Processes involved in biochemical response to pesticides by lizard Podarcis siculus (Rafinesque-Schmaltz, 1810) - A field study.

Although reptiles are non-target organisms of pesticide applications, their ecological niche and trophic role suggest that the use of these compounds in agriculture can have toxicological effects on them. Our recent field study on Italian wall lizard Podarcis siculus in hazelnut orchards evidenced that the use of pesticides-mixtures, consisting of thiophanate-methyl (TM), tebuconazole (TEB), deltamethrin (DM), lambda-cyhalothrin (LCT), besides copper sulphate, induced an increase of the total antioxidant capacity toward hydroxyl radicals and caused DNA damage; however, it did not cause neurotoxicity, and did not induce the glutathione-S-transferases' activities. These results raised some questions which were answered in this study by carrying out analyses on 4 biomarkers and 5 chemical substances in the tissues of non-target organisms coming from treated fields: cytochrome P450, catalase, total glutathione, and malondialdehyde, TM, TEB, DM, LCT and Cu. Our results highlighted a partial accumulation of different chemicals, the involvement of two important mechanisms of defence, and some cellular damages after exposure to the considered pesticides. In details, 1) LCT and DM were not accumulated in lizard muscle, copper remained at basal levels, whereas TM and TEB were uptaken with a partial metabolization of TM; 2) the cytochrome P450 and the catalase were involved in lizard biochemical responses to pesticides-mixtures used for "conventional" farming treatment; 3) "conventional" treatment with pesticides caused damage to lipids, besides DNA, probably related to the excess of hydroxyl radicals.

Linking agricultural practices to lizard trophic behaviour: An ecological approach.

Among intensive agricultural practices, pesticides, mowing, and heavy agricultural machineries have become an important tool to maximize harvesting and secure animal husbandry. However, they are also cause of agricultural ecosystem decline, often leading to degradation of key micro-habitat features for many species, higher predation risk and lower food availability. We investigated the diet and foraging ecology of the Italian wall lizard in agricultural areas to determine whether different management practices (conventional, organic, and control) can affect (i) the structure of the trophic niche of the species; (ii) prey diversity, the degree of individual specialization, and the overall population feeding strategy; (iii) lizards' health status. Faecal pellets were collected for diet composition analyses, while prey diversity in the environment was estimated by placing adhesive traps. Lizards' body condition did not differ among management type although males from control field resulted slightly larger than those from conventional and organic areas. The species showed a generalist (conventional and organic areas) and mixed (control area) feeding strategy with a preference for coleopterans. Although a different prey diversity was found in control areas compared to organic and conventional ones, diet composition and the importance of specific food items was similar among management types. This may suggest that management activities may have affected the overall prey availability and indirectly influenced lizard trophic behaviour. Our study provides a comprehensive knowledge on the feeding ecology of P. siculus in managed habitats, which may have useful implications for the overall conservation of lizards in agricultural environments.

Biological responses in pesticide exposed lizards (Podarcis siculus).

The release of contaminants as herbicides, fungicides and insecticides into the environment has been listed as one of the six major contributors to the global decline of reptiles. Although reptiles may face severe risk from contaminants due to their ecology and physiology, they are currently less studied than other vertebrate groups. In the present work, we investigated if and how different types of field treatment (conventional and organic) affected the health status of Italian wall lizard (Podarcis siculus) individuals in central Italy. We chose a multi-biomarker approach that evaluated the biological responses of lizards to the treatment by means of AChE activity in the nervous system, biotransformation enzymes activities and oxidative stress in the liver, micronuclei frequency measured in the erythrocytes, and rate of intestinal parasitic infection. Our findings showed evidence of effects of treatment in conventional areas and between sexes with significant oxidative stress due to hydroxyl radicals, that caused DNA damage. No difference of intestinal parasite infections was found among treatments. Podarcis siculus seems to be a good bioindicator in ecotoxicological studies and potentially in risk assessment of pesticides, although further analyses in laboratory and in the field are needed to achieve more accurate quantification of specific pesticide effects in relation to known exposure history and to understand if other mechanisms were involved in the toxicity and detoxification process of pesticides for this species.

Fluctuating asymmetry as biomarker of pesticides exposure in the Italian wall lizards (Podarcis siculus).

The extensive use of pesticides in agricultural environments produces drastic effects on wildlife, hence the need for less invasive indicators of environmental stress to monitoring the impact of agriculture treatments on biological systems. Fluctuating asymmetry (FA), as measure of developmental instability, has recently been proposed as reliable biomarker of populations stress due to environmental disturbance. We investigate femoral pores (FP) and dorsal head shape (HS) traits in populations of the Italian wall lizard inhabiting agricultural environments to examine whether different pesticide exposures (conventional, organic and control) can cause distinctive degree of FA. High-resolution photographs of FP and HS were taken in the field with a digital camera. The number of FP were counted twice on both sides and HS was analysed using geometric morphometrics with 25 landmarks and 12 semilandmarks. Individuals under conventional management showed higher levels of FA compared to control ones, and females exhibited higher FA levels than males for the FP. However, no significant difference was found for the HS trait. Our study provided evidence that FA may have a real potential as biomarker of population stress in wall lizards, highlighting the importance in the choice of the experimental design and the traits adopted for estimating DI.

First molecular identification of the tapeworm Mesocestoides litteratus from an Italian wall lizard (Podarcis siculus).

The cyclophyllidean cestodes of the genus Mesocestoides are parasites infecting a variety of carnivorous vertebrates. The complete life cycle of these tapeworms is not clear yet, but some reptiles, amphibians, birds and micro-mammals have been indicated as intermediate hosts. Although Mesocestoides spp. are considered endemic in Europe, infections by the metacestode form, the tetrathyridium, are reported less commonly than are infections by adult worms. In the present study, a peritoneal infection by Mesocestoides tetrathyridia in a wall lizard (Podarcis siculus) collected in central Italy is described. The phylogenetic position of the metacestodes was assessed using the barcode region COI and species delimitation methods, i.e. Automatic Barcode Gap Discovery (ABGD) and Bayesian implementation of the Poisson Tree Processes model (bPTP). COI sequence analysis assigned the isolates from the wall lizard to Mesocestoides litteratus, as confirmed by species delimitation and phylogenetic analyses. M. litteratus has been observed in Europe mainly in the definitive hosts (dogs, cats and foxes), and never identified in the Mediterranean region. This study represents the first evidence of parasitic infection by tetrathyridia of M. litteratus in P. siculus in Italy.