Entomopathogenic fungi naturally infecting the eucalypt bronze bug,Thaumastocoris peregrinus (Heteroptera: Thaumastocoridae), in Uruguay

Thaumastocoris peregrinus Carpintero & Dellapé (Heteroptera: Thaumastocoridae) is a sap‐sucking insect that feeds on leaves of Eucalyptus. In Uruguay, it was detected in 2008 causing significant economic losses in Eucalyptus plantations. At present, there is no efficient control for this pest; thus, the use of biological control agents seems to be an environmentally friendly alternative to reduce the damage caused by this insect. The aims of this study were to isolate and identify the species of entomopathogenic fungi that naturally infect T. peregrinus in Uruguay and to characterize and select the most virulent isolates towards this pest. Individuals of T. peregrinus were collected in eight Eucalyptus plantations infested by the pest. The entomopathogenic fungi were isolated and identified by observation of their micromorphological characteristics, and their identity was confirmed by molecular methods. The pathogenicity and virulence against T. peregrinus of the isolated entomopathogenic fungi were evaluated. Isolates causing the highest insect mortality were selected to evaluate the effect of temperature and water activity on conidial viability. Entomopathogenic fungi were found in very low number with the prevalence of less than 3%. Isolates corresponded to Beauveria, Fusarium, Isaria, Lecanicillium, Paecilomyces, Pochonia, Purpureocillium and Simplicillium genera. Two species, B. pseudobassiana and L. muscarium, were first recorded in Uruguay. Among all the tested species, an isolate of B. bassiana (FI 2403) showed the highest virulence followed by an isolate of B. pseudobassiana. The isolate of B. bassiana presented the highest percentage of spore germination at the three temperatures and the highest viability at low water activities. Isolate FI 2403 was selected as a promissory candidate for the development of a commercial formulation against T. peregrinus.     

Diversity and Coexistence of Ectoparasites in Small Rodents in a Tropical Dry Forest

To understand the mechanisms driving species diversity is central to community ecology. Here, we explored if habitat partitioning is associated with a species‐rich ectoparasite community in small rodents from a tropical dry forest in western Mexico. We trapped 199 mice in three 0.5 ha‐plots from eight small rodent species for every two months, from July 2011 to April 2012, and collected their ectoparasites. We identified 17 species of mites, two sucking lice species, two phoretic species, and one commensal species. The most abundant ectoparasite species was Steptolaelaps liomydis, representing 42 percent of all ectoparasites collected; seven ectoparasite species had < 10 individuals. Eighteen ectoparasite species (of 22 species) were collected from the most abundant rodent Liomys pictus. C‐score and the number of checkerboard species pairs were significantly higher against a random expectation. Ectoparasite species in L. pictus mice showed host microhabitat partitioning; Fahrenholzia ehrlichi and Fahrenholzia texana were found only in the anterior dorsal area, Ornithonysus sp. occurred along the dorsal part, Ixodes species were restricted to the ears, and Steptolaelaps liomydis was found throughout the body. We also identified ectoparasite communities with distinct species composition in two rodent species that use contrasting macrohabitats (L. pictus, strictly terrestrial; Peromyscus perfulvus, mostly arboreal). The remaining and low abundant rodent species showed a species‐poor ectoparasite community composition. We conclude that habitat partitioning at both macro and microhabitat scales appeared to characterize the species‐rich ectoparasite community. Conversely, most rodent host species with low abundances showed a species‐poor ectoparasite community.     

Spawning and maternal‐care behaviours of a copulating sculpin, Radulinopsis taranetzi

The fertilization mode, and spawning and egg‐care behaviours of the sculpin Radulinopsis taranetzi were investigated in the laboratory. Embryonic development began only after the eggs came into contact with sea water. Females spawned c . 1000 eggs and covered them with sand using their pectoral and caudal fins. Unlike other cottids, the females guarded the egg masses after spawning. During the parental period, the supramaxillary lamina and mandibular lamina of females extended to form a disc‐like structure, which was used to 'suck' water from near the surface of the egg mass. The frequency and duration of this 'sucking' behaviour increased gradually until hatching, which occurred after 23–26 days at 8° C. The oxygen consumption of the embryos was positively related to the 'sucking' activity. All females in this study spawned only once during the spawning season, in contrast with the paternal‐care copulating cottids, which are multiple spawners.     

EPG技术在昆虫学研究中的应用及进展

刺吸行为电图(electrical penetration graph, EPG) 技术在植食性刺吸式昆虫,如蚜虫、粉虱、叶蝉和蓟马等研究中的应用日益深入,尤其是对蚜虫和粉虱的研究,已涉及寄主专化性、植物的抗虫机制以及病毒传播等领域。该文从蚜虫和粉虱等典型的刺吸式昆虫入手,介绍EPG技术的研究进展和应用前景。     

Evaluation of responses of five cowpea (Vigna unguiculata (L.) Walp.) varieties to field infestation by major insect pests of cowpea

The study was conducted to evaluate yield response of five cowpea (Vigna unguiculata (L.) Walp.) varieties to field infestation and damage by major insect pests of cowpea. Three local varieties of cowpea, namely, Sokoto, Oloyin and Drum, and two International Institute of Tropical Agriculture (IITA) varieties, IT 90K-277-2 and IT90K-76, were planted on the Teaching and Research Farm of University of Agriculture, Abeokuta (UNAAB), Ogun State, Nigeria in September, 2006 and repeated in September, 2007. The experiment was laid out in Randomised Complete Block Design in split plots arrangement. Insecticidal spray constitutes the main plot while variety was the sub-plot. The main plot size was 19.4 m × 19 m and each of the sub-plot was 2.4 m × 3 m. The space between sub-plots was 1 m. Data from the sprayed plots were significantly (P < 0.05) higher than the unsprayed ones in the two seasons. Irrespective of season, the unsprayed plot of IT 90K-277-2 has a significantly (P < 0.05) high incidence of Ootheca mutabilis. The local variety, “Drum” has the highest incidence of flower thrip – Megalurothrips sjostedti in the two planting seasons. The highest mean number of peduncles/plant and pods/plant was in “IT 90K-277-2”. In both seasons, “IT90K-76” has a significantly (P < 0.05) lower number of damaged seeds and pods and “Oloyin” a significantly (P < 0.05) higher mean number of total pod sucking bugs. The grain yield was in the order IT90K-76 > Oloyin > IT 90K-277-2 > Sokoto > Drum.     

One proboscis,two tasks: Adaptations to blood-feeding and nectar-extracting in long-proboscid horse flies (Tabanidae,Philoliche)

Female Pangoniinae in the tabanid fly genus Philoliche can display remarkably elongated proboscis lengths, which are adapted for both blood- and nectar-feeding. Apart from their role as blood-sucking pests, they represent important pollinators of the South African flora. This study examines the morphology of the feeding apparatus of two species of long-proboscid Tabanidae: Philoliche rostrata and Philoliche gulosa – both species display adaptations for feeding from a diverse guild of long-tubed flowers, and on vertebrate blood. The heavily sclerotised proboscis can be divided into two functional units. The short, proximal piercing part is composed of the labrum-epipharynx unit, the hypopharynx and paired mandible and maxilla. The foldable distal part is composed of the prementum of the labium which solely forms the food canal and is responsible for nectar uptake via the apical labella. The proboscis works as a drinking straw, relying on a pressure gradient provided by a two-part suction pump in the head. Both proboscis and body lengths and suction pump dimensions show a significantly correlated allometric relationship with each other. This study provides detailed insights into the adaptations for a dual diet using an elongated sucking proboscis, and considers these adaptations in the context of the evolution of nectar feeding in Brachycera.