Industrial pollution affects behaviour of the leafmining moth Stigmella lapponica

Abstract

We explored the impacts of industrial air pollution on the behaviour of the leafmining moth Stigmella lapponica (Wocke) (Lepidoptera: Nepticulidae) by comparing the characteristics of larval gallery mines in mountain birch [Betula pubescens ssp. czerepanovii (Orlova) H€ amet-Ahti (Betulaceae)] leaves collected from unpolluted forests and from heavily polluted industrial barrens surrounding the copper-nickel smelter in Monchegorsk in north-western Russia. Population density of S. lapponica, survival of larvae, length of the completed mine, and width of its terminal part did not differ between polluted and unpolluted sites. Females in unpolluted sites only rarely (16%) oviposited on the apical half of the leaf and the larval mortality in mines that started in the apical part of the leaf was 83%. A significantly larger (38%) proportion of mines started in the apical half of the leaves in polluted sites, and the larval mortality in these mines was only 45%. The between-habitat difference in the choice of the oviposition sites by S. lapponica is the first demonstration of the adaptive plasticity of oviposition behaviour in a leafmining insect. This difference was not explained by specific leaf weight which did not vary within leaves. Larvae mining in polluted leaves extended 25% farther between turns, and the galleries turned more sharply than in unpolluted leaves. This result confirms the abilities of leafmining larvae to evaluate the quality of the ingested food and adjust their behaviour accordingly. Thus, pollution modifies both the preference of S. lapponica females for oviposition sites within a birch leaf and the behaviour of S. lapponica larvae mining these leaves. This is one of the first records of changes in insect behaviour in natural environment disturbed by industrial pollution.

Decreased losses of woody plant foliage to insects in large urban areas are explained by bird predation

“…The samples were taken to the laboratory, where they were sorted by species (using an online identification guide: Ellis, ) and then classified as either undamaged empty mines left by larvae which successfully completed their development (i.e., survived individuals) or mines containing dead larvae or opened by predators (i.e., dead individuals). Earlier studies demonstrated that mine size decreases, distance between the turns of larval gallery increases and angle of turns decreases with an increase in quality of plant foliage as a food for leafminers (Kozlov & Zvereva, ; Low & Hanley, ; Low et al., ; Stiling et al., ). Therefore, to compare plant quality between habitats, we studied undamaged empty mines of Stigmella confusella and Stigmella lapponica .…”

“…Therefore, to compare plant quality between habitats, we studied undamaged empty mines of Stigmella confusella and Stigmella lapponica . Twenty‐five randomly selected mines of each species from each habitat were measured following the protocol described by Kozlov and Zvereva (). Each mine was approximated by a broken line made up of straight segments following the line of excrements as closely as possible (8–61 segments per mine).…”

Poleward increase in feeding efficiency of leafminer Stigmella lapponica (Lepidoptera: Nepticulidae) in a latitudinal gradient crossing a boreal forest zone

“…The standard instruments of Adobe PhotoShop 2020 were used to measure the length of each segment (to the nearest 0.06 mm) and the angle between two adjacent segments (to the nearest 1°). The segment length and the angles of the turns of the mine (excluding those at the intersections with leaf veins) were averaged for each mine prior to analysis following the protocol developed by Kozlov and Zvereva (2016).…”

“…In northern Europe, mines of S. lapponica are equally frequent on B. pubescens and B. pendula, and the mine densities (per unit of host biomass) decrease toward the north (Kozlov et al, 2013). Females preferentially oviposit on the basal half of a leaf, but they relax this preference in areas affected by severe industrial pollution (Kozlov & Zvereva, 2016).…”

“…on their preferences of a particular part of a leaf), as well as on the amount of food consumed by a larva and on its size at the end of larval development (Boomsma et al, 1987;Zvereva & Kozlov, 2006;Morton & Pereyra, 2011). Previous studies have suggested that different factors, such as leaf fluctuating asymmetry (FA) and mine shape, can serve as indicators of leaf quality for a miner (Cornelissen & Stiling, 2005;Kozlov & Zvereva, 2016). Therefore, leafmining insects are ideally suited for studying plant-herbivore interactions along geographical gradients.…”