Food supplementation to optimize inoculative release of the predatory bug Macrolophus pygmaeus in sweet pepper

Abstract

Biological control is widespread in management of greenhouse sweet pepper crops. Several species of predatory mites, bugs, and parasitoids are used against a wide range of pest species. However, biological control of particular pests like aphids, caterpillars, and the tobacco whitefly, Bemisia tabaci Gennadius, remains problematic. Macrolophus pygmaeus Rambur (Hemiptera: Miridae) is a generalist predatory bug which is used on a large scale in Western European tomato greenhouses. It has already been demonstrated that M. pygmaeus is a valuable biocontrol option in sweet pepper crops, but it has yet to find its way into common practice. Macrolophus pygmaeus should be introduced at the start of the growing season and determining an optimal release strategy is a key step in this process. In tomato crops, M. pygmaeus requires supplemental food releases to reach sufficient population numbers and dispersal levels. In this study, the need for food supplementation in sweet pepper is investigated. Three strategies were tested: (1) no food supplementation, (2) local food supplementation, and (3) full field food supplementation. Both population numbers and dispersal rates of the second generation were higher under the third strategy. Macrolophus pygmaeus oviposits near food sources, therefore dispersal rates are higher when food is more spread out. Pest control was achieved in all treatments, but faster and at lower pest levels under the full field strategy.

Is leaf pruning the key factor to successful biological control of aphids in sweet pepper?

“…When pests are scarce or absent, it will turn to plant feeding and thus sustain a population that can prevent pest outbreaks . Introducing M. pygmaeus at the beginning of the season accompanied by a correct food supplementation strategy is sufficient to establish a population in sweet pepper greenhouses . Previous research has shown M. pygmaeus is capable of strongly reducing aphid population growth in sweet pepper, but complete control has not always been achieved …”

“…This requires a release strategy that is both effective and efficient. Brenard et al . developed an optimal release strategy for M. pygmaeus in sweet pepper.…”

“…developed an optimal release strategy for M. pygmaeus in sweet pepper. It consists of introducing the bugs a week after planting and providing supplemental food in a full field fashion to ensure sufficient population growth and dispersal . The optimal food supplementation scheme involves providing Artemia spp.…”

“…Macrolophus pygmaeus received full field food supplementation of 0.09 g m −2 Artemia spp. cysts (Artefeed, Koppert Biological Systems) on the day of release and then weekly for another 6 weeks, according to the protocol as described in Brenard et al . Food was distributed throughout the greenhouse by means of a mini‐airbug (Koppert Biological Systems).…”

Biweekly supplementation with Artemia spp. cysts allows efficient population establishment by Macrolophus pygmaeus in sweet pepper

“…In greenhouse tomato crops, an optimal supplementation scheme consists of weekly food applications during 6–8 weeks, as this is the time it takes for a generation of M. pygmaeus to develop (Moerkens et al., ). In contrast to tomato, sweet pepper crops have pollen available for the bugs, but food supplementation is still required to reach a sufficiently high population at the start of the season and to ensure quick dispersal the food should be supplemented in a full‐field fashion (Brenard et al., ). Although full‐field food supplementation in sweet pepper yields the best results, growers are not always inclined to apply this method due to higher food and labour costs.…”