimp were weighted and sub-adults were divided by sex: males present petasma and females present thelycum. Data were collected on the experimental day at 19:30; 20:30; 00:30; 1:30; 05:30; 06:30; 13:30 and 14:30 h. At each time point, shrimp were observed for 20-min periods, in which we noted down which compartment the shrimp was occupying at 2-min intervals. Thus, for each period we had eleven observations (88 observations per day). For observations at night, it was used dim red light that did not affect shrimp behaviour. At each 20-min period, it was observed visit frequency in each substrate, if shrimp was burred or not or if it was swimming. There was not significant difference between light and dark burry activity for females. Swimming activity was significantly higher at night, mainly at 00:30 and 01:30 h. All L. vannamei shrimp showed preference for sediment B. This animal presents cyclic activity, spends the day light period buried and swims at night

Use of repellents for honeybees (Apis mellifera L.) in vitro in the yellow passion-fruit (Passiflora edulis Deg) crop and in confined beef cattle feeders

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

Implicações do odor na percepção e escolha de parceiro

Why are we attracted to some people but not to other ones? How is this attraction established? Which signs are characteristic of a good partner? These and many other questions concerning how mate attraction and mate selection work out among humans have been intriguing behavioral scientists. It is well-known that beauty indicates something about a potential mate s health. The odor may indicate a similar assessment, if we can assess how pheromones are integrated into human sexual behavior. However, what is the relation between age preference and body scent evaluation? In order to investigate this question, this study´s objective was identifying evidences which show that olfactory cues might reveal the potential mate s age and that it coincides with the ideal mate s profile. To produce the stimuli, men and women had to wear cotton t-shirts for three nights in order to have their body odor impregnated. After that, opposite-sex individuals evaluated the intensity and attractivity of these odor impregnated tshirts according to two Likert scales (4 points scale for intensity; 7 points scale for attractivity). We found differences between men and women on body scent perception, that indicates a better scent discrimination for women when it concerns the perception of potential mate s age. Another finding was the negative correlation between intensity and attractiveness perception for both sexes. We also verified that mate selection strategies are plural, more than one tactic simultaneously fitting in the same strategy, but all of them are related to differential investment of each sex on their own reproductive success

Female preferences based on male nutritional chemical traits

Selection favors females that attend to reliable information about male genetic quality and fitness. Male nutritional condition can be a significant sign of mate quality since poor nutrition can be related to reduced sperm quality, low sperm quantity, sexually transmitted diseases, and parasites. We tested whether female Nile tilapia, Oreochromis niloticus, preferred the chemical cues of males that were well fed with high-protein diet over those fed with low-protein diet. Females do not only discriminate between males but also show a preference for well-fed males, discriminating between the odors with respect to nutritional state, suggesting that they were responding to a food-specific chemical cue. It is therefore likely that nutritional condition is related to the production of pheromones in males. Our results suggest that information about male nutritional state can be conveyed in chemical cues and that females attend to these cues during mate choice.

Discrimination of bile acids by the rainbow trout olfactory system: evidence as potential pheromone

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

Changes in the morphology and ultrastructure of the Dufour's gland during the life cycle of the bumble bee queen, Bombus terrestris L-(Hymenoptera : Bombini)

The Dufour's gland is found closely associated with the sting apparatus of all female hymenopterans, playing multiple roles among bees. In some species of Bombus the gland may be involved in production of nestmate recognition pheromones, but in B. terrestris its function is not certain yet. The morphology of the :Dufour's gland of B. terrestris queens and the ultrastructural features of its cells were studied in different ages and behavioural stages using routine transmission electron microscopy. Measurements of the length and the diameter of the gland in the same conditions were also made. The Dufour's gland of the queen increases significantly in size (both in length and in diameter) with age and reproductive activity the ultrastructural features of the gland show electrondense material that comes from the haemolymph. This material is also present in the intercellular spaces, and is conducted to the subcuticular space, to be released directly into the glandular lumen. Hence at least part of the secretion is probably taken up directly from the haemolymph. The ultrastructural features indicate a more active phase of the gland corresponding to the period of egg-laying of the queen, and a decrease in activity when the queen is in hibernation as well as after the competition point. In conclusion, the gland is probably involved in reproduction, more specifically, in the marking off eggs.

Class III glands in the abdomen of Meliponini

Class III tegumentar glands were studied in workers, as well as in queens and males when available, of 56 Meliponini species. The presence and development of these glands varies widely among and within species. However, the queen typically has more glands than do workers, and males rarely have any. Gland development in workers was evaluated by counting and determining the size of cells in histological sections. Laying queens were found to have more active gland cells than did virgins. Cell numbers and cell ultrastructure differed among glands similarly located in workers, queens and males. Cell size and ultrastructure also varied from tergite to tergite. In conclusion, since it is likely that most of them produce pheromones, the wide variability in these glands suggests that they are important to social interaction.

