633 research outputs found
Comparative radial growth of Pinus halepensis Mill. and Pinus brutia in Israël
Comparaison de la croissance en diamètre dans un peuplement mixte de pin d'Alep et de pin Brutia dans huit régions d'Israël
Kairomonal response of the parasitoid Anagyrus spec. nov. near pseudococci to the sex pheromone of the vine mealybug
The occurrence of a kairomonal response of the parasitoid
Anagyrus
spec. nov. near
pseudococci
(Hymenoptera: Encyrtidae) to (+)-(1
R,
3
R
)-
cis
-2,2-dimethyl-3-isopropenyl-cyclobutanemethanol
acetate (PcA, namely, planococcyl acetate) and (
S
)-(+)-lavandulyl senecioate (LS), the respective
female sex pheromones of its hosts, the citrus mealybug,
Planococcus citri
(Risso) and the vine mealybug,
Planococcus ficus
(Signoret) (Homoptera: Pseudococcidae) was investigated. Attraction to the
pheromones was tested by employing pheromone traps in field trials and by static air olfactometer
bioassays in the laboratory. Female wasps showed a significant response to LS, in both field and
olfactometer experiments. No significant response was registered to the sex pheromone of
P. citri.
Despite the similarity between the structures of LS and its analogue (
S
)
-
(+)-lavandulyl isovalerate
(LI), no significant response to the latter compound was observed. It seems that differences between
the structures of the carboxylate moiety of the respective molecules (LS and LI) markedly affect the
kairomonal attractiveness to the parasitoid. The kairomonal response of
Anagyrus
spec. nov. near
pseudococci
was neither influenced by the host habitat nor by the host species on which it developed. This suggested
innate behaviour of
Anagyrus
spec. nov. near
pseudococci
, possibly derived from evolutionary relationships
between the parasitoid and
P. ficus
. The practical implications of the results are discussed
Attraction of Planococcus ficus males to racemic and chiral pheromone baits: flight activity and bait longevity
The vine mealybug (VM), Planococcus ficus (Signoret), is a worldwide pest
and affects mainly grapevine and figs. In Israel, (S)-lavandulyl senecioate
[(S)-LS] and (S)-lavandulyl isovalerate [(S)-LI] were identified from
VM reared for several generations on potato sprouts, when compared
with the identification of only (S)-LS from feral females. Racemic lavandulyl
senecioate (LS) can be used for fieldwork because the unnatural
enantiomer is benign and does not affect the activity of the pheromone.
Lures loaded with 200 lg of LS remained active for 24 weeks but it is
recommended to replace lures after 12 weeks to preserve constant and
high attractiveness. Delta sticky traps, baited with 50 or 200 lg of LS
were used to determine the daily flight pattern and the seasonal flight
activity including vine plant infestation. A positive correlation between
peak mealybug density and male capture was observed strengthening
the usefulness of the pheromone traps for monitoring the pest. Addition
of racemic or the two enantiomers of lavandulyl isovalerate (LI) to LS
decreased the capture of VM males. The level of inhibition varied during
2003–2004. Both enantiomers of LI displayed the same antagonistic
activity. Addition of (S)-lavandulol to the pheromone resulted in shutdown
of the traps. Inhibition by the antipode, (R)-lavandulol, was moderate
indicating a certain degree of chiral discriminatio
Probable overwintering of adult Hyalomma rufipes in Central Europe
Hyalomma spp. ticks (Acari: Ixodidae) represent a public health threat because of their prominent role in the transmission of Crimean- Congo haemorrhagic fever (CCHF) virus. Moreover, these ticks can transmit other medically important arboviruses such as Thogoto, Dhori, West Nile, and Bhanja viruses; human pathogenic bacteria like Rickettsia conorii, R. aeschlimannii, and Anaplasma marginale; and protozoans like Theileria annulata and Babesia caballi (Huba ´lek and Rudolf, 2011). Many records of larval and nymphal H. marginatum ticks on birds migrating from North Africa and Southern Europe into Central and Northern Europe have been published
Type-2 fuzzy linear systems
Fuzzy Linear Systems (FLSs) are used in practical situations where some of the systems parameters or variables are uncertain. To date, investigations conducted on FLSs are restricted to those in which the uncertainty is assumed to be modeled by Type-1 Fuzzy Sets (T1FSs). However, there are many situations where considering the uncertainty as T1FSs may not be possible due to different interpretations of experts about the uncertainty. Moreover, solutions of FLSs are T1FSs which do not provide any information about a measure of the dispersion of uncertainty around the T1FSs. Therefore, in this research a model of uncertain linear equations system called a type-2 fuzzy linear system is presented to overcome the shortcomings. The uncertainty is represented by a special class of type-2 fuzzy sets – triangular perfect quasi type-2 fuzzy numbers. Additionally, conditions for the existence of a unique type–2 fuzzy solution to the linear system are derived. A definition of a type-2 fuzzy solution is also given. The applicability of the proposed model is illustrated using examples in the pulp and paper industry, and electrical engineering
Decay constants and mixing parameters in a relativistic model for q\barQ system
We extend our recent work, in which the Dirac equation with a
``(asymptotically free) Coulomb + (Lorentz scalar ) linear ''
potential is used to obtain the light quark wavefunction for mesons
in the limit , to estimate the decay constant and the
mixing parameter of the pseudoscalar mesons. We compare our results for the
evolution of and with the meson mass to the non-relativistic
formulas for these quantities and show that there is a significant correction
in the subasymptotic region. For and \lms
=0.240{\rm ~GeV} we obtain: and and .Comment: 13 pages, Latex, 3 figures (included
- …