Manuel González-Núñez

Arthropods were sampled in organic and conventional cherry orchards over two growing seasons using pitfall traps, yellow sticky traps, and branch shaking. The data obtained from both production systems were compared using linear mixed effects models and principal response curves (PRCs). The diversity of families and the total abundance of arthropods captured by the three sampling methods were significantly greater in the organic orchards. Phytophagous and predatory arthropods in cherry tree canopies, soil-dwelling predators and parasitoids captured in yellow sticky traps were significantly more abundant in organic orchards. Although no significant differences in the total abundance of Coccinellidae between crop managements were recorded, species richness and abundance, excluding that of Stethorus pusillus (Herbst) (Coleoptera: Coccinellidae), were significantly greater in the organic plots. According to the PRC analyses, the taxa most favoured by organic management were the predatory families Anthocoridae, Lycosidae, Staphylinidae, Gnaphosidae, Philodromidae, Hybotidae, Nabidae, Carabidae and Thomisidae; the parasitoids belonging to Pteromalidae, Mymaridae, Braconidae, Bethylidae, Platygastridae and Aphelinidae; and the phytophagous Monosteira unicostata (Mulsant & Rey) (Hemiptera: Tingidae) (poplar lace bug) and aphids. The predatory coccinellid species most favoured by organic cropping were Adalia decempunctata (L.) (Coleoptera: Coccinellidae), Adalia bipunctata (L.) (Coleoptera: Coccinellidae) and Scymnus interruptus (Goeze) (Coleoptera: Coccinellidae). In contrast, some groups of arthropods were more abundant in conventionally managed orchards, among which spider mites and their predatory species S. pusillus (Herbst) stood out. Therefore, this study revealed a great benefit of organic cherry cultivation for most groups of predators and parasitoids although some phytophagous species were also favoured.

Aim of study: The European honey bee (Apis mellifera L.) is threatened due to diverse pressures, including the habitat fragmentation, the pests or diseases which affect them and the misuse of plant protection products (PPPs). This work aimed to evaluate and compare the degree of exposure of A. mellifera to PPPs residues in orchards, in both conventional and organic production. Area of study: Region of Murcia (Spain). Material and methods: During a three-year period, field monitoring campaigns were organised in peach and apricot orchards under both conventional and organic managements and coinciding with the flowering period. The evaluation of exposure relied on chemical characterisation of pesticide residues using a non-targeted screening by high resolution accurate mass (HRAM) spectrometry. Main results: The findings of this study reveal that pesticide residues were detected in honey bees captured in both conventional and organic orchards. Pesticide residues tentatively identified were carbetamide, flufenacet, iprovalicarb, isoprocarb and spiromesifen. Since honey bees, particularly the forager bees, fly up to several km away from the hive to collect pollen and nectar, they may visit conventionally managed plots where crops are treated with PPPs. Research highlights: This study evinces that, in orchards, the forager bees are exposed to agrochemicals during their foraging activity on the flowers of treated fruit trees, either in contiguous or distant plots. The exposure of bees to pesticide residues in organic orchards can be due to the high persistence of some of these substances in the environment, or to the proximity of other orchards where PPPs are applied.

Rhagoletis cerasi (L.) is the most damaging pest of cherries in Europe and Western Asia and it has been recently introduced in North America. Females sting the ripening cherries and tolerance of damaged fruit is very low (R. cerasi on a large-scale use. A folded yellow sticky trap with a homemade ammonium acetate dispenser was the most efficient and also the cheapest one. The efficacy of mass trapping using this device was evaluated in farm-scale trials. With low pest pressure, mass trapping was sufficient to obtain commercially acceptable fruit. With high pest pressure, mass trapping reduced the number of insecticide (spinosad) applications while keeping damage below the economic threshold. Therefore, mass trapping can be a useful tool for managing R. cerasi and reducing insecticide application.

