Plant-Insect Interactions on Dicots and Ferns From the Miocene of Argentina

Abstract

The study of plant-insect interactions provides valuable information about the ecology of feeding behavior and the relationships between the host plant and the producer insect. Records of feeding traces are relatively rare for the Miocene of South America. Here, new records of plant-insect interactions on dicot leaves and fern fronds from the middle and late Miocene of Argentina are presented. In total, 1204 dicot and fern impressions were analyzed including 384 from the San José Formation and 856 from the Palo Pintado Formation. Traces of arthropod herbivory are found on 303 foliar impressions, 288 from the Palo Pintado Formation and just 15 from the San José Formation. Forty-four percent of all traces were found on Thelypteris interrupta (Willd.) Iwatsuki 1963 (Thelypteridaceae), followed by Cedrela fissiliformis Anzótegui and Horn 2011 (Meliaceae) (15.1%) and Schinus herbstii Anzótegui 1998 (Anacardiaceae) (11.3%). Thelypteris interrupta is associated with a low diversity of Damage Types, mainly hole and window feedings, indicating a monospecific relationship with the trace maker. On the other hand, the high abundance and diversity of damage types found on C. fissiliformis and S. herbstii denote that these plants were hosting a more diverse group of arthropods. Likewise, the lower number of traces identified in the San José Formation corresponds to the xeric conditions established during the middle Miocene in northwestern Argentina. These conditions changed in the late Miocene, at least in some regions, to a humid climate, promoting an increase in phytophagy that is evidenced by the abundance recorded in the Palo Pintado Formation.

Insect herbivory immediately before the eclipse of the gymnosperms: The Dawangzhangzi plant assemblage of Northeastern China

“…Feeding event occurrences, a metric introduced earlier (Robledo et al ., 2018) and later expanded in a different form (Xiao et al ., 2021), consists of 3 814 separate feeding events in the total dataset (Table 1; Appendix S11). When these data are partitioned by FFG, the first to third ranks are oviposition (45.25%), piercing and sucking (28.03%), and mining (11.27%), accounting for 84.56% of feeding event occurrences and indicating a pattern similar to DT frequency.…”

“…Like herbivorized surface area, feeding event occurrences provide data for determining interaction strengths (frequencies) between a source plant and each of its DT links (see Swain et al, 2021). An earlier version of feeding event occurrences was used to measure insect feeding damage (Robledo et al, 2018); however, unlike the version presented here, it was based not on insect feeding behavior but rather on identification of ichnotaxa.…”

Generating and testing hypotheses about the fossil record of insect herbivory with a theoretical ecospace

“…Examples discussed here include the proportion of feeding occurrences belonging to external foliage feeding and to piercing and sucking; damage type evenness; damage type evenness compared to floral evenness; floral diversity; damage type diversity compared to floral diversity; and the prevalence of each functional feeding group, best quantified through the amount of herbivorized surface area. Feeding occurrences are defined here as the number of times that a damage type occurs on an individual plant specimen; these data are rarely collected in studies of fossil herbivory (Robledo et al, 2018;Ma et al, 2020).…”

“…Some floral assemblages do not contain any seeds and other non-foliar specimens, and of those that do, the non-foliar specimens may or may not be included in published datasets. Within angiosperm-dominated floras, ferns, gymnosperms, and monocots may (Robledo et al, 2018;Giraldo et al, 2021) or may not (Azevedo Schmidt et al, 2019;Currano et al, 2019) be examined. Criteria for inclusion in comparative analyses can even vary within the same research group, with some workers using a wider definition of foliage that includes needles, liverworts, phyllids, photosynthetic wings of seeds, and even flattened horsetail axes (Prevec et al, 2009;Labandeira et al, 2018), and others using a narrower definition restricted to multi-veined broad leaves or leaves with a defined midvein (Schachat et al, 2014(Schachat et al, , 2015(Schachat et al, , 2018(Schachat et al, , 2020.…”

Generating and testing hypotheses about the fossil record of insect herbivory with a theoretical ecospace

“…Some floral assemblages do not contain any seeds and other non-foliar specimens, and of those that do, the non-foliar specimens may or may not be included in published datasets. Within angiosperm-dominated floras, ferns, gymnosperms, and monocots may (Robledo et al, 2018;Giraldo et al, 2021) or may not (Azevedo Schmidt et al, 2019;Currano et al, 2019) be examined. Criteria for inclusion in comparative analyses can even vary within the same research group, with some workers using a wider definition of foliage that includes needles, liverworts, phyllids, photosynthetic wings of seeds, and even flattened horsetail axes (Prevec et al, 2009;Labandeira et al, 2018), and others using a narrower definition restricted to multi-veined broad leaves or leaves with a defined midvein (Schachat et al, 2014(Schachat et al, , 2015(Schachat et al, , 2018(Schachat et al, , 2020.…”