Body and head lice (Pediculus humanus humanus and Pediculus humanus capitis, respectively) are typical ectoparasites of humans. They differ not only in the ecological habitat but also in the vector competence in spite of their conspecific nature. Only body lice transmit several bacterial pathogens to humans, including Bartonella quintana, Rickettsia prowazekii and Borrelia recurrentis. In this study, the proliferation rates of two model bacteria, a gram positive Staphylococcus aureus and a gram negative Escherichia coli, were determined following bacterial challenge by cuticular injection. Both bacteria proliferated rapidly in body lice at the early stage of bacterial challenge but not in head lice, suggesting that head lice have more sensitive immune responses to these bacteria. In vivo phagocytosis assay revealed that head lice have much higher phagocytic activity against E. coli than body lice whereas only slight differences in phagocytic activity against S. aureus were observed between the two lice species. Taken together, these findings suggest that the reduced phagocytosis activity of body lice contributes, at least in part, to their higher vector competence.

Two biogenic monoamines, octopamine and 5-hydroxytryptamine (5-HT), are known to play immune mediators in insects. They induce hemocyte behaviors by stimulating cytoskeleton rearrangement. However,it is not clear how they activate the hemocytes in terms of intracellular signal transduction. This study analyzed their interactions with signal pathways implicated in nodule formation via eicosanoids or hemocyte locomotory behavior via a small GTPase. Both octopamine and 5-HT increased hemocytic nodule formation in response to bacterial challenge in the beet armyworm, Spodoptera exigua. However, their immune mediation was inhibited by a treatment of dexamethasone (a specific inhibitor to phospholipase A2). In the presence of phentolamine (a specific antoganist to octopamine) or ketanserin (a specific antoganist to 5-HT), the inhibitory activity of dexamethasone was rescued by adding arachidonic acid (a precursor of eicosanoid biosynthesis). These results suggest that the mediation of nodule formation by the two monoamines is followed by eicosanoid signaling. Two monoamines also induced up-regulation of circulating hemocyte counts in S. exigua. This increase of hemocyte counts was not explained by de novo production of hemopoietic organ because even ligation between thorax and abdomenin order to block hemolymph circulation did not inhibit the increase of circulating hemocyte counts by octopamine.A small GTPase, Rac1, appeared to be involved in this hemocyte mobilization from a sessile compartment in S. exigua. Inhibition of Rac1 activity significantly suppressed hemocyte spreading behavior and the hemocyte mobilization. In summary, octopamine and 5-HT mediate cellular immune responses of S. exigua via eicosanoid signal or independently by activating Rac1 following increase of cAMP in the hemocytes.

Hemolin is a member of the immunoglobulin (Ig) superfamily and contains four Ig domainsthat are similar to neural cell adhesion molecules. It has been regarded as a recognition molecule at immune challenge in insects. This study showed that hemolin of Plutella xylostella was expressed during pupal and adult stages but absent in all larval instars without any immune challenge. It is, however, strongly induced by the injection of Escherichia coli or its lipopolysaccharide in hemocytes, fat body and gut. A double-stranded RNA (dsRNA) interference experiment revealedits role in activation of prophenoloxidase (PPO) in the hemolymph during bacterial infection. Also its involvement in cellular defense was investigated in its mediation of the adherence of hemocytes to rat blood erythrocytes which was knocked down by its dsRNA. Finally, its physiological significance in pupal stage was confirmed by using dsRNA, which significantly prevented adult development. Therefore, it is concluded that hemolin plays roles in both immune and adult development in P. xylostella.

A light-emitting diode (LED) is most efficient in terms of economic benefits. The aim of the present study was to evaluate the effects of LED lighting intensity on milk production, milk composition, and the immune response of Holstein cows. Thirty-eight lactating cows were assigned to four experimental groups: control group (exposed natural daylight without LED light) and three LED treatment group (50 lux; natural daylight and 6 h LED light of 50 lux intensity, 100 lux; natural daylight and 6 h LED light of 100 lux intensity, 200 lux; natural daylight and 6 h LED light of 200 lux intensity). There was a significant effect on the decrease ratio in milk production in 200 lux group. Lactose was significantly increased in 100 lux than the other LED treated groups. In addition to the hemolytic biochemical analysis, AST and β-HB were significantly increased in the 50 lux than the other groups. Prolactin and IGF-1 levels were significantly increased in 200 lux compared to other groups. Besides, cortisol was significantly higher in 50 lux and lowered in the 200 lux than the control, while IgA and IgG were not significant among the groups. Therefore, it was concluded that LED lighting intensity had some impact on blood parameters and immune responses in dairy cows with increased milk production.

Light is an essential and powerful element to animals. A light-emitting diode (LED) is most efficient in terms of economic benefits. The aim of the present study was to evaluate the effects of LED lighting time on milk production, milk composition, and the immune response of Holstein cows. Forty lactating cows were assigned to four experimental groups: control; natural daylight, treatment; am3-6, pm6-12 and pm6-am6. We found that there was no significant effect on the decrease ratio in milk production among the groups. Milk urea nitrogen (MUN) was significantly decreased in pm6-am6 and pm6-12 than the control. With regard to the hemolytic biochemical analysis, GLU was significantly increased and CRE, T-BIL were significantly decreased in the pm6-12 than the control. IGF-1 levels were significantly increased in pm6-12 compared to other groups. Besides, cortisol was significantly lowered in the pm6-12 than the control, while prolactin, IgA and IgG were not significant among the groups. In addition, catalase and glutathione peroxidase were also significantly increased in pm6-12 than the control. However, antioxidant enzyme activity and superoxide dismutase were not significant among the experimental groups. Therefore, it was concluded that LED lighting time had some impact on blood parameters and immune responses in dairy cows without any changes in milk production.