| Phenacoccus solenopsis Tinsley, was first found in the North America in 1898. Now it has become a serious worldwide invasive exotic pest, and was recorded in Guangdong Province, China in 2008. Phenacoccus solenopsis is omnivorous with a wide host range, and most parts of China are its suitable habitat. The potential invasion of P. solenopsis might incur a high risk to China’s agricultural industry. The mealybug P. solenopsis has been included in the "People’s Republic of China entry plant quarantine pest list", and was regarded as the National Agricultural forestry plant quarantine pests.Studies of P. solenopsis is mainly focused on its biological charateristics and relevant control methods, however, detailed information on its reproduction mode and sex pheromone has not been investigated. In present sutdy, we investigated the effects of mating on the development and oviposition of female P. solenopsis. And we also did a preliminary study on its sex pheromone. Our results are listed below.Firstly, we investigated the effects of mating behaviour on the characteristics of female P. solenopsis, including adult longevity, body size of mated females and their oviposition behaviour. Our results showed that unmated females could not lay eggs. In contrast, the females that were delayed in mating could lay eggs, and its spawning period, daily fecundity, and spawning total fecundity was significantly decreased, but the longevity and body size was significantly increased compared to normal mated females.Anatomy observation indicated that mating behaviour also exerted some effects on the development of reproductive system of P. solenopsis. At the same time, we did a TEM observation on the sepermatheca, and found that mated female’s sepermatheca is full of sperm, but the sepermatheca of unmated female is empty. Oocytes in the unmated female could not become mature and were resorbed by maternal somatic cells for a lack of sperm. Delay-mated females could make a trade-off between maintenance and reproduction by a nutritional rearrangement, which indicated that females could resorb the resources from eggs for a longer survival when they couldn’t get mated. Once mated, females would lay eggs, and their physiological state got reset, but the lifespan was shorter than unmated females. Taken together, our results confirmed that the production of P. solenopsis is by amphimixis, but not by parthenogenesis, and males play an indispensible role in the reproduction of P. solenopsis.Secondly, we did a preliminary study to explore the sex pheromone of P. solenopsis. We examined the attraction beheaviour of males towards the volatiles emitted from virgin females and mated feemales. Different treatments has been set as follows:single virgin female; 3 virgin females; single mated female; 3 mated female; blank control. Compared the results of the number of males attracted by them, we found that male P. solenopsis showed a preference to the odors from single adult virgin female and this attraction was not affected by the number of virgin females. The odor from blank control without female and mated females had no attraction to the males. We speculated that adult female P. solenopsis cease the release of sex pheromone once mated. Previous study have shown that the fecundity of the multiple mating female is similar to the female with once mating behaviour, indicating that the first mating behaviour play a key role in reproduction of P. solenopsis. t. Taken all the results together, we reason that there could be information exchange between female and male P. solenopsis by a given sex pheromone. |
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