Khouzama Knio

Insecticide resistance to organophosphates in Culex pipiens complex from Lebanon.

BackgroundAnalysis of Culex pipiens mosquitoes collected from a single site in Lebanon in 2005, revealed an alarming frequency of ace-1 alleles conferring resistance to organophosphate insecticides. Following this, in 2006 the majority of municipalities switched to pyrethroids after a long history of organophosphate usage in the country; however, since then no studies have assessed the impact of changing insecticide class on the frequency of resistant ace-1 alleles in C. pipiens.MethodsC. pipiens mosquitoes were captured indoors from 25 villages across the country and subjected to established methods for the analysis of gene amplification at the Ester locus and target site mutations in ace-1 gene that confer resistance to organophosphates.ResultsWe conducted the first large-scale screen for resistance to organosphosphates in C. pipiens mosquitoes collected from Lebanon. The frequency of carboxylesterase (Ester) and ace-1 alleles conferring resistance to organophosphates were assessed among C. pipiens mosquitoes collected from 25 different villages across the country between December 2008 and December 2009. Established enzymatic assay and PCR-based molecular tests, both diagnostic of the major target site mutations in ace-1 revealed the absence of the F290V mutation among sampled mosquitoes and significant reduction in the frequency of G119S mutation compared to that previously reported for mosquitoes collected from Beirut in 2005. We also identified a new duplicated ace-1 allele, named ace-1D13, exhibiting a resistant phenotype by associating a susceptible and a resistant copy of ace-1 in a mosquito line sampled from Beirut in 2005. Fisher’s exact test on ace-1 frequencies in the new sample sites, showed that some populations exhibited a significant excess of heterozygotes, suggesting that the duplicated allele is still present. Starch gel electrophoresis indicated that resistance at the Ester locus was mainly attributed to the Ester2 allele, which exhibits a broad geographical distribution.ConclusionsOur analysis suggests that the frequency of resistant ace-1 alleles in mosquito populations can be downshifted, and in certain cases (F290V mutation) even eliminated, by switching to a different class of insecticides, possibly because of the fitness cost associated with these alleles.

The fate and persistence of zineb, maneb, and ethylenethiourea on fresh and processed tomatoes

Tomatoes grown under greenhouse conditions were sprayed with radiolabelled maneb and zineb to determine the extent of degradation of these fungicides to ethylenethiourea (ETU) and to study the persistence of ETU on the fruits. The total (14C) residues decreased from 0.082 mg/kg and 0.11 mg/kg at day 0 to 0.023 mg/ kg and 0.05 mg/kg at day 20, on zineb- and maneb-treated fruits, respectively. This reduction was mainly due to the rapid growth of the fruits. ETU residues on tomato fruits were found to decline with time. A sharp reduction in ETU content was observed during the first 24h after treatment, followed by a slow decline in the following 5 days. ETU content was reduced by about 80% by day 20 after the fungicide application, and the concentration of EU, the major degradation product of ETU, doubled during the same period. Studies with tomatoes fortified with (14C) ETU (0.006 mg/kg) prior to processing into tomato paste showed that 70% of the radioactivity was lost during washing of the tomatoes in water. Further losses of ETU occurred during boiling of the juice (6%) and during storage of the tomato paste for a period of 3 weeks (3%).

Flowerhead-infesting fruit flies (Diptera: Tephritidae) on thistles (Asteraceae), in Lebanon

A survey of flowerhead-infesting tephritids on thistles was conducted in Lebanon during 1995–1998. Twenty thistle species belonging to the Asteraceae yielded 18 species of tephritids. Out of the 18 reared tephritids, 15 are reported for the first time to occur in Lebanon. Seventeen new host species and 11 new host genera for those tephritids are also reported for the first time.

