Fatty acid composition of Heterorhabditis sp. during storage

Fitters, Paul F.L.; Patel, Mavji N.; Griffin, Christine T.; Wright, Denis J.

doi:10.1016/s0305-0491(99)00102-9

Cited by 20 publications

(8 citation statements)

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“…Such divergence is probably related to the high genetic variability that exists among isolates of a given nematode species. Several studies have demonstrated variability in the morphology (Stock et al, 2000), genetics (Gaugler et al, 1989), physiology (Fitters et al, 1999), infectivity (Griffin & Downes, 1991), and climatic adaptation (Solomon et al, 1999) of different isolates of the same species.…”

Section: Resultsmentioning

confidence: 99%

Selection of entomopathogenic nematodes for the control of the fruit fly Ceratitis capitata (Diptera: Tephritidae)

Rohde

Moino

Carvalho

et al. 2012

Agraria

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Entomopathogenic nematodes are considered excellent biological control agents, with greater potential against soil insect pests and pests of cryptic environments. The fruit fly Ceratitis capitata is considered one of the main fruit crop pests worldwide. This insect stays in the soil during a phase of life, where it becomes a target for entomopathogenic nematodes. The objective of this study was to evaluate the pathogenicity and virulence of entomopathogenic nematodes on C. capitata. The bioassays were organized with four replications, containing 10 individuals; 1 mL of a nematode suspension containing 200 IJ/insect was applied. The most virulent isolates against C. capitata larvae were selected and applied at concentrations of 0, 50, 100, 150, 200, 250, 300, 350 and 400 IJ/insect. All isolates were pathogenic for C. capitata. The S. carpocapsae ALL and Heterorhabditis sp. RSC01 isolates were the most virulent against the larval stage, with mortalities of over 85%. As to the pupal stage, isolates Heterorhabditis sp. PI, Heterorhabditis sp. JPM4, H. bacteriophora HP88, S. feltiae and S. glaseri were the best, with mortalities ranging between 35 and 44%.Key words: biological control, mediterranean fruit fly, pathogenicity Seleção de nematoides entomopatogênicos visando ao controle da mosca das frutas Ceratitis capitata (Diptera: Tephritidae) RESUMONematoides entomopatogênicos são considerados excelentes agentes de controle biológico demonstrando maior potencialidade em insetos-praga de solo e de ambientes crípticos. A mosca das frutas Ceratitis capitata é considerada uma das principais pragas para a fruticultura mundial. Este inseto passa uma fase de sua vida no solo, tornando-se alvo em potencial para esses entomopatógenos. Assim, teve-se como objetivo avaliar a patogenicidade e a virulência de nematoides entomopatogênicos sobre C. capitata. Os bioensaios foram realizados com quatro repetições contendo 10 indivíduos e aplicado 1 mL de suspensão de nematoides com 200 JI/inseto. Os isolados que se apresentaram mais virulentos para larvas de C. capitata foram selecionados e aplicados nas concentrações de 0, 50, 100, 150, 200, 250, 300, 350 e 400 JI/inseto. Verificou-se que todos os isolados foram patogênicos para C. capitata. Os isolados S. carpocapsae ALL e Heterorhabditis sp. RSC01 foram os mais virulentos para a fase larval causando mortalidade superior a 85%. Em relação à fase de pupa os isolados Heterorhabditis sp. PI, Heterorhabditis sp. JPM4, H.

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Section: Resultsmentioning

confidence: 99%

Selection of entomopathogenic nematodes for the control of the fruit fly Ceratitis capitata (Diptera: Tephritidae)

Rohde

Moino

Carvalho

et al. 2012

Agraria

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“…They have considerable energy reserves, mainly neutral lipid which can constitute up to 40% of the IJ weight (Selvan et al, 1993;Abu Hatab & Gaugler, 1997;Fitters et al, 1999). These extensive reserves enable them to survive for weeks or even months in soil or storage (Patel et al, 1997;Qiu & Bedding, 2000;Hass et al, 2002).…”

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confidence: 99%

Spontaneous and induced activity of Heterorhabditis megidis infective juveniles during storage

