Search Results (15)

Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) is a common pest in poultry farms, causing significant economic damage, spreading easily and quickly. The species is resilient, adaptable, and capable of thriving in a variety of environments, and both larvae and adults can hide in hard-to-reach places; thus, control becomes highly challenging. Moreover, the species has developed resistance to commonly used insecticides, increasing the need to adopt integrated pest management strategies. Hence, this study examined the mortality dynamics of A. diaperinus larvae exposed to the entomopathogenic nematodes (EPNs) Heterorhabditis downesi Stock, Griffin & Burnell 2002 (Rhabditida: Heterorhabditidae) and Steinernema kraussei (Steiner, 1923) (Rhabditida: Steinernematidae) across a range of temperatures, dose rates, and exposure intervals. The patterns of larval mortality closely followed the classical EPN infection timeline: limited mortality during the first hours, a pronounced increase between day 2 and 4, and high cumulative mortality after day 8. Steinernema kraussei produced moderate early mortality, increasing by day 8, across all tested temperatures, reflecting its relatively slower but effective infection progression. In contrast, H. downesi induced higher early mortality at moderate temperatures and stronger dose-dependent responses. Temperature significantly modulated infection in both species, with reduced performance at 35 °C, particularly for H. downesi, although high-dose treatments achieved substantial mortality. The significant temperature × dose × time interactions align with established EPN biology and previous research on both species and, overall, the results confirm that they both possess strong pathogenic potential against A. diaperinus, while their performance characteristics support their suitability as biological control agents for poultry facilities. Full article

The tarnished plant bug, Lygus lineolaris Palisot de Beauvois (Hemiptera: Miridae), is an economically important pest of row crops worldwide. Ten isolates of entomopathogenic nematodes (EPNs) (Rhabditida: Steinernematidae and Heterorhabditidae) were evaluated against the third instar nymphal stage of the tarnished plant bug and its generalist predator, the sculpted damsel bug, Nabis roseipennis Reuter (Hemiptera: Nabidae), one of the most abundant and commonly encountered damsel bugs in cotton and soybean agroecoscapes across the Southeastern United States. The objectives of these experiments were to assess the infectivity of entomopathogenic nematodes (EPN) by direct topical exposure against the sculpted damsel bug and tarnished plant bug, whether the predator prey choice is affected by EPN infection, and if feeding on EPN-infected tarnished plant bug (TPB) prey items could result in cross-infection of the predator. Mortality rates at a concentration of 200 infective juveniles (IJs)/mL significantly differed among isolates and insect species, ranging from 30% to 93% for tarnished plant bugs and from 6% to 38% for sculpted damsels, respectively. The third instars of L. lineolaris were more susceptible to the ten nematode isolates than N. roseipennis. Higher pathogenicity on the tarnished plant bug and a low mortality potential make strains HbHP88, HbVS, Sc17c+e, and SfSN the most promising candidates for the biological control of L. lineolaris under lab and greenhouse conditions while preserving beneficial predators of the Southeastern United States. Full article

Vector-borne diseases pose a severe threat to human and animal health. Culex pipiens L. (Diptera: Culicidae) is a widespread mosquito species and serves as a vector for the transmission of infectious diseases such as West Nile disease and Lymphatic Filariasis. Synthetic insecticides have been the prime control method for many years to suppress Cx. pipiens populations. However, recently, the use of insecticides has begun to be questioned due to the detrimental impact on human health and the natural environment. Therefore, many authorities urge the development of eco-friendly control methods that are nontoxic to humans. The bacterial associates [Xenorhabdus and Photorhabdus spp. (Enterobacterales: Morganellaceae)] of entomopathogenic nematodes (EPNs) (Sterinernema spp. and Heterorhabditis spp.) (Rhabditida: Heterorhabditidae and Steinernematidae) are one of the green approaches to combat a variety of insect pests. In the present study, the mosquitocidal activity of the cell-free supernatants and cell suspension (4 × 10⁷ cells mL⁻¹) of four different symbiotic bacteria (Xenorhabdus nematophila, X. bovienii, X. budapestensis, and P. luminescens subsp. kayaii) was assessed against different development stages of Cx. pipiens (The 1st/2nd and 3rd/4th instar larvae and pupa) under laboratory conditions. The bacterial symbionts were able to kill all the development stages with varying levels of mortality. The 1st/2nd instar larvae exhibited the highest susceptibility to the cell-free supernatants and cell suspensions of symbiotic bacteria and the efficacy of the cell-free supernatants and cell suspensions gradually declined with increasing phases of growth. The highest effectiveness was achieved by the X. bovienii KCS-4S strain inducing 95% mortality to the 1st/2nd instar larvae. The results indicate that tested bacterial symbionts have great potential as an eco-friendly alternative to insecticides. Full article

