Antibiosis interaction of black soldier flies (Hermetia illucens) (Diptera: Stratiomyidae) with house fly (Musca domestica) (Diptera: Muscidae)

@#Black soldier fly (Hermetia illucens (Linnaeus, 1758)) larvae inhibit oviposition of house fly (Musca domestica Linnaeus, 1758) by releasing a semiochemical, although in some situations, inhibition is only partial. We hypothesized that there is a certain period in the life cycle of black soldier fly when it can cause antibiosis of the house fly. Choice and non-choice tests were used to separately examine the effectiveness of each developmental stage of black soldier fly (egg, larval (phase I, II, and III), prepupal and pupal stages) and crude extract of larvae on house fly oviposition. Tests using each developmental stage were compared with controls lacking black soldier fly. The effects of black soldier fly on the number of newly hatched house fly larvae were evaluated and there was a significant difference between the test and control in the number of eggs laid by house fly for all phases of the black soldier fly larval stage. Strong inhibition was found in some black soldier fly larval phases. Significant differences in the numbers of house fly eggs oviposited in food containers treated with crude extract were found when compared with a control, confirming that chemicals from black soldier fly larvae resulted in inhibition of oviposition of house fly. The results from experiment also indicated that chemicals from black soldier larvae influenced the number of house fly larvae newly hatched from eggs.

Effects of hydrological cycles and water body connectivity on abundance and co-occurrence of two Neotropical Curculionidae species / Efeito do ciclo hidrológico e da conectividade das baías do Pantanal na abundância e co-ocorrência de duas espécies de Curculionidae Neotropical

Abstract: The effect of the hydrological cycle on the abundance of adults and larvae of the weevils Cyrtobagous salviniae and Cyrtobagous singularis in the Pantanal was tested and related to the host-plant abundance, limnological variables, and hydrological connectivity of 10 "bays" (lakes and ponds) along the Cuiabá River. Adults and larvae of C. salviniae were more abundant than C. singularis, and larvae and adult abundance differed significantly both within and between the two species. Adults and larvae of both species were more abundant in connected bays, but only C. salviniae responded to both connectivity and hydrological cycle, with the highest abundances during the high-water and rising-water periods for adults and larvae, respectively. Abundance of C. singularis was negatively related to the predominance of C. salviniae, and populations of adults and larvae of both species were slightly and negatively related to the limnological variables and host-plant abundance. The results showed that the temporal variation in larval and adult abundance and dominance of C. salviniae is influenced by hydrological cycle and connectivity, but not by limnological variables and host-plant abundance.

Resumo: O efeito do ciclo hidrológico sobre a abundância de adultos e larvas dos curculionídeos Cyrtobagous salviniae e Cyrtobagous singularis do Pantanal foi testado e relacionado com a abundância das plantas hospedeiras, variáveis limnológicas e conectividade hidrológica de 10 baías do rio Cuiabá. Os adultos e larvas de C. salviniae foram mais abundantes do que C. singularis, e a abundância de larvas e adultos diferiu significativamente intra e interespecificamente. Adultos e larvas de ambas espécies foram mais abundantes em baías conectadas, mas apenas C. salviniae respondeu ao ciclo hidrológico, com a maior abundância de adultos durante o período de cheia, e maior abundância de larvas na enchente. A abundância de C. singularis foi relacionada negativamente com a predominância de C. salviniae, e a abundância de adultos e larvas de ambas espécies foi fraca e negativamente relacionada com as variáveis limnológicas e abundância das plantas hospedeiras. Os resultados demonstraram que a variação temporal na abundância de larvas e adultos e a dominância de C. salviniae foram influenciadas pela conectividade e ciclo hidrológico, mas não pelas variáveis limnológicas e abundância das macrófitas aquáticas.

