Citrus tristeza virus (CTV) (genus Closterovirus) is a plant pathogen which infects economically ... more Citrus tristeza virus (CTV) (genus Closterovirus) is a plant pathogen which infects economically important citrus crops such as sweet oranges, mandarins, limes and grapefruit varietals. Within the last 70 years, an estimated 100 million citrus trees have been destroyed due to CTV infection worldwide. Present measures to contain CTV infection include scouts for visual assessment, and molecular analysis methods such as enzyme linked immunosorbent assay and reverse transcription polymerase chain reaction. Volatile organic compound (VOC) profiling may offer an alternative method of disease detection. In this study, we used a ''Twister TM '' sorbent system for infield VOC sampling. Chemical analysis was performed with thermal desorption gas chromatography time-of-flight mass spectrometry, and data were subjected to unsupervised and supervised analysis. Samples were collected from healthy trees, those with asymptomatic CTV, and those with CTV that were coinfected with a secondary unrelated bacterial infection of Spiroplasma citri, the causal agent of citrus stubborn disease (Stubborn). A total of 383 VOCs were detected across three classes: healthy control trees, CTV infected, and CTV coinfected with Stubborn. Mathematical models of this data were built to successfully differentiate: (a) healthy trees from CTV infected trees; (b) healthy trees from both CTV and CTV coinfected with Stubborn; and (c) to effectively differentiate between healthy trees and CTV infected trees, without consideration of Stubborn coinfection (the model would work on both singly or coinfected trees). The putative CTV biomarkers observed were terpenoid based (myrcene, carene, ocimene, bulnesene), two alcohols (n-undecanol, surfynol) and two acetones (geranyl acetone and neryl acetate).
Biology and parasitism rates of Pteromalus nr. myopitae (Hymenoptera: Pteromalidae), a newly disc... more Biology and parasitism rates of Pteromalus nr. myopitae (Hymenoptera: Pteromalidae), a newly discovered parasitoid of olive fruit fly Bactrocera oleae (Diptera: Tephritidae) in coastal California a b s t r a c t An undescribed wasp, Pteromalus nr. myopitae (Hymenoptera: Pteromalidae) opportunistically parasitizes the olive fruit fly Bactrocera oleae (Rossi) (Diptera: Tephritidae), an introduced pest of olives in California. The native or typical host of P. nr. myopitae is unknown. We demonstrate that P. nr. myopitae is a solitary, ectoparasitic, idiobiont parasitoid of the third instar host inside fruit, and pupation occurs in the host tunnel. Reproduction of P. nr. myopitae on B. oleae in olives in the laboratory and in field cages generally failed. Host-feeding was not observed, and adults fed honey and water lived longer than those provided with water alone. Parasitism in non-commercial olives in the moderate coastal climate of San Luis Obispo occurred primarily from August to October, and was absent from a nearby location with more extreme climate and a low population of B. oleae. Greater parasitoid numbers were associated with greater host densities, and proportion of hosts parasitized was generally higher at lower host densities during 2 years of the study. The geographic range of the parasitoid extends along the coast from San Francisco Bay to Ensenada, Baja California, Mexico, and also inland in the Sacramento Valley, with one record in the San Joaquin Valley. The potential of the parasitoid as a biological control agent of B. oleae is probably low, however, the extent of its interference with other parasitoids being considered for release in California is unknown and warrants further study.
Citrus tristeza virus (CTV) (genus Closterovirus) is a plant pathogen which infects economically ... more Citrus tristeza virus (CTV) (genus Closterovirus) is a plant pathogen which infects economically important citrus crops such as sweet oranges, mandarins, limes and grapefruit varietals. Within the last 70 years, an estimated 100 million citrus trees have been destroyed due to CTV infection worldwide. Present measures to contain CTV infection include scouts for visual assessment, and molecular analysis methods such as enzyme linked immunosorbent assay and reverse transcription polymerase chain reaction. Volatile organic compound (VOC) profiling may offer an alternative method of disease detection. In this study, we used a ''Twister TM '' sorbent system for infield VOC sampling. Chemical analysis was performed with thermal desorption gas chromatography time-of-flight mass spectrometry, and data were subjected to unsupervised and supervised analysis. Samples were collected from healthy trees, those with asymptomatic CTV, and those with CTV that were coinfected with a secondary unrelated bacterial infection of Spiroplasma citri, the causal agent of citrus stubborn disease (Stubborn). A total of 383 VOCs were detected across three classes: healthy control trees, CTV infected, and CTV coinfected with Stubborn. Mathematical models of this data were built to successfully differentiate: (a) healthy trees from CTV infected trees; (b) healthy trees from both CTV and CTV coinfected with Stubborn; and (c) to effectively differentiate between healthy trees and CTV infected trees, without consideration of Stubborn coinfection (the model would work on both singly or coinfected trees). The putative CTV biomarkers observed were terpenoid based (myrcene, carene, ocimene, bulnesene), two alcohols (n-undecanol, surfynol) and two acetones (geranyl acetone and neryl acetate).
Biology and parasitism rates of Pteromalus nr. myopitae (Hymenoptera: Pteromalidae), a newly disc... more Biology and parasitism rates of Pteromalus nr. myopitae (Hymenoptera: Pteromalidae), a newly discovered parasitoid of olive fruit fly Bactrocera oleae (Diptera: Tephritidae) in coastal California a b s t r a c t An undescribed wasp, Pteromalus nr. myopitae (Hymenoptera: Pteromalidae) opportunistically parasitizes the olive fruit fly Bactrocera oleae (Rossi) (Diptera: Tephritidae), an introduced pest of olives in California. The native or typical host of P. nr. myopitae is unknown. We demonstrate that P. nr. myopitae is a solitary, ectoparasitic, idiobiont parasitoid of the third instar host inside fruit, and pupation occurs in the host tunnel. Reproduction of P. nr. myopitae on B. oleae in olives in the laboratory and in field cages generally failed. Host-feeding was not observed, and adults fed honey and water lived longer than those provided with water alone. Parasitism in non-commercial olives in the moderate coastal climate of San Luis Obispo occurred primarily from August to October, and was absent from a nearby location with more extreme climate and a low population of B. oleae. Greater parasitoid numbers were associated with greater host densities, and proportion of hosts parasitized was generally higher at lower host densities during 2 years of the study. The geographic range of the parasitoid extends along the coast from San Francisco Bay to Ensenada, Baja California, Mexico, and also inland in the Sacramento Valley, with one record in the San Joaquin Valley. The potential of the parasitoid as a biological control agent of B. oleae is probably low, however, the extent of its interference with other parasitoids being considered for release in California is unknown and warrants further study.
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Papers by Therese Kapaun