Spodoptera frugiperda is a highly destructive and polyphagous pest that causes severe damage to various crops, especially maize. The wide use of chemical insecticides to control S. frugiperda results in resistance against commonly used chemicals and resistant mutations will expand in populations accompanied by a spread to vulnerable areas. Consequently, more effective and friendly strategies must be explored to minimize losses caused by S. frugiperda. Entomopathogenic nematodes (EPN) are good candidates for the biological control of different species of insect pests, including S. frugiperda. In the current study, the infective capabilities of the EPN species HbSD, belonging to Hetrerorhabditis bacteriophora, were evaluated against S. frugiperda under laboratory, greenhouse and field conditions. In laboratory assays, HbSD was highly virulent against 3rd/5th instar larvae, which was related to HbSD concentration and exposure durations. In greenhouse assays, spraying aqueous HbSD also showed good performance in killing larvae on maize leaves. However, the virulence of HbSD decreased in field trials where many adverse factors affecting survival and efficacy were encountered by HbSD. Overall, our study provides an alternative EPN for the biological control of S. frugiperda with the potential to be developed as a sustainable option for efficient pest management. Full article

Stored-product commodities are attacked by numerous insect species. The adulticidal effects of entomopathogenic nematodes (EPNs) on grains remain uninvestigated. Thus, in the current study, seven doses of the EPNs Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae), Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae), and Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae) were inoculated on wheat kernels against adults of Trogoderma granarium Everts (Coleoptera: Dermestidae), Tenebrio molitor L. (Coleoptera: Tenebrionidae), and Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae). Complete mortality (100.0%) of T. granarium was recorded after exposure for eight days to the highest dose of 50,000 Infective Juveniles/mL (IJs/mL) of all tested EPN species. At the same exposure interval, 62.2%, 85.6%, and 76.7% of T. molitor were killed by 50,000 IJs/mL of H. bacteriophora, S. carpocapsae, and S. feltiae, respectively. The highest mortality of A. diaperinus (11.1%) was documented eight days post-exposure to 50,000 IJs/mL of H. bacteriophora. In general, T. granarium was highly susceptible, followed by T. molitor and A. diaperinus. Concerning EPN species, S. carpocapsae exhibited the highest insecticidal capacity, followed by S. feltiae and H. bacteriophora. Trogoderma granarium and T. molitor can be sufficiently managed by the highest dose of 50,000 IJs/mL of all three EPNs and by S. carpocapsae, respectively. However, A. diaperinus was not affected by any EPNs. Full article

The codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), is one of the major pests in pome fruit production worldwide. Heavy treatment of the larvae of C. pomonella with insecticides triggered the development of resistance to many groups of insecticides. In addition, the increasing concern about the adverse effects of synthetic insecticides on human health and the environment has led to the development of sustainable and eco-friendly control practices for C. pomonella. The entomopathogenic nematodes (EPNs) (Steinernema and Heterorhabditis spp.) and their endosymbionts (Xenorhabdus and Photorhabdus spp.) represent a newly emerging approach to controlling a wide range of insect pests. In the present study, field surveys were conducted in apple orchards to isolate and identify EPNs and their endosymbionts and evaluate their insecticidal efficacy on the larvae of C. pomonella. EPNs were isolated from 12 of 100 soil samples (12%). Seven samples were identified as Steinernema feltiae (Filipjev, 1934) (Rhabditida: Steinernematidae), whereas five samples were assigned to Heterorhabditis bacteriophora (Poinar, 1976) (Rhabditida: Heterorhabditidae). The pathogenicity of the EPN species/isolates was screened on the last instar larvae of G. mellonella. The two most pathogenic isolates from each EPN species were tested against fifth instar larvae of C. pomonella under controlled conditions. The maximum mortality (100%) was achieved by all EPN species/isolates at a concentration of 100 IJs/larva 96 h after treatment. The endosymbionts of selected H. bacteriophora and S. feltiae species were identified as Photorhabdus luminescens subsp. kayaii and Xenorhabdus bovienii, respectively. The mortality rates ranged between 25 and 62% when the fifth larval instar larvae of C. pomonella were exposed to the treatment of cell-free supernatants of symbiotic bacteria. In essence, the present survey indicated that EPNs and their symbiotic bacteria have good potential for biological control of C. pomonella. Full article

Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) is a serious pest that infects maize. Insecticides or entomopathogenic nematodes are used to control the root-damaging larvae. However, such treatments are reportedly inconsistent in terms of efficacy under farming conditions. To better understand the reasons behind these inconsistencies, we studied the control efficacy of seed coatings, such as clothianidin; granular soil insecticides, such as cypermethrin and tefluthrin; and fluid-applied entomopathogenic nematodes, such as Heterorhabditis bacteriophora (Rhabditida: Heterorhabditidae). We assessed the influence of 12 biotic and 20 abiotic factors on the reduction of Diabrotica v. virgifera populations and on the prevention of root damage in 20 field-scale experiments in Hungary between 2010 and 2020. Results confirmed that all treatment types are able to control pest populations and prevent root damage, but with high variability. Our analyses showed that most investigated factors, for example, air temperature, most soil parameters, and pest infestation levels, did not influence the efficacy of the treatments. The efficacy of clothianidin in preventing root damage decreased slightly with increasing soil bulk density but improved with late maize sowing, and therefore late treatment, as well as with increasing soil moisture in July. The efficacy of cypermethrin in preventing damage improved slightly with increasing clay content in the soil. Tefluthrin was slightly less effective in reducing D. v. virgifera with increasing soil moisture in June. However, all these factorial influences were minor in their absolute effects. Surprisingly, none of the investigated factors seemed to influence the efficacy of H. bacteriophora. In conclusion, the efficacy of chemical and biological treatments against this soil pest remains difficult to predict under farming conditions. Full article

The European grapevine moth (EGVM) Lobesia botrana (Lepidoptera: Tortricidae) is a relevant pest in the Palearctic region vineyards and is present in the Americas. Their management using biological control agents and environmentally friendly biotechnical tools would reduce intensive pesticide use. The entomopathogenic nematodes (EPNs) in the families Steinernematidae and Heterorhabditidae are well-known virulent agents against arthropod pests thanks to symbiotic bacteria in the genera Xenorhabdus and Photorhabdus (respectively) that produce natural products with insecticidal potential. Novel technological advances allow field applications of EPNs and those bioactive compounds as powerful bio-tools against aerial insect pests. This study aimed to determine the viability of four EPN species (Steinernema feltiae, S. carpocapsae, S. riojaense, and Heterorhabditis bacteriophora) as biological control agents against EGVM larval instars (L1, L3, and L5) and pupae. Additionally, the bioactive compounds from their four symbiotic bacteria (Xenorhabdus bovienii, X. nematophila, X. kozodoii, and Photorhabdus laumondii subsp. laumondii, respectively) were tested as unfiltered ferment (UF) and cell-free supernatant (CFS) against the EGVM larval instars L1 and L3. All of the EPN species showed the capability of killing EGVM during the larval and pupal stages, particularly S. carpocapsae (mortalities of ~50% for L1 and >75% for L3 and L5 in only two days), followed by efficacy by S. feltiae. Similarly, the bacterial bioactive compounds produced higher larval mortality at three days against L1 (>90%) than L3 (~50%), making the application of UF more virulent than the application of CFS. Our findings indicate that both steinernematid species and their symbiotic bacterial bioactive compounds could be considered for a novel agro-technological approach to control L. botrana in vineyards. Further research into co-formulation with adjuvants is required to expand their viability when implemented for aboveground grapevine application. Full article