Detection of Leishmania parasites in the blood of patients with isolated cutaneous leishmaniasis

BACKGROUND The consequences of the spread of Leishmania parasites to the blood from lesions in patients with cutaneous leishmaniasis are numerous. To assess the magnitude of this invasion we conducted the present study on patients referred to the American University of Beirut Medical Center for cutaneous leishmaniasis. METHODS Patients referred for the management of cutaneous leishmaniasis were included in the study. Skin and blood cultures for Leishmania were taken from these patients. RESULTS One hundred sixty-two patients were proven to have cutaneous leishmaniasis by pathology; 52% were males and 44% females (gender information was missing for 4%). Patient age ranged from 5 months to 70 years. None of the patients had received treatment for Leishmania. We obtained parasite isolates from 85 patients (52.5%), proven by cultures from skin and blood/blood components. Interestingly, the parasite was isolated in the blood and blood components of 50 patients (30.9%). Isoenzyme analysis confirmed the fact that the organisms in blood and skin were the same; from the 28 isolates that were positive in both skin and blood, eight isolates were Leishmania major and two were Leishmania tropica. The remaining isolates, whether positive in both blood and skin or in either of these tissues, skin or blood and its products, were Leishmania infantum sensu lato. CONCLUSIONS In the current study, the detection rate of parasites in the blood of patients with cutaneous leishmaniasis was high. This illustrates the invasive characteristic of the parasite that has escaped the skin. Testing should be considered in areas other than Lebanon, especially around the Mediterranean basin. Whether these findings support the administration of systemic treatment for cutaneous leishmaniasis or not needs to be confirmed in larger prospective studies.

The epidemiology of leishmaniases in Lebanon.

The prevalence of leishmaniasis in Lebanon was studied in 1993-97 for a Lebanese population sample of about 81,000 subjects (60% rural and 40% urban) constituting roughly 3.4% of the total population. The prevalence of cutaneous leishmaniasis was found to be 0.18% in the rural versus 0.41% in the urban areas. Visceral leishmaniasis was practically non-existent in both environments. In addition, skin tests were done and anti-Leishmania antibodies were sought in a sample of the population at risk in the rural area. Skin tests were positive in 2.5% of the tested subjects, and 1% of the normal population had elevated levels of anti-Leishmania antibodies. The difference between the prevalence of clinical disease and positive skin testing and/or antibodies may be due to the existence of past or present subclinical disease. An unexpected finding was that the prevalent dermotropic parasite in Lebanon belongs to the L. donovani complex. Further characterization of the isolates by molecular techniques and definition of the transmission cycle of this parasite may explain our epidemiological findings.

Terellia fuscicornis (Diptera: Tephritidae): biological and morphological adaptation on artichoke and milk thistle

The biology, morphology, and genetics of Terellia fuscicornis on cultivated artichoke and its new recorded host, Silybum marianum, are examined. Morphometrically, the two host‐associated populations were distinct. Except for egg length, all immature stages of the artichoke‐associated population were larger. Principal component analysis, based on head and wing measurements, showed that the adults from both populations clustered into two groups, with the adults reared from artichoke being larger. The ovipositor was significantly longer and blunter in the artichoke‐associated females, reflecting the larger flower heads exploited. Male terminalia measurements showed significant differences between the two populations. Several differences in courtship behaviour were detected between the two populations. Although the two populations show allochronic isolation, sequencing of two mitochondrial genes, ND1 and COI, and one nuclear gene, 18S, revealed no genetic differences between the two populations.

Host‐race formation in Chaetostomella cylindrica (Diptera: Tephritidae): Morphological and morphometric evidence

Chaetostomella cylindrica is a highly oligophagous tephritid infesting the flower heads of six genera and 10 species of thistles in Lebanon, and is predominant on two hosts in sympatry, Notobasis syriaca and Onopordum illyricum. Adult flies emerging from N. syriaca fit more closely the description of the species with respect to the colour and pattern on the mesonotum. This study compares morphometrically and morphologically the host races associated with N. syriaca and O. illyricum. Immatures of both races were similar, but all stages of the Onopordum‐associated race were significantly larger. Morphometric studies, based on two head and five wing measurements, using canonical discriminant analysis, allowed for the differentiation of the host races with more than 70% accuracy. The aculeus shape and length differed significantly between females of both races. The holotype of Trypeta lurida Loew 1844 was examined and appeared closer to the Onopordum host race. Chaetostomella cylindrica appears to be a complex of cryptic and reproductively isolated species. Present address: Mohammad S. Al‐Zein, Old Dominion University, Norfolk, VA, USA.

