Effects of Entomopathogenic Nematodes on the Predator Calosoma granulatum in the Laboratory

Abstract

Entomopathogenic nematodes (EPNs) are used in inundative biological control of pests, such as Spodoptera frugiperda, which is targeted primarily when it enters the soil to form pupae. Within insects, EPNs require 7-15 days to form new infective juveniles (IJs); however, if the insect carcass is predated during this period, the population dynamics of nematodes and predators in the soil may be affected. In the soil, S. frugiperda is predated by carabid beetle Calosoma granulatum, which feeds on carcasses and living insects. The aim of the study was to analyze the direct effects of EPN contact with the predator and the effects of EPNs parasitizing prey on predator feeding. The predator C. granulatum and EPN H. amazonensis isolates RSC 5 and JPM 4, which have activity against S. frugiperda, were used. Laboratory experiments were conducted with topical application of IJs on the predator, as were experiments with and without choice using S. frugiperda larvae that were either healthy or infected by EPNs as prey. It was found that only the first instar predator larvae are susceptible to EPNs when applied topically at concentrations greater than 150 IJs/mL. The third instar larvae and adults avoid feeding on infected larvae, but the repulsion occurs only after symbiotic bacteria are released by EPNs inside the host. When predator only had access to infected carcasses as food, most larvae died during the 6 days of feeding. The results obtained shown that in general, these two native isolates of H. amazonensis, are safe for the native predator C. granulatum.

Interactions between Entomopathogenic Nematodes and Entomophagous Insects

“…The earwigs were found to have the ability to avoid feeding on nematode-infected prey [23]. Also, the third larval instar and adults of tha carabid predator, Calosoma granulatum (Coleoptera), avoided feeding on Spodoptera frugiperda larvae infected with H. amazonensis [24]. When the predator 1 st instar larvae had access to the infected cadavers as food, most of them died within 6 days of feeding.…”

Transmission Success of Entomopathogenic Nematodes Used in Pest Control

“…Recently, laboratory tests on three cyprinid fish species showed they were also sensitive to SDFs, rejecting G. mellonella larvae killed by Heterorhabditis or Steinernema species, and preferentially feeding on freeze-killed mosquito ( Aedes aegypti ) larvae compared to nematode-killed ones [ 169 ]. Tests on the carabid beetle Carabus granulatum , a predator of the lepidopteran host of H. amazonensis , showed that larvae and adults both avoided feeding on infected larvae when they had a choice [ 170 ]. In forced feeding experiments, the consumption of infected larvae led to a high mortality of the predator [ 170 ].…”

“…Tests on the carabid beetle Carabus granulatum , a predator of the lepidopteran host of H. amazonensis , showed that larvae and adults both avoided feeding on infected larvae when they had a choice [ 170 ]. In forced feeding experiments, the consumption of infected larvae led to a high mortality of the predator [ 170 ]. However, not all insects are repelled by nematode-infected hosts.…”

“…Nematodes can also be in direct competition with other organisms. In the case of the carabid C. granulatum cited above [ 170 ], the predator is not only a threat for the integrity of the host cadaver, and thus for the reproduction success of nematodes; IJs and beetles compete for the same resources, that is, living prey or hosts. Consequently, the inundative use of EPNs could decrease the number of insect prey available for predators, with consequences on their populations.…”

Rattus norvegicus (Berkenhout, 1769) (Rodentia: Muridae)’un entomopatojen bakteriler ile enfekte böcek kadavralarına tepkisinin belirlenmesi

“…This compound(s) was renamed as "scavenger deterrent factor" (SDF) as it also deters other scavengers such as wasps and crickets from feeding on cadavers with the mutualistic bacteria (Gülcü et al, 2012). Subsequently, different scavenging and omnivorous arthropod species (i.e., earwigs, cockroaches, beetles, and collembolans) have been reported to be deterred from feeding on insects killed by the EPN/bacterium complex (Uluğ et al, 2014;Mertz et al, 2015;Jones et al, 2016). Besides invertebrate animals, two avian species, Erithacus rubecula (L., 1758) (Passeriformes: Muscicapidae) and Parus major (L., 1758) (Passeriformes: Paridae) (Fenton et al, 2011;Jones et al, 2017) and two cyprinid fish species Devario aequipinnatus (McClelland, 1839) (Cypriniformes: Cyprinidae) and Alburnoides bipunctatus (Bloch, 1782) (Cypriniformes: Cyprinidae) (Raja et al, 2017) have also been deterred from feeding on insects killed by the EPN/bacterium complex or by the mutualistic bacterium alone.…”