Mealybugs are under a strict regulation at foreign trades of agricultural products because they are one of the most economically damaging groups of insects on food crops and ornamental plants. However, the absence of morphological characteristics enabling the discrimination of early life stages often cause a significant delay or rejection of a shipment when infested fruit is discovered, causing significant economic loss. A polymerase chain reaction-based method for species identification was developed for six mealybug species known to infest Korean pears including two regulated insects, Planococcus kraunhiae (Kuwana) and Crisicoccus matsumotoi (Siraiwa). Six sets of species-specific primers were designed based on the sequence comparison of the internal transcribed spacer 1 and 2 regions. Efficiency tests against 29 mealybug samples showed that this method could effectively discriminate different mealybug species regardless of their developmental stages. Blind tests against 11 field collected mealybug nymph samples indicated that a single polymerase chain reaction is enough to discriminate unidentified mealybugs collected on Korean pears. This new method will facilitate trade and export requirements, as well as identify the species at any stage of mealybug intercepted.
The development of the endosperm in Gleditsia is marked by the growth of the average nucleus from 141 μ3 on June 12 to 978 μ3 on July 14. At the time of formation of a cellular endosperm the average nuclear volume commences dropping and by July 20 reaches an average of 224 μ3 throughout the endosperm. In Podophyllum at the time of cell formation the average nuclear volume begins to drop from a value of about 2850 μ3 and falls to a value of from 500 μ3 to 770 μ3, the latter estimates depending upon the mode of fixation of the material. The volume decrease in the Podophyllum endosperm nucleus is accompanied by a fall in mean relative DNA content of the average nucleus, as determined by microspectrophotometry with the two wavelength method. The possibility of degeneration of some of the higher “ploid” types is considered, as well as depolyploidization.
The development of the endosperm in Gleditsia is marked by the growth of the average nucleus from 141 ,.3 on June 12 to 978,.3 on July 14. At the time of formation of a cellular endosperm the average nuclear volume commences dropping and by July 20 reaches an average of 224,.3 throughout the endosperm. In Podophyllum at the time of cell formation the average nuclear volume begins to drop from a value of about 2850 ,.3 and falls to a value of from 500 ,.3 tu 770,.3, the latter estimates depending upon the mode of fixation of the material. The volume decrease in the Podophyllum endosperm nucleus is accompanied by a fall in mean relative DNA content of the average nucleus, as determined by microspectrophotumetry with the two wavelength method. The possibility of degeneration of some of the higher "ploid" types is considered, as well as depolyploidization.
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