Morphology of the sternal gland in workers of Coptotermes gestroi (Isoptera, Rhinotermitidae)

The sternal gland is considered the only source of trail pheromones in termites. The morphology of the sternal gland was investigated in workers of Coptotermes gestroi using transmission and scanning electron microscopy. The results showed a small bilobed gland at the anterior part of the fifth abdominal sternite. The cuticular surface of the sternal gland showed a V-shaped structure with two peg sensilla in elevated socket and various campaniform sensilla. Pores and cuticular scale-like protuberances also occur in the glandular area. The ultrastructure showed a gland composed of class I cells and two different types of class 3 cells distinguished by location, different size and electron-density of secretory vesicles. Small class 3 cells (type 1) of the anterior lobe are inserted among class I cells and have weakly electron-dense vesicles associated with mitochondria, glycogen and smooth endoplasmic reticulum. The class 3 cells (type 2) of posterior lobe showed many round electron-lucent vesicles of secretion, abundant free ribosomes and a well-developed Golgi apparatus. Each class 3 cell is connected to the cuticle by a cuticular duct constituted by the receiving canal and the conducting canal. The secretion of class I cells is stored in an inner subcuticular reservoir that is delimited by the microvilli of these cells. This inner reservoir is large and crossed by the campaniform sensilla and ducts of two types of class 3 cells that open outside of the insect body. An exterior reservoir also is present between the fourth and fifth sternite. The complex structure of the sternal gland suggests multicomponents for the trail pheromone in the worker of C gestroi. (c) 2005 Elsevier Ltd. All rights reserved.

Tegumentary epithelial glands in the abdomen of virgin and physogastric queens of the stingless bee Scaptotrigona postica Latreille (Meliponini: Trigonina)

Nas operárias das abelhas eussociais, regiões do epitélio tegumentar do abdome podem hipertrofiar-se e tornarem-se glandulares, sendo responsáveis pela produção de cera usada na contrução dos alvéolos de cria. Nos meliponíneos, epitélio com essas características também foi observado nas rainhas, porém sua função ainda continua desconhecida. Teria esse epitélio função homóloga nas operárias? As rainhas, além da função reprodutiva, desempenhariam funções na colônia até então consideradas exclusivas das operárias? Para tentar colaborar no esclarecimento dessas questões realizou-se um estudo histológico e ultra-estrutural das glândulas epiteliais tegumentares do terceiro tergito em rainhas virgens e fisogástricas de Scaptotrigona postica Latreille. Os resultados morfológicos mostraram que o epitélio glandular existe e é facilmente discernível no terceiro tergito das rainhas, sendo muito mais desenvolvido nas fisogástricas do que nas virgens. A ultra-estrutura mostrou que há diferenças no tipo de organização do retículo endoplasmático liso entre as rainhas, o que, juntamente com os resultados da histologia e morfometria, indicam poder haver diferenças funcionais desse epitélio entre elas. Como já observado na literatura, nas rainhas virgens tal epitélio pode estar envolvido na produção de cera e confecção de alvéolos de cria, porém sua função nas rainhas fisogástricas é totalmente desconhecida. A hipótese lançada no presente estudo é de que esse epitélio pode estar envolvido na produção de feromônios que irão atuar nas interações sociais da rainha poedeira.

Dufour glands in the hymenopterans (Apidae, Formicidae, Vespidae): a review

Anexas ao aparelho do ferrão dos himenópteros aculeados encontram-se as glândulas de veneno e as de Dufour. A glândula de veneno é originada das glândulas associadas ao ovopositor dos himenópteros ancestrais não aculeados, já a glândula de Dufour é menos derivada, homóloga das glândulas colateriais dos outros insetos, sendo encontrada em todas as fêmeas dos himenópteros. Nestes insetos sua função é, em grande parte, desconhecida, mas, em formigas, parece estar envolvida com a comunicação e a defesa e, nas abelhas não sociais, com a construção e a proteção do ninho. Nas vespas pode estar relacionada ao reconhecimento parental. Foram observadas diferenças morfológicas e na composição química da secreção da glândula de Dufour entre as espécies, bem como na mesma espécie, entre as castas dos himenópteros sociais e entre indivíduos da mesma casta desempenhando diferentes funções ou pertencentes a ninhos diferentes. Portanto, nos himenópteros, sua função original de produzir substâncias para proteger os ovos ou favorecer a ovoposição parece ter sido substituída ou complementada com a função de produzir semioquímicos com função na comunicação.

Tergal glands in termite soldiers of the subfamily Syntermitinae (Isoptera: Termitidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Chemical communication in isoptera

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Size differences in the Dufour gland of Apis mellifera Linnaeus (Hymenoptera, Apidae) between and within the female castes

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

Effect of the juvenile hormone on the development of the mandibular gland in workers' pupae of Apis mellifera L. (Hymenoptera, Apidae)

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