Entomopathogenic nematodes (Rhabditida: Steinernematidae and Heterorhabditidae) are a group of organisms capable of infecting larvae of insects living in soil, including representatives of the family Scarabaeidae. Their insecticidal activity is related to the presence of symbiotic bacteria Xenorhabdus spp. or Photorhabdus spp. in the alimentary tract, which are released into the insect body, leading to its death caused by bacterial toxins and septicemia. Although the antibacterial activities of symbionts of entomopathogenic nematodes have been well described, there is insufficient knowledge of the interactions between these bacteria and microorganisms that naturally inhabit the alimentary tract of insects infested by nematodes. In this study, 900 bacterial strains isolated from midgut samples of Amphimallon solstitiale larvae were tested for their antagonistic activity against the selected five Xenorhabdus and Photorhabdus species. Cross-streak tests showed significant antibacterial activity of 20 isolates. These bacteria were identified as Bacillus [Brevibacterium] frigoritolerans, Bacillus toyonensis, Bacillus wiedmannii, Chryseobacterium lathyri, Chryseobacterium sp., Citrobacter murliniae, Enterococcus malodoratus, Paenibacillus sp., Serratia marcescens and Serratia sp. Since some representatives of the intestinal microbiota of A. solstitiale are able to inhibit the growth of Xenorhabdus and Photorhrhabdus bacteria in vitro, it can be assumed that this type of bacterial interaction may occur at certain stages of insect infection by Steinernema or Heterorhabditis nematodes. Full article

The natural presence of entomopathogenic nematodes (EPNs) has been investigated in the Piedmont region (Northern Italy) in areas infested by the Japanese beetle Popillia japonica. Thirty-nine out of 155 soil samples (25.2%) were positive for EPNs. Most of the samples contained only steinermatids (92.3%), 5.1% contained heterorhabditids, and one sample (2.6%) contained both genera. All the recovered isolates were identified at species level both morphologically and molecularly. Steinernema carpocapsae was the most abundant and it was mainly distributed in open habitats, such as perennial meadows, uncultivated soils, and cropland, characterized by sandy loam soil texture and acidic pH. Steinernema feltiae has been found associated mainly with closed habitats such as coniferous and deciduous woodland, characterized by sandy loam-texture and extremely acidic soil. The three isolates of Heterorhabditis bacteriophora were collected only in open habitats (perennial meadows and uncultivated fields) characterized by strongly acidic soils with sandy loam texture. The virulence of all EPN natural strains was evaluated by laboratory assays against P. japonica third-instar larvae collected during two different periods of the year (spring, autumn). The results showed that larval mortality was higher for pre-wintering larvae than post-wintering ones. The five more promising EPN isolates were tested in the semi-field assay in which H. bacteriophora natural strains have been shown to be more efficient in controlling P. japonica grubs. All of these results are finally discussed considering the use of these natural EPNs as biological control agents against P. japonica, within an eco-friendly perspective of management. Full article

The largest group of cabbage plant pests are the species in the owlet moth family (Lepidoptera: Noctuidae), the most dangerous species of which is the cabbage moth (Mamestra brassicae L.). In cases of heavy infestation by this insect, the surface of plants may be reduced to 30%, with a main yield loss of 10–15%. The aim of the present study was to assess the susceptibility of M. brassicae larvae to nine native nematode isolates of the species Steinernema feltiae (Filipjev) and Heterorhabditis megidis Poinar, Jackson and Klein under laboratory conditions. The most pathogenic strains were S. feltiae K11, S. feltiae K13, S. feltiae ZAG11, and S. feltiae ZWO21, which resulted in 100% mortality at a temperature of 22 °C and a dosage of 100 infective juveniles (IJs)/larva. The least effective was H. megidis Wispowo, which did not exceed 35% mortality under any experimental condition. For most strains, there were significant differences (p ≤ 0.05) in the mortality for dosages between 25 IJs and 50 IJs, and between 25 IJs and 100 IJs, at a temperature of 22 °C. Statistical analysis of the effect of temperature on mortality showed that only strain H. megidis Wipsowo exhibited significant differences (p ≤ 0.05) when applied at dosages of 50 IJs and 100 IJs. Full article

