Mariana Monteiro de Castro

Foundation pattern, productivity and colony success of the paper wasp, Polistes versicolor

Abstract Polistes versicolor (Olivier) (Hymenoptera: Vespidae) colonies are easily found in anthropic environments; however there is little information available on biological, ecological and behavioral interactions of this species under these environmental conditions. The objective of this work was to characterize the foundation pattern, the productivity, and the success of colonies of P. versicolor in anthropic environments. From August 2003 to December 2004, several colonies were studied in the municipal district of Juiz de Fora, Southeastern Brazil. It was possible to determine that before the beginning of nest construction the foundress accomplishes recognition flights in the selected area, and later begins the construction of the peduncle and the first cell. As soon as new cells are built, the hexagonal outlines appear and the peduncle is reinforced. Foundation of nests on gypsum plaster was significantly larger (p < 0.0001; &khgr;2 test) in relation to the other types of substrate, revealing the synantropism of the species. On average, the P. versicolor nest presents 244.2 ± 89.5 (100–493) cells and a medium production of 171.67 ± 109.94 (37–660) adults. Cells that produced six individuals were verified. Usually, new colonies were founded by an association of females, responsible for the success of 51.5%. Although these results enlarge knowledge on the foundation pattern of P. versicolor in anthropic environments, other aspects of the foundation process require further investigation.

Nesting of the Fire Ant Solenopsis saevissima (Hymenoptera: Formicidae) in an Urban Environment

Abstract Ants of the genus Solenopsis are common in urban environments due to their abilities to explore resources and to establish nesting sites, which helps their proliferation and also increases the occurrence of encounters with people and severe stinging. We aimed to increase understanding of this species in urban areas, so this study attempted to answer these questions: Are certain seasons more amenable to the founding of new colonies? Does colony size vary among seasons? What sites are used by these colonies in an urban environment? Observations were carried out every 2 weeks from May 2011 to Apr 2012 in Juiz de Fora, Minas Gerais, southeastern Brazil. For each active colony the site and the dimensions of the nest were registered. We showed that colonies of Solenopsis saevissima (Smith, 1855) were present in urban areas during the entire yr, with the highest incidence in the wet season, and nesting sites were associated mainly with vegetation. Because the dry season (Apr—Aug) was the period that had the smallest number of active colonies, this period could be considered the most favorable for area-wide control operations, but an individual mound treatment approach in the dry season should be take into consideration the occurrence of cryptic mounds.

Nesting substrata, colony success and productivity of the wasp Mischocyttarus cassununga

Nesting substrata, colony success and productivity of the wasp Mischocyttarus cassununga. Colonies of the wasp Mischocyttarus cassununga (von Ihering, 1903) are easily found in urban areas. However, in spite of the massive presence of this species in cities, little is known about its nesting habits, colony success and productivity. The present study aimed at answering the following questions: What are the substrates used for nesting by M. cassununga? What is the main foundation strategy adopted by M. cassununga in urban areas: a solitary female or associative foundation? Is there a relationship between foundation strategies and colony success? Is the total number of cells per nest related to the number of adults produced? The study was conducted in Juiz de Fora, southeastern Brazil, from December 2006 to November 2007. Nesting in man-made substrata seems to be a common strategy in M. cassununga (90.9%), with preference for nest building with a horizontal comb facing north. The colonies were established mainly by groups of foundresses (67.6%), with a success of 84%. The number of brood cells produced per nest was 71.74 ± 45.25 (18-203), and it was positively correlated with the number of adults produced. Hence, we can say that the nests founded by M. cassununga are located mainly in man-made substrata and mostly founded by a group of females. The cell reuse behavior increases the number of adults produced, as it optimizes foraging. These characteristics together with its behavior and nesting habits promote the success of this species in thriving in urban environments.

The Performance of Dominance Indices for Constructing Dominance Hierarchies in Mischocyttarus and Polistes Wasps (Hymenoptera, Vespidae)

ABSTRACT A common problem during the construction of dominance hierarchies is the occurrence of tied ranks that make it difficult to find correlations between the dominance hierarchy and other biological variables. Among the factors that affect the ability of indices to give unique ranks are the noninteracting pairs of individuals and reversals. Based on these two factors, researchers have compared the performance of dominance indices, among them, the Clutton-Brock index (CBI), an index that measures wins and losses with quality values between pairs of individuals and does not consider the number of wins and losses; the Davids score (DS), that corrects for this drawback in one way by considering the proportion of the wins and losses of each individual; and the frequency-based dominance index (FDI), which also consists of a modification of the CBI by considering the frequencies of direct and indirect wins and losses. Since there is no universal index for all interaction networks, comparing different indices could be a helpful step before selecting one for use. Additionally, studies on Polistes and Mischocyttarus have used different, non-standardized and subjective ways to access dominance hierarchies. In this study, we first described the proportion of non-interacting pairs and reversals in colonies of the social wasps Mischocyttarus cassununga, Mischocyttarus Cerberus, Polistes simillimus and Polistes versicolor. Then, the efficiencies of 3 dominance indices, CBI, DS and FDI in given unique ranks (absence of tied ranks) were compared.

Variation in Nesting Behavior of the Arboreal Ant Camponotus sericeiventris (Hymenoptera: Formicidae)

This is the first record of nesting in the soil by the ant Camponotus sericeiventris (Guerin-Meneville, 1838), which has arboreal habit. The study was conducted in southeastern Brazil, in an ant colony located in a subterranean site. This study describes, for the first time, the ability of this arboreal species to vary its nesting site by the occupation of an unusual place in an urban environment; and this study demonstrates that this species is an interesting model for studies in urban environments. Este e o primeiro registro de nidificacao em solo para a formiga Camponotus sericeiventris (Guerin-Meneville, 1838). O estudo foi desenvolvido no sudeste do Brasil, em uma colonia localizada em area subterrânea, que possui habito arboricola. Esse estudo e o primeiro relato que descreve a capacidade de variar o local de nidificacao da especie arboricola, por meio da ocupacao de local incomum em ambiente urbano o que torna a especie um modelo interessante para estudos nesse tipo de ambiente. View this article in BioOne

Foundress Association in the Paper Wasp Polistes simillimus (Hymenoptera: Vespidae)

Abstract In many animal species, females are faced with at least 2 reproductive options: independent or cooperative breeding. Some individuals in cooperative groups choose to help in rearing the broods of conspecific females. Through observations of how females of Polistes simillimus Zikán, 1951 (Hymenoptera: Vespidae) started new nests in the field, we investigated whether ecological constraints and the geographic variations explain group formation in this species. The founding of nests was studied between 1996 and 2000 in various localities of 2 states of southeastern Brazil. Weekly observations were carried out on 109 pre-worker nests. We kept track of 40 colonies in Minas Gerais State and 69 in São Paulo State, each started either by a single female or by an association of females. There was a chance that worker production would become numerically similar in both solitary and associative colonies in both states. An increased number of foundresses did not improve the chance of colony success in Minas Gerais State, but it improved this chance in São Paulo State, so that colonies each with 3 or more foundressess were always successful. In colonies in both states, nest cell productivity was higher with a greater number of associated females per nest. Females were able to start building nests alone, being the only reproductive, or 2 or more females could cooperate to found a nest, thus increasing worker production. However, the type of environment chosen to establish the nest (anthropogenic or natural) seemed to influence strongly the choice of the founding strategy.