Invader Competition with Local Competitors: Displacement or Coexistence among the Invasive Khapra Beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae), and Two Other Major Stored-Grain Beetles?

Abstract

Local potential competitor species are important determinants of the invasibility of an environment even when widely recognized invasive species are concerned since it may compromise its establishment. Thus, the outcome of the direct competition among the invasive khapra beetle, Trogoderma granarium, and the cosmopolitan species lesser grain borer, Rhyzopertha dominica and rice weevil, Sitophilus oryzae, and thus the likelihood of establishment of T. granarium under their co-occurrence, was here explored in paddy rice and wheat, at temperatures between 25 and 35°C and through 200 days of storage. Insect infestations were higher in wheat rather than in paddy rice. Trogoderma granarium was unable to displace any of the competing species under two and three-species competition experiments retaining lower adult population than both local competitors at the lowest temperature level. Rhyzopertha dominica prevailed in paddy rice, while S. oryzae prevailed in wheat. Paradoxically, T. granarium adults retained low population growth but contributed more for the total frass production and grain loss, much more than that recorded for R. dominica. Nonetheless, T. granarium larvae exhibited high population numbers 130 days after the introduction of the parental individuals. At higher temperature levels (30 and 35°C) the numbers of T. granarium larvae were extremely high even after 65 days, while the numbers of the other two species rapidly declined. Interestingly, the simultaneous presence of R. dominica and S. oryzae was beneficial for the population growth of T. granarium. Consequently, T. granarium has the ability to outperform other primary stored-product insects at high temperatures, while its presence at low temperatures remains for long periods apparently unaffected by other co-occurring species. Hence, T. granarium, in wheat, is able to outcompete other major species of stored-product insects at elevated temperatures, while at 25°C this species can maintain low numbers of individuals for long periods, which can rapidly produce population outbursts when the prevailing conditions are suitable for its development.

The interaction effect between intraspecific competition and seed quality on the life‐history traits of the seed‐feeding beetleAcanthoscelides macrophthalmus

“…Increased fecundity in the presence of competition, although usually unexpected, has been observed in other studies. For example, Kavallieratos et al () found that the population growth of the khapra beetle Trogoderma granarium (Everts) was favored by the presence of two other competitor species, particularly in high temperatures. Sakka & Athanassiou () observed that in some particular conditions (concerning host species and temperature), the progeny production of Dinoderus porcellus (Lesne) was increased in the presence of two other competing beetle species, the bostrychids Rhyzopertha dominica (Fabricius) and Prostephanus truncatus (Horn).…”

Do temperature, relative humidity and interspecific competition alter the population size and the damage potential of stored-product insect pests? A hierarchical multilevel modeling approach

“…Resource competition is a common biotic factor that may affect the population outcome among living organisms (Le Bourlot et al, 2014;Pedruski et al, 2015). It may affect several biological features, such as population size of herbivorous species (Karban, 1986;Athanassiou et al, 2014Athanassiou et al, , 2017aKavallieratos et al, 2017b), progeny production, fitness and prey consumption of beneficial insects (Xu et al, 2013;Cusumano et al, 2016;Papanikolaou et al, 2016). In addition, direct or indirect competitive interactions between species may lead to displacement of established species from a habitat (Reitz and Trumble, 2002).…”

“…For example, insects, mainly coleopterans, are responsible for huge grain losses of up to 57% in Africa (Kumar and Kalita 2017). Several stored-product coleopterous species co-exist in storage facilities and consequently compete for the same food resources (Smith and Lessells, 1985;Smith, 1990Smith, , 1991Athanassiou et al, 2003Athanassiou et al, , 2005Athanassiou et al, , 2011Athanassiou et al, , 2017aKavallieratos et al, 2017b). Although competition is considered a serious issue in storage ecosystem (Smith and Lessells, 1985;Smith, 1990Smith, , 1991Kavallieratos et al, 2017b) there is a gap of knowledge regarding interspecific competition.…”

“…Several stored-product coleopterous species co-exist in storage facilities and consequently compete for the same food resources (Smith and Lessells, 1985;Smith, 1990Smith, , 1991Athanassiou et al, 2003Athanassiou et al, , 2005Athanassiou et al, , 2011Athanassiou et al, , 2017aKavallieratos et al, 2017b). Although competition is considered a serious issue in storage ecosystem (Smith and Lessells, 1985;Smith, 1990Smith, , 1991Kavallieratos et al, 2017b) there is a gap of knowledge regarding interspecific competition. The significance of interspecific competition in stored-product insect pests has recently been highlighted, demonstrating its effect in community structure (Athanassiou et al 2014(Athanassiou et al , 2017aKavallieratos et al 2017b).…”

“…Although competition is considered a serious issue in storage ecosystem (Smith and Lessells, 1985;Smith, 1990Smith, , 1991Kavallieratos et al, 2017b) there is a gap of knowledge regarding interspecific competition. The significance of interspecific competition in stored-product insect pests has recently been highlighted, demonstrating its effect in community structure (Athanassiou et al 2014(Athanassiou et al , 2017aKavallieratos et al 2017b).…”