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14. Attack rates of Sirex noctilio and patterns of pine tree defenses and mortality in northern Patagonia.

Author

Martinson, S.J., Fernádez Ajó, A.A., Martínez, A.S., Krivak-Tetley, F.E., Villacide, J.M., Ayres, M.P., and Corley, J.C.

Subjects
LODGEPOLE pine, PONDEROSA pine, PINE, TREES, MORTALITY, LOBLOLLY pine
Abstract

Accidental and intentional global movement of species has increased the frequency of novel plant–insect interactions. In Patagonia, the European woodwasp, Sirex noctilio , has invaded commercial plantations of North American pines. We compared the patterns of resin defenses and S. noctilio -caused mortality at two mixed-species forests near San Carlos de Bariloche, Argentina. We observed lower levels of resin flow and higher levels of mortality in Pinus contorta compared with Pinus ponderosa. In general, S. noctilio attacked trees with lower resin compared with neighboring trees. Resin production in P. ponderosa was not related to growth rates, but for P. contorta , slower growing trees produced less resin than faster growing conspecifics. For all infested trees, attack density and number of drills (ovipositor probes) per attack did not vary with resin production. Most attacks resulted in one or two drills. Attack rates and drills/attack were basically uniform across the bole of the tree except for a decrease in both drills/attack and attack density in the upper portion of the crown, and an increase in the attack density for the bottom 10% of the tree. Planted pines in Patagonia grow faster than their counterparts in North America, and produce less resin, consistent with the growth-differentiation balance hypothesis. Limited resin defenses may help to explain the high susceptibility of P. contorta to woodwasps in Patagonia. [ABSTRACT FROM AUTHOR]

Published
2019
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17. The influence of gustatory and olfactory experiences on responsiveness to reward in the honeybee

Author

Ramírez, G.P., Martínez, A.S., Fernández, V.M., Bielsa, G.C., and Farina, W.M.

Subjects
odor, animal experiment, honeybee, taste, conditioning, motivation, imago, food processing, Animals, controlled study, animal, smelling, reward, nonhuman, article, scoring system, sucrose, nerve cell plasticity, Bees, task performance, Smell, memory consolidation, physiology, Apis mellifera, bee, Apoidea
Abstract

Background: Honeybees (Apis mellifera) exhibit an extraordinarily tuned division of labor that depends on age polyethism. This adjustment is generally associated with the fact that individuals of different ages display different response thresholds to given stimuli, which determine specific behaviors. For instance, the sucrose-response threshold (SRT) which largely depends on genetic factors may also be affected by the nectar sugar content. However, it remains unknown whether SRTs in workers of different ages and tasks can differ depending on gustatory and olfactory experiences. Methodology: Groups of worker bees reared either in an artificial environment or else in a queen-right colony, were exposed to different reward conditions at different adult ages. Gustatory response scores (GRSs) and odor-memory retrieval were measured in bees that were previously exposed to changes in food characteristics. Principal Findings: Results show that the gustatory responses of pre-foraging-aged bees are affected by changes in sucrose solution concentration and also to the presence of an odor provided it is presented as scented sucrose solution. In contrast no differences in worker responses were observed when presented with odor only in the rearing environment. Fast modulation of GRSs was observed in older bees (12-16 days of age) which are commonly involved in food processing tasks within the hive, while slower modulation times were observed in younger bees (commonly nurse bees, 6-9 days of age). This suggests that older food-processing bees have a higher plasticity when responding to fluctuations in resource information than younger hive bees. Adjustments in the number of trophallaxis events were also found when scented food circulated inside the nest, and this was positively correlated with the differences in timing observed in gustatory responsiveness and memory retention for hive bees of different age classes. Conclusions: This work demonstrates the accessibility of chemosensory information in the honeybee colonies with respect to incoming nectar. The modulation of the sensory-response systems within the hive can have important effects on the dynamics of food transfer and information propagation. © 2010 Ramírez et al. Fil:Ramírez, G.P. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Fernández, V.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Farina, W.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Published
2010

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