Molecular Markers of Pesticide Resistance and Pathogens in Head Lice

Background: Human head lice (Pediculus humanus capitis) are obligate blood-sucking external parasites that live at the base of hair shafts near the scalp. An estimated 6-12 million head louse infestations (HLI) occur each year among children 3 to 11 years of age. Resistance to insecticides is considered to be a major factor in the increasing number of HLI. We evaluated geographically distant lice for the occurrence and prevalence of biomarkers of resistance to permethrin, the most commonly used over-the-counter (OTC) pediculicide. Lice were also tested for carriage of Bartonella quintana, the etiological agent of trench fever. Methods: Human lice were collected in the U.S., Russia, and Madagascar in 2004 - 2014. DNA was extracted and a 332-bp fragment of the louse house-keeping gene encoding the alpha-subunit of the sodium channel was amplified by PCR. Permethrin resistance mutation L932F was detected by restriction fragment length polymorphism analysis. Detection of B. quintana was performed using a TaqMan assay. Results: DNA was isolated from 502 lice, including: 213 head lice from Georgia, USA, 163 body lice from Russia, and 116 head lice from Madagascar. The L932F mutation was detected in 98% of head lice from the U.S, 1.41% of body lice from Russia, and 20% of head lice from Madagascar. DNA from B. quintana was detected in 64% (n=161) of body lice from Russia and 10.% of head lice from the U.S. (n=213). Conclusions: Evidence for the presence of B. quintana in head lice from Georgia, USA was obtained for the first time, which suggests frequent exposure to this pathogen may occur in the state. The rate of L932F mutation varied in lice from distantly separated regions and was most prevalent in lice from Georgia, USA. It is possible that current OTC permethrin based head louse treatments are widely ineffective in the USA

Effect of Electronic Cold-PasteurizationTM (ECPTM) on Fruit Quality and Postharvest Diseases during Blueberry Storage

With the growing popularity of blueberries and the associated increase in blueberry imports and exports worldwide, delivering fruit with high quality, longer shelf-life, and meeting phytosanitary requirements has become increasingly important. The objective of this study was to determine the effects of electron beam irradiation using a new Electronic Cold-PasteurizationTM (ECPTM) technology on fruit quality, microbial safety, and postharvest disease development in two southern highbush blueberry cultivars, ‘Farthing’ and ‘Rebel’. Fruit packed in clamshells were subjected to four levels of ECPTM irradiation (0, 0.15, 0.5, and 1.0 kGy) and evaluated for fruit quality attributes, surface microbial load, and postharvest disease incidence during various storage times after treatment and cold storage. Overall, there was no effect of irradiation on visual fruit quality in either cultivar. Fruit firmness and skin toughness in ‘Farthing’ was reduced following irradiation at 1.0 kGy, but no such effect was observed in ‘Rebel’. Other fruit quality characteristics such as fruit weight, total soluble solids content, or titratable acidity were not affected. Irradiation at 1.0 kGy significantly reduced total aerobic bacteria and yeast on the fruit surface, and in the case of ‘Rebel’, also levels of total coliform bacteria. There was no significant effect of irradiation on postharvest disease incidence in these trials. Overall, data from this study suggests that an irradiation dose lower than 1.0 kGy using ECPTM can be useful for phytosanitary treatment in blueberry fruit while avoiding undesirable effects on fruit quality in a cultivar-dependent manner

Detection and Quantitation of Candidatus Riesia Pediculola in Human Lice

Background: Candidatus Riesia pediculicola is a gram-negative obligate intracellular bacterium, which is the primary endosymbiont of human lice The presence of Riesia is crucial in providing the lice with essential B vitamins, nicotinic acid, pantothenic acid, and beta-biotin. Several genes responsible for pantothenic acid synthesis are encoded on the Riesia plasmid. We tested whether the Riesia plasmid is always present in different samples of human head and body lice and whether the plasmid copy numbers differs with the life stage and sex. Methods: Head and body human lice were identified morphologically and their sex and life stage was recorded. DNA was extracted from each louse using the QIAamp DNA Mini Kit (Qiagen) and concentration determined using Nanodrop (Fisher Scientific). The integrity of each extract was determined by targeting 159-bp louse chromosome and 101-bp louse mitochondrial gene amplified by EvaGreen PCR. Two quantitative PCR (qPCR) assays were developed and amplification conditions were optimized for detection of Riesia plasmid and Riesia chromosome genes. Testing was performed for individual DNA samples in duplicate followed by melting curve analysis of each amplicon to verify the absence of secondary PCR products. Relative gene Riesia copy numbers were determined and statistical analysis was done using t-test. Results: All 81 DNA louse samples extracted (35 head lice and 46 body lice) tested positive for louse chromosome and mitochondrial gene fragments by EvaGreen PCR. Relative copy number of Riesia plasmid gene was similar in male, female and nymphs of head lice from Georgia, USA and its average (+ standard deviation) ranged from 1.72 + 1.0 to 2.8 + 2.46. Likewise, relative copy number of Riesia plasmid gene was similar in male, female and nymphs of body lice from Russia but its average (ranged from 1.25 + 0.86 to 2.37 + 2.61) was slightly lower compared to head lice (P=0.03), though it had comparable ratio. Conclusions: Riesia was ubiquitous and its plasmid content is similar in human and body lice from different geographic regions and throughout different stages of lice. Whether its copy numbers vary following feeding needs further investigation