Developing Citrus Huanglongbing (HLB) Management Strategies Based on the Severity of Symptoms in HLB-Endemic Citrus-Producing Regions.

Citrus Huanglongbing (HLB), also known as greening, is a destructive disease caused by the fastidious, phloem-colonizing bacteria Candidatus Liberibacter spp.; 'Ca. Liberibacter asiaticus' (Las) is the most prevalent of the species causing HLB. The Asian citrus psyllid (ACP, Diaphorina citri) transmits Las. HLB is threatening citrus production worldwide, and there is no cure for infected trees. Management strategies targeting diseased trees at different stages of colonization by Las are needed for sustainable citrus production in HLB-endemic regions. We evaluated the effect of the combinations of plant defense elicitors, nitrogen (N) fertilizer, and compost on mildly diseased trees. We tested thermotherapy on severely diseased trees and assessed tree protectors to prevent feeding by ACP, thus preventing Las from being transmitted to new plantings that replaced HLB-moribund trees. After four applications over two consecutive growing seasons we found that the combination of compost, urea, and plant defense elicitors ß-aminobutyric acid, plus ascorbic acid and potassium phosphite with or without salicylic acid, slowed down the progression of HLB and reduced disease severity by approximately 18%, compared with the untreated control. Our data showed no decline in fruit yield, indeed treatment resulted in a higher yield compared with the untreated control. Thermotherapy treatment (55°C for 2 min) exhibited a suppressive effect on growth of Las and progress of HLB in severely diseased trees for 2 to 3 months after treatment. The tree protectors prevented feeding by ACP, and therefore young replant trees remained healthy and free from infection by Las over the 2-year duration of the experiment. Taken together, these results may contribute to a basis for developing a targeted approach to control HLB based on stage of host colonization, application of plant defense elicitors, N fertilizer, compost, thermotherapy, and tree protectors. There is potential to implement these strategies in conjunction with other disease control measures to contribute to sustainable citrus production in HLB-endemic regions.

Efficacy of a new self-supporting low-profile bednet for personal protection against Anopheles farauti (Diptera: Culicidae) in a village in Papua New Guinea.

A new United States (U.S.) self-supporting low-profile bednet was designed by Walter Reed Army Institute of Research in collaboration with Breakthrough Technologies. The bednet incorporated permethrin-impregnated screening into a frame that erected automatically when removed from its bag. The new U.S. bednet was compared with the current Australian Defense Force (ADF) mosquito bednet at Buka Island, North Solomons Province, Papua New Guinea, in March 1999. At the time of the test, Anopheles farauti Laveran was the most abundant biting mosquito. Both bednet types provided >97.8% protection compared with an unprotected collector. The untreated U.S. Army prototype bednet provided better protection than the untreated ADF bednet against mosquitoes entering the bednet during the night.

Malaria control in central Malaita, Solomon Islands. 1. The use of insecticide-impregnated bed nets.

The present study investigated the use of insecticide-impregnated bed nets by communities in central Malaita, Solomon Islands. Qualitative and quantitative data were collected by: (1) questionnaire administration to 124 care-givers of children aged 0-10 years of age; (2) 20 focus group discussions; (3) two structured observations of bed net re-impregnation, and (4) interviews with key informants. Ninety-four percent of all care-givers had bed nets, but only 62% had sufficient bed nets for all household members. Fifty-two percent used bed nets throughout the year and 70% of care-givers reported that all their children slept under bed nets. Although coastal householders considered malaria and mosquitoes more of a problem than inland householders, overall bed net compliance did not differ. Factors affecting bed net ownership were cost and community expectation of free bed nets. Bed net use was affected by four factors: (1) seasonality (99% used bed nets during the rainy season, 52% used them all year); (2) mosquito nuisance (59% of respondents reported that protection against mosquitoes was the main reason for using a bed net); (3) weather (68% of care-givers would not use a bed net if the weather was hot), and (4) low density of mosquitoes (respondents who used bed nets as protection against mosquito nuisance were more likely not to use bed nets when mosquitoes were few than those who used bed nets for malaria protection (odds ratio (OR), 3.9; 95% confidence interval (CI), 1.4-12.0). Protection against malaria was the main reason children slept under bed nets. Children from households where bed nets were used for malaria protection were more likely to sleep under bed nets than children from households where nets were used as protection from mosquitoes only (OR, 2.7; 95% CI, 1.3-5.9). Other factors that affected children's bed net use were, age (users were significantly younger than non-users; chi(2)=7.9, degrees of freedom=1, P=0.005) and sufficiency of bed nets (OR, 2.0; 95% CI, 1. 3-7.0).

Estudo sobre o uso de mosquiteiros impregnados com deltametrina em uma área endêmica de malária na Amazônia brasileira / Use of deltametrine impregnated mosquito nets in an endemic malaria region in the brazilian Amazon

Uma investigaçäo sobre mosquiteiros com deltametrina foi efetuada no município de Costa Marques, Rondônia. Em um grupo de 20 moradias na localidade de Porto Murtinho, situada à margem direira do Rio Säo Miguel, foram instalados, mosquiteiros näo impregnados. Um grupo controle de 20 residências, sem usar mosquiteiros de qualquer tipo, foi escolhido na localidade de Aguas Francas, às margens da BR-429, que loga Costa Marques a Presidente Medici, Rondônia. Os mosquiteiros fechados, de pano de algodäo, foram impregnados, com deltametrina, na dosagem de 20 mg/m2. Após distribuidos os mosquiteiros em fevereiro de 1992, foram feitas revisöes clínicas, parasitológicas e entomológicas, a cada dois meses até fevereiro de 1992, foram feitas revisöes clínicas, parasitológicas e entomológicas, a cada dois meses, até fevereiro de 1993...