Taro Colocasia esculenta is a staple food in most countries of the South Pacific region. However,... more Taro Colocasia esculenta is a staple food in most countries of the South Pacific region. However, the recent changes in the climatic conditions and the associated factors became a threat to growing taro in the region. Rising sea level and frequent dry and wet conditions had led to increased soil salinity which is a limiting factor in producing taro in these atoll islands. The aim of this research was to screen selected taro varieties based on their ability to tolerate salinity conditions in Samoa. Effects of three salinity levels (0.2, 3% and 5%), and growth hormones Benzylaminopurine (BAP) and Thidiazuron (TDZ) were examined on growth and development of in vitro grown taro varieties. Plant height, number of leaves, and number of roots produced were compared in the selected varieties. Results suggest that all varieties had callus induction and regeneration in MSO medium. Addition of BAP induced better growth and the plants produced higher number of leaves, while TDZ improved roots p...
Parasitoid fitness depends on its ability to manipulate reproductive strategies when in competiti... more Parasitoid fitness depends on its ability to manipulate reproductive strategies when in competition. This study investigated the parasitism and sex allocation strategies of the parasitic wasp Diaeretiella rapae McIntosh at a range of host (Brevicoryne brassicae L.) and conspecific densities. The results suggest that D. rapae females adjust their progeny production and progeny sex ratio with changing competition. When foraging alone, female D. rapae parasitize larger number of B. brassicae nymphs when the number of available hosts is increased, but the overall proportion of parasitized hosts decreases with increase in host density. The proportion of female offspring also decreases with elevated host density. Increase in the number of female D. rapae foraging together increased total parasitism, but reduced relative contribution of each individual female. The number of female progeny decreased when multiple females competed for the same host. However, foraging experience in the presence of one or more conspecifics increased the parasitism rate and proportion of female progeny. Competing females were more active during oviposition and had shorter lives. The study suggests that both host and foundress (female parasitoid) densities have significant effect on progeny production, sex allocation, and longevity of foraging females.
The reproductive fitness of a parasitoid depends on the oviposition decisions of a female in resp... more The reproductive fitness of a parasitoid depends on the oviposition decisions of a female in response to competition. The present study investigated the oviposition and sex ratio of offspring produced by the parasitic wasp Diaeretiella rapae while competing with other conspecific females and at different host densities. The number of Brevkoryne brassicae nymphs parasitised by female D. rapae increased with the number of nymphs offered to them.
Mating and oviposition complement each other in parasitoid reproduction; delay in either of these... more Mating and oviposition complement each other in parasitoid reproduction; delay in either of these activities has disparate consequences for the fitness of the parasitoid. We investigated the effects of mating and oviposition delay on parasitism rate and progeny sex ratio in a parasitic wasp Diaeretiella rapae. Egg dynamics in the ovaries of females of different ages, and females which completed different numbers of oviposition bouts were also examined. Delay in mating and oviposition adversely affected reproductive performance of both male and female D. rapae. Delayed oviposition resulted in reduced parasitism rates in both mated and unmated females. The progeny sex ratio was female-biased, but the proportion of female offspring decreased towards the end of D. rapae life. Although females emerged with developed eggs, the egg load in the ovaries of unmated and naïve females initially increased then continuously decreased with age, suggesting partial resorption of eggs towards the end of a females life. Oviposition rate of unmated females was low before mating. The extent of mating delay experienced by females affected the sex ratio of their progeny, causing overproduction of males. Delayed mating did not affect the courting capacity of males, but reduced the number of their offspring and proportion of female offspring. The duration of copulation was longer in older males. The results of this study clearly indicate the importance of parasitoid age in biological control programmes, and suggests the use of 1–2 days old D. rapae for best results.► Female Diaeretiella rapae emerge with developed eggs. ► Oviposition delay resulted in decreased parasitism by D. rapae. ► Delay in mating did not affect courting but affected the reproductive capacity of male and female D. rapae. ► Mating delay caused overproduction of male D. rapae. ► One-two day old D. rapae adults could perform more efficiently than younger or older adults as biocontrol agents.
Cultural and religious connections; community engagement; wellness and entry adjustment amongst i... more Cultural and religious connections; community engagement; wellness and entry adjustment amongst international students in Palmerston North.