Host races in Chaetostomella cylindrica (Diptera: Tephritidae): genetic and behavioural evidence.

The highly oligophagous tephritid Chaetostomella cylindrica infests the flower heads of six genera and ten species of thistles in Lebanon. It predominantly utilizes two hosts occurring in sympatry, Notobasis syriaca and Onopordum illyricum. Previous work showed that adult flies emerging from N. syriaca fit more closely the description of the species, particularly with respect to the colour and pattern on the mesonotum; furthermore, significant differences were observed between the aculeus shape and length. This study investigates the biology of the immatures and compares adults from the two host races behaviourally and genetically. Larvae of both races fed in a similar way, with each larva destroying 3-10 achenes; however, the oviposition behaviour of females differed. Females of the Onopordum-associated flies laid an average of three eggs per head, and deposited the eggs glued to each others in a cluster, while females of the Notobasis-associated flies deposited their eggs unattached, usually with one egg per head. Subtle differences were also observed in the post-mating behaviour of adult males. DNA sequencing of an amplified fragment of the mitochondrial NADH-dehydrogenase subunit 1 gene revealed 44 single nucleotide polymorphisms in 622 base pairs. A PCR-RFLP method was developed to distinguish the two host-associated populations. Together with previously published morphometric studies, our data show that C. cylindrica consists of distinct host races, which seem to be reproductively isolated as two separate genetic lineages were observed.

Mulch Type Effects on Strawberries Grown in a Mild Winter Climate

Abstract The influence of several types of plastic mulches in enhancing earliness, maximizing production, and reducing insect infestation of strawberries grown in a tunnel greenhouse in a mild Mediterranean climate was evaluated in two growing seasons. In 1996-1997, yield of ‘Oso Grande’ during the first three weeks of harvest was the highest on the black on white mulch (B/W), followed by black (B) white (W), and clear (C). Total yield was comparable among all mulches. Mite infestation (mites being the main pest of strawberries in the region), and the heaviest weed growth occurred under C, resulting in weaker plants. In 1998-1999, yield of ‘Camaros’a was consistently higher on reflective mulch (R) in comparison to C, B, and green (G). We observed a high degree of resistance to mite infestation in ‘Camaros’a, where mites appeared only during the last week of harvest. The R mulch had the lowest count of mites, thrips, aphids and whiteflies at all sampling dates. The highest counts of those pests were on C mulch. We recommend the R mulch, for its enhancement of yield, reduced insect and mite infestation, and weed control properties in a mild winter-spring growing climate.

Atypical Systemic Leishmaniasis to Be Considered in the Differential of Patients Presenting with Depressed Immunity

Background Systemic leishmaniasis has been known to present with prolonged fever, hepatosplenomegaly and wasting. Beside this classical form, a sub-clinical form has been identified. It is described with either one or two of the above symptoms missing; other findings have been reported instead, such as lymphadenopathy and anemia. In this report, we reveal a third unsuspected form which we are referring to as “atypical”. Methodology/Principal Findings Patients suspected to be immune-deficient were referred to our immunology specialized laboratory to study some aspects of their immune functions (not normally covered in the general laboratory). Multiple specialized tests were performed, including microscopic examinations using appropriate stains, and mainly cultures of biopsies on several types of specialized media. 19·4% of 160 patients were found to have close to normal laboratory profiles, but exhibited dysfunctional macrophages laden with Leishmania parasites. Conclusions/Significance Findings such as the ones we obtained allowed us to uncover the presence of patients with an atypical form of systemic leishmaniasis. It presents with symptoms masquarading a condition in which the immune system is non functional. This predisposes patients to recurrent secondary infections resulting in clinical pictures with a great variety of signs and symptoms. These findings alerted us to the fact that systemic leishmaniasis presents with a much wider spectrum of signs and symptoms than so far suspected and is far more common than diagnosed to date. Furthermore, among these 31 patients was a number of adults. This proved that in our area systemic leishmaniasis is surely not limited to the pediatric age group. Our recommendation is to entertain the diagnosis of atypical systemic leishmaniasis in any patient with an unexplained depressed immunity state and in whom no obvious immunologic defect can be identified.