Genetic basis of triatomine behavior: lessons from available insect genomes

Triatomines have been important model organisms for behavioural research. Diverse reports about triatomine host search, pheromone communication in the sexual, shelter and alarm contexts, daily cycles of activity, refuge choice and behavioural plasticity have been published in the last two decades. In recent times, a variety of molecular genetics techniques has allowed researchers to investigate elaborate and complex questions about the genetic bases of the physiology of insects. This, together with the current characterisation of the genome sequence of Rhodnius prolixus allows the resurgence of this excellent insect physiology model in the omics era. In the present revision, we suggest that studying the molecular basis of behaviour and sensory ecology in triatomines will promote a deeper understanding of fundamental aspects of insect and, particularly, vector biology. This will allow uncovering unknown features of essential insect physiology questions for a hemimetabolous model organism, promoting more robust comparative studies of insect sensory function and cognition.

Ants and their effects on an insect herbivore community associated with the inflorescences of Byrsonima crassifolia (Linnaeus) H.B.K. (Malpighiaceae)

The effects of ants on the insect community on inflorescences of Byrsonima crassifolia (Malpighiaceae) were tested in an ant exclusion experiment in a cerrado vegetation in southeastern Brazil. Forty-four species of insects (23 families) and nine species of ants (6 genera and 3 subfamilies) were found on the inflorescences of B. crassifolia. The exclusion of ants, primarily Camponotus sericeiventris and Camponotus spp., reduced the treehopper population to 20% of the original abundance. Ant exclusion and time influenced the abundance of chewing (Exclusion, P<0.001; Time, P<0.002), and sucking insects (Exclusion, P<0.02; Time, P<0.01). Twice as many chewing and sucking insects were found on ant-excluded inflorescences as compared to control inflorescences (P<0.001). One and half more sucking insects were found on ant-excluded than on control inflorescences. Only time significantly influenced the richness of chewing and sucking insects associated with B. crassifolia inflorescences. Inflorescences on control branches were significantly less attacked by herbivores than inflorescences on ant-excluded branches (P<0.001). Therefore, these results suggest that the presence of ants alters the structure of insect herbivore community associated with B. crassifolia.

Combination of diatomaceous earth and powder deltamethrin for insect control in stored corn

The use of diatomaceous earth (DE) is a very efficient insect control measure in stored grain IPM due to its low cost, easy application, reduction of active ingredient residues, lower environmental contamination and operator safety. The objective of this research was to evaluate the efficacy of different dosages of DE mixed with powder deltamethrin for controlling Sitophilus zeamais in stored corn. Samples of 100 g of clean and dry corn, in three replicates, were submitted to the following treatments: DE (Keepdry®), at the dosages of 500, 750 and 1000 g/t; powder deltamethrin (K-Obiol®) at 0,5 g a.i. /t and 1,0 g a.i. /t; and combinations of the lowest and highest DE dosages with the two dosages of deltamethrin. Thirty adults of S. zeamais were placed in each vial with the treated grains and kept in environment chambers at 25ºC. Mortality was evaluated from the 1st to the 28th day. In the treatments mixing DE with deltamethrin or deltamethrin alone, the mortalyti was registered since the first day. In the treatments using only DE, the first dead insects were recorded after the 3rd day, especially in the highest dosages. After the 7th day, however, there was no statistical difference among all treatments, except for the lowest dosage of DE which reached a satisfactory control level only by the 14th day. It was concluded that treatments using DE combined with low dosages of powder deltamethrin represent an efficient control measure against S. zeamais in stored corn because insect mortality is faster than in treatments using DE alone and residues of active ingredients are much lower than using the insecticide in high dosages.

Morphological studies on castes of Protopolybia chartergoides (Hymenoptera, Vespidae, Epiponini) observed in colonies during male production stage

Social wasps are important for the study of social behavior evolution because their colonies present different degrees of caste differentiation, from morphologically similar to highly conspicuous, associated with the occasional presence of intermediate females, which bears developed ovaries but no insemination. In the Polistinae, depending on the taxon, such differentiation can be discreet or conspicuous. This work intended to study morphological and physiological differences between castes in Protopolybia chartergoides by using morphometric analyses associated with multivariate statistical analyses and physiological evaluations from females' ovarian development. Results evidence low morphological and physiological differences among the castes in P. chartergoides, indicating three groups of females: queens, workers and intermediates. In this way, it was possible to suggest that Protopolybia chartergoides presents post-imaginal caste differentiation (or a very subtle form of pre-imaginal determination).

