Coccinellids are important aphid predators in horticultural crops around the world and are used in classical (Rondoni et al. 2021) and augmentative (Albajes et al. 2002) biological control programs. In the Neotropical region several species have deserved attention as potential biological control agents mainly in horticultural crops (Zalazar and Salvo 2007; Dode and Romero Sueldo 2013; Fonseca et al. 2017; Dos Santos et al. 2020).
The more frequent aphidophagous coccinellids in argentinian horticultural crops are the natives Cycloneda sanguinea L., Eriopis connexa (Germar), and Coleomegilla quadrifasciata octodecimpustulata (Mulsant), and the exotic Harmonia axyridis (Pallas) (Del Pino et al. 2012; Rizzo, 2020). Cycloneda sanguinea, E. connexa and C. quadrifasciata octodecimpustulata have Neotropical distribution (González 2014), and these species are present in several crops as corn, sunflower, alfalfa, fruit trees, horticultural crops, and spontaneous vegetation (Saini 2004; Engel et al. 2020; Castresana and Paz 2019). The first two coccinellid species can be considered good aphid control agents as they have high consumption rates on aphid species frequently found in horticultural crops (Rocca et al. 2017, 2021). Coleomegilla quadrifasciata octodecimpustulata is a more generalist predator, feeding on immature and adult prey, including aphids, thrips, scale insects, psyllids, whiteflies, mites, and eggs and immature stages of coleopterans and lepidopterans (Lixa et al. 2010), and its potential as biological control agents have not been studied. On the other hand, H. axyridis, native to Asia, is widely distributed worldwide (Camacho-Cervantes et al. 2017; Roy et al. 2016), and it has been introduced as a biological control agent or accidentally in many countries. Due to several traits -larger size than other coccinellids, high predatory capacity, high fecundity and fertility, superior competitive ability in relation to other coccinellid species by exploitation and interference - it became an invasive exotic species and could displace several native coccinellids (Roy et al. 2016; Brown and Roy 2018). In South America, there are reports of such displacements of native species in Chile and Brazil (Grez et al. 2016; Martins et al. 2009). In Argentina this species was introduced in 1986 (García et al. 1999) and nowadays it is widely distributed in the country (Wagner et al. 2017; Werenkraut et al. 2020).
The temporal and spatial cooccurrence of different species of coccinellids creates opportunities for intraguild predation that could negatively affects their coexistence (Schellhorn and Andow 1999; Burgio et al. 2002; Michaud 2002). This interaction is usually bidirectional and asymmetric (Michaud and Grant 2003), and its outcome is determined by several factors such as species identity, developmental stages, relative body size, mobility, behavior, and encounter rates of the individuals who participate in the interaction (Lucas et al. 1998; Lucas 2012). In turn, different developmental stages exhibit different degrees of susceptibility to intraguild predation, being eggs, small larvae, pupae, and molting stages especially susceptible (Hodek and Evans 2012). It is known, for example, that H. axyridis exerts a strong asymmetric intraguild predation on eggs and larvae of C. sanguinea (Michaud 2002) and E. connexa (Mirande et al. 2015), and Rocca et al. (2017, 2019) found asymmetric intraguild predation between E. connexa and C. sanguinea, being the former the strongest intraguild predator on eggs and larvae of C. sanguinea. However, the interaction between C. quadrifasciata octodecimpustulata and the other three species is already unknown. The knowledge of the cooccurrence of C. sanguinea, E. connexa, C. quadrifasciata octodecimpustulata, and H. axyridis in horticultural crops, as well as the intraguild predation between them, is relevant to develop efficient biological control programs involving native biological control agents in the presence of exotic species.
We studied the spatial and temporal cooccurrence of these coccinellid species in eggplant crop, Solanum melongena L. (Solanaceae), which is economically important in many countries of the world and also in Argentina (CHBA 2005). This crop, like many other horticultural crops, is affected by the aphids Aphis gossypii (Glover) and Myzus persicae (Sulzer) (Del Pino et al. 2012; Rizzo, 2020), that extract the sap from the plants and reduce their photosynthetic capacity, deform the tender shoots, produce honeydew leading to the development of sooty mold, and also and most important, they are vectors of viruses (Srinivasan 2009). The aims of this work were: 1) to describe the abundance of H. axyridis, C. sanguinea, E. connexa, and C. quadrifasciata octodecimpustulata, and the spatial and temporal cooccurrence of these species in the eggplant crop, and 2) to estimate, in the laboratory, the intensity and symmetry of the IGP between C. quadrifasciata octodecimpustulata and the other coccinellid species.