In a survey amongst mature and post graduate students at Massey University, Palmerston North in 2011 there were indications that local religious & cultural communities served an important role as sources of information and assistance in settlement outcomes for international students and their families. The role of such connections was further reinforced in this subsequent study where the authors sought to explore further the cultural adaptation amongst a broad group of international students in Palmerston North with reference to factors that may aid settlement or act as barriers to good settlement outcomes. Through a methodology of a short survey and complementary focus groups and interviews the experiences of a range of international students were explored as to engagement with the local community groups and how such engagement facilitated a sense of belonging, participation, inclusion and recognition. This in turn contributed to growth in wellness through a lessening of acculturative stresses, a heightening awareness of social supports and a perception of paths to overcome language and communication barriers in the wider community. The sample of international students included young, single undergraduate students as well as post graduate, mature and married with family students. In this paper the authors draw from the Maori health model, Te Whare Tapa Wha and make suggestions relating to entry adjustment programmes for international students to seek to achieve a balance whereby the international student adjustment includes the spiritual as well as physical, social and mental aspects
1. The reproductive fitness of a parasitoid depends on its mating and ovipositing success. Virgin... more 1. The reproductive fitness of a parasitoid depends on its mating and ovipositing success. Virgin haplodiploid females can reproduce, but produce only males, and may diminish fitness by producing more male offspring than required. Therefore, females must decide on whether to mate or oviposit first.2. This study was conducted to assess the mating versus ovipositing decision and its impact on the reproductive fitness of Diaeretiella rapae (Hymenoptera: Aphididae), an endoparasitoid of the cabbage aphid Brevicoryne brassicae (Hemiptera: Aphididae).3. When newly emerged females were given a choice between mating and ovipositing, about 62% of D. rapae females preferred to mate before ovipositing. Those females who oviposited before mating parasitised only 10% of the available aphids. After mating, females superparasitised their hosts with fertilised eggs, which resulted in a highly female-biased sex ratio in the offspring.4. Mating success was very high (91%) in the presence of hosts (cabbage aphid nymphs) compared with that in the absence of aphids. However, mating success was not influenced by the quality (size) of the hosts present in the mating arena, despite a parasitoid preference for larger hosts during oviposition. The time between pairing and mating was also shorter in the presence of host aphids. The mean number of aphids parasitised and the parasitism rate were significantly greater after mating.
A strong relationship exists between body size and fitness in parasitoids. However, it is unclear... more A strong relationship exists between body size and fitness in parasitoids. However, it is unclear whether the relationship is symmetric or asymmetric in males and females. The present study investigated the body size and fitness relationship in Diaeretiella rapae emerged from small and large nymphs of cabbage aphid Brevicoryne brassicae. A positive relationship existed between the size of the aphid host and growth of parasitoid larva developing in it. The fitness gain in males and females was not proportionate to their body size gain. Females mated with larger males produced 10 % more female offspring than females mated with smaller males. However, females that developed in large hosts produced 62 % more offspring (total male and female) than the females emerged from smaller hosts. The findings suggest that the number of offspring and the progeny sex ratio were affected by the body size of both male and female D. rapae.
Reproductive activities of naturally occurring population of Diaeretiella rapae (M'Intosh) (Hymen... more Reproductive activities of naturally occurring population of Diaeretiella rapae (M'Intosh) (Hymenoptera: Aphidiinae) on Myzus persicae were studied during spring season in New Zealand. The cabbage seedlings were highly infested with the aphids (272±25 individuals/plant) with about 30% on average parasitised by D. rapae. Rate of parasitism was positively correlated with the aphid density (R 2=0.64). Adult emergence from aphid mummies was 90%, with a higher frequency of females than males. Increase in female/male sex ratio was found between early and late spring (1.1 vs. 1.8). Mating in D. rapae occurred throughout the day. Nearly half of the mating pairs collected were male–male pairs, which were especially prevalent during morning and evening while more male–female mating pairs were found during midday. Male–male mounting was probably because of low number of virgin females in morning and evening populations. About 80% females were mounted by smaller size males. Male–male mounting is discussed in correlation with operational sex ratio of D. rapae population.
Taro Colocasia esculenta is a staple food in most countries of the South Pacific region. However,... more Taro Colocasia esculenta is a staple food in most countries of the South Pacific region. However, the recent changes in the climatic conditions and the associated factors became a threat to growing taro in the region. Rising sea level and frequent dry and wet conditions had led to increased soil salinity which is a limiting factor in producing taro in these atoll islands. The aim of this research was to screen selected taro varieties based on their ability to tolerate salinity conditions in Samoa. Effects of three salinity levels (0.2, 3% and 5%), and growth hormones Benzylaminopurine (BAP) and Thidiazuron (TDZ) were examined on growth and development of in vitro grown taro varieties. Plant height, number of leaves, and number of roots produced were compared in the selected varieties. Results suggest that all varieties had callus induction and regeneration in MSO medium. Addition of BAP induced better growth and the plants produced higher number of leaves, while TDZ improved roots p...
