Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto

About: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto is a based out in . It is known for research contribution in the topics: Population & Genus. The organization has 2143 authors who have published 3674 publications receiving 71071 citations. The organization is also known as: FFCLRP & FFCLRP-USP.

Appetite for self-destruction: suicidal biting as a nest defense strategy in Trigona stingless bees

Abstract: Self-sacrificial behavior represents an extreme and relatively uncommon form of altruism in worker insects. It can occur, however, when inclusive fitness benefits are high, such as when defending the nest. We studied nest defense behaviors in stingless bees, which live in eusocial colonies subject to predation. We introduced a target flag to nest entrances to elicit defensive responses and quantified four measures of defensivity in 12 stingless bee species in Sao Paulo State, Brazil. These included three Trigona species, which are locally known for their aggression. Species varied significantly in their attack probability (cross species range = 0–1, P < 0.001), attack latency (7.0–23.5 s, P = 0.002), biting duration of individual bees (3.5–508.7 s, P < 0.001), and number of attackers (1.0–10.8, P < 0.001). A “suicide” bioassay on the six most aggressive species determined the proportion of workers willing to suffer fatal damage rather than disengage from an intruder. All six species had at least some suicidal individuals (7–83 %, P < 0.001), reaching 83 % in Trigona hyalinata. Biting pain was positively correlated with an index of overall aggression (P = 0.002). Microscopic examination revealed that all three Trigona species had five sharp teeth per mandible, a possible defensive adaptation and cause of increased pain. Suicidal defense via biting is a new example of self-sacrificial altruism and has both parallels and differences with other self-sacrificial worker insects, such as the honey bee. Our results indicate that suicidal biting may be a widespread defense strategy in stingless bees, but it is not universal.

The reactivity of nitrosyl ruthenium complexes containing polypyridyl ligands

Abstract: A series of cis nitrosyl complexes containing polypyridyl ligands were prepared and characterized as cis-[RuL(bpy)2(NO)](PF6)3 (L = pyridine, 4-picoline, or 4-acetylpyridine), by elemental analysis, u.v.–vis. and i.r. spectroscopy, and by electrochemical techniques such as cyclic voltammetry, differential pulse voltammetry, spectroelectrochemistry, and coulometry. The complexes exhibit stretching frequencies ν(NO) at ca. 1950 cm−1 indicating that nitrosyl group has a sufficiently high degree of nitrosonium ion (NO+) character. In non-aqueous solution, the reduction of these complexes induce nitrosyl to nitro conversion. In aqueous solution the reduction product is cis-[RuL(bpy)2(NH3)]2+ formed by a six electron mechanism. The nitrosyl compounds are susceptible to nucleophilic attack by hydroxide ion. The equilibrium constants were determined.