Harmonia axyridis have become extremely popular through their extensive elytra and spot variation for many years. However, phenotypic polymorphism and striking visual phenotypes are not yet to be extensively studied. With growing attention to polymorphism of H. axyridis, it is imperative to study involved in genomic research in order to elucidate the molecular mechanisms underlying the diversity of elytra variation. To figure out suitable approach for analyzing genes of H. axyidis, we assessed RNAi as a tool for functional analysis. In order to demonstrate the utility of RNAi technique on H. axyridis, we conducted cDNA library screening to affirm silencing effect. We choose random genes from cDNA clones and the random genes were synthesized into dsRNA. After the injection of dsRNA into last instar larvae, we observed morphological defects or deaths. To investigate the effectiveness of knockdown in H. axyridis, we performed quantitative real time PCR on H. axyridis that appears the most distinctive features. These results provide that RNAi is highly applicable in H. axyridis and it will be useful for the gene functional analysis.
Pyrifluquinazon, as a quinazinalone chemical group, based on a new mode of biological activity. It is reported that mode of action is modifies insect behavior, rapidly stopping feeding such that insects starve to death. Time-release feature and mortality effect on M. persicae using different pyrifluquinazon nano type and non-nano type were compared. Pyrifluquinazon nano type was formulated with different molecular weight and density of used chitosan (CS 30000 0.1% and CS 3000 0.3%). In the CS 30,000 0.1%, the mortality was weakly occurred at early time, but steadily increased after 4days. Finally, we confirmed more than 70% mortality as a peak at 16days. In CS 3000 0.3%, the mortality showed about 70% until 18days as a effective controlled release. Also, We examine time-release feature and mortality effect on M. persicae according to the different pyrifluquinazon nano type(CS 30000 0.1% and CS 3000 0.3%) of concentrations. The CS 30000 0.1% bioassay results of different concentration were showed that the highest concentration(100ppm) was measured better mortality than other concentration at 0 day, but cannot confirm different effect about dissimilar concentration. However, increasing rates of M. persicae were low as treatment concentrate was high. In CS 3000 0.3% 100ppm concentration bioassay result, aphid mortality reached peak at 24 days and increasing rate also low. Additionally, for the comparing of bioassay and feeding behavior of M. persicae against pyrifluquinazon nano types and non-nano type, EPG technique was carried out. In case of non nano type, feeding inhibition efficacy was showed during 4 days after treatment, but appeared similar level with control after 10days. In CS 3000 0.3% 50ppm, residual efficacy was specially showed until 28days after treatment whereas treatments with CS 30000 0.1% were similar to the control after 22days. These result show that the change of feedinng behavior and motrality of M. persicae is correlated with the change of nano type or non nano type of pyrifluquinazon.
Several species of the genus Aphidius are used in biological control programs against aphid pests throughout the world and their behavior and physiology are well studied. But despite knowing the importance of sensory organs in their behavior, their antennal structure is largely unknown. In this study, the external morphology and distribution of the antennal sensilla on the antennal of both female and male adults of A. colemani were described using scanning electron microscopy (SEM). Generally, the filaform antennae of males (1,515.20±116.48 ㎛) are longer than females (1,275.06±116.42㎛). Antennae of this species is made up of scape, pedicel and flagellomeres. Male and female antennae differed in the total number of flagellomeres as 15 in males and 13 in females. Female and male antennae of A. colemani has samely seven types of sensilla. We classified sensilla placodea, Bohm bristles, 2 types of sensilla coeloconica, , 2 types of sensilla basiconica as with a tip pore and with wall pores, sensilla trichodea. In addition, the possible functions of the above sensilla types are discussed in light of previously published literature; mechanoreception(Bohm bristles, sensilla coeloconicaⅡ and sensilla trichodea) and chemoreception(sensilla coeloconicaⅠ, sensilla basiconicaⅠ,Ⅱ and sensilla placodea). Future studies on the functional morphology of the antennal sensilla of A. colemani using transmission electron microscopy (TEM) coupled with electrophysiological recordings will likely confirm the functions of the different sensilla identified in this study.
