Abstract. A common assumption in models of insecticide resistance evolution is the association between resistance and fitness costs in the absence of insecticides. There is empirical evidence of such associations, but their physiological basis (and mitigation) is little investigated. Pyrethroid-resistant populations of the maize weevil Sitophilus zeamais (Coleoptera: Curculionidae) offer this opportunity. Pyrethroid resistance in this species was initially observed in five Brazilian states by 1995, but the phenomenon apparently decreased and did not spread to other regions, probably due to the occurrence of a fitness disadvantage in resistant individuals in the absence of insecticides. The present investigation aims to verify whether differences in respiration rate and fat body morphology are related to differences in rate of development in Brazilian populations of S. zeamais resistant to insecticides, and thereby provide evidence for the existence (or not) of a physiological fitness cost acting against insecticide resistance in maize weevils. This may occur due to a possible energy trade-off between insecticide resistance and other physiological processes associated with development and reproduction. To achieve this, studies of the rate of development, respiration and fat body cytomorphology are carried out in one insecticide-susceptible (from Sete Lagoas) and two resistant populations (from Jacarezinho and Juiz de Fora) of S. zeamais. The resistant population from Jacarezinho shows that higher body mass is associated with higher energy reserves (larger trophocyte area) for development and reproduction, as well as for insecticide resistance. However, the resistant population from Juiz de Fora does not appear to have large enough energy allocation for insecticide-resistance expression and development and/or reproductive performance, suggesting a tradeoff between resistance and other life history traits.

Polyphenism is the phenomenon in which alternative phenotypes are produced by a single genotype in response to environmental cues. An extreme case is found in social insects, in which reproductive queens and sterile workers that greatly differ in morphology and behavior can arise from a single genotype. Experimental evidence for maternal effects on caste determination, the differential larval development toward the queen or worker caste, was recently documented in Pogonomyrmex seed harvester ants, in which only colonies with a hibernated queen produce new queens. However, the proximate mechanisms behind these intergenerational effects have remained elusive. We used a combination of artificial hibernation, hormonal treatments, gene expression analyses, hormone measurements, and vitellogenin quantification to investigate how the combined effect of environmental cues and hormonal signaling affects the process of caste determination in Pogonomyrmex rugosus. The results show that the interplay between insulin signaling, juvenile hormone, and vitellogenin regulates maternal effects on the production of alternative phenotypes and set vitellogenin as a likely key player in the intergenerational transmission of information. This study reveals how hibernation triggers the production of new queens in Pogonomyrmex ant colonies. More generally, it provides important information on maternal effects by showing how environmental cues experienced by one generation can translate into phenotypic variation in the next generation.

Sewage sludge is an organic matter-rich material with abundant fractions of nitrogen and other macro and micronutrients, essential for plant growth and development such as Acacia mangium Willd. (Fabales: Fabaceae) used in recovering actions of degraded areas. The objective of this study was to evaluate over 24 months the abundance and diversity of chewing and pollinator insects and arthropod predators on A. mangium plants and the mass production and soil coverage by this plant, fertilized with dehydrated sewage sludge, in a degraded area. The experimental design was in randomized blocks with two treatments (with and without dehydrated sewage sludge) and 24 replications. The number of leaves per branch and branches per plant, defoliation percentage by chewing insects, soil cover and abundance of chewing and pollinator insects and arthropod predators were higher on A. mangium plants fertilized with dehydrated sewage sludge. Nasutitermes sp. (Blattodea: Termitidae) and Trigona spinipes F. (Hymenoptera: Apidae) were the most observed insects on trunks and leaves, respectively, of A. mangium plants fertilized with dehydrated sewage sludge. The A. mangium fertilization increases the populations of different insect and spider groups on this plant.

This study evaluated the insecticidal activity of garlic, Allium sativum Linnaeus (Amaryllidaceae) essential oil and their principal constituents on Tenebrio molitor. Garlic essential oil, diallyl disulfide, and diallyl sulfide oil were used to compare the lethal and repellent effects on larvae, pupae and adults of T. molitor. Six concentrations of garlic essential oil and their principal constituents were topically applied onto larvae, pupae and adults of this insect. Repellent effect and respiration rate of each constituent was evaluated. The chemical composition of garlic essential oil was also determined and primary compounds were dimethyl trisulfide (19.86%), diallyl disulfide (18.62%), diallyl sulfide (12.67%), diallyl tetrasulfide (11.34%), and 3-vinyl-[4H]-1,2-dithiin (10.11%). Garlic essential oil was toxic to T. molitor larva, followed by pupa and adult. In toxic compounds, diallyl disulfide was the most toxic than diallyl sulfide for pupa > larva > adult respectively and showing lethal effects at different time points. Garlic essential oil, diallyl disulfide and diallyl sulfide induced symptoms of intoxication and necrosis in larva, pupa, and adult of T. molitor between 20–40 h after exposure. Garlic essential oil and their compounds caused lethal and sublethal effects on T. molitor and, therefore, have the potential for pest control.