Parasitoid fitness depends on its ability to manipulate reproductive strategies when in competiti... more Parasitoid fitness depends on its ability to manipulate reproductive strategies when in competition. This study investigated the parasitism and sex allocation strategies of the parasitic wasp Diaeretiella rapae McIntosh at a range of host (Brevicoryne brassicae L.) and conspecific densities. The results suggest that D. rapae females adjust their progeny production and progeny sex ratio with changing competition. When foraging alone, female D. rapae parasitize larger number of B. brassicae nymphs when the number of available hosts is increased, but the overall proportion of parasitized hosts decreases with increase in host density. The proportion of female offspring also decreases with elevated host density. Increase in the number of female D. rapae foraging together increased total parasitism, but reduced relative contribution of each individual female. The number of female progeny decreased when multiple females competed for the same host. However, foraging experience in the presence of one or more conspecifics increased the parasitism rate and proportion of female progeny. Competing females were more active during oviposition and had shorter lives. The study suggests that both host and foundress (female parasitoid) densities have significant effect on progeny production, sex allocation, and longevity of foraging females.
The reproductive fitness of a parasitoid depends on the oviposition decisions of a female in resp... more The reproductive fitness of a parasitoid depends on the oviposition decisions of a female in response to competition. The present study investigated the oviposition and sex ratio of offspring produced by the parasitic wasp Diaeretiella rapae while competing with other conspecific females and at different host densities. The number of Brevkoryne brassicae nymphs parasitised by female D. rapae increased with the number of nymphs offered to them.
Mating and oviposition complement each other in parasitoid reproduction; delay in either of these... more Mating and oviposition complement each other in parasitoid reproduction; delay in either of these activities has disparate consequences for the fitness of the parasitoid. We investigated the effects of mating and oviposition delay on parasitism rate and progeny sex ratio in a parasitic wasp Diaeretiella rapae. Egg dynamics in the ovaries of females of different ages, and females which completed different numbers of oviposition bouts were also examined. Delay in mating and oviposition adversely affected reproductive performance of both male and female D. rapae. Delayed oviposition resulted in reduced parasitism rates in both mated and unmated females. The progeny sex ratio was female-biased, but the proportion of female offspring decreased towards the end of D. rapae life. Although females emerged with developed eggs, the egg load in the ovaries of unmated and naïve females initially increased then continuously decreased with age, suggesting partial resorption of eggs towards the end of a females life. Oviposition rate of unmated females was low before mating. The extent of mating delay experienced by females affected the sex ratio of their progeny, causing overproduction of males. Delayed mating did not affect the courting capacity of males, but reduced the number of their offspring and proportion of female offspring. The duration of copulation was longer in older males. The results of this study clearly indicate the importance of parasitoid age in biological control programmes, and suggests the use of 1–2 days old D. rapae for best results.► Female Diaeretiella rapae emerge with developed eggs. ► Oviposition delay resulted in decreased parasitism by D. rapae. ► Delay in mating did not affect courting but affected the reproductive capacity of male and female D. rapae. ► Mating delay caused overproduction of male D. rapae. ► One-two day old D. rapae adults could perform more efficiently than younger or older adults as biocontrol agents.
Cultural and religious connections; community engagement; wellness and entry adjustment amongst i... more Cultural and religious connections; community engagement; wellness and entry adjustment amongst international students in Palmerston North.
In a survey amongst mature and post graduate students at Massey University, Palmerston North in 2011 there were indications that local religious & cultural communities served an important role as sources of information and assistance in settlement outcomes for international students and their families. The role of such connections was further reinforced in this subsequent study where the authors sought to explore further the cultural adaptation amongst a broad group of international students in Palmerston North with reference to factors that may aid settlement or act as barriers to good settlement outcomes. Through a methodology of a short survey and complementary focus groups and interviews the experiences of a range of international students were explored as to engagement with the local community groups and how such engagement facilitated a sense of belonging, participation, inclusion and recognition. This in turn contributed to growth in wellness through a lessening of acculturative stresses, a heightening awareness of social supports and a perception of paths to overcome language and communication barriers in the wider community. The sample of international students included young, single undergraduate students as well as post graduate, mature and married with family students. In this paper the authors draw from the Maori health model, Te Whare Tapa Wha and make suggestions relating to entry adjustment programmes for international students to seek to achieve a balance whereby the international student adjustment includes the spiritual as well as physical, social and mental aspects
1. The reproductive fitness of a parasitoid depends on its mating and ovipositing success. Virgin... more 1. The reproductive fitness of a parasitoid depends on its mating and ovipositing success. Virgin haplodiploid females can reproduce, but produce only males, and may diminish fitness by producing more male offspring than required. Therefore, females must decide on whether to mate or oviposit first.2. This study was conducted to assess the mating versus ovipositing decision and its impact on the reproductive fitness of Diaeretiella rapae (Hymenoptera: Aphididae), an endoparasitoid of the cabbage aphid Brevicoryne brassicae (Hemiptera: Aphididae).3. When newly emerged females were given a choice between mating and ovipositing, about 62% of D. rapae females preferred to mate before ovipositing. Those females who oviposited before mating parasitised only 10% of the available aphids. After mating, females superparasitised their hosts with fertilised eggs, which resulted in a highly female-biased sex ratio in the offspring.4. Mating success was very high (91%) in the presence of hosts (cabbage aphid nymphs) compared with that in the absence of aphids. However, mating success was not influenced by the quality (size) of the hosts present in the mating arena, despite a parasitoid preference for larger hosts during oviposition. The time between pairing and mating was also shorter in the presence of host aphids. The mean number of aphids parasitised and the parasitism rate were significantly greater after mating.
