Pest species diversity enhances control of spider mites and whiteflies by a generalist phytoseiid predator

Abstract

To test the hypothesis that pest species diversity enhances biological pest control with generalist predators, we studied the dynamics of three major pest species on greenhouse cucumber: Western flower thrips, Frankliniella occidentalis (Pergande), greenhouse whitefly, Trialeurodes vaporariorum (Westwood), and two-spotted spider mites, Tetranychus urticae Koch in combination with the predator species Amblyseius swirskii Athias-Henriot. When spider mites infested plants prior to predator release, predatory mites were not capable of controlling spider mite populations in the absence of other pest species. A laboratory experiment showed that predators were hindered by the webbing of spider mites. In a greenhouse experiment, spider mite leaf damage was lower in the presence of thrips and predators than in the presence of whiteflies and predators, but damage was lowest in the presence of thrips, whiteflies and predators. Whitefly control was also improved in the presence of thrips. The lower levels of spider mite leaf damage probably resulted from (1) a strong numerical response of the predator (up to 50 times higher densities) when a second and third pest species were present in addition to spider mites, and (2) from A. swirskii attacking mobile spider mite stages outside or near the edges of the spider mite webbing. Interactions of spider mites with thrips and whiteflies might also result in suppression of spider mites. However, when predators were released prior to spider mite infestations in the absence of other pest species, but with pollen as food for the predators, we found increased suppression of spider mites with increased numbers of predators released, confirming the role of predators in spider mite control. Thus, our study provides evidence that diversity of pest species can enhance biological control through increased predator densities.

Generalist Predators, Food Web Complexities and Biological Pest Control in Greenhouse Crops

“…So far, this aspect of mixed diets has been ignored in theoretical models about apparent competition. Not only whiteflies, but also spider mites were controlled better by the presence of thrips through apparent competition (Messelink et al, 2010). Although A. swirskii is not an effective predator of spider mites because it is strongly hindered by the webbing, it can prevent the formation of new colonies of spider mites when there are other prey, such as thrips, available.…”

Compatibility of Amblyseius swirskii with Beauveria bassiana: two potentially complimentary biocontrol agents

“…Marketed primarily for whitefly (Hemiptera: Aleyrodidae) and thrips (Thysanoptera: Thripidae) control, both of which are major pests in tomatoes, peppers, cucumbers and ornamentals (Malais and Ravensberg 2003), this polyphagous predator can suppress pest outbreaks on its own (Messelink et al 2006;Chow et al 2010;Messelink et al 2010;Calvo et al 2011). Combining its use with other BCAs can enhance pest control particularly when the BCAs do not compete directly but exploit different life stages of the same pest (Calvo et al 2009;Dogramaci et al 2011).…”

“…Conversely, A. swirskii can interfere with other BCAs by inter-and intraguild predation (hyperpredation) (Buitenhuis et al 2010;Messelink et al 2011). In the field, A. swirskii is primarily used preventatively to avert pest establishment and for controlling light whitefly and thrips infestations (Messelink et al 2010;Calvo et al 2011). At high pest pressure, curative control by predatory mites is often insufficient and corrective applications with chemical pesticides or biopesticides may be required (Calvo et al 2009;Medd and GreatRex 2014).…”

Enhancing pest management in sweet pepper by the exploitation of zoophytophagy

“…Pyralidae) or decapsulated dry cysts of the brine shrimp Artemia franciscana Kellogg (Anostraca: Artemiidae) have been reported (Nomikou et al, 2002;van Houten et al, 2005avan Houten et al, , 2005bMesselink et al, 2006, Messelink et al, 2010Nguyen et al, 2013;Calvo et al, 2015). Sweet pepper area (ha) under BC (A); Percentage of farms with BC (B) (Almería region), (Blom, 2017;Calvo et al, 2015).…”

“…Complementary, A. swirskii is released for controlling whiteflies (Nomikou et al, 2002;Calvo et al, 2009a) but it can also manage thrips (Messelink et al, 2006), broad mites (van Maanen et al, 2010 and to a lesser extent, spider mites (Messelink et al, 2010). In spite of the broad diet range of both predators, the BC system is still challenged due to aphids.…”