The impacts of metals and metalloids on insect behavior

Abstract

In toxicology studies, the use of death as an endpoint often fails to capture the effects a pollutant has on disruptions of ecosystem services by changing an animal's behavior. Many toxicants can cause population extinctions of insect species at concentrations well below the EC 25 , EC 50 , or EC 90 concentrations traditionally reported from short-term bioassays. A surprising number of species cannot detect metal and metalloid contamination, and do not always avoid food with significant metal concentrations. This frequently leads to modified ingestion, locomotor, and reproductive behaviors. For example, some species show a tendency to increase locomotor behaviors to escape from locations with elevated metal pollution, whereas other insects greatly decrease all movements unrelated to feeding. Still others exhibit behaviors resulting in increased susceptibility to predation, including a positive phototaxis causing immatures to move to exposed positions. For purposes of reproduction, the inability to avoid even moderately polluted sites when ovipositing can lead to egg loss and reduced fitness of offspring. Ultimately, impaired behaviors result in a general reduction in population sizes and species diversity at contaminated sites, the exceptions being those species tolerating contamination that become dominant. Regardless, ecosystem services, such as herbivory, detritus reduction, or food production for higher trophic levels, are disrupted. This review evaluates the effects of metal and metalloid pollution on insect behaviors in both terrestrial and aquatic systems reported in a diverse literature scattered across many scientific disciplines. Behaviors are grouped by ingestion, taxis, and oviposition. We conclude that understanding how insect behavior is modified is necessary to assess the full scope and importance of metal and metalloid contamination.

Extensive Variation in Cadmium Tolerance and Accumulation among Populations of Chamaecrista fasciculata

“…These characteristics indicate that this population has potential as a cadmium hyperaccumulator. Our findings of between-population variation in accumulation are consistent with previous research that has demonstrated that cadmium accumulation varies widely between populations [55], and that cadmium hyperaccumulation may be a population-specific rather than species-wide trait [25]. To our knowledge, there is no current available information about the distribution or presence of partridge pea populations in cadmium-contaminated soils.…”

Effect of lead and cadmium ions upon the pupariation and morphological changes in Calliphora vicina (Diptera, Calliphoridae)

“…This is in accord with Morgen and Trumble (2010), indicating that high metal concentrations frequently lead to modified ingestion, locomotor and reproductive disturbances (decreased egg laying and reduced fitness of offspring). However, C. vicina can be classified as a heavy metal-tolerant insect, with adaptations enabling to tolerate exposure to relatively high concentrations of some heavy metals (Gall et al, 2015).…”

Prior host feeding experience influences ovipositional but not feeding preference in a polyphagous insect herbivore

“…Zinc, known to negatively affect insect feeding and behavior (Mogren & Trumble, 2010), had a negative effect on leaf consumption by O. sulcatus in our study. It was not demonstrated whether such relationships hold true in no-choice situations, but the fact that blackcurrant had the highest concentrations of C and Zn, two conditions known to negatively affect insect performance (Awmack & Leather, 2002;Mogren & Trumble, 2010), is compatible with it being an inferior host in which plant chemistry was influencing O. sulcatus. It was not demonstrated whether such relationships hold true in no-choice situations, but the fact that blackcurrant had the highest concentrations of C and Zn, two conditions known to negatively affect insect performance (Awmack & Leather, 2002;Mogren & Trumble, 2010), is compatible with it being an inferior host in which plant chemistry was influencing O. sulcatus.…”