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Cayabyab B.F.,University of the Philippines at Los Banos | Alcantara E.P.,University of the Philippines at Los Banos | Sumalde A.C.,University of the Philippines at Los Banos | Gonzales P.G.,University of the Philippines at Los Banos | And 5 more authors.
Journal of the International Society for Southeast Asian Agricultural Sciences | Year: 2015

Ostrinia furnacalis Guenee commonly known as Asian Corn Borer (ACB) is the major pest of corn in the Philippines. This study attempted to determine the frequency of Cry1Ab resistance alleles in ACB that will serve as quantitative baseline data for monitoring ACB resistance in Bt corn in the Philippines. The initial frequency of Cry1Ab resistance alleles in ACB collected from corn farms in Lubao, Pampanga, Philippines was studied using the F2 screen method from March 2006 to December 2008. A total of 2,606 females of ACB were used to establish 800 isofemale lines. From these isofemale lines, 37,702 larvae from the F2 screen were susceptible to the toxin, Cry1Ab protein. The mortality rate for all the isofemale lines peaked during the first seven days of exposure to Cry1Ab. Two hundred fifty three (253) isofemale lines or 10% were observed to be partially positive to the toxin wherein four (4) isofemale lines (15, 19, 116, and 121) have survivors and successfully reached adult stage. However, due to the low survival of ACB larvae of each isolines, unsynchronized adult emergence and high percentage of male moth emergence, the re-testing of resistance to the isofemale lines were unsuccessful. Furthermore, an equal number of ACB larvae (37,702) were used for the control. A total of one thousand twenty seven (1,027) or 2.88% mortality was observed. This small percentage mortality from the control can be attributed to mechanical injury from handling. The calculated frequency of resistance alleles (E [pR]) was 3.12×10-4. This shows that the resistance allele is rare. © 2015 International Society for Southeast Asian Agricultural Sciences. All rights reserved.

Cumagun C.J.R.,University of the Philippines at Los Banos | Aguirre J.A.,Bureau of Plant Industry | Relevante C.A.,East West Seed Company | Balatero C.H.,East West Seed Company
Plant Protection Science | Year: 2010

Fusarium oxysporum is responsible for a large range of diseases on economically important crops such as bitter gourd and bottle gourd. Pathogenicity and aggressiveness of F. oxysporum in bitter gourd and bottle gourd isolated from two breeding stations of East-West Company in the Philippines namely San Ildefonso, Bulacan and Lipa, Batangas were tested. Eleven F. oxysporum isolates from bitter gourd and 12 isolates from bottle gourd were inoculated on 7-day and 1-month-old bitter gourd and bottle gourd plants in the greenhouse. All F. oxysporum isolates from bitter gourd were pathogenic on 7-day-old and 1-month-old bitter gourd and nine out of 12 isolates from bottle gourd were pathogenic on bottle gourd. Three isolates from the infested soil were non-pathogenic on bottle gourd. There was a significant difference in aggressiveness of the isolates on their natural hosts (P ≤ 0.05). There also was a significant difference in the aggressiveness of isolates pathogenic on bitter gourd from Batangas and Bulacan (P ≤ 0.05) but isolates from Batangas and Bulacan had similar aggressiveness as bottle gourd (P ≥ 0.05). Aggressiveness of F. oxysporum on 7-day-old bitter gourd and bottle gourd was significantly different compared to those on 1-month-old plants, demonstrating an effect of the host age onaggressiveness. Correlations between aggressiveness of F. oxysporum isolates on 7-day-old and 1-month-old bitter gourd and bottle gourd were moderate (r = 0.63, 0.78). Out of 12 isolates from bottle gourd, only one isolate was pathogenic on 7-day-old bitter gourd. Four of the isolates from bitter gourd were pathogenic on 7-day-old bottle gourd but not on 1-month-old bottle gourd. No cross infection was observed on mature plants.