Insect feeding preferences on Piperaceae species observed in São Paulo city, Brazil

Piperaceae species have been placed among the basal angiosperm and are adapted to a variety of habitats including moist forests, secondary vegetation and dry high lands. The major anatomical/morphology features are of small trees, vines, and shrubs for Piper species, while the epiphytic and succulent characteristics are predominant forms among Peperomia species. Their secondary chemistry can be mostly represented by amides, phenylpropanoids/lignoids, and chromenes in addition to a phletoria of biosynthetically mixed-origin secondary compounds. Although several amides and lignans are known as insecticides, several phytophagous insects, among which some considered pests of economic importance, have been observed feeding vigorously on Piperaceae species. Herein we describe the feeding preferences of fourteen phytophagous species of Coleoptera, Lepidoptera and Hemiptera over approximately fifty Piperaceae species observed in São Paulo, SP, Brazil, in a long-term basis.

More than one inseminated female in colonies of the independent-founding wasp Mischocyttarus cassununga von Ihering (Hymenoptera, Vespidae)

In the primitively eusocial wasps, especially Polistini and Mischocyttarini tribes, the physiological condition of each individual is strongly associated with its dominance status in the colonial hierarchy. As a rule, in independent-founding wasps, female wasps are all morphologically alike, and their role is apparently quite flexible even as adults. However, some studies have shown that differences in body size can exist between reproductive and non-reproductive females. Thus, the present study aimed at detecting differences between reproductive (inseminated) and non-reproductive (uninseminated) individuals based on morphological and physiological parameters. We tape-recorded the daily behavioural repertory of six colonies of Mischocyttarus cassununga for determining the hierarchical dominance in the field, and then collected these colonies (in different cycle stages) for measuring 13 set characters, and assessing the physiological condition of each individual by inspecting their fat bodies and ovaries. Our results revealed that inseminated and uninseminated females are not significantly different in relation to body size, in spite of first group shows higher average than second in almost all measured parts. The physiological evaluation of each individual demonstrated more than one inseminated female per colony during all stages of the colony cycle, suggesting a strategic condition of this species against difficulties (predation and parasitism of the colony) in nature.

Pattern of attack of a galling insect reveals an unexpected preference-performance linkage on medium-sized resources

Pattern of attack of a galling insect reveals an unexpected preference-performance linkage on medium-sized resources. The Plant Vigor Hypothesis (PVH) predicts oviposition preference and higher offspring performance on longer and fast-growing shoots, and although several studies have tested its predictions, long-term studies concerning the patterns of host selection by galling species are still lacking. The PVH was tested in this study using Bauhinia brevipes (Fabaceae) as the host of a leaf gall midge, Asphondylia microcapillata (Diptera, Cecidomyiidae) during three consecutive years. Shoots were collected from the same 80 plants between 2001 and 2003 and shoot length, number of healthy and galled leaves, gall number, and mortality factors were recorded. Nearly 600 galls were found on the 5,800 shoots collected. Medium-sized shoots supported from 46 to 70% of all galls, with greater gall survival rate in 2002 and 2003. A decrease in parasitism rate coupled with an increase in gall predation lead to a constant similar gall survivorship rate in all years (x = 22.7%). Although gall abundance varied among years (122 in 2001, 114 in 2002 and 359 in 2003) preference for longer shoots was not observed because the percentage of galled shoots and galled leaves were higher on medium shoot length classes in all years. The observed distribution of gall abundance and galled shoots were always greater than the expected distribution on medium shoot length classes. These findings do not support the PVH, and show that A. microcapillata can maximize the female preference and larval performance on medium-sized shoots of B. brevipes.

Seasonal flight and resource collection patterns of colonies of the stingless bee Melipona bicolor schencki Gribodo (Apidae, Meliponini) in an Araucaria forest area in southern Brazil

Melipona bicolor schencki occurs in southern Brazil and at high elevations in southeastern Brazil. It has potential for use in meliponiculture but this stingless bee species is vulnerable to extinction and we have little knowledge about its ecology. In order to gather essential information for species conservation and management, we made a study of seasonal flight activities in its natural environment. We sampled bees entering the nests with pollen, nectar/water and resin/mud, in five colonies during each season. In parallel, we analyzed the influence of hour of the day and meteorological factors on flight activity. Flights were most intense during spring and summer, with daily mean estimates of 2,100 and 2,333 flights respectively, while in fall and winter the daily flight estimate was reduced to 612 and 1,104 flights, respectively. Nectar and water were the most frequently-collected resources, followed by pollen and building materials. This preference occurred in all seasons, but with variations in intensity. During spring, daily flight activity lasted over 14 hours; this period was reduced in the other seasons, reaching eight hours in winter. Meteorological factors were associated with 40.2% of the variation in flight and resource collection activity. Apparently, other factors that we did not measure, such as colony needs and availability of floral resources, also strongly influence the intensity of resource collection.