Aproximaciones experimentales para la evaluación de interacciones alelopáticas entre corales hermatípicos y cianobacterias marinas bentónicas en el Caribe Colombiano / Experimental approaches for the evaluation of allelopathic interactions between hermatypic corals and marine benthic cyanobacteria in the colombian caribbean

ABSTRACT Blooms of marine benthic cyanobacteria are recurrent in several locations at the Colombian Caribbean. In these events, cyanobacteria grow over the substrate and benthic organisms although their effect has not been fully assessed. This study evaluated interactions between cyanobacteria and hermatypic corals, in order to identify any deleterious effects that could be related to allelopathic mechanisms. Organic extracts from cyanobacteria collected in San Andres, Old Providence and Rosario islands were tested against embryos of the reef-building coral Orbicella annularis. The indirect effect of cyanobacterial extracts was also assessed by resuspending the extracts in seawater and monitoring polyp retraction and recovery of the coral Madracis mirabilis (=auretenra). Additionally, the effect of direct contact between cyanobacterial extracts and the coral Porites porites was assessed by incorporating cyanobacterial extracts into Phytagel™ gels and placed in direct contact with the coral. After 24, 48 and 72 h of exposure, chromatographic profiles of associated zooxanthellae was evaluated by HPLC. A deleterious effect on the zooxanthellae was evidenced by an increase in pheophytin, a degradation product from chlorophyll. The competitive abilities of algae and cyanobacteria should be considered as a constraint to reef restoration initiatives. Cyanobacteria have the ability to compete with corals due to their growth rates, defenses against herbivory and potentially allelopathic mechanisms.

RESUMEN Afloramientos de cianobacterias marinas bentónicas son recurrentes en varias localidades del Caribe colombiano. En estos eventos, las cianobacterias crecen sobre el sustrato y organismos bentónicos sin que su efecto se haya evaluado completamente. Este estudio evaluó interacciones entre cianobacterias y corales hermatípicos con el fin de identificar efectos perjudiciales que podrían estar relacionados con mecanismos alelopáticos. Extractos orgánicos de cianobacterias recolectadas en las islas de San Andrés, Providencia y las Islas del Rosario fueron evaluados contra embriones del coral hermatípico Orbicella annularis. También se evaluó el efecto indirecto de extractos de cianobacterias resuspendidos en agua de mar para determinar retracción de pólipos y recuperación del coral Madracis mirabilis (=auretenra). Adicionalmente, se evaluó el efecto del contacto directo de extractos de cianobacterias y el coral Porites porites mediante la incorporación de los extractos en geles de PhytagelTM dispuestos en contacto directo con el coral. Después de 24, 48 y 72 h de exposición, los perfiles cromatográficos de las zooxantelas asociadas al coral fueron evaluados por HPLC. Un efecto negativo sobre las zooxantelas se evidenció por el incremento en feofitina, producto de degradación de la clorofila. Las capacidades competitivas de algas y cianobacterias debieran considerarse como un factor que podría incidir negativamente en iniciativas de restauración arrecifal. Las cianobacterias tienen la capacidad de competir con corales debido a sus tasas de crecimiento, defensas contra herbivoría y potenciales mecanismos alelopáticos.

Interferência e nível de dano econômico de Brachiaria plantaginea e Ipomoea nil na cultura do feijão comum / Interference and economic threshold of Brachiaria plantaginea and Ipomoea nil in the common bean crop

As pesquisas acerca do impacto da interferência das plantas daninhas sobre as culturas normalmente são realizadas com uma única espécie infestante, quando na realidade podem ocorrer diversas. Os objetivos deste trabalho foram avaliar a interferência de Brachiaria plantaginea e Ipomoea nil sobre o rendimento de grãos do feijoeiro (Phaseolus vulgaris) e determinar o nível de dano econômico (NDE) de cada espécie na cultura. Foram realizados dois experimentos a campo com as cultivares de feijão 'IPR Graúna' (Grupo Preto) e 'UTF-06' (Grupo Carioca) em convivência com infestações mistas em diferentes proporções aleatórias das espécies B. plantaginea e I. nil. Modelos de regressão múltiplos foram utilizados para determinar a capacidade de interferência de cada espécie daninha sobre a produtividade da cultura. O impacto de interferência de cada planta de I. nil correspondeu a 2,6 e 0,25 quando comparada a cada planta de B. plantaginea, dependente das proporções relativas na comunidade infestante e das condições de cada experimento. A cultivar 'IPR Graúna' apresentou maior habilidade competitiva do que 'UTF-06'. O NDE foi dependente da proporção relativa de cada espécie daninha na comunidade e foi obtido sob baixas infestações (<16 plantas m-2) em todas as condições testadas e simuladas.

