Search results for "Insects"

Automatic image‐based identification and biomass estimation of invertebrates

2020

Understanding how biological communities respond to environmental changes is a key challenge in ecology and ecosystem management. The apparent decline of insect populations necessitates more biomonitoring but the time-consuming sorting and expert-based identification of taxa pose strong limitations on how many insect samples can be processed. In turn, this affects the scale of efforts to map and monitor invertebrate diversity altogether. Given recent advances in computer vision, we propose to enhance the standard human expert-based identification approach involving manual sorting and identification with an automatic image-based technology. We describe a robot-enabled image-based identificat…

Natural enemies emerging in cereal fields in spring may contribute to biological control

2022

1.Biological pest control is known to depend on landscape heterogeneity. However, such relationship shows irregular pattern and seems influenced by local farming practices and natural enemies that overwinter within crop fields. The objective of this study was to assess the contribution of emerging natural enemies in spring to biological control, and their response to the interaction between landscape heterogeneity and farming intensity. 2.We monitored the overwintering insect community using emergence traps and measured the local potential pest predation using prey cards in 30 cereal fields, in spring in France. Study fields were selected along a landscape heterogeneity gradient and farming…

Data from: Collective defence portfolios of ant hosts shift with social parasite pressure

2014

Host defences become increasingly costly as parasites breach successive lines of defence. Because selection favours hosts that successfully resist parasitism at the lowest possible cost, escalating coevolutionary arms races are likely to drive host defence portfolios towards ever more expensive strategies. We investigated the interplay between host defence portfolios and social parasite pressure by comparing 17 populations of two Temnothorax ant species. When successful, collective aggression not only prevents parasitation but also spares host colonies the cost of searching for and moving to a new nest site. However, once parasites breach the host's nest defence, host colonies should resort…

Data from: Fitness costs of worker specialisation for ant societies

2015

Division of labour is of fundamental importance for the success of societies, yet little is known about how individual specialization affects the fitness of the group as a whole. While specialized workers may be more efficient in the tasks they perform than generalists, they may also lack the flexibility to respond to rapid shifts in task needs. Such rigidity could impose fitness costs when societies face dynamic and unpredictable events, such as an attack by socially parasitic slavemakers. Here, we experimentally assess the colony-level fitness consequences of behavioural specialization in Temnothorax longispinosus ants that are attacked by the slavemaker ant T. americanus. We manipulated …

Data from: The parasite’s long arm: a tapeworm parasite induces behavioural changes in uninfected group members of its social host

2015

Parasites can induce alterations in host phenotypes in order to enhance their own survival and transmission. Parasites of social insects might not only benefit from altering their individual hosts, but also from inducing changes in uninfected group members. Temnothorax nylanderi ant workers infected with the tapeworm Anomotaenia brevis are known to be chemically distinct from nestmates and do not contribute to colony fitness, but are tolerated in their colonies and well cared-for. Here, we investigated how infected workers affect colony aggression by manipulating the presence of tapeworm-infected workers and analysing whether their absence or presence resulted in behavioural alterations in …

Data from: Gene expression is more strongly associated with behavioural specialisation than with age or fertility in ant workers

2018

The ecological success of social insects is based on division of labour, not only between queens and workers, but also among workers. Whether a worker tends the brood or forages is influenced by age, fertility and nutritional status, with brood carers being younger, more fecund and more corpulent. Here, we experimentally disentangle behavioural specialisation from age and fertility in Temnothorax longispinosus ant workers and analyse how these parameters are linked to whole-body gene expression. A total of 3644 genes were associated with behavioural specialisation which is ten times more than associated with age and 50 times more than associated with fertility. Brood carers were characteriz…

Bioenergy willow: protection from the negative impact of biological factors

2017

W rozdziale przedstawiono wyniki badań patologii bakteryjnych oraz grzybicowych wierzby, oraz szkodników i chwastów, które prowadzą do zaginięcia roślin lub znacznego spadku plonu biomasy plantacji energetycznych. Wyświetlono metody ochrony i zapobiegania.

Subtropical streams harbour higher genus richness and lower abundance of insects compared to boreal streams, but scale matters

2018

Aim: Biological diversity typically varies between climatically different regions, and regions closer to the equator often support higher numbers of taxa than those closer to the poles. However, these trends have been assessed for a few organism groups, and the existing studies have rarely been based on extensive identical surveys in different climatic regions. Location: We conducted standardized surveys of wadeable streams in a boreal (western Finland) and a subtropical (south-eastern Brazil) region, sampling insects identically from 100 streams in each region and measuring the same environmental variables in both regions. Taxon: Aquatic insects. Methods: Comparisons were made at the scale…

Monitoraggio e valutazione del danno degli insetti defogliatori su diverse specie di Quercus in Sicilia

Most of the insects feeding on oaks are usually ‘in balance’ with their host trees, causing occasional damage. When severe defoliations regularly occur, oak trees vulnerability to the complex of factors causing the overall decline syndrome can increase. Assessing canopy damage due to defoliating insects through the usually adopted visual methods is quite difficult, requiring highly experienced operators and a long time spent to collect field data. The present research has been carried out to investigate the different susceptibility of Sicilian oak species to defoliating insect attacks, in particular the oak moth Tortrix viridana (L.) (Lepidoptera Tortricidae), with the aim to assess the rel…

Testing the effectiveness of pyrazine defences against spiders

2020

Insects live in a dangerous world and may fall prey to a wide variety of predators, encompassing multiple taxa. As a result, selection may favour defences that are effective against multiple predator types, or target-specific defences that can reduce predation risk from particular groups of predators. Given the variation in sensory systems and hunting tactics, in particular between vertebrate and invertebrate predators, it is not always clear whether defences, such as chemical defences, that are effective against one group will be so against another. Despite this, the majority of research to date has focused on the role of a single predator species when considering the evolution of defended…