A protocol for managing the main diseases and pests of sweet cherry in Spain (New IPM) has been implemented in order to reduce the use of pesticides. This New IPM includes nonchemical strategies, such as biological products against diseases and mass trapping of pests, and adjusts the timing and number of pesticide applications according to damage thresholds and a predictive model of diseases based on climatic factors. The New IPM was compared—in commercial orchards from the main cherry-producing areas in Spain (Aragon and Extremadura)—to the integrated management usually carried out in these areas (Standard IPM). Furthermore, a multiresidue method for the determination of the residues in cherries was developed. The number of applications, active ingredients used, and residue levels in fruit were reduced very significantly with this New IPM without affecting the effectiveness in the control of the main cherry diseases (brown rot, shot-hole, and leaf-spot) and pests (European cherry fly, spotted wing drosophila, and black cherry aphid). Neither significant differences in the abundance and diversity of microorganisms in flowers and fruit nor soil and canopy dwelling arthropods were observed between the two protocols, although some positive effects of this New IPM were seen on some groups of natural enemies.

The use of genetically modified varieties tolerant to herbicides (HT varieties) and resistant to insects (Btvarieties) in combination with application of a broad-spectrum herbicide such as glyphosate could be an effective option for the simultaneous control of weeds and pests in maize. Nevertheless, the possible impact of these tools on nontarget arthropods still needs to be evaluated. In a field study in central Spain, potential changes in populations of canopy-dwelling arthropods inBtmaize under different weed management options, including glyphosate application, were investigated. Canopy-dwelling arthropods were sampled by visual inspection and yellow sticky traps. TheBtvariety had no effect on any group of studied arthropods, except for the expected case of corn borers-the target pests ofBtmaize. Regarding the effects of herbicide regimes, the only observed difference was a lower abundance of Cicadellidae and Mymaridae on yellow sticky traps in plots not treated with pre-emergence herbicides. This effect was especially pronounced in a treatment involving two glyphosate applications. The decrease in Cicadellidae and Mymaridae populations was associated with a higher density of weeds in plots, which may have hindered colonization of the crop by leafhoppers. These differences, however, were only significant in the last year of the study. The low likelihood of the use of glyphosate- and herbicide-tolerant varieties for weed control triggering important effects on the nontarget arthropod fauna of the maize canopy is discussed.

A farm-scale investigation was conducted to evaluate the potential impact of integrating glyphosate into different weed management programs when cultivating herbicide-tolerant maize in central Spain from 2012 to 2014. The weed management programs were (1) a conventional weed management with pre- and post-emergent herbicide applications, (2) a weed management program in which the number and total amount of conventional herbicides applied were reduced, and (3) three weed management programs that comprised either two post-emergent applications of the herbicide glyphosate, or only one glyphosate application combined with pre- and/or post-emergent herbicides. Weed density throughout each cropping season was greater in those weed management programs that did not include a pre-emergence application of herbicides than those that did. Moreover, none of the weed management programs affected the richness and species diversity of the weeds or reduced yields. Although the impact of the different programs was similar in terms of weed species diversity, the composition of the weed community differed and this effect must be considered when providing agroecosystem services. Our results indicate that glyphosate-tolerant maize provides an additional tool that allows integrated weed control of the weed populations without reducing yields.

Information on the effect of temperature on biological parameters of phytophagous insects is one of the tools in IPM programs, as it allows prediction of risk situations in the field. This work reports the effect of temperature on reproductive parameters and longevity of one of the most important current pests of almond orchards in the Mediterranean basin, the poplar lace bug, Monosteira unicostata (Mulsant & Rey) (Hemiptera: Tingidae). The temperatures tested were 22, 25, 28, 31, 34 and 37ºC, always at 60 ± 10% relative humidity and under a L16:D8 photoperiod. Extreme temperatures had an adverse effect on preoviposition period, total fecundity and daily fecundity while increasing values of oviposition period and adults longevity were registered for decreasing temperatures. Male longevity was higher than female longevity, and mortality pattern differed between sexes for all temperatures but 37ºC. The nonlinear Lactin model described accurately the effect of temperature on the intrinsic rate of natural increase of M. unicostata populations and predicted the optimum temperature for population increase at 34.1ºC, at which the population doubling time is 3.6 days. Produced values of lower and upper thresholds for M. unicostata populations were 14.8 and 38.8ºC, respectively. This characterizes the poplar lace bug as a very important pest in the Mediterranean basin, with an increasing potential risk in a global warming scenario.