A strong relationship exists between body size and fitness in parasitoids. However, it is unclear... more A strong relationship exists between body size and fitness in parasitoids. However, it is unclear whether the relationship is symmetric or asymmetric in males and females. The present study investigated the body size and fitness relationship in Diaeretiella rapae emerged from small and large nymphs of cabbage aphid Brevicoryne brassicae. A positive relationship existed between the size of the aphid host and growth of parasitoid larva developing in it. The fitness gain in males and females was not proportionate to their body size gain. Females mated with larger males produced 10 % more female offspring than females mated with smaller males. However, females that developed in large hosts produced 62 % more offspring (total male and female) than the females emerged from smaller hosts. The findings suggest that the number of offspring and the progeny sex ratio were affected by the body size of both male and female D. rapae.
Reproductive activities of naturally occurring population of Diaeretiella rapae (M'Intosh) (Hymen... more Reproductive activities of naturally occurring population of Diaeretiella rapae (M'Intosh) (Hymenoptera: Aphidiinae) on Myzus persicae were studied during spring season in New Zealand. The cabbage seedlings were highly infested with the aphids (272±25 individuals/plant) with about 30% on average parasitised by D. rapae. Rate of parasitism was positively correlated with the aphid density (R 2=0.64). Adult emergence from aphid mummies was 90%, with a higher frequency of females than males. Increase in female/male sex ratio was found between early and late spring (1.1 vs. 1.8). Mating in D. rapae occurred throughout the day. Nearly half of the mating pairs collected were male–male pairs, which were especially prevalent during morning and evening while more male–female mating pairs were found during midday. Male–male mounting was probably because of low number of virgin females in morning and evening populations. About 80% females were mounted by smaller size males. Male–male mounting is discussed in correlation with operational sex ratio of D. rapae population.
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Papers by Rashmi Kant
In a survey amongst mature and post graduate students at Massey University, Palmerston North in 2011 there were indications that local religious & cultural communities served an important role as sources of information and assistance in settlement outcomes for international students and their families. The role of such connections was further reinforced in this subsequent study where the authors sought to explore further the cultural adaptation amongst a broad group of international students in Palmerston North with reference to factors that may aid settlement or act as barriers to good settlement outcomes. Through a methodology of a short survey and complementary focus groups and interviews the experiences of a range of international students were explored as to engagement with the local community groups and how such engagement facilitated a sense of belonging, participation, inclusion and recognition. This in turn contributed to growth in wellness through a lessening of acculturative stresses, a heightening awareness of social supports and a perception of paths to overcome language and communication barriers in the wider community. The sample of international students included young, single undergraduate students as well as post graduate, mature and married with family students. In this paper the authors draw from the Maori health model, Te Whare Tapa Wha and make suggestions relating to entry adjustment programmes for international students to seek to achieve a balance whereby the international student adjustment includes the spiritual as well as physical, social and mental aspects
In a survey amongst mature and post graduate students at Massey University, Palmerston North in 2011 there were indications that local religious & cultural communities served an important role as sources of information and assistance in settlement outcomes for international students and their families. The role of such connections was further reinforced in this subsequent study where the authors sought to explore further the cultural adaptation amongst a broad group of international students in Palmerston North with reference to factors that may aid settlement or act as barriers to good settlement outcomes. Through a methodology of a short survey and complementary focus groups and interviews the experiences of a range of international students were explored as to engagement with the local community groups and how such engagement facilitated a sense of belonging, participation, inclusion and recognition. This in turn contributed to growth in wellness through a lessening of acculturative stresses, a heightening awareness of social supports and a perception of paths to overcome language and communication barriers in the wider community. The sample of international students included young, single undergraduate students as well as post graduate, mature and married with family students. In this paper the authors draw from the Maori health model, Te Whare Tapa Wha and make suggestions relating to entry adjustment programmes for international students to seek to achieve a balance whereby the international student adjustment includes the spiritual as well as physical, social and mental aspects