Diversity and phenology of epigeal Coleoptera assemblages in lettuce and tomato crops in Northern Buenos Aires province, Argentina

Abstract

Epigeic coleopteran species are linked by complex trophic webs and implicated in several ecosystem services for agriculture. Although there are reports of grounddwelling Coleopterans inhabiting main extensive agroecosystems, their assemblages in horticultural crops in Argentina have been little explored. We examined the community structure of epigeal Coleoptera assemblages of Curculionidae, Carabidae, Staphylinidae and Coccinellidae species, in lettuce and tomato crops located in Northern Buenos Aires province, over a 3-year sampling period (2010 to 2013) by using pit-fall traps. Crop species and cycles, and phytosanitary measures (conventional and organic farming), were main factors considered as infl uencing the insect species composition, abundance and seasonal occurrence in the assemblages. Seventy coleopteran species were identifi ed. The curculionids Ceutorhynchini sp. and Phyrdenus muriceus (Germar), the carabid Scarithes anthracinus Dejean, the coccinelid Eriopis connexa (Germar) and the staphylinids Aleochara sp. and Aleochara obscurus Bernhauer are the most common species in lettuce and tomato crops in the region studied. Especially the carabids, staphylinids and E. connexa are known act as natural enemies of several pests in the agroecosystems studied. Coleopteran assemblages found in lettuce differed from those associated to tomato crops, being the cropping season the main factor that infl uenced the community structure.

Disentangling the Benefits of Organic Farming for Beetle Communities (Insecta: Coleoptera) in Traditional Fruit Orchards

“…According to previous studies [6,[70][71][72][73], our results showed that coleopteran communities are highly correlated with plant communities. Conventional orchards were very similar in their composition of plants and beetles, again illustrating how the constraining nature of management practices leads to more homogeneous communities [24,54,74]. Organic orchards, however, showed a more heterogeneous composition; moreover, orchards located on the same hillside aspect seemed to harbor slightly more similar plant and beetle communities.…”

“…These species have a natural tolerance for some herbicides or exhibit traits that allow them to withstand the negative effects of this treatment [74]. In our examination of coleopterans, families that exploit widely distributed resources, such as Coccinellidae or Curculionidae, contributed more to the structure of conventional orchards, reflecting how more generalist beetles are less constrained by management practices such as weed and pest control [24,77].…”

“…Among the processes mentioned, pesticide application is considered one of the biggest drivers of insect decline. This is mainly due to the impact of insecticides via lethal and sub-lethal effects; however, it also results from the alteration of habitat features caused by herbicides since plant species composition, strongly affected by this management practice, commonly shapes insect communities [18,[22][23][24].…”

“…Coleopterans are trophically diverse insects that occur in high abundance and richness in cropped areas and are very sensitive to environmental changes [6,24,[37][38][39]. Consequently, they are one of the most studied groups of insects in agricultural systems.…”