International Congress BIOLOGICAL PRODUCTS - Gruppo di ...

It can be reproduced in vivo at 15°C and in liquid culture at 20°C without loosing its cold activity. A product based on
this nematode is actually under development.
- Bio-insecticide based on endotoxins produced by a particular strain of the nematode symbiotic bacterium
Photorhabdus luminescens
It has been discovered (Ragni et al., 1997) a newly characterize strain of Photorhabdus luminescens, denominated
XP01, which is highly toxic when directly administered by food contamination assays to neonates larvae of the
Lepidopetran pests Mamestra brassicae and Cydia molesta. Further characterization made with Mamestra brassicae, as
target insect, showed that the activity of this strain is caused by an intracellular compound that is not secreted into the
culture media. In fact, the surnatant of fermented broth of XP01 had no toxic activity and this discovery was different
from what was reported for the W-14 strain of P. luminescens (Bowen et al., 1998). It was demonstrated that the toxic
effect of XP01 is maintained even when the bacterial cells are killed. The discovery of Photorhabdus luminescens strain
XP01 indicates the existence of a presumably new family of entomotoxic proteins present in Photorhabdus and
probably in Xenorhabdus spp. These insecticidal toxins could be used as an active bio-pesticide ingredient in a similar
manner to the delta-endotoxins of B. thuringiensis. This new source of natural toxins could help both the fight against
the development of insects resistance as well as serve as sources of novel specific activities in combination with other
known biopesticides.
Further studies could lead to understanding of the genetic control involved in the expression of XP01 insecticidal
toxins.
Conclusions: An Analysis of the Commercial Entomopathogenic Nematode Product
In this type of analysis, commercial and scientific factors should be sorted into four categories either as ‘Strengths,
‘Weakness’, ‘Opportunity’, or ‘Threat’ (source: Pest Management Resource Centre with the following information as
available at the site: http://www.pestmanagement.co.uk/special/microb/com_prod.html).
Product Strengths
- Consistent supply available; supply will be consistent when sales forecasts is accurate and production levels are
predictable. Most EPN species can be produced on a large scale, up to a capacity of 80,000 litre fermenters, at a
concentration of 150-300,000 infective juveniles per millilitre.
- The product is safe and ‘natural’; comprehensive data packages have been developed to support the safety claims
made about EPN products. Workers benefit from not having to wear protective clothing during product application.
Studies have also shown that EPN applications do not have a significant impact on non-target insects (Georgis et al.,
1991).
- Products do not require registration; registration regulations vary from country to country and have not
been standardized in Europe. In most countries EPN’s are regarded as animals and are exempt from pesticide
regulations. This means that once efficacy data has been generated, products can be introduced. The commercial
advantage of this is that product sales can begin at least three years faster than conventional products.
- Products are easy to use; no additional equipment is required to apply EPN products, instructions have been
designed to be similar to conventional pesticides making their use familiar to growers.
Product Weaknesses
- The insect life cycle; the susceptible stage of the insect life cycle may be in an inaccessible niche, or in a niche
unsuitable for EPN survival. For example, excessively wet-dry soil or foliage.
- Insect behaviour; insect behaviour or physiology may reduce EPN product efficacy. Gaugler (1988) suggested
that the tendency of quiescent soil insects, especially pupae, to release carbon dioxide in bursts rather than
continuously reduced the ability of infective juveniles to follow a chemical gradient to the host. It has been reported
that when exposed to infective juveniles of Steinernema carpocapsae Weiser (All strain) American cockroaches,
Peripaneta americana (L), actively groomed nematodes from legs and antennae to prevent infection.
- Efficacy may be limited at hot and cold temperature; for example, control of black vine weevil Otiorhynchus
sulcatus (F.) larvae in blackcurrant crops by Steinernema carpocapsae was limited at temperatures below 15 °C.
- Product formulation; products should have a shelf life at room temperature. This can provide more flexibility in the
distribution system. For example, a product shelf life at room temperature makes it easier to deliver and store the
product in a warm climate, or the distributor could reduce costs by taking more products at one delivery and risk a
temporary reduction in sales. Conversely, if the growers have cold storage facilities, as in the mushroom market, a
sophisticated formulation may not be required, reducing development costs.
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