Temperature Dependence for Survival, Development, and Reproduction of the Cactus Cochineal Dactylopius opuntiae (Cockerell).

The effect of temperature on Dactylopius opuntiae (Cockerell) life cycle parameters was evaluated at 20, 23, 26, 32, and 40 ± 1 °C, 65 ± 5% RH, and a photoperiod of 12 L:8 D. Temperatures ranging from 26 °C to 32 °C were suitable for survival, development, and reproduction of D. opuntiae. The total developmental time of females ranged from 94.23 d (20 °C) to 43.55 d (40 °C). The average development time of males from egg to death ranged from 26.97 days at 32 °C to 50.75 days at 20 °C. The probability that a newly laid egg would survive to the adult stage was highest at 26 °C and 32 °C (44-60%). The parthenogenesis in females was not observed during our study. The longest oviposition period was observed when the cochineal was reared at 32 °C (17.97 days), and the highest fecundity was observed at 32 °C (355.29 egg/female). The highest proportion of females (0.80) was observed at 40 °C. According to the age-stage-two-sex life table, the highest value of the intrinsic rate of natural increase (rm) was recorded at 32 °C. The lower developmental thresholds for the total pre-adult female and male and adult female and male stages, were 10.15, 12.21, 10.54, and 21.04 °C, respectively. Dactylopius opuntiae females needed a higher thermal constant (769.23 D°) than males (357.14 D°) to achieve their development and reach the mature adult stage. These findings will be useful for the development of an integrated pest management strategy for D. opuntiae.

Moroccan entomopathogenic nematodes as potential biocontrol agents against Dactylopius opuntiae (Hemiptera: Dactylopiidae).

Dactylopius opuntiae (Cockerell) (Hemiptera: Dactylopiidae) or prickly pear cochineal, is the most damaging pest on cactus species with heavy economic losses worldwide. The efficacy of two Moroccan EPN isolates; Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae) and Heterorhabditis bacteriophora (Poinar) (Rhabditida: Heterorhabditidae) (applied at 25, 50, and 75 IJs cm-2) against D. opuntiae nymphs and young females were evaluated under both laboratory bioassays and field conditions. Results showed that S. feltiae was more effective, causing higher mortality of nymphs and adult females (98.8% and 97.5%, respectively) after 8 days of exposure, resulting in an LT50 value of 5.9 days (nymph) and 6.0 days (young female). While, H. bacteriophora had lower mortalities (83.8% for nymph and 81.3% for adult females). For the cochineal nymphs and adult females, no significant difference was observed among S. feltiae at 25, 50, and 75 IJs cm-2, and the positive control, D-limonene applied at 0.5 g/L which was used due to its high effectiveness against nymphs and females of D. opuntiae. In the field experiment, D-limonene at 0.5 g/L and S. feltiae applied at 75 IJs cm-2 were effective in reducing nymph and adult female populations by 85.3-93.9% at 12 days of post exposure period. To our knowledge, this work is the first report on the use of EPNs to control D. opuntiae. Thus, in addition to D-limonene, both Moroccan EPN isolates S. feltiae, and H. bacteriophora could be used as part of the integrated pest management strategy against D. opuntiae. Many factors such as temperature can affect the establishment and effectiveness of EPNs under field conditions. Therefore, additional studies under field conditions are needed.

Chemical Composition and Insecticidal Potential of Six Essential Oils from Morocco against Dactylopius opuntiae (Cockerell) under Field and Laboratory Conditions.

The carmine cochineal Dactylopius opuntiae (Cockerell) is the major insect pest of the prickly-pear cactus Opuntia ficus-indica (L.) in Morocco. The present study investigated the insecticidal activities of six essential oils (EOs) against nymphs and adult females of D. opuntiae applied singly or in combination with a detergent under laboratory and field conditions. Under laboratory conditions, M. pulegium and O. vulgare L. essential oils showed a high level of insecticidal activity at 5%, with 98% and 92% females' mortality, respectively, 5 days after treatments. The M. pulegium and O. vulgaris oils at 5% applied in combination with black soap at (60 g/L) induced the highest toxic activity on adult females, 100% and 96% at 5 days after treatments, respectively. Under field conditions, M. pulegium and O. vulgare oils at 5% in combination with black soap (60 g/L) showed the highest adult female mortalities with 96.33 and 92.56%, respectively, 7 days after the first application. The double application of M. pulegium oil at 5% significantly increased the mortality of adult females up to 91%, 5 days after the second spray. GC-MS analysis revealed that the most abundant constituent of M. pulegium and O. vulgare oils was pulegone (84.69%) and durenol (76.53%), respectively. These findings showed that the use of M. pulegium and O. vulgare in combination with black soap or in double sprays could be incorporated in the management package for the control of the wild cochineal D. opuntiae, as a safe and natural alternative to chemical insecticides.

Potential of Moroccan entomopathogenic nematodes for the control of the Mediterranean fruit fly Ceratitis capitata Wiedemann (Diptera: Tephritidae).

