The hypothesis that small body size is correlated with preference for young leaves was tested in a community of leaf-chewing insect herbivores feeding on Ficus wassa in a humid tropical forest in Papua New Guinea. Feeding experiments on 48 species of herbivorous insects revealed a negative correlation between body size and a preference for feeding on young leaves. While small species preferred young leaves, large species showed no preferences, or preferred young leaves only slightly. This relationship was found for the entire leaf-chewing community, as well as for many of the constituent taxa on several taxonomic levels, from orders to genera. Taxonomic position of a species played little role in determining its preferences. It is proposed that higher toughness and lower nutrient content may act as complementary defences, which prevent small insects from feeding on mature foliage. While the low nutrient content of mature leaves may affect smaller herbivores due to their relatively higher metabolic rate and lower digestion efficiency, their toughness complicates feeding mechanically and may prevent the compensatory feeding necessary to offset the low nutritive value of mature leaves.
In this study we examine differences in the occurrence of life history stages of the destructive fish ectoparasite Argulus foliaceus (L., 1758) on eight fish species (stickleback, rudd, roach, gudgeon, bream, tench, crucian carp and common carp) sampled from a mixed-species recreational fishing lake on nine occasions during late spring and summer. Total numbers of A. foliaceus, as well as the number of larval, juvenile and adult parasite stages, from each fish were recorded along with the fish species. Lice generally exhibited an aggregated distribution approximating a negative binomial distribution. Significant differences in the prevalence, intensity and intensity frequency distribution were observed between life history stages and between host species. In general, all life history stages of A. foliaceus exhibited an over-dispersed distribution. However, larval lice did show some degree of aggregation particularly within the stickleback samples. Infection data for parasite larval stages suggested that sticklebacks are more likely to be infected than other host species. For adult lice, however, carp appeared to be the main host. We propose that A. foliaceus infection characteristics are predominantly determined by the level of host exposure to the parasite and its life history stages (larval, juvenile and adult) rather than by an innate difference in host susceptibility related to individual host factors such as immune responses. We conclude that host exposure is determined by the parasite-host behavioural interplay related to species-specific ecology and behavioural traits such as microhabitat preference and normal swimming speed.
The present study evaluates the performance of OptiMAL-IT® test and nested PCR assay in detection of malaria parasites. A total of 76 randomly selected blood samples collected from two malaria endemic areas were tested for malaria parasites using microscopy and OptiMAL-IT® test in the field. PCR assays were performed in the laboratory using DNA extracted from blood spots of the same samples collected on the FTA™ classic cards. Of the total of 61 field confirmed malaria positive samples, only 58 (95%) were detected positive using microscopy in the laboratory. Sensitivity, specificity, positive predictive value, negative predictive value and false discovery rate of OptiMal-IT® in comparison to the microscopy were 93%, 83%, 95%, 79% and 5%, respectively. On the other hand, the sensitivity and specificity of PCR assay were 97% and 100 %, respectively, whereas positive predictive value, negative predictive value and false discovery rate were 100%, 90% and 0%, respectively. The overall performance of OptiMal-IT® and PCR assays for malaria diagnosis was 76% and 97%, respectively. PCR assay enabled the identification of infection with Plasmodium malariae Laveran, 1881 in four samples misidentified by microscopy and Plasmodium-specific antigen (PAN) identified by the OptiMAL-IT® test. In addition to the standard methods, such PCR assay could be useful to obtain the real incidence of each malaria parasite species for epidemiological perspectives.
Ophiotaenia bonneti sp. n. is described from the intestine of the frog Rana vaillanti Brocchi, 1877 (Anura: Ranidae) from San Gerardo, Guanacaste, Costa Rica. The new species is characterized by the testes 100-177 in number, the genital pores situated anteriorly, the osmoregulatory canals overlapping the testis field, the cirrus pouch length as 15-24% of proglottis width, and the uterus with 18-32 ramified diverticula on each side. It differs from the 23 known species of the genus Ophiotaenia La Rue, 1911, parasitic in amphibians, by one to several morphological characters. It differs from O. gracilis Jones, Cheng et Gillespie, 1958, the most morphologically similar species, in the sucker diameter in % of scolex diameter and in the morphology of the eggs - funnel-like depression and embryophore closely investing the oncosphere in O. gracilis. We generally observe a very low mean prevalence of the Proteocephalidea in Neotropical amphibians (about 0.41%-3%), but in the case of some host species, the prevalence can reach up to 25%. We conclude that these cestodes exhibit a strict host specificity of the oioxene type. Ophiotaenia junglensis Srivastava et Capoor, 1980 is considered a species inquirenda. Batrachotaenia hernandezi (Flores-Barroeta, 1955) becomes Ophiotaenia hernandezi (Flores-Barroeta, 1955) comb. n., B. tigrina (Woodland, 1925) becomes O. tigrina (Woodland, 1925) comb. n. and B. ceratophryos (Parodi et Widakowich, 1916) becomes O. ceratophryos (Parodi et Widakowich, 1916) comb. n.