Fitters¹,

Griffin²

2004

Nematol

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Summary -Infective juveniles (IJ) of three Heterorhabditis megidis isolates, HF85, EU17 and UK211, were stored in water at 20 • C for up to 10 weeks. At 2-week intervals, activity, infectivity, energy reserves and survival were measured. There was no difference between the three isolates in infectivity, which increased significantly over the first 2 weeks and declined gradually thereafter. IJ became inactive during storage. Out of storage, the highest activity was recorded in week 0: nearly all IJ were active within the first minute of observation and remained active for the 20-min observation period. With increasing storage time, an increasing proportion of IJ were inactive in the first minute, reaching 83-96% by week 6. The time taken by 50% of the IJ to become active (AT 50 ) initially increased with nematode age, reaching a maximum of 3-7 min in week 4 or 6 (depending on isolate) but subsequently declined to 2-4 min in week 10. By the time the IJ were becoming more readily activated in weeks 6-8, 75% of the lipid reserves had been depleted, and IJ had started to die. This greater propensity to become active with age may represent a switch to risk-taking behaviour in the face of impending starvation.

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“…was a contributory factor to the poorer survival of Heterorhabditis spp., though this was not supported by Menti et al (2003). DiVerences in the lipid composition of freshly harvested H. megidis EU17, UK211, and HF85 were not large (Fitters et al, 1999) and are unlikely to have contributed to the intraspeciWc diVerences in survival or rate of energy depletion rate seen here. However, the importance of glycogen and protein as energy sources has not been investigated for these isolates.…”

Section: Discussionmentioning

confidence: 60%

“…Lipids, carbohydrate (especially glycogen), and protein, accumulated during the preceding juvenile stages within the host, all provide energy for IJs during storage (Lewis et al, 1995;Qiu and Bedding, 2000;Selvan et al, 1993b). Lipid is the main energy reserve, constituting between 32 and 49% of IJ body weight (Fitters et al, 1999;Lewis et al, 1995;Menti et al, 2003;Selvan et al, 1993b). In most species of EPN, activity and infectivity decline as lipids are depleted (Lewis et al, 1995;).…”

Section: Introductionmentioning

confidence: 99%

Survival, starvation, and activity in Heterorhabditis megidis (Nematoda: Heterorhabditidae)

Fitters

Griffin

2006

Biological Control

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Infective juveniles (IJs) of entomopathogenic nematodes do not feed but have ample stored energy reserves and can survive for several months in soil or in water. IntraspeciWc variation in survival of Heterorhabditis megidis has been observed for eight isolates of H. megidis stored in water at 20°C for up to 14 weeks with the 50% survival time (ST 50 ) ranging from 5.6 to 12.5 weeks. How important physical and behavioral attributes were in explaining this variation in survival was explored using stepwise regression. Included in the analysis were: initial energy reserves (measured by image analysis densitometry), size (area and length) the time at which 50% of energy reserves were depleted (ET 50 ), and motility (head movements/min in week 0). Energy depletion rate, ET 50 , is an important predictor of survival, explaining 93.8% of the variation in ST 50 among isolates. Energy depletion rate was highest in the Wrst week, a time at which H. megidis IJs were spontaneously active during storage. By week 5, when IJs had begun to die, some individuals had completely depleted their energy reserves, supporting the hypothesis that death was a result of starvation. In a second stepwise regression, performed to explore what factors contribute to variation in rate of energy depletion, motility accounted for 60.1% of the variation in ET 50 . With the inclusion of initial energy reserves, length, and area, 88.5% of the variation was accounted for. We conclude that intraspeciWc variation in survival of H. megidis in water is due largely to variation in rates of depletion of energy reserves, which in turn is strongly associated with levels of locomotory activity.

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Fatty acid composition of Heterorhabditis sp. during storage

Cited by 20 publications

References 20 publications

Selection of entomopathogenic nematodes for the control of the fruit fly Ceratitis capitata (Diptera: Tephritidae)

Selection of entomopathogenic nematodes for the control of the fruit fly Ceratitis capitata (Diptera: Tephritidae)

Spontaneous and induced activity of Heterorhabditis megidis infective juveniles during storage

Survival, starvation, and activity in Heterorhabditis megidis (Nematoda: Heterorhabditidae)

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