Evidences that human disturbance simplify the ant fauna associated a Stachytarpheta glabra Cham. (Verbenaceae) compromising the benefits of ant-plant mutualism

Interaction among species, like ants and plants through extrafloral nectaries (EFNs), are important components of ecological communities’ evolution. However, the effect of human disturbance on such specific interactions and its ecological consequences is poorly understood. This study evaluated the outcomes of mutualism between ants and the EFN-bearing plant Stachytarpheta glabra under anthropogenic disturbance. We compared the arthropod fauna composition between two groups of twenty plant individuals, one in an area disturbed by human activities and one in a preserved area. We also check the plant investment in herbivory defense and the consequential leaf damage by herbivore. Our results indicate that such disturbances cause simplification of the associated fauna and lack of proper ant mutualist. This led to four times more herbivory on plants of disturbed areas, despite the equal amount of EFN and ant visitors and low abundance of herbivores. The high pressure of herbivory may difficult the re-establishment of S. glabra, an important pioneer species in ferruginous fields, therefore it may affect resilience of this fragile ecological community.As interações entre espécies, como por exemplo formigas e plantas através de nectários extraflorais (NEFs), são importantes componentes na evolução das comunidades. Entretanto, pouco é conhecido sobre os efeitos dos impactos antrópicos em interações específicas e suas consequências ecológicas. Este estudo avaliou os resultados do mutualismo entre formigas e NEF em Stachytarpheta glabra em área impactada pela atividade humana. Nós comparamos a composição e estrutura da fauna de artrópodes, em quarenta plantas de dois grupos, um impactado por atividades humanas e o outro preservado. Nós também avaliamos o investimento da planta em defesas contra herbívoros e os danos foliares causados por herbívoros. Nossos resultados indicam que os distúrbios causam a simplificação da fauna associada e a ausência de uma formiga mutualista anti-herbívoros. Isto leva a quatro vezes mais herbivoria nas plantas da área impactada, a despeito da mesma quantidade encontrada para NEF e formigas visitantes. A grande pressão de herbivoria pode dificultar o reestabelecimento de S. glabra, uma espécie pioneira importante nos campos ferruginosos, dessa forma, afetando a resiliência dessa comunidade ecológica ameaçada

Ceratocystis wilt pathogens: History and biology-highlighting C. Cacaofunesta, the causal agent of wilt disease of cacao

Ceratocystis is a genus of ascomycete fungi that includes aggressive pathogens of economically important plants worldwide. This fungus is the causal agent of Ceratocystis wilt disease and canker disease, which often kills the plant causing major losses in agricultural production. In the last two decades, emerging diseases related to Ceratocystis infections have been greatly increased. Ceratocystis wilt of cacao is caused by C. cacaofunesta, one of the three well-established host-specific pathogens in the genus. Ceratocystis wilt of cacao has caused sporadic epidemics in the Americas, but its importance is often underestimated. Furthermore, the disease represents a serious threat to the world’s cacao production due to the risk of pathogen spread. Silvicultural practices in cacao agroforests, the marketing of seeds, and cacao grafting in association with a minimal knowledge of the biology of the pathogen effectively contributed to this threat. This chapter explores the controversial taxonomic and evolutionary history of the genus Ceratocystis as well as the biology of C. cacaofunesta. © Springer International Publishing Switzerland 2016