We investigated the effect of the feeding behaviour of young larvae of Pieris rapae crucivora Boisduval (Pieridae) on parasitism by the parasitoid wasp, Cotesia glomerata (L.) (Braconidae). Young, 1st-3rd instar larvae used approximately three sites for feeding each day. When not feeding, they moved a short distance away from the feeding sites (= feeding marks) and rested. For first, second and third instar larvae, the distances from the new mark, made within 24 h, to larva at rest were, respectively, about 3.5 mm, 5 mm and more than 10 mm. To resume feeding, they moved back to one of the former feeding sites or a new site. The percentage of the feeding marks older than 24 h that attracted parasitoids was less than 50%. Time spent searching for hosts by a parasitoid was short. Larvae placed 5 mm or more from a feeding mark were less parasitized than the larvae placed near a mark. The number of feeding marks affected parasitism. When comparing single-marked and triple-marked leaves, the percentage parasitism of the larvae on the latter was significantly lower than that of the larvae on the former. On triple-marked leaves, parasitoids visited each mark unevenly. Accordingly, the time spent searching each mark differed significantly among the marks. Because of this confusing effect, hosts are considered to be reducing the risk of parasitism. Our results demonstrate that the feeding habits of young larvae of P. rapae crucivora are adaptive in terms of reducing the risk of parasitism by C. glomerata., Aya Nakayama, Keiji Nakamura, Jun Tagawa., and Obsahuje bibliografii
Haemadipsid leeches are among the most successful terrestrial invertebrates in Bornean rainforests. They are very common ectoparasites of vertebrates, and their abundance has facilitated the conduction of numerous projects in the fields of ecology, zoogeography and taxonomy. We undertook research on two species inhabiting lowland dipterocarp forest, Haemadipsa picta Moore, 1929 and Haemadipsa subagilis (Moore, 1929), in order to address the following questions: (a) is there a difference in leech abundance between trails and off-trails?; (b) is ambush location dependent on specimen size or is species-specific?; (c) is intra- and interspecific competition limited by differences in foraging behaviours or vertical niche partitioning? Our results clearly show that H. picta is more abundant on trails than on off-trails and is vertically dispersed within the understory; the size of a specimen is strongly correlated with plant height. Haemadipsa subagilis was found not to exhibit such patterns. We suggest a possible lowering of interspecific competition between these species as a result of: (i) size-dependent dispersion of H. picta (together with reduction of intraspecific competition); and (ii) habitat specialisation of H. subagilis. Moreover, we provide new observations on their foraging behaviour., Piotr Gąsiorek, Hanna Różycka., and Obsahuje bibliografii
Článek popisuje tzv. závislý způsob zakládání kolonie u mravenců. Ten má několik stupňů závislosti - od závislosti na cizím mraveništi pouze v počátku vzniku kolonie (dočasná závislost) až po trvalé soužití dvou mravenčích druhů. To má několik stupňů, počínaje prostým hostováním (xenobióza) a konče příležitostným (fakultativním) otrokářstvím - tzv. inkvilinie, nebo trvalým (obligatorním) otrokářstvím - tzv. duloze. Trvalé otrokářství je spojeno s nutností pořádat otrokářské výpravy za plodem pomocných mravenců (otroků). Mimo jiné je jich využito i pro založení nové kolonie otrokářů., Dependent ways of nest foundation in some ant species are described. These include various types of social parasitism ranging from temporary parasitism to both optional and obligatory slavery. The latter is the strongest form of dependence of the slave-making ant on its slaves and is accompanied by the inability of the slaver species to survive without its slaves. On the other hand, slave-making ants are famous for their orientation in the field and movement over long distances. These abilities are used, e.g., by the European Amazon Ant (Polyergus rufescens) in its special strategy of nest foundation based on cooperation between workers and the freshly inseminated queen during a slavery raid., and Pavel Amcha.