The Mediterranean fruit fly, Ceratitis capitata Wiedemann, is a deleterious pest worldwide affecting fruit production. The entomopathogenic nematodes (EPNs) are a potential biocontrol agent that could be effectively used to control this Mediterranean fruit fly. In this study, five EPN strains reported from different fields in Morocco were evaluated for their efficacy against C. capitata. In laboratory assays, Steinernema feltiae-SF-MOR9, S. feltiae-SF-MOR10 and Heterorhabditis bacteriophora-HB-MOR7 strains showed significantly higher infectivity and penetration rates when compared to the other strains. S. feltiae-SF-MOR9 caused the highest larval mortality rate (80%) at 50 infective juveniles (IJs) cm-2. However, additional results showed that both S. feltiae strains were significantly effective in controlling C. capitata larvae in apricot (Prunus armeniaca) fruits on soil surface with high mortality rate at 50 and 100 IJs cm-2. Different soil textures and moisture levels resulted in a significant variation in EPN strain virulence against C. capitata. Sandy clay loam soil in combination with 50 IJs cm-2 of S. feltiae (SF-MOR9 or SF-MOR10) caused a higher mortality rate of C. capitata larvae. Furthermore, applying these EPN strains at 50-100 IJs cm-2 in combination with 10-15% moisture level showed optimal results against C. capitata larvae. Therefore, those two Moroccan EPN strains could be used as promising eco-friendly biological agents against C. capitata.

Occurrence of the Root-Knot Nematode species in Vegetable Crops in Souss Region of Morocco.

Root-knot nematodes 'Meloidogyne spp' are the most destructive group of plant parasitic nematodes causeing serious losses in vegetables crops and this damages worsened when crops grown under greenhouses conditions. In this sutdy, the distribution and characterization of root-knot nematode species collected from the Souss region of Morocco where vegetables crops intensively cultivated were determined by using both morphological and molecular tools. Out of the 110 samples collected from different greenhouses 91 (81.7%) were found to be infested with root-knot nematodes. Thirty-seven populations of root-knot nematodes were morphologically identified based on perineal patterns as well as molecularlly using species-specific primers. The obtained results indicated that Meloidogyne javanica and M. incognita were identified in 86.4% and 13.5% of the total populations, respectively. The lowest incidence of root-knot nematodes (64%) was found in Toussous, whereas the highest frequencies of 100% and 90% were detected in Taddart and Biogra, respectively. As the majority of the samples have been infested with Meloidogyne species; this indicates that there is an urgent need to provide farmers with a proper control strategy.

Phytoalexins from the Vitaceae: biosynthesis, phytoalexin gene expression in transgenic plants, antifungal activity, and metabolism.

Resistance of plants to infection by phytopathogenic microorganisms is the result of multiple defense reactions comprising both constitutive and inducible barriers. In grapevine, the most frequently observed and best characterized defense mechanisms are the accumulation of phytoalexins and the synthesis of PR-proteins. Particular attention has been given here to stilbene phytoalexins produced by Vitaceae, specifically, their pathway of biosynthesis (including stilbene phytoalexin gene transfer experiments to other plants) and their biological activity together with fungal metabolism.

On the origin and spread of the Scab disease of apple: out of central Asia.

BACKGROUND: Venturia inaequalis is an ascomycete fungus responsible for apple scab, a disease that has invaded almost all apple growing regions worldwide, with the corresponding adverse effects on apple production. Monitoring and predicting the effectiveness of intervention strategies require knowledge of the origin, introduction pathways, and population biology of pathogen populations. Analysis of the variation of genetic markers using the inferential framework of population genetics offers the potential to retrieve this information. METHODOLOGY/PRINCIPAL FINDINGS: Here, we present a population genetic analysis of microsatellite variation in 1,273 strains of V. inaequalis representing 28 orchard samples from seven regions in five continents. Analysis of molecular variance revealed that most of the variation (88%) was distributed within localities, which is consistent with extensive historical migrations of the fungus among and within regions. Despite this shallow population structure, clustering analyses partitioned the data set into separate groups corresponding roughly to geography, indicating that each region hosts a distinct population of the fungus. Comparison of the levels of variability among populations, along with coalescent analyses of migration models and estimates of genetic distances, was consistent with a scenario in which the fungus emerged in Central Asia, where apple was domesticated, before its introduction into Europe and, more recently, into other continents with the expansion of apple growing. Across the novel range, levels of variability pointed to multiple introductions and all populations displayed signatures of significant post-introduction increases in population size. Most populations exhibited high genotypic diversity and random association of alleles across loci, indicating recombination both in native and introduced areas. CONCLUSIONS/SIGNIFICANCE: Venturia inaequalis is a model of invasive phytopathogenic fungus that has now reached the ultimate stage of the invasion process with a broad geographic distribution and well-established populations displaying high genetic variability, regular sexual reproduction, and demographic expansion.