Seasonality in insect abundance in the "Cerrado" of Goiás State, Brazil

Seasonality in insect abundance in the "Cerrado" of Goiás State, Brazil. Many studies have provided evidence that tropical insects undergo seasonal changes in abundance and that this is partly due to alternation between the dry and rainy seasons. In the Brazilian "Cerrado" (savannah), this season alternation is particularly evident. The purpose of this work was to study the seasonal abundance of insects in a "Cerrado" area in the municipality of Pirenópolis, Goiás State, Brazil. The insects were captured fortnightly using a light trap between September 2005 and August 2006. The insects collected were separated at the order level and counted. Faunistic analysis was performed to select the predominant insect orders, a multiple linear regression to examine the relation between climatic variables (temperature and precipitation) with the abundance of insects and a circular distribution analysis to evaluate the existence of seasonality in the abundance of insect orders. A total of 34,741 insect specimens were captured, belonging to 19 orders. The orders with the greatest number of specimens were Hymenoptera (8,022), Coleoptera (6,680), Diptera (6,394), Lepidoptera (6,223), Isoptera (2,272), Hemiptera (2,240) and Trichoptera (1,967), which represent 97.3% of all the specimens collected. All the orders, except for Diptera, Isoptera and Trichoptera, showed a relationship with the climate variables (temperature), and all the orders, except for Diptera, presented a grouped distribution, with greater abundance in the transition from the end of the dry season (September) to the start of the rainy one (October/November). A discussion about seasonality on the abundance of the insects is presented.

The effect of environment on development and survival of pupae of the necrophagous fly Ophyra albuquerquei Lopes (Diptera, Muscidae)

The effect of environment on development and survival of pupae of the necrophagous fly Ophyra albuquerquei Lopes (Diptera, Muscidae). Species of Ophyra Robineau-Desvoidy, 1830 are found in decomposing bodies, usually in fresh, bloated and decay stages. Ophyra albuquerquei Lopes, for example, can be found in animal carcasses. The influence of environmental factors has not been evaluated in puparia of O. albuquerquei. Thus, the focus of this work was motivated by the need for models to predict the development of a necrophagous insect as a function of abiotic factors. Colonies of O. albuquerquei were maintained in the laboratory to obtain pupae. On the tenth day of each month 200 pupae, divided equally into 10 glass jars, were exposed to the environment and checked daily for adult emergence of each sample. We concluded that the high survival rate observed suggested that the diets used for rearing the larvae and maintaining the adults were appropriate. Also, the data adjusted to robust generalized linear models and there were no interruptions of O. albuquerquei pupae development within the limits of temperatures studied in southern Rio Grande do Sul, given the high survival presented.

Origin of samples of Cannabis sativa through insect fragments associated with compacted hemp drug in South America

Origin of samples of Cannabis sativa through insect fragments associated with compacted hemp drug in South America. Insects associated with a seizure of Cannabis sativa L. may indicate the origin of the illicit drug. Nevertheless, no work regarding this subject has been previously published for South America. In the present investigation, seven kilograms of vegetal material (C. sativa) were inspected for insect fragments. Three species were identified and used to test the origin of the seizure of cannabis plant material: Euschistus heros (Fabricius, 1794), Thyanta perditor (Fabricius, 1794) (Heteroptera, Pentatomidae), and Cephalotes pusillus (Klug, 1824) (Hymenoptera, Formicidae). These insect species restricted the geographic origin of the drug to the Neotropical region, and their distribution patterns showed an overlap of the State of Mato Grosso (Brazil), Argentina, and Paraguay. Based on this information, two of the three major C. sativa growing areas in South America were excluded: (1) the Colombian territory and (2) northeastern Brazil.

