•Liquid egg-yolk is an alternative ingredient for EPN production in monoxenic liquid culture.•The IJ yield production is doubled by adding liquid egg-yolk to the culture medium.•In vitro cultured ...Steinernema carpocapsae JAP1 maintain his virulence against Galleria mellonella.
Dehydrated egg yolk is usually incorporated as a powder into the liquid medium to supply protein for entomopathogenic nematodes (EPNs) culture. This study aimed to evaluate the yield production of Steinernema carpocapsae strain JAP1 cultured in 10 mL of the P2 medium with fresh liquid egg-yolk (P2-LEY) and powdered egg-yolk (P2-PEY) into orbitally shaken bottles at 130 rpm and 28 °C for 16 days. The nematode inoculum was transferred from the surface layer of a solid culture with 21.5 % of infective juveniles (IJs), to achieve an initial concentration of 2000 ± 200 IJs·mL−1. Using P2-LEY, the maximum concentration was improved to 265 000 nematodes·mL−1 with 60% of the population in the IJ stage. In addition, the mortality of Galleria mellonella due to confrontation with these juveniles was 61%, which shows a non-statistical difference with the virulence of IJs in vivo reared in host insects. We concluded that LEY is a suitable component for the liquid culture mass production of nematodes. These results are discussed in light of information on the nutritional differences between LEY and PEY and their emulsifier attributes.
According to kin selection theory, individuals show less aggression towards their relatives. Limited dispersal promotes interactions among relatives but also increases competition among them. The ...evolution of cooperation in viscous populations has been subject of mainly theoretical exploration. We investigated the influence of relatedness on aggression in males of entomopathogenic nematode Steinernema longicaudum that engage in lethal fighting. In a series of in vitro experiments, we found that both competitor male group size and relatedness influence male mortality rates. Higher relatedness led to progressively lower rates of male mortality. In experimentally infected insects, wherein large numbers of males and females interact, the proportion of dead and paralysed (= terminally injured) males was higher when infection was established by infective juveniles originating from a mixture of three lines than in those infected by a single line. The results collectively show that Steinernema longicaudum males recognize their kin and consequently male mortality rates are lower in groups consisting of more related males. Furthermore, this monotonic negative relationship between aggression and relatedness suggests that kin selection benefits are still substantial even under extreme competition. Our experiments also suggest that kin recognition in entomopathogenic nematodes has a genetic basis rather than being strictly based on environmental cues. We discuss our findings within the theoretical context of the evolution of altruistic/cooperative behaviour in structured populations.
•Research on entomopathogenic nematodes in Latin America is full of remarkable discoveries.•In the last 30 years, 16 out of 20 Latin-American countries have initiated EPN research programs.•16 out of ...117 recognized species have been described, many of them endemic to the region.•More than 170 target pests have been evaluated in laboratory and field conditions.
Since the 1980s, research into entomopathogenic nematodes (EPNs) in Latin America has produced many remarkable discoveries. In fact, 16 out of the 117 recognized species of EPNs have been recovered and described in the subcontinent, with many more endemic species and/or strains remaining to be discovered and identified. In addition, from an applied perspective, numerous technological innovations have been accomplished in relation to their implementation in biocontrol. EPNs have been evaluated against over 170 species of agricultural and urban insects, mites, and plant-parasitic nematodes under laboratory and field conditions. While much success has been recorded, many accomplishments remain obscure, due to their publication in non-English journals, thesis dissertations, conference proceedings, and other non-readily available sources. The present review provides a brief history of EPNs in Latin America, including current findings and future perspectives.