The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte (Coleoptera, Chrysomelidae), is an important insect pest of maize in North America and Central and Eastern Europe. In Central Europe, the larvae emerge in May and its three instars feed intensively on maize roots in June, causing plant lodging that leads to a loss of economic yield. A three-year field experiment (2016–2018) was conducted to compare the effectiveness i) of soil-applied granular insecticide based on the active ingredient tefluthrin, ii) of maize seeds dressed with thiacloprid, and iii) entomopathogenic nematodes Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae, product Dianem) against WCR larvae. An additional treatment with alcohol ethoxylate (i.e., soil conditioner) mixed with entomopathogenic nematodes was performed in 2017 and 2018 to check for any increase of entomopathogenic nematodes’ effectiveness. Field tests were carried out in two fields infested naturally with a WCR pest population, one in Bučečovci (Eastern Slovenia) and the other in Šmartno pri Cerkljah (northern Slovenia), exhibiting dissimilar pedo-climatic conditions and soil pest densities. The treatments were performed in five replicates per experiment in each year. The efficacy of the treatments was very similar at both locations, despite the approximately five-fold lower WCR soil pest densities in northern than in eastern Slovenia, as well as being constant over time. The largest number of WCR beetles was observed in the negative control, followed by that of beetles subjected to thiacloprid treatment (insignificant decrease taking into account the entire three-year dataset). Treatments with tefluthrin (44.1 ± 11.7%), H. bacteriophora (46.2 ± 7.4%), and H. bacteriophora + alcohol ethoxylate (49.2 ± 1.8%) significantly decreased the numbers of emerging beetles. Treatments of thiacloprid, H. bacteriophora, and H. bacteriophora + alcohol ethoxylate additionally led to significantly increased maize plant weights. Furthermore, entomopathogenic nematodes were able to persist in maize fields for almost five months at both experimental locations in silty and sandy loam soils. It was concluded that the control of WCR larvae in maize using the entomopathogenic nematode H. bacteriophora is as effective as a tefluthrin treatment, and could thus offer a sustainable Diabrotica v. virgifera biological control management option in Europe. Full article

Entomopathogenic nematodes from the two genera Steinernema and Heterorhabditis are widely used as biological agents against various insect pests and represent a promising alternative to replace pesticides. Efficacy and biocontrol success can be enhanced through improved understanding of their biology and ecology. Many endogenous and environmental factors influence the survival of nematodes following application, as well as their transmission success to the target species. The aim of this paper is to give an overview of the major topics currently considered to affect transmission success of these biological control agents, including interactions with insects, plants and other members of the soil biota including conspecifics. Full article

The sweet potato weevil (Cyclas formicarius Fabr.) remains a serious threat to sweet potato (Ipomoea batatas Poir.) production and is considered the most destructive pest of sweet potatoes in the field and storagein the Philippines. Chemical control of the weevil is seldom practiced by farmers because they find it too costly, it may increase the chance for pesticide resistance, and because of public concern of its effectson non-target organisms. The use of biological controls such as entomopathogenic nematodes (EPN) could offer an effective, economical, and environmentally-friendly alternative management of the weevil. This study determined the occurrence and distribution of entomopathogenic nematodes in selected sweet potato growing areas in the Philippines. Using soil from 13 sweet potato growing areas, EPNs were recovered using the insect baiting method. Morbid insect larvae were suspended in sterile water for 48 h, and the suspension was examined under a stereomicroscope for the presence of EPN. Out of 47 samples collected from the 13 sweet potato production areas, 39 (82%) were positive for the presence of EPNs. Preliminary identification of the EPNs through morphological characters showed that they belonged to Rhaditida: Heterorhabditidae and Steinernematidae. This is the first report on the occurrence of EPNs in sweet potato fields in the Philippines, and their distribution strongly supports the possibility of utilizing them in an IPM management approach as biological agents against the sweet potato weevil. Morphometric and molecular-based identification and pathogenicity studies are underway. Full article

Dalotia coriaria (Kraatz) (Coleoptera: Staphylinidae) and entomopathogenic nematodes (Rhabditida: Heterorhabditidae and Steinernematidae) are two soil-dwelling biological control agents used to manage western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) and fungus gnats Bradysis spp. (Diptera: Sciaridae) in glasshouses. Growers often use multiple natural enemies to achieve economic control, but knowledge of interactions among natural enemies is lacking. We conducted a laboratory bioassay to test the pathogenicity of four commercially available nematode species—Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhbditidae), Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae), S. feltiae (Filipjev), and S. riobrave Cabanillas et al.—to third instar and adult D. coriaria. Third instars were three times more susceptible than the adults to the entomopathogenic nematodes. Mortality for D. coriaria adults and third instars treated with S. feltiae and H. bacteriophora was lower than the mortality for D. coriaria adults and third instars treated with S. carpocapsae and S. riobrave. Neither infective juvenile foraging behavior nor size correlates with D. coriaria mortality. Dalotia coriaria appears to be most likely compatible with applications of S. feltiae and H. bacteriophora. Full article