The longtail mealybug Pseudococcus longispinus is the main arthropod pest of persimmon in Spain. The parasitoid Anagyrus fusciventris has been identified as the most abundant and widely distributed biological control agent of P. longispinus in the main persimmon-producing areas. This parasitoid exhibits haplodiploidy, and recent research suggests that mated females might experience sperm depletion when mating opportunities are limited. This thesis has first evaluated the effect of different mating conditions on the fecundity and sex ratio of A. fusciventris under controlled conditions. Contrary to previous studies and assumptions, mating status did not affect the fecundity and sex ratio of A. fusciventris. However, the sex ratio was strongly male-biased; around 80% of the offspring were males. This high male-biased sex ratio was primarily attributed to copulation problems and, therefore, the second part of this thesis analysed the courtship sequence and mating behaviour of A. fusciventris with males and females subjected to different mating statuses. The mating success rate of A. fusciventris was relatively low in virgin couples (39%) and extremely low in previously mated couples (6%). Interestingly, both sexes exhibited behaviours that reduced mating success; previously mated males displayed decreased responsiveness to new mating opportunities, potentially due to pheromonal cues from mated females, while previously mated females actively avoided further mating by running away from virgin males during chasing. Additionally, both virgin and mated females alternated between moving continuously and remaining stationary in response to male mounting attempts, further complicating mating success. From this observation, the fecundity and progeny sex ratio of A. fusciventris could be enhanced by increasing the number of males released alongside females in an augmentative biological control program. This will help improve the likelihood of successful mating. Future research should explore the influence of female responses to male mounting behaviour on mating outcomes.
The longtail mealybug Pseudococcus longispinus is the main arthropod pest of persimmon in Spain. The parasitoid Anagyrus fusciventris has been identified as the most abundant and widely distributed biological control agent of P. longispinus in the main persimmon-producing areas. This parasitoid exhibits haplodiploidy, and recent research suggests that mated females might experience sperm depletion when mating opportunities are limited. This thesis has first evaluated the effect of different mating conditions on the fecundity and sex ratio of A. fusciventris under controlled conditions. Contrary to previous studies and assumptions, mating status did not affect the fecundity and sex ratio of A. fusciventris. However, the sex ratio was strongly male-biased; around 80% of the offspring were males. This high male-biased sex ratio was primarily attributed to copulation problems and, therefore, the second part of this thesis analysed the courtship sequence and mating behaviour of A. fusciventris with males and females subjected to different mating statuses. The mating success rate of A. fusciventris was relatively low in virgin couples (39%) and extremely low in previously mated couples (6%). Interestingly, both sexes exhibited behaviours that reduced mating success; previously mated males displayed decreased responsiveness to new mating opportunities, potentially due to pheromonal cues from mated females, while previously mated females actively avoided further mating by running away from virgin males during chasing. Additionally, both virgin and mated females alternated between moving continuously and remaining stationary in response to male mounting attempts, further complicating mating success. From this observation, the fecundity and progeny sex ratio of A. fusciventris could be enhanced by increasing the number of males released alongside females in an augmentative biological control program. This will help improve the likelihood of successful mating. Future research should explore the influence of female responses to male mounting behaviour on mating outcomes.
Biological control of the longtail mealybug Pseudococcus longispinus in persimmon: mating behaviour and mass-rearing of its main parasitoid Anagyrus fusciventris
SAMU, MOHAMED
2023/2024
Abstract
The longtail mealybug Pseudococcus longispinus is the main arthropod pest of persimmon in Spain. The parasitoid Anagyrus fusciventris has been identified as the most abundant and widely distributed biological control agent of P. longispinus in the main persimmon-producing areas. This parasitoid exhibits haplodiploidy, and recent research suggests that mated females might experience sperm depletion when mating opportunities are limited. This thesis has first evaluated the effect of different mating conditions on the fecundity and sex ratio of A. fusciventris under controlled conditions. Contrary to previous studies and assumptions, mating status did not affect the fecundity and sex ratio of A. fusciventris. However, the sex ratio was strongly male-biased; around 80% of the offspring were males. This high male-biased sex ratio was primarily attributed to copulation problems and, therefore, the second part of this thesis analysed the courtship sequence and mating behaviour of A. fusciventris with males and females subjected to different mating statuses. The mating success rate of A. fusciventris was relatively low in virgin couples (39%) and extremely low in previously mated couples (6%). Interestingly, both sexes exhibited behaviours that reduced mating success; previously mated males displayed decreased responsiveness to new mating opportunities, potentially due to pheromonal cues from mated females, while previously mated females actively avoided further mating by running away from virgin males during chasing. Additionally, both virgin and mated females alternated between moving continuously and remaining stationary in response to male mounting attempts, further complicating mating success. From this observation, the fecundity and progeny sex ratio of A. fusciventris could be enhanced by increasing the number of males released alongside females in an augmentative biological control program. This will help improve the likelihood of successful mating. Future research should explore the influence of female responses to male mounting behaviour on mating outcomes.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/70924