Entomopathogenic nematodes (EPNs) are insect parasitic nematodes of the genera Het-erorhabditis and Steinernema. These nematodes are symbiotically associated with the bacteria, Photorhabdus and ...Xenorhabdus, respectively. National parks in Thailand are a potentially rich resource for recovering native EPNs and their symbiotic bacteria. The objectives of this study are to isolate and identify EPNs and their bacterial flora from soil samples in four national parks in Thailand and to evaluate their efficacy for controlling mosquito larvae. Using a baiting method with a Galleria mellonella moth larvae and a White trap technique, 80 out of 840 soil samples (9.5%) from 168 field sites were positive for EPNs. Sequencing of an internal transcribed spacer resulted in the molecular identification of Heterorhabditis nematode isolates as H. indica, H. baujardi and Heterorhabditis SGmg3, while using 28S rDNA sequencing, Steinernema nematode species were identified as S. guang-dongense, S. surkhetense, S. minutum, S. longicaudum and one closely related to S. yirgalemense. For the symbiotic bacterial isolates, based on recA sequencing, the Photorhabdus spp. were identified as P. luminescens subsp. akhurstii, P. luminescens subsp. hainanensis and P. luminescens subsp. australis. Xenorhabdus isolates were identified as X. stockiae, X. indica, X. griffiniae, X. japonica and X. hominickii. Results of bioassays demonstrate that Photorhabdus isolates were effective on both Aedes aegypti and Culex quinquefasciatus. Therefore, we conclude that soil from Thailand’s national parks contain a high diversity of entomopathogenic nematodes and their symbiotic bacteria. Photorhabdus bacteria are larvicidal against culicine mosquitoes and may serve as effective biocontrol agents.
The polyphagous Mediterranean fruit fly or Medfly, Ceratitis capitata, which is an economically important pest species to fruit growers globally, including those in South Africa, spends part of its ...life cycle in the soil as a final instar larva and pupa. Entomopathogenic nematodes (EPNs) of the families Steinernematidae and Heterorhabditidae are insect-killing parasites that occur naturally in soils worldwide. The main aim of this study was to identify local, South African EPN species highly pathogenic against Medfly larvae entering the soil to pupate. Eighty soil samples were taken from fruit orchards in the Western and Northern Cape provinces of South Africa, and baited with susceptible host insects, including the target pest. The identity of the EPNs isolated was verified using molecular techniques. The pathogenicity of five local EPN species were screened in the laboratory by inoculating single third instar Medfly larvae with 100 infective juveniles (IJs) in 50 μl of water. After 48 h, high Medfly larval mortality was obtained, with no significant difference being found between the nematode species, and the experiment was therefore repeated at a lower concentration of infective juveniles. The pathogenicity of the most virulent EPN, Heterorhabditis noenieputensis, along with Steinernema yirgalemense, was further tested by inoculating 100 ml of sterilised sand with 2000 IJs. After 24 h, 10 third instar Medfly larvae were added to the sand. High mortality of Medfly larvae, using H. noenieputensis, promises well for local EPN species, which could be used as a biological control agent against the Medfly, within an integrated pest management system.
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•Heterorhabditis noenieputensis and Steinernema yirgalemense showed high virulence.•No fully formed Medfly pupae were infected by local entomopathogenic nematodes.•In sand, H. noenieputensis infected Medfly larvae, which died as infected pupae.•Heterorhabditis noenieputensis is 14 times more potent than S. yirgalemense.
Many species of slugs are considered serious pests in agriculture and horticulture around the world. In Europe, slugs of the genera
Arion
and
Deroceras
are the most harmful pests in agriculture. ...Therefore, the main goal of this study was to evaluate the effect of the whole-cell metabolites of 10 strains of five
Xenorhabdus
and three slug-parasitic nematodes (
Phasmarhabditis hermaphrodita
,
Phasmarhabditis bohemica
, and
Phasmarhabditis apuliae
) on the feeding behaviour and repellent effect on target slugs and evaluate a new possible means of biocontrol of these pests. The repellent and anti-feedant effects of nematode-killed insects, metabolites, slug-parasitic nematodes and a combination of metabolites and nematodes were studied through experimental designs: sand-filled plastic boxes divided into two parts in several modifications: with dead
Galleria mellonella
killed by nematodes, lettuce treated with bacterial metabolites and lettuce placed on the treated sand. We found that slugs avoid eating
G. mellonella
killed by nematodes, while they eat freeze-killed
G. mellonella
. Similarly, they avoid the consumption of lettuce in areas treated with bacterial metabolites (the most effective strains being
Xenorhabus bovienii
NFUST,
Xenorhabdus kozodoii
SLOV and JEGOR) with zero feeding in the treated side. All three
Phasmarhabditis
species also provided a significant anti-feedant/repellent effect. Our study is the first to show the repellent and anti-feedant effects of metabolites of
Xenorhabdus
bacteria against
Arion vulgaris
, and the results suggest that these substances have great potential for biocontrol. Our study is also the first to demonstrate the repellent effect of
P. apuliae
and
P. bohemica
.
