Ground-active arthropod response to distance from the Mediterranean seashore in coastal sand areas of western Israel

Information on the effects of distance from the seashore on soil biotic communities is limited and restricted to soil arthropods and microarthropods. The aim of this study, conducted in a sand-dune area, was to distinguish the changes of a ground-active arthropod community along a 4-km-transect from the seashore going inland. Pitfall traps were set up in open spaces at four locations (L1, through L2, L3, and L4 going inland) through the year. The abiotic gradient from the seashore going inland was found to be mostly dependent on seasonality. Group richness was found to be remarkably greater at the L2, L3, and L4 locations compared with the L1 location in winter, and at the L2 and L3 locations compared with the L1 location in spring. The Fisher α index was 0.32?±?0.21, 3.51?±?0.87, 5.04?±?0.70, and 4.86?±?0.54 in winter and 3.29?±?0.55, 13.79?±?1.49, 10.12?±?1.24, and 5.06?±?0.62 in spring at the L1, L2, L3, and L4 locations, respectively. Regarding abundance and group richness, the trophic relationships between predators, phytophages, omnivores, and saprophages were remarkably affected by both location and seasonality. The dominant groups and dominant index distribution of ground-active arthropod communities were found to follow a similar pattern. Soil organic carbon content was found to be the key factor driving the ground-active arthropod community structure along a coastal gradient going inland in winter and spring. We conclude that the distribution, trophic composition, and diversity index are affected by both location and seasonality, while total abundance is consistently affected by location across all three seasons.     

Mass rearing of the florida wax scale,Ceroplastes floridensis,for production of natural enemies

A method was developed for mass rearing the Florida wax scale (FWS),Ceroplasta floridensis Comstock — an important pest of citrus and other fruit trees in the Mediterranean basin — for production of natural enemies. The effect of host plant species, intensity of illumination and scale insect density on survival and size of the FWS was studied.Myrtus communis was found to be the most efficient host plant, and the required intensity of illumination was 200 µmol m^-2s^-1(with a photoperiod of 12L: 12D). Under these conditions, a density of 500 scale insects per plant could be achieved without reducing the size of the FWS below that required for the development of natural enemies.     

Foraging behavior of two species of the genuschilocorus (coccinellidae: coleoptera): a comparative study

The searching behavior of two coccinellid beetles of the genusChilocorus (Coccinellidae: Coleoptera) was compared. The main components of the searching behavior of larvae and adults - speed of search and change of angle before and after successful encounter with hosts - were compared within and between species. Both species (at the larval and adult stages) changed their searching behavior following successful encounter, by increasing the angle and number of turns per unit of time. These changes were coupled with reductions in the speed of locomotion. The intensity of the changes differed significantly between the species.C. bipustulatus demonstrated a stronger response in the degree of change in angle thanC. kuwanae. As time elapsed and unsuccessful search continued, the beetles returned to their original pattern of search. Both species allocated an increasing proportion of their time to patches of hosts, in accordance with host density.     

Effects of variable temperatures on responses ofAphytis melinus andA. lingnanensis to host density

The effects of three variable temperature regimes (18–24, 24–29, and 29–35°C) on the responses of two species of the genusAphytis Howard (Hymenoptera: Aphelinidae), parasitic upon the California red scale, were studied, and a test to analyze parasite behavior was developed.Aphytis lingnanensis Compere was generally more efficient thanA. melinus DeBach; however, whereas a high temperature regime (29–35°C) had a negative effect on the responses ofA. lingnanensis, it improved those ofA. melinus. The two species distributed their eggs in clumps, but were able to respond to increasing host density by reducing the number of eggs laid per encounter. The combined effects of numerical, and functional responses of the two species on host population were considered, with special reference to the mechanism of competitive displacement.     

Diapause induction in field populations of the codling moth,Cydia Pomonella,in Northern Israel

Diapause induction in field populations of the codling moth,Cydia pomonella L., was studied for three consecutive seasons (1984–86) in two commercial apple orchards in Upper Galilee. One orchard was located in the Hula Valley and the other in the high mountain region. The onset of diapause sometimes occurred during increasing day-length, before the summer solstice. This phenomenon represents a small proportion of the population which is probably genetically univoltine. The critical photoperiod which induces 50% diapause (= CPhP₅₀) varied up to 5 days within the valley region, up to 6 days within the mountain region, and up to 7 days between the two regions. The trend of this variation was consistent: the CPhP₅₀ of the valley poulation preceded that of the mountain on both ‘Jonathan’ and ‘Granny Smith’ apple varieties and, within each location, the CPhP₅₀ on the early-ripening ‘Jonathan’ preceded that of the late-ripening ‘Granny Smith’. The higher prediapause temperatures of the Hula Valley caused earlier diapause induction as compared with the lower temperatures of the mountain region. Immature fruits delayed diapause induction in comparison with mature ones.     

A comparative study of the effects of constant temperatures on development time and survival of two coccinellid beetles of the genusChilocorus

The effect of constant temperatures on duration and rate of development and on survival of two species of predatory beetles of the genusChilocorus (Coleoptera: Coccinellidae) (one endemic and one imported) was studied. The observed data were analyzed and compared applying three different methods. The methods based on the logistic curve provided a better fit to the observed data as compared with the widely used Blünck-Bodenheimer equation. The imported speciesC. kuwanae had a faster rate of development than the endemic speciesC. bipustulatus at the lower temperatures tested (18°, 22°C), but it could not complete its development at 32°C. Survival ofC. kuwanae was considerably lower than that of the endemic species. As both species are active during the summer, it was concluded that the sensitivity ofC. kuwanae to high temperatures provides at least a partial explanation to the fact that this species has not become established yet in Israel.     

Biological control of the florida red scale,Chrysomphalus aonidum,in israel by two parasite species: Current status in the coastal plain

For the last 20 years there has been a trend of dynamic change in the relative composition of the parasite complex of the Florida red scale,Chrysomphalus aonidum (L.), in Israel —Aphytis holoxanthus DeBach (an ectoparasite) being gradually replaced byPteroptrix smithi (Compere) (an endoparasite). Monthly sampling of fruits and leaves in citrus groves located along the coastal plain in Israel indicated that the Florida red scale is effectively controlled by its parasites. The two parasite species coexist in the citrus groves,P. smithi generally being the dominant species. Parasitism byA. holoxanthus is relatively low during autumn and winter, increasing gradually during the spring and reaching a peak between May and August. Parasitism byP. smithi remains relatively high throughout the year.