The multicolored Asian ladybird beetle, Harmonia axyridis, is a generalist predator of aphids also, shows a high level of phenotype polymorphism in color pattern of elytra. Although, it is not sure about genetic information of color polymorphism, it has been confirmed that this phenomenon comes from their genetic traits. The color of H. axyridis elytra is mainly composed of black and red pigment. Phenoloxidase (PO) plays an important role in many insect physiological functions, i.e. sclerotization and pigmentation of cuticle and melanization of parasites. Following activation, PO catalyses the hydroxylation of tyrosine and subsequent oxidation of phenolic substance into quinines, which are further converted to melanin. However, the molecular bases of H. axyridis color pattern formation are almost unknown but it may be that the different pro-POs have different expression. In this study, total RNA samples from four each color pattern individuals, for example, succinea 1, succinea 2, conspicua and spectabilis was extracted. A cDNA enconding pro-PO was molecular cloned from each color pattern of H. axyridis and its putative amino acid sequence shared homology with pro-PO of other insects. We are pursuing to elucidate that their pro-PO sequence will be similar with those other insect PPO sequence. There are also regions of high sequence similarity, including putative activation site and two copper binding sites.
Several species of the genus Aphidius are used in biological control programs against aphid pests throughout the world and their behavior and physiology are well studied. But despite knowing the importance of sensory organs in their behavior, their antennal structure is largely unknown. In this study, the external morphology and distribution of the antennal sensilla on the antennal of both female and male adults of A. colemani were described using scanning electron microscopy (SEM). Generally, the filaform antennae of males (1,565.60± 194.64㎛) are longer than females (1,303.83±156.41㎛). Antennae of this species is made up of scape, pedicel and flagellomeres. Male and female antennae differed in the total number of flagellomeres as 15 in males and 13 in females. Female and male antennae of A. colemani has samely ten types of sensilla. We classified 3 types of sensilla trichodea as without pores, with a tip pore and with wall pores, 3 types of sensilla coeloconica, 1 sensilla placodea and 1 Bohm bristles. In addition, the possible functions of the above sensilla types are discussed in light of previously published literature; mechanoreception (Bohm bristles and sensilla coeloconica) and olfaction (sensilla trichodea and sensilla placodea). Future studies on the functional morphology of the antennal sensilla of A. colemani using transmission electron microscopy (TEM) coupled with electrophysiological recordings will likely confirm the functions of the different sensilla identified in this study.
To identify DNA markers linked to a elytra polymorphism, amplified fragment length polymorphism (AFLP) analysis was performed on DNA samples from four each colour pattern individuals (2 females and males), for example, succinea 1, succinea 2, conspicua, and spectabilis. As a result of performing AFLP analysis with the restriction endonuclease combination EcoRⅠ and Mse I, total of 2,269 AFLP fragments which were specific to succinea, conspicua and spectabilis was identified using 24 different AFLP primer combinations. Among these 2,269 fragments, 16 bands which were the most specific to one color patterns were isolated, cloned and sequenced. Subsequent UPGMA cluster analysis revealed that population of H. axyridis was divided four major group and these genetic tree showed that H. axyridis elytra colour diversity was affected by genetic polymorphism. It is considered that these genetic analyses may be facilitated the understanding of molecular genetic mechanism related with the wing colour pattern formation in this species.
The bulb storability of eight red and ten yellow onion (Allium cepa L.) cultivars grown primarily in Korea was evaluated. During storage, sprouting occurred earlier in red cultivars than in yellow cultivars. In addition, the ratio of sprouted to unsprouted bulbs increased more rapidly in red cultivars than in yellow cultivars. However, not all yellow cultivars had strong storabilities. Bulb storability of three yellow cultivars was as poor as that of red cultivars, suggesting only a slight possibility of a pleiotropic effect of color and bulb storability. Meanwhile, F3 lines of a red cultivar selected based on stronger storabilities showed intermediate storabilities between those of the red and yellow cultivars, implying that strong storability could be obtained by successive selection. In contrast, F1 hybrids from crosses between yellow and red breeding lines showed poor storability compared with the yellow cultivars, indicating that poor storability may be dominant over strong storability. The relationships between color and other traits that potentially affect storability, such as fresh and dry weight, water content, and firmness of bulbs, were evaluated. No significant differences in these traits were observed between the two colors, although the water content of yellow cultivars and the dry weight of red cultivars were slightly higher than their counterparts. Correlation analyses between bulb storability and other traits, including weight, water content, and firmness, also showed no significant correlations. In this study, no correlations were identified between bulb color, storability, and other traits. However, based on these results, red cultivars with stronger storabilities could be developed through successive selection of bulbs with stronger storabilities.