José E. Belda

Preplant release of Nesidiocoris tenuis and supplementary tactics for control of Tuta absoluta and Bemisa tabaci in greenhouse tomato

An early release system developed for Nesidiocoris tenuis Reuter (Heteroptera: Miridae) could provide a good control of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) in tomato. Tuta absoluta and the whitefly Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) often appear simultaneously in tomato crops and this might affect control capacity. Therefore, the new approach needs to be tested in a situation with both pests present. In addition, Bacillus thuringiensis Berliner and Trichogramma achaeae Nagaraja & Nagarkatti (Hymenoptera: Trichogrammatidae) have been shown to be effective against T. absoluta and could be a supplement to N. tenuis. Two experiments were carried out to evaluate the potential of this approach and its combination with supplementary control agents against T. absoluta. In the first experiment four treatments were compared (T. absoluta, B. tabaci, T. absoluta + N. tenuis, and T. absoluta + B. tabaci + N. tenuis) and N. tenuis was able to control T. absoluta and B. tabaci either alone or together. In the second experiment, five treatments were compared: T. absoluta, T. absoluta + N. tenuis, T. absoluta + N. tenuis + T. achaeae, T. absoluta + N. tenuis + B. thuringiensis, and T. absoluta + N. tenuis + T. achaeae + B. thuringiensis. Nesidiocoris tenuis again proved capable of significantly reducing T. absoluta populations, and the implementation of additional agents did not increase its effectiveness.

Development of a biological control‐based Integrated Pest Management method for Bemisia tabaci for protected sweet pepper crops

The tobacco whitefly, Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), is a key pest in commercial sweet pepper crops in southeast Spain. Its biological control is currently based on augmentative introductions of the parasitic wasp Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae), which need to be occasionally supplemented with pesticide applications. These pesticides can be harmful for the biological control agents. Therefore, it is important to improve the current strategy by reducing dependency on pesticides. Two potential solutions are conceivable: addition of another effective biocontrol agent or application of pesticide prior to the release of biocontrol agents. The mirid bug Nesidiocoris tenuis Reuter (Heteroptera: Miridae) and the predatory mite Amblyseius swirskii Athias‐Henriot (Acari: Phytoseiidae) are promising candidates as additional biocontrol agents. The aim of the present study was to test these possible solutions in two subsequent trials, i.e., a ‘selection’ and an ‘improvement’ experiment. In the selection experiment, four treatments were compared: E. mundus, N. tenuis + E. mundus, A. swirskii + E. mundus, and A. swirskii + N. tenuis + E. mundus. Amblyseius swirskii appeared able to significantly increase effectiveness against the pest, in contrast to N. tenuis, which did not contribute to whitefly control. The best strategy was the combination of E. mundus and A. swirskii. In the improvement experiment, three treatments were compared: E. mundus, A. swirskii + E. mundus, and A. swirskii + E. mundus + pesticides. Amblyseius swirskii again proved capable of significantly reducing whitefly populations, and the implementation of pesticides before the release of the biocontrol agents was shown to increase the effectiveness against the pest even more.

Development of an economic rearing and transport system for an arid-adapted strain of the predatory mite, Neoseiulus californicus, for spider mite control

Neoseiulus californicus (McGregor) is a relatively effective phytoseiid predator against spider mites reported from the Americas (North and South), Africa, the Mediterranean basin, and Japan. This study was a collaborative effort to identify and mass-rear a strain of N. californicus that is more efficacious under arid conditions than the standard commercial strain from California (USA). N. californicus strains were collected in arid areas worldwide. Discriminant analysis performed with 30 morphological variables allowed for their separation. The performance of these strains under arid conditions and on selected host plants was evaluated in laboratory and semi-field trials. Development and survival of eggs and juveniles differed among strains and humidities. Female performance (survival, oviposition) was influenced by strain but not by humidity. The Californian reference strain was superior to all others, when considering both adaptation to dry conditions and power of population increase at low humidities. Whole potted plant trials (cucumber, strawberry, and pepper) confirmed this result. Field trials were conducted to compare this new product to the standard commercial strain of Phytoseiulus persimilis Athias-Henriot. To identify possible influence of symbiotic bacteria on strains of N. californicus general primers for the 16S rDNA gene were used in a PCR. Among other bacteria, a Spiroplasma, closely related to the one found in various arthropods, was detected in two strains, and it was further characterized. No influence on the hosts developmental time, fecundity, and sex ratio could be detected. To provide this product at an affordable cost for European growers an economic rearing and delivery system for N. californicus was developed and its marketing potential in Europe and neighboring countries was estimated.