Integration of the SIT with Biocontrol for Greenhouse Insect Pest Management

Background:

Greenhouses and other confined locations provide ideal conditions for the rapid build-up of pest populations as they are largely protected from predators and parasitoids. Many of these pests have been exposed to high insecticide pressure over many generations and resistance has developed in many of them. Biocontrol agents are widely used to combat these pests, but not all are well controlled with biocontrol agents and when a pest gets out of control it has to be controlled with pesticides, which then disrupts other biocontrol and pollination.

The SIT is compatible with biological control and can complement biocontrol for those pests that are otherwise difficult to control, reducing crop losses, pesticide residues in food and risk to workers. Augmentative biological control has historically focused mainly on crops grown in confined areas. Recently there is more attention for crops grown outside. For SIT the opposite direction can be observed: historically SIT has focused on area wide pest management, but with this CRP SIT will now enter confined areas such as greenhouses.

Objective:

The overall objective is to advance development and implementation of SIT for integration with other biocontrol in greenhouses. The project has three specific objectives:

a. Drosophila suzukii:

Drosophila suzukii (Diptera: Drosophilidae) is an exotic pest of stone fruits and berries that has recently invaded Europe (Italy, France, Belgium, Austria inter alia), North America (United States and Canada) and South America (Brazil) and now has a worldwide distribution. This pest attacks a wide range of soft fruits with preference for blueberry, strawberry and raspberry, crops that can be grown in confined cropped systems. The female flies lay eggs under the skin of maturing fruits and the developing larvae feed on the fruit tissues thereby causing the fruit to collapse.

When left uncontrolled the flies can cause complete loss of the harvests. Currently the control relies mostly on the application of chemical insecticides that need to be applied a few days before the fruits are harvested and may cause a threat for the health of workers and consumers. In addition specific cultural practices such as mass trapping, netting and strict hygiene are being used. Research on natural enemies (predators and parasitoids) is ongoing, but no biological control solutions are readily available.

Radiation biology experiments are ongoing on D. suzukii in collaboration with FAO/IAEA and at least two laboratories are conducting research on mass rearing under the Suzukill project that is a multidisciplinary and international research project funded by both the French ANR and the Austrian FWF (https://suzukill.univ-rennes1.fr/). The FAO/IAEA has had many requests from member countries about developing conventional SIT for D. suzukii.

b. Spodoptera and Helicoverpa group:

Spodoptera exigua, S. frugiperda and Helicoverpa armigera (Lepidoptera: Noctuidae) share a similar biology. All three species are known as pest of both outdoor crops and of important greenhouse crops such as tomato, peppers and eggplant. Biocontrol of these species relying on egg-parasitoids such as Trichogramma sp. (Hymenoptera: Trichogrammatidae) or Telenomus sp. (Hymenoptera: Scelionidae) are often insufficiently effective because of the short timespan to parasitize the eggs. Also, the commercially available Bacillus thuringiensis strains appear to be insufficiently effective.

For each of these species, SIT for area wide pest management has been developed in the past but these were never operationalized. Because of the past work on SIT, data on the rearing of these species and the radiation biology is available. This will allow the research to quickly focus on demonstrating efficiency in greenhouses. Because the SIT for Lepidoptera normally relies on F1 sterility, a certain degree of damage needs to be tolerated. For fruit crops this tolerance is expected as the caterpillars primarily feed on the leaves, not on the fruits. On the other hand, the F1 sterility will result in increased numbers of sterile eggs in the crop. These eggs will improve the efficiency of egg parasitoids if these were to be combined with the SIT. If crop damage is not tolerable, full sterility can be considered but the high doses necessary reduce the efficacy of the control.

Because of the similarities in the biology of these three species, coordinating the research will allow for exchange of the results and is expected to lead to strong synergisms.

c. Tuta absoluta and Neoleucinodes elegantalis:

Tuta absoluta (tomato leaf miner) (Lepidoptera: Gelechiidae) and Neoleucinodes elegantalis (eggplant stem borer or tomato borer) (Lepidoptera: Crambidae) are two emerging pests of Solanaceous crops of South-American origin. Tuta absoluta has currently spread eastward, through Europe as far as India, and northward up to Mexico. Following its introduction into Europe, North Africa and the Middle East, T. absoluta has already caused extensive economic damage. The impact of the pest includes severe yield loss reaching 100%, increasing tomato prices, bans on the trade of tomato including seedlings, an increase in synthetic insecticide applications, disruption of integrated management programmes of other tomato pests, and an increase in the cost of crop protection. Considering its high biotic potential, its ability to adapt to various climatic conditions and the speed with which it has colonized Europe and North Africa, the potential invasion of African and especially Asian tomato crops by T. absoluta will probably impact heavily on the livelihood of local tomato growers and tomato agribusinesses in these regions. Tuta absoluta in Europe is currently sufficiently controlled by the predatory mirid bugs Nesidiocorus tenuis and Macrolophus pygmeus (Heteroptera: Miridae). However, these invertebrate biocontrol agents, native to Europe, will not be a control option when the pest reaches North America or Asia, which are outside of the natural enemies’ native ranges. Control of the pest in South America is currently based largely on chemical control. Therefore, development of SIT for Tuta absoluta could provide a sustainable alternative. Radiation biology data for T. absoluta suggest doses of 200–250 Gy could be used to induce inherited sterility in T. absoluta males.

Neoleucinodes elegantalis (tomato borer or eggplant stem borer) is a major pest of tomatoes and other Solanaceous fruit crops (e.g. Solanum melongena and Capsicum sp.) that occurs in South and Central America. N. elegantalis is absent from other regions, but is considered a threat due to the importance of tomato and other Solanaceous fruit crops in many other regions. It has been intercepted several times by the Netherlands (1 interception in 2009 and 3 in 2012) during import inspections of eggplant from Suriname and control of passenger baggage at Schiphol airport. Consequently, it has been added to the EPPO Alert List.

The objective of developing a SIT program for T. absoluta and N. elegantalis is twofold; firstly providing a more sustainable control method for currently invaded areas where biocontrol is not yet developed and secondly provide an eradication method for these Solanaceous pests in the event they invade new areas.

Participants:

Participation is anticipated from the following countries: Argentina, Australia, Belgium, Brazil, Canada, China, Colombia, Ecuador, France, Germany, Israel, Italy, Japan, Mexico, Netherlands, Peru, Spain, Thailand, UK and USA.

Reports:

Project Officer:

Andrew Parker and Carlos Caceres