Impact of Nosema sp. Infection on Nutritional Physiology and Growth of the Tasar Silkworm Antheraea mylitta

( Sudhansu Sekhar Rath ),( Mrinal Kanti Singh ),( Suryanarayana N ) 한국잠사학회 2009 International Journal of Industrial Entomology Vol.19 No.2

Nosema sp. infection in the Indian tasar silkworm, Antheraea mylitta exerts a complex of influences on its host. The instar duration was extended significantly (P<0.001) except in 1st instar. The infected larvae took about 48 days to reach the spinning stage against 40 days in the uninfected ones. The final weight attained by the larva at the end of each instar of development declined significantly following infection, as did weight gain and relative growth rate (RGR). The growth recorded/ day declined in infected larvae compared to uninfected ones from 8.2% during 1st instar to 43.3% during 5th instar. Food ingestion and digestion increased with advancement of the instar significantly irrespective of the status of the larvae but the relative consumption rate (RCR) declined. These parameters significantly declined in infected larvae (except food digested during 2nd instar). The decline was more during 3rd instar. In contrast, the approximate digestibility (AD %) was significantly higher in infected larvae than uninfected ones leaving the 1st instar larvae unaffected. The efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD) did not change in a patterned way following the microsporidia (Nosema sp.) infection. The values of ECI significantly changed during 2nd, 3rd and 5th instars; while the change in ECD during 2nd, 4th and 5th were significant. During the entire larval life all the parameters tends to decline significantly following microsporidia infection but AD registered a significant increase. Nosema sp. spore concentration has increased 270.7 times during larval development in the course of experimentation.

Male Mating History in Antheraea mylitta and its Effect on Ejaculation Size and Female Reproductive Fitness

( Sudhansu Sekhar Rath ) 한국잠사학회 2011 International Journal of Industrial Entomology Vol.22 No.2

Reproductive activity in the economically important insect, Antheraea mylitta is very important because the female reproduces only once in her life time and the aging is very rapid and costly. It is a capital breeder and strictly a monoandrous species. To know how strategically the insect behaves and the male allocates its ejaculate resource more prudently during its successive mating with virgin females to maximize its own fitness and the fitness of the female with whom it mated, both being most important to sericulture industry. So, the present study was undertaken and the results revealed fresh and virgin females always prefer to mate with fresh virgin males (84%) and receives high dose of ejaculates leading to higher hatchability than to virgin males of one day old (13.7%) and one day old males with mating experience (2.3%). The ejaculation size (as referred to eupyrene sperm count in the ejaculation) declined significantly over successive mating (r = -0.9931, P < 0.001), so also the male body weight (r = -0.9560, P < 0.001). The quantity of ejaculate passed to female also dramatically declined during aging (r = -0.9982, P < 0.001). It was found that male weight contribute substantially to the quantum of ejaculate (r = -0.9519, P < 0.001), so also higher fecund females receive relatively more ejaculate than the lower group to reach higher reproductive fitness. The life time fecundity was found to be 334±31.

Male Mating History in Antheraea mylitta and its Effect on Ejaculation Size and Female Reproductive Fitness

Rath, Sudhansu Sekhar Korean Society of Sericultural Science 2011 International Journal of Industrial Entomology Vol.22 No.2

Reproductive activity in the economically important insect, Antheraea mylitta is very important because the female reproduces only once in her life time and the aging is very rapid and costly. It is a capital breeder and strictly a monoandrous species. To know how strategically the insect behaves and the male allocates its ejaculate resource more prudently during its successive mating with virgin females to maximize its own fitness and the fitness of the female with whom it mated, both being most important to sericulture industry. So, the present study was undertaken and the results revealed fresh and virgin females always prefer to mate with fresh virgin males (84%) and receives high dose of ejaculates leading to higher hatchability than to virgin males of one day old (13.7%) and one day old males with mating experience (2.3%). The ejaculation size (as referred to eupyrene sperm count in the ejaculation) declined significantly over successive mating (r = -0.9931, P < 0.001), so also the male body weight (r = -0.9560, P < 0.001). The quantity of ejaculate passed to female also dramatically declined during aging (r = -0.9982, P < 0.001). It was found that male weight contribute substantially to the quantum of ejaculate (r = -0.9519, P < 0.001), so also higher fecund females receive relatively more ejaculate than the lower group to reach higher reproductive fitness. The life time fecundity was found to be $334{\pm}31$.

Impact of Quantitative Feeding on Nutritional Parameters of Fifth Instar Larvae of Antheraea mylitta

Rath, Sudhansu Sekhar Korean Society of Sericultural Science 2010 International Journal of Industrial Entomology Vol.20 No.2

Feeding is an important aspect of insect nutrition which in turn supports growth, development, reproduction and survival. The impact of quantitative feeding on nutritional parameters of fifth instar Antheraea mylitta larvae was studied by providing fresh leaves of Terminalia tomentosa for 1 to 4 times a day. All the parameters improved upon providing fresh diets more times over the single diet (1FD). The absolute body weight increased with increase in number of feeds/day significantly (P<0.001). While the maximum weight recorded was 29.61 g in 1FD, the respective weights for two feeds/day (2FD), three feeds/day (3FD) and four feeds/day (4FD) were 39.41 g, 40.63 g and 42.66 g respectively. Feeding period and instar duration were declined (P<0.001) and survival increased significantly (P<0.001) upon increase in the number of diets. Nutritional indices like ingestion, digestion, relative consumption rate (RCR), relative growth rate (RGR) and gain in body weight increased significantly with the increase in number of feeds/day, but approximate digestibility (AD) and efficiency of conversion of ingested food (ECI) declined, while efficiency of conversion of digested food (ECD) did not change.

Impact of Quantitative Feeding on Nutritional Parameters of Fifth Instar Larvae of Antheraea mylitta

( Sudhansu Sekhar Rath ) 한국잠사학회 2010 International Journal of Industrial Entomology Vol.20 No.2

Feeding is an important aspect of insect nutrition which in turn supports growth, development, reproduction and survival. The impact of quantitative feeding on nutritional parameters of fifth instar Antheraea mylitta larvae was studied by providing fresh leaves of Terminalia tomentosa for 1 to 4 times a day. All the parameters improved upon providing fresh diets more times over the single diet (1FD). The absolute body weight increased with increase in number of feeds/day significantly (P<0.001). While the maximum weight recorded was 29.61 g in 1FD, the respective weights for two feeds/day (2FD), three feeds/day (3FD) and four feeds/day (4FD) were 39.41 g, 40.63 g and 42.66 g respectively. Feeding period and instar duration were declined (P<0.001) and survival increased significantly (P<0.001) upon increase in the number of diets. Nutritional indices like ingestion, digestion, relative consumption rate (RCR), relative growth rate (RGR) and gain in body weight increased significantly with the increase in number of feeds/day, but approximate digestibility (AD) and efficiency of conversion of ingested food (ECI) declined, while efficiency of conversion of digested food (ECD) did not change.