Greenhouse whitefly: Will the unwanted greenhouse whitefly make it in the wild?

September 2, 2014

Greenhouses have improved the possibilities of invasion of greenhouse whitefly into the wild in the boreal region, new study finds. Genetic analysis sheds new light on the survival of whiteflies in Finland and helps to plan efficient pest management.

Irina Ovcarenko, research scientist at the MTT Agrifood Research Finland, has studied and ecology of greenhouse whitefly (Trialeurodes vaporariorum) in her thesis. Greenhouse whitefly is a widespread invasive , which has occurred in Finland since the year 1920. It does not belong to the original fauna of the country, but survives in Finland as it finds suitable overwintering habitats in greenhouses. Carefully planned reduces crop damages.

"Genetic analyses revealed that the same whitefly populations persist in the majority of the sampled greenhouses for two years. Year-round greenhouse crop producers should avoid planting new crop without complete extermination of not only from the old crop, but also from the greenhouse premises," Ovcarenko says.

Insecticide-treated populations able to recover

Ovcarenko's findings show that genetic diversity of greenhouse whitefly is lower in the Finnish greenhouses compared with Greece, where whiteflies are able to persist outdoors all year round. Furthermore, global genetic diversity of greenhouse whitefly is low. Generally, low genetic diversity results in species' decreased ability to adapt. However, whiteflies are able to recover from insecticide treatments and maintain even high levels of genetic diversity in their local populations.

"It was surprising to find medium to high levels of local genetic diversity and no signs of harmful genetic bottlenecks in whiteflies from greenhouses, where new crops are planted every year and insecticides cause frequent mortality," Ovcarenko says.

Moreover, low global genetic diversity has not reduced adaptation or invasion potential of the Finnish population. Whitefly is a generalist herbivore, which feeds on many plant species, but it may also specialize in feeding on greenhouse crops. Tomato and cucumber are the most common crops in the Finnish greenhouse cluster and initial signs of evolution of specialized races for these host plants were found in the study.

"Continuous cultivation of the same greenhouse crop species creates possibilities for host adaptation. Formation of these races may increase pest abundance and lead to a higher extent of crop damage," Ovcarenko says.

Despite initial signs of host race formation, whiteflies prefer natural species to cultivated crops as host plants, which could facilitate pest dispersal into natural vegetation in spring.

"Whiteflies are able to use numerous outdoor plants around greenhouses as seasonal habitats in summer. The same population of whiteflies may, therefore, return from these wild plants to newly planted greenhouse in August and September," Ovcarenko says.

Biological pest control pays off

The study showed that resistance to common insecticide pymetrozine varies considerably among the Finnish whitefly populations. Therefore, Ovcarenko recommends pest management should start at individual company level by maintaining pest free surroundings and monitoring for early detection of the pest. Results indicated that it pays off to maintain chemical free greenhouse crop production. If biological pest control was used, whitefly populations were more susceptible to insecticides, whereas whiteflies from greenhouses treated with insecticides over the years showed initial signs of resistance development.

The most important step to reduce crop damage and tackle invasion is to standardize practices in dense greenhouse areas. The study has motivated farmers to exchange information and monitor whiteflies outside greenhouses, in potato and strawberry fields.

"Co-operation is the key for sustainable pest management. To reduce pest dispersal potential to other agroecosystems, synchrony in pest monitoring, exterminations and crop rotations among crop producers is advised," Ovcarenko concludes.

Explore further: Whitefly confused by cacophony of smells

Related Stories

Controlling whiteflies the natural way

December 6, 2011

U.S. Department of Agriculture (USDA) scientists are showing Arizona cotton growers how to reduce their dependence on broad-spectrum insecticides by controlling sweetpotato whiteflies with greener alternatives.

Recommended for you

Knowledge gap on the origin of sex

May 26, 2017

There are significant gaps in our knowledge on the evolution of sex, according to a research review on sex chromosomes from Lund University in Sweden. Even after more than a century of study, researchers do not know enough ...

The high cost of communication among social bees

May 26, 2017

(—Eusocial insects are predominantly dependent on chemosensory communication to coordinate social organization and define group membership. As the social complexity of a species increases, individual members require ...

Why communication is vital—even among plants and funghi

May 26, 2017

Plant scientists at the University of Cambridge have found a plant protein indispensable for communication early in the formation of symbiosis - the mutually beneficial relationship between plants and fungi. Symbiosis significantly ...

Darwin was right: Females prefer sex with good listeners

May 26, 2017

Almost 150 years after Charles Darwin first proposed a little-known prediction from his theory of sexual selection, researchers have found that male moths with larger antennae are better at detecting female signals.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.