The researches about the impact of weed interference on crops are usually performed with a single weed species, when in reality there are numerous. The objective of this study was to evaluate the interference of Brachiaria plantaginea and Ipomoea nil on the grain yield of French beans (Phaseolus vulgaris) and to determine the economic weed threshold (EWT) of each species on the crop. Two field experiments were conducted with bean cultivars 'IPR Graúna' (Black group) and 'UTF-06' (Carioca group) in coexistence with random proportions of mixed infestations of B. plantaginea and I. nil. Multiple regression models were used to determine the interference abi1lity of each weed species on crop productivity. The interference ability of each plant of I. nil corresponded to 2.6 and 0.25 of each B. plantaginea, dependent on the relative proportions on the weed community and on the conditions of each experiment. Cultivar 'IPR Graúna' showed higher competitive ability than 'UTF-06'. The EWT was dependent on the relative proportion of each weed species in the community and was reached under low infestation (<16 plants m-2) in all conditions tested and simulated.

Residence advantage in heterospecific territorial disputes of Erythrodiplax Brauer species (Odonata, Libellulidae) / Vantagem do residente nas disputas territoriais interespecíficas entre espécies de Erythrodiplax (Odonata, Libellulidae)

Residence advantage in heterospecific territorial disputes of Erythrodiplax Brauer species (Odonata, Libellulidae). Territories are the outcome of interactions determining where and how long individuals settle. To odonate species, aggressive disputes are not so common since the outcome can be predetermined by advantages such as residency, age, and body size. However, it is possible to predict that at heterospecific disputes, larger body-sized or more aggressive species have some profits overcoming these individual advantages, generating patterns of species hierarchy. Here, I studied the aggressiveness of five Erythrodiplax species (Odonata, Libellulidae) during territorial disputes and verified if larger body-sized species are more aggressive than smaller ones or if the residence advantage prevails on the heterospecific disputes. Larger species were not more aggressive than smaller ones and winners of intra- and interspecific territorial disputes were defined mainly by the residence. So, the residence advantage between heterospecific opponents appears to prevail over any other asymmetry among these species. This pattern may occur because, despite the territorial behaviour in dragonfly males, heterospecific disputes may not increment male reproductive success because it may not increase their access to females.

Territórios resultam de interações comportamentais que determinam onde e por quanto tempo um indivíduo consegue se estabelecer. Para espécies de Odonata, as disputas agressivas entre machos são raras, pois, vantagens pré-existentes como idade, tamanho corporal ou residência definem o vencedor. Entretanto, é possível esperar que nas interações interespecíficas, espécies de maior tamanho corporal ou mais agressivas possam ter vantagens nas disputas, sobrepujando as vantagens individuais pré-existentes e gerando um padrão hierárquico entre as espécies. Neste trabalho, eu estudei a agressividade exibida por espécies de Erythrodiplax (Odonata, Libellulidae) e verifiquei se espécies maiores são mais agressivas ou se a vantagem do residente prevalece também nas disputas interespecíficas. Espécies maiores não são mais agressivas e os vencedores das disputas territoriais intra- e inter-específicas foram machos residentes. Logo, a vantagem do residente parece prevalecer sobre qualquer assimetria existente entre as espécies estudadas, o que pode ocorrer porque, apesar do comportamento territorial exibido por elas, o recurso defendido pelos machos é o acesso às fêmeas e vencer disputas interespecíficas pode não afetar positivamente o sucesso reprodutivo dos mesmos.