Van Engelsdorp D.,Bureau of Plant Industry | Van Engelsdorp D.,Pennsylvania State University | Speybroeck N.,Institute of Tropical Medicine | Speybroeck N.,Catholic University of Louvain | And 11 more authors.
Journal of Economic Entomology | Year: 2010

Colony collapse disorder (CCD), a syndrome whose defining trait is the rapid loss of adult worker honey bees, Apis mellifera L., is thought to be responsible for a minority of the large overwintering losses experienced by U.S. beekeepers since the winter 2006-2007. Using the same data set developed to perform a monofactorial analysis (PloS ONE 4: e6481, 2009), we conducted a classification and regression tree (CART) analysis in an attempt to better understand the relative importance and interrelations among different risk variables in explaining CCD. Fifty-five exploratory variables were used to construct two CART models: one model with and one model without a cost of misclassifying a CCD-diagnosed colony as a non-CCD colony. The resulting model tree that permitted for misclassification had a sensitivity and specificity of 85 and 74%, respectively. Although factors measuring colony stress (e.g., adult bee physiological measures, such as fluctuating asymmetry or mass of head) were important discriminating values, six of the 19 variables having the greatest discriminatory value were pesticide levels in different hive matrices. Notably, coumaphos levels in brood (a miticide commonly used by beekeepers) had the highest discriminatory value and were highest in control (healthy) colonies. Our CART analysis provides evidence that CCD is probably the result of several factors acting in concert, making afflicted colonies more susceptible to disease. This analysis highlights several areas that warrant further attention, including the effect of sublethal pesticide exposure on pathogen prevalence and the role of variability in bee tolerance to pesticides on colony survivorship. © 2010 Entomological Society of America.

Herradura L.H.,Bureau of Plant Industry | Lobres M.A.N.,Bureau of Plant Industry | Davide R.G.,University of the Philippines at Los Banos | De Waele D.,Catholic University of Leuven | And 2 more authors.
Archives of Phytopathology and Plant Protection | Year: 2013

The in vitro reproductive fitness on carrot discs and the in vivo pathogenicity on selected FHIA (Fundación Hondureña de Investigaciónes Agrícola) banana hybrids of a population of Radopholus similis isolated from banana in Davao, Philippines, were investigated at the Bureau of Plant Industry, Davao City, Philippines. It was shown that on carrot discs following inoculation with 25 females, the Davao population had the highest population density and multiplication rate compared with two other R. similis populations from the Philippines (Los Baños and Quezon) and two exotic populations of R. similis (from Uganda and Indonesia). According to the Gompertz model, the Davao population also had a short lag phase and a high maximum specific growth. Following inoculation with one single female, the Davao population also had the highest multiplication rate and the highest proportion of juveniles and females compared with the other four populations included in the experiments. Nine weeks after inoculation with 1000 vermiforms, the R. similis population from Davao had reduced the plant height of the FHIA hybrids included in the experiment (FHIA-3, FHIA-4, FHIA-5, FHIA-18 and FHIA-23) on average by 37%, plant girth by 5.3-40.9%, shoot weight by 20.1-65.8% and root weight by 31.7-69.7%, indicating the high pathogenicity of this population on banana. FHIA-4 was tolerant to R. similis infection. © 2013 Copyright Taylor and Francis Group, LLC.

Gergerich R.C.,University of Arkansas | Welliver R.A.,Bureau of Plant Industry | Gettys S.,Bureau of Plant Industry | Osterbauer N.K.,Plant Health Program | And 7 more authors.
Plant Disease | Year: 2015

The expansion of fruit production and markets into new geographic areas provides novel opportunities and challenges for the agricultural and marketing industries. Evidence that fruit consumption helps prevent nutrient deficiencies and reduces the risk of cardiovascular disease and cancer has assisted in the expansion of all aspects of the fruit industry. In today's competitive global market environment, producers need access to the best plant material available in terms of genetics and health if they are to maintain a competitive advantage in the market. An ever-increasing amount of plant material in the form of produce, nursery plants, and breeding stock moves vast distances, and this has resulted in an increased risk of pest and disease introductions into new areas. One of the primary concerns of the global fruit industry is a group of systemic pathogens for which there are no effective remedies once plants are infected. These pathogens and diseases require expensive management and control procedures at nurseries and by producers locally and nationally. Here, we review (i) the characteristics of some of these pathogens, (ii) the history and economic consequences of some notable disease epidemics caused by these pathogens, (iii) the changes in agricultural trade that have exacerbated the risk of pathogen introduction, (iv) the path to production of healthy plants through the U.S. National Clean Plant Network and state certification programs, (v) the economic value of clean stock to nurseries and fruit growers in the United States, and (vi) current efforts to develop and harmonize effective nursery certification programs within the United States as well as with global trading partners. © 2015 The American Phytopathological Society.

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