Key points
• Slugs avoid eating G. mellonella killed by entomopathogenic nematodes.
• Bacterial metabolites have a strong repellent and antifeedant effect on slugs.
• Presence of slug parasitic nematodes increases the repellent effect of metabolites.
•Entomopathogenic nematodes are promising biocontrol agents in a number of different habitats.•Foliar application of entomopathogenic nematodes presents various unique challenges.•Inherent ...characteristics of Cydalima perspectalis and Buxus foliage confer suitability for control using entomopathogenic nematodes.
Worldwide biodiversity decline is caused by multiple factors, including pesticides. Aside from their applications in agriculture, the uptake of pesticides in urban gardens is widespread. Here, we review the potential of controlling pests of ornamental garden plants, like the boxtree moth Cydalima perspectalis Walker, 1859 (Lepidoptera: Crambidae), using entomopathogenic nematodes (Heterorhabdidae & Steinernematidae). Nematode biocontrol is highly suitable, particularly for small-scale control such as in boxtree plantings. Boxtree (Buxus spp.) is an ornamental shrub widely used in public and private grounds across Europe. Over the past decade boxtree has suffered heavily from the destructive boxtree moth, an invasive and persistent pest species of East-Asian origin. Widespread application of insecticides has been effective, yet resistance to these compounds is accumulating. The dense foliage of boxtree shrubs facilitates the correct tuning of moisture and temperature conditions required for nematode mediated pest control. Warm weather, without direct sunlight, on moist to wet foliage appear to be the most suitable conditions. We conclude that the use of entomopathogenic nematodes for controlling pests, such as the boxtree moth, may limit damage to horticulture and provide a safe and environmentally friendly form of control in urban spaces.
The obscure mealybug, Pseudococcus viburni (Signoret) (Hemiptera: Pseudococcidae), is an important polyphagous, cosmopolitan insect pest of fruit crops, including apples, pears and grapes. The ...mealybug negatively affects fruit production both in South Africa and globally by feeding on phloem sap, excreting large amounts of sugar and water as a carbohydrate-rich sugary substance, known as honeydew, onto the leaves and fruit. Honeydew causes severe secondary damage, as it promotes the growth of sooty mould, which decreases the amount of photosynthesis, thus affecting the development of the host plant. Fruit consignments with fruits stained with sooty mould or suspected of containing live or dead mealybugs are rejected when exported, due to the strict phytosanitary standards. Managing mealybugs in agroecosystems is difficult, due to their small body size and cryptic nature. Currently, control relies on the use of chemicals and, to some extent, on biological control. However, using such methods has proven to be ineffective in the management of P. viburni. Entomopathogens, such as entomopathogenic fungi (EPF) and entomopathogenic nematodes (EPNs), have been used across agricultural production areas to control a wide range of agricultural pest insects. The current review provides an overview of the biology and control of P. viburni, with special reference to biological control using EPF and EPNs in South African orchards, in an integrated pest management system.
Entompathogenic nematodes are found worldwide in a wide array of soil habitats with a broad host range and significant variation in foraging strategies. The primary use of entomopathogenic nematodes ...(EPNs) in managed plant systems has been focused on inundative releases in a biopesticide strategy. Little effort has been placed in investigating the use of natural occurring or adapted EPN strains for long-term suppression of pest outbreaks in managed systems. This study examined the potential of EPN isolates from Northern New York (NNY), inoculated at a low level (250 million IJ/ha), which are climate adapted and their persistent characteristics preserved to maintain population levels in agricultural fields (N = 82) for multiple years and across crop rotation (alfalfa:corn:alfalfa). Persistence levels for Steinernema carpocapsae (Weiser) (Rhabditida:Steinernematidae) ranged between 8 and 12% of the soil cores assayed in continuous alfalfa and 1–14% of the soil cores assayed in continuous corn rotated from EPN treated alfalfa. Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae) residual persistence level ranged between 17 and 32% in continuous alfalfa and 22–41% in continuous corn rotated from EPN treated alfalfa. Combined EPN level ranged between 27 and 43% of the soil cores in continuous alfalfa and 28–55% in continuous corn rotated from EPN-treated alfalfa. Inspection of individual fields suggested EPN populations established in prior years at the residual soil core level of 18–35% can respond positively to an increase of susceptible hosts in both alfalfa and corn, often increasing their presence to 100%.
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