Copper is an essential metal that occurs chronically in the environment and affects the development and physiology of aquatic insects. In excess amounts, it can impair their nervous system and behaviour. We tested the anti-predatory behaviour of Cx. pipiens larvae after seven days exposure with several concentrations of copper up to 500 mg L−1. We measured responses to non- consumptive (predation cues) and consumptive predation (dragonfly larvae) across two generations. We also tested the accumulated effect of copper on AChE enzyme activity. We exposed half of treated and control larvae to predation cues (water with predator odour and crushed conspecifics) and the other half to water without predation cues. We evaluated total distance moved and velocity. Copper reduced the distance moved and velocity, with stronger effects in the second generation. Copper had no significant effect on larvae eaten by dragonflies. Copper inhibited the AChE enzyme across both generations at 500 µg L−1. Copper can affect the nervous system directly by inhibiting AChE activity, and possibly also by impairing the olfaction sensors of the larvae, resulting in larval inability to detect predation cues.
Natural interactions between herbivorous insect pests and their host plants are expected to be altered significantly as atmospheric CO2 concentrations (aCO2) continue to rise according to climate change scenario. The possible effect of enriched CO2 (eCO2) environments on these interactions is under attention. To better understand such effects on select insect growth parameters; early (3rd) and penultimate (6th) instar larvae of the Cotton Leaf Worm Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae), reared on the cotton plant leaves Gossypium barbadense L. (Malvacae) grown under either ambient (aCO2 = 350 ppm) or enriched (eCO2 = 700 ppm) atmospheres were investigated.
A study was conducted on assemblies of various orthopteran species from distinct habitats in the Satoyama region, Kanazawa City, Ishikawa Prefecture, Japan, and a total of 50 distinct orthopteran species were registered. These species were represented by 10 families and were belonged to 17 subfamilies and 27 tribes. Results based on stereo-microscopic examination of the mandibular morphology and the analysis of gut contents suggested seven proposed feeding groups for these collected orthopteran species. Among the examined subfamilies, family Tettigoniidae proved to be the most diverse in mandibular structure and four feeding groups were assigned. This was followed by family Acrididae, which showed three feeding groups. Other families contained only single feeding group. It was noted that only five species, from family Acrididae, were graminivorous with their mandibles characterized by comparatively very short incisors and relatively wide molar regions. The analysis of gut contents of these five species proved to contain more than 80% monocotyledonous plant species. Predation and scavenging as feeding habits were also recorded in some orthopteran species.