Cocoon production and hatching rates of Branchiura sowerbyi Beddard (Oligochaeta: Tubificidae)

Abstract

Branchiura sowerbyi Beddard, 1892 is a Tubificidae species abundant in tropical limnic environments and associated with sediments rich in organic matter and elevated temperatures. The present study aimed at obtaining information on laying and hatching rates of B. sowerbyi cocoons under laboratory conditions. In order to do this, specimens of B. sowerbyi were placed in beakers (250 ml) containing clay sediment and distilled water and kept at 25ºC. The obtained cocoons were placed in beakers of 100 ml and kept in conditions similar to the mature individuals. Fifty seven cocoons were collected, with a mean of 0.13 cocoons·individual-1·day-1 and 1.21 (±0.08) eggs·cocoon-1. Hatching time was approximately two weeks and hatching rate was 44.93%. The results obtained were different from the ones found by other authors for B. sowerbyi. According to the literature, different populations of the same species can present distinct biological aspects, such as the number of cocoons, hatching rates and growth.

The effect of temperature on the reproduction of Limnodrilus hoffmeisteri (Oligochaeta: Tubificidae)

“…However, in his work, ASTON (1973) found an average of five eggs per cocoon, while in the present study we obtained an average of 3.25 eggs per cocoon. Both MARCHESE & BRINKHRUST (1996) and NASCIMENTO & ALVES (2008) have observed that Branchiura sowerbyi Beddard, 1892 produced fewer eggs per cocoon at 25°C in relation to L. hoffmeisteri in this study (1.94 ± 0.13 and 1.21 ± 0.08, respectively). Figure 2 shows a cocoon of L. hoffmeisteri.…”

“…The presence of young individuals of L. hoffmeisteri suggests that the species needs less than 21 days to complete the full embryonic development. NASCIMENTO & ALVES (2008) have observed that the embryonic development of B. sowerbyi took 15 days at 25°C. The present study shows that, similarly to what ASTON (1973) has previously observed under laboratory conditions, the largest production of eggs and cocoons of L. hoffmeisteri occurred when the worms were raised at 25°C.…”

Influence of body weight and substrate granulometry on the reproduction of Limnodrilus hoffmeisteri (Oligochaeta: Naididae: Tubificinae)

“…This agrees with our findings here, which showed that more than 80% of the young specimens hatched within 8 to 12 days after the cocoon was laid. This period is shorter than that observed for B. sowerbyi (14 to 16 days) under similar temperature conditions (NASCIMENTO & ALVES 2008, LOBO & ALVES 2011. ASTON (1973) observed that L. hoffmeisteri is capable of developing from an embryo to a mature individual in less than five weeks.…”

<strong><em>Branchiura sowerbyi</em> Beddard, 1892 (Oligochaeta: Naididae) as a test species in ecotoxicology bioassays: a review</strong>

“…Marchese & Brinkhurst (1996) found that a higher rate of cocoon production was achieved at 30°C, and a larger number of juveniles per cocoon at 25°C. Among cocoon cultures, at this temperature, full embryonic development and subsequent hatching take nearly three weeks (Nascimento & Alves 2008;Lobo & Alves 2011).…”

“…Dornfeld et al (2006), for instance, reported different densities throughout sampled parts of the Salto Grande reservoir (Americana, São Paulo, Brazil), ranging between 44 and 8711 ind.m -2 . When cultivated in laboratory conditions (25°C), this species exhibits low hatching rate: 34.4%- Marchese & Brinkhurst (1996), 31.0%- Ducrot et al (2007) and 44.93%- Nascimento & Alves (2008). However, the survival rate among juveniles is high and can reach 96% (Ducrot et al, 2007).…”