Insect galls of restinga areas of Ilha da Marambaia, Rio de Janeiro, Brazil

Insect galls of restinga areas of Ilha da Marambaia, Rio de Janeiro, Brazil. This study carried out an insect gall inventory in restinga areas of Ilha da Marambaia, in the municipality of Mangaratiba, Rio de Janeiro, Brazil. Sampling was carried out monthly from April 2010 to March 2011 along the full extension of seven beaches. A total number of 147 gall morphotypes associated with 70 plant species were found, distributed in 33 plant families, and at least 54 genera. Myrtaceae was the botanical family with the highest richness of gall morphotypes and host species, followed by Bignoniaceae, Fabaceae, Asteraceae, Euphorbiaceae, Sapindaceae, and Malpighiaceae. Most of the gall morphotypes occurred in leaves (78 morphotypes), 38 in stems, 14 in flowers, eight in buds and fruits, and one in adventitious roots. The galling insects belong to the five orders: Diptera, Coleoptera, Hemiptera, Lepidoptera, and Thysanoptera. Cecidomyiidae (Diptera) was the most common galling taxon (78 morphotypes), represented by 87 species, being 78 gallers, seven inquilines and two predators. In addition to the gallers, parasitoids, inquilines, and predators were also found.

Effect of Bacillus sphaericus Neide on Anopheles (Diptera: Culicidae) and associated insect fauna in fish ponds in the Amazon

ABSTRACTWe analyzed the effects of Bacillus sphaericus on Anopheles larvae and on the associated insect fauna in fish farming ponds. Five breeding sites in the peri-urban area of the city of Manaus, AM, Brazil, were studied. Seven samples were collected from each breeding site and B. sphaericus was applied and reapplied after 15 days. The samples were made at 24 h before application, 24 h post-application and 5 and 15 days post-application. We determined abundance, larval reduction and larval density for Anopheles, and abundance, richness, Shannon diversity index and classified according to the functional trophic groups for associated insect fauna. A total of 904 Anopheles larvae were collected and distributed into five species. Density data and larval reduction demonstrated the rapid effect of the biolarvicide 24 h after application. A total of 4874 associated aquatic insects belonging to six orders and 23 families were collected. Regression analysis of diversity and richness indicated that the application of the biolarvicide had no influence on these indices and thus no effect on the associated insect fauna for a period of 30 days. B. sphaericus was found to be highly effective against the larvae of Anopheles, eliminating the larvae in the first days after application, with no effect on the associated insect fauna present in the fish ponds analyzed.

Insect galls of a protected remnant of the Atlantic Forest tableland from Rio de Janeiro State (Brazil)

ABSTRACT Insect galls of a protected remnant of the Atlantic Forest tableland from Rio de Janeiro State (Brazil): Galling insects in Rio de Janeiro state are known by their great diversity, despite most of the surveys have been done in restinga. This paper investigated the insect galls from a remnant of Atlantic Forest located in São Francisco de Itabapoana municipality, Rio de Janeiro state, Brazil. The galling insect fauna was surveyed from March, 2013 to April, 2014 at the Estação Ecológica Estadual de Guaxindiba. 143 gall morphotypes were found in 31 plant families, 60 genera and 82 species. Fabaceae, Myrtaceae and Sapindaceae were the main host families, being Trichilia, Tontelea and Eugenia the main host genera. Most galls occured on leaves, with globose shape, green and glabrous. Diptera (Cecidomyiidae), Hemiptera, and Lepidoptera were the inducing orders and the associated fauna comprised parasitoids (Hymenoptera), inquilines (Lepidoptera, Coleoptera, and Hemiptera: Coccoidea), successors (Psocoptera, Collembola and Acari), and predators (Pseudoscorpiones). Three plant genera and nine plant species are recorded for the first time as host of galls in Brazil. All the records are new to the municipality, and the distribution of 15 galling species is extended to the North of the state of Rio de Janeiro.

Does Bt maize cultivation affect the non-target insect community in the agro ecosystem?

ABSTRACT The cultivation of genetically modified crops in Brazil has led to the need to assess the impacts of this technology on non-target species. Under field conditions, the potential effect on insect biodiversity was evaluated by comparing a homogeneous corn field with conventional and transgenic maize, expressing different Bt proteins in seven counties of Minas Gerais, Brazil. The richness pattern of non-target insect species, secondary pests and natural enemies were observed. The results do not support the hypothesis that Bt protein affects insect biodiversity. The richness and diversity data of insects studied were dependent on the location and other factors, such as the use of insecticides, which may be a major factor where they are used.