Biological Control Of Greenhouse Pests Research Articles

Verbena × hybrida and Scaevola aemula flowers provide nutrients for the reproduction of Nesidiocoris tenuis used for biological pest control in greenhouses

Verbena × hybrida and Scaevola aemula flowers provide nutrients for the reproduction of Nesidiocoris tenuis used for biological pest control in greenhouses

Potential Aphid Population Regulation by Aphidius colemani (Hymenoptera: Aphidiidae) in Response to Host Density, Parasitoid Density, and Age.

Aphidius colemani Viereck is an important parasitoid of green peach aphid [Myzus persicae (Sulzer)], a serious pest of greenhouse crops. Augmentation of natural enemies is the most used approach to biological control of greenhouse pests. Yet, the optimal release time, rate, and age of natural enemies are often unclear. Here we tested the influence of population density of both A. colemani and M. persicae, as well as parasitoid age, on parasitism and sex allocation. We aim is to provide information for cost-effective aphid biological control programs. We show that 1) parasitoid females increased parasitism and produced more female-biased offspring with an increase of aphid density, 2) a moderate increase of parasitoid release rate elevated parasitism and daughter production when aphid density was high, 3) parasitism rate declined with an increase of aphid density but the moderate increase of parasitoid release rate eased the decline rate, and 4) 3-d-old parasitoids parasitized more aphids than younger ones but parasitoid age had no effect on daughter production. These findings suggest that A. colemani females can adjust their ability to regulate the aphid population in response to aphid population dynamics. In augmentative programs, a moderate increase of parasitoid release when aphid density is high could achieve effective control and a release of 3-d-old parasitoids could lead to a better control outcome.

The effect of banker plants and pre-plant release on the establishment and pest control of Macrolophus pygmaeus in tomato greenhouses

Biological pest control in greenhouses generally depends on the release of natural enemies. Macrolophus pygmaeus (Hemiptera: Miridae) is one of the most used predators in European vegetable crops. However, its long establishment time is considered as one of the main drawbacks in regard to pest control. Pre-plant release in nurseries and the use of banker plants are strategies frequently used to enhance the response of predatory mirids. The aim of this work was to determine how the length of the pre-plant release period in banker plants (PRP) and banker plant species influenced the establishment and population dynamics of M. pygmaeus and its pest control in tomato crops. Two PRPs (24 h and 30 days) and two banker plants (tomato, Solanum lycopersicum—Solanaceae, and Ballota hirsuta—Lamiaceae) were assayed in a complete factorial design with three replicates, in individual greenhouses. The proportion of individuals established, founder population, abundance and population growth rate of M. pygmaeus were significantly higher for the long than for the short PRP. For the long PRP, the founder population and abundance of M. pygmaeus in greenhouses were higher when B. hirsuta, rather than tomato, was used as banker plant. Lower incidences of Bemisia tabaci (Hemiptera: Aleyrodidae) and Tuta absoluta (Lepidoptera: Gelechiidae) were registered in greenhouses with the long PRP, while the effect of the banker plant was not significant. The higher proportions of individuals established and higher population growth rates of M. pygmaeus in the greenhouses with the largest founder populations suggest the implication of Allee effects.

Occupational asthma from biological pest control in greenhouses

Commercially available insects and mites are increasingly used in the biological control of whiteflies and other pests in greenhouses. We describe 2 greenhouse workers who were exposed and sensitized to the insects used for biological pest control at their workplace and who were diagnosed with occupational asthma (OA) and occupational rhinitis (OR). The cases are presented in Table I. Both patients gave their written consent.

Optimal nutrient foraging strategy of an omnivore: Liebig's law determining numerical response

The paper is aimed at a theoretical explanation of the following phenomenon. In biological pest control in greenhouses, if an omnivore agent is released before the arrival of the pest, the agent may be able to colonize, feeding only on plant and then control its arriving prey to a low density. If the pest arrives before the release of the agent, then it tends to reach a high density, in spite of the action of the agent. This means that according to the initial state, the system displays different stable equilibria, i.e. bistable coexistence is observed. Based on the biological situation, the explaining theoretical model must take into account the stoichiometry of different nutrients and the optimal foraging of the omnivore agent. We introduce an optimal numerical response which depends on the optimal functional responses and on the ‘mixed diet–fitness’ correspondence determined by ‘egg stoichiometry’, in our case by Liebig's Law; moreover we also study the dynamical consequences of the latter when the plant is “inexhaustible”. In our model, we found that under Holling type II functional response, the omnivore–prey system has a unique equilibrium, while for Holling type III, we obtained bistable coexistence. The latter fact also explains the above phenomenon that an omnivore agent may control the pest to different levels, according to the timing of the release of the agent.

Movement of greenhouse whitefly and its predators between in- and outside of Mediterranean greenhouses

Some Mediterranean greenhouses are inserted in a landscape of open fields, non-agricultural and woody habitats. Both the greenhouse whitefly and its polyphagous predators are well adapted to protected and field crops. The phenology and intensity of whitefly and predator exchange between greenhouses and surrounding habitats were investigated in two different zones of northern Spain. Whiteflies colonised greenhouses earlier and built up high populations before predators established in the crop. Both the abundance of vegetation and the topographic characteristics of the environment surrounding greenhouses affected the numbers of predators entering the tomato crop through the greenhouse openings whereas whitefly migration was only affected by the topography around the greenhouses. These results are discussed in terms of biological control of greenhouse pests by naturally occurring predators.

Open rearing of generalist predators: A strategy for improvement of biological pest control in greenhouses

Open rearing of generalist predators: A strategy for improvement of biological pest control in greenhouses

Advances and Perspectives in the Biological Control of Greenhouse Pests with Special Reference to Colombia

This paper analyses the state of the art of biological control of greenhouse pests with special reference to Colombia, one of the world's largest producers of cut flowers. After a discussion of the use and impacts of selected natural enemies on a variety of arthropod pests in greenhouses, suggestions on how to enhance the effectiveness of inundative release strategies further to achieve successful biological control of key pests are provided.

Functional response of Neoseiulus barkeri Hughes on two-spotted spider mite (Acari: Tetranychidae)

Generalist predatory mites are the common phytoseiid fauna in many agroecosystems, but little attention has been paid to their potential as biological control agents. In this study, we determined the functional responses of adult females of the generalist predator Neoseiulus barkeri Hughes on eggs, larvae, and adults of the two-spotted spider mite, Tetranychus urticae Koch, in the laboratory. Predation experiments were conducted on pepper leaf discs over a 24 h period at 25±1°C, 70–80% RH and 16L:8D photoperiod. Prey densities ranged 5 to 80 eggs, or 5 to 40 larvae, or 1 to 8 female adults of T. urticae per disc. The predation rate of N. barkeri adult females on T. urticae eggs was the same as on its larvae, but the predation rate on adult females was much lower. The role of generalist predatory mites in integrated and biological control of greenhouse pests was discussed.