The midgut epithelium of bees is formed by the digestive cells, responsible for enzyme secretion and nutrient absorption and for small regenerative cells that are placed in nests scattered among the digestive cells. During metamorphosis, the larval midgut epithelium degenerates and a new adult midgut epithelium is built during larval differentiation of regenerative cells. The present work focuses on the midgut epithelial modifications during the post-embryonic development of the stingless bee Melipona quadrifasciata anthidioides worker and the occurrence of regenerative cell proliferation during midgut metamorphosis in order to test the hypothesis that adult midgut epithelium of worker bees results from regenerative cell proliferation during the pupal stage. Regenerative cell proliferation was detected during larval lifespan. Larval aging is followed by an increase in the number and the size of the nests of regenerative cells. Larval epithelium degeneration begins 2 days after the start of defecation process and in this period the nests of regenerative cells are in contact by means of cytoplasmic extension which have many septate desmosomes and gap junctions. The BrdU immunoreactive regenerative cells were found in the prepupae 12 h after BrdU injection, suggesting that regenerative cell population increase during this larval period. Regenerative cell proliferation results in the increase of the regenerative cell population and not in the formation of new digestive cells because the proliferation of regenerative cells would not be enough to reestablish the nests of regenerative cells and at the same time form new adult digestive cells. In this sense the hypothesis that digestive adult cells originate from regenerative cell proliferation during midgut metamorphosis in M. quadrifasciata anthidioides was rejected.

No abstract

The effects of diet on development of Podisus nigrispinus (Dallas) (Het., Pentatomidae) were studied at 25°C, relative humidity of 60 ± 10%, and photoperiod of 14 h light : 10 h dark. Development times of P. nigrispinus nymphs were similar when fed with third or fifth instar larvae of cotton leafworm (Alabama argillacea Hübner) (Lep., Noctuidae) or Tenebrio molitor L. (Col., Tenebrionidae). When fed with housefly larvae (Musca domestica L.) (Dipt., Muscidae) or artificial diet, the predator had a longer development time. Independent of diet, instar or sex, the females of P. nigrispinus showed a longer longevity than the males. The total survival of the nymphal stage, on the different diets, varied from 22.46 (fed with housefly) to 77.33% (fed with T. molitor larvae). P. nigrispinus males were heavier when fed with third or fifth instar cotton leafworm larvae than when fed with artificial diet. The weight of the females varied from 37.91 (with artificial diet) to 64.68 mg (with fifth instar cotton leafworm larvae). Independently of the diet, newly emerged females of P. nigrispinus were heavier than the males. Females of P. nigrispinus which were fed with fifth instar cotton leafworm larvae had heavier ovaries than those fed other diets.

Abstract(The species of mayflies (Ephemeroptera: Insecta) recorded from Brazil). A checklist of the Brazilian Ephemeroptera fauna with all species, genera and families recorded from the country, including the states for which every species is reported, and the pertinent reference is presented. Comments on the status of knowledge of the Brazilian mayfly fauna are also provided. Up to date, 10 families, 63 genera, and 166 species are recorded. Baetidae and Leptophlebiidae have more than 50% of all records, while the North and Southeastern regions are significantly better studied than the other areas of the country.Key words: Brazil, mayflies, records, status of knowledge, South-America. Resumo(As espécies de Ephemeroptera (Insecta) registradas para o Brasil). Uma lista da fauna de Ephemeroptera do Brasil, com todas as espécies, gêneros e famílias registrados para o país é apresentada, incluindo os estados para os quais as espécies estão reportadas assim como a bibliografia pertinente. Comentários acerca do estado atual do conhecimento da fauna brasileira também são tecidos. Até o presente momento 10 famílias, 63 gêneros e 166 espécies estão registrados. As famílias Baetidae e Leptophlebiidae compreendem mais de 50% de todos os registros, enquanto as regiões Norte e Sudeste são significativamente melhor estudadas que as demais. Palavras