The Effect of Arthropod Biomass on Lizard Abundance

The effects of biocontrol and the potential risks associated with them are of interest to many researchers. In the Virgin River area of Nevada, natural resource managers have done studies of various removal techniques on the non-native Tamarix spp. strands. One such area of focus is the use of biocontrol in the form of the tamarisk leaf beetle (Diorhabda spp.), and the resulting changes in the environment from the defoliation of the trees. Previous studies have shown that removal of the plants can potentially be beneficial to lizards. But do changes in the environment change the amount of food available? We were interested to see if the amount of arthropod biomass from these areas had a relationship with the lizard abundance. Taking arthropod collection data from the Virgin River, we compared it with arthropod data over several years, before and after Diorhabda was introduced in 2010. Arthropod biomass data was obtained by taking the collected arthropods and drying them in an oven and weighing them. Results show that there is no correlation between the arthropod numbers or biomass with the amount of lizards in the area, that biomass was greatest after biocontrol introduction, and biomass was highest in mixed Tamarix and native tree strands versus just Tamarix strands. In conclusion, arthropod numbers and biomass have shown to be a poor indicator of lizard abundance, and factors such as temperature changes in the environment might be a better indicator of the changing abundance of lizards.