Long-term monitoring and microbiological control programs against lepidopteran defoliators in Sardinian cork oak forests (Italy)

The gypsy moth, Lymantria dispar (L.), and the tent caterpillar, Malacosoma neustrium (L.), are the main cork oak, Quercus suber L., pests in the Mediterranean area and cause complete defoliation in large forest districts. In order to control infestations, large scale aerial applications of insecticides based on Bacillus thuringiensis subsp. kurstaki (Btk) have been carried out in Sardinia (Italy) since 2001. This paper evaluated the frequency of outbreaks in forest districts with varying homogeneity of land use, forest areas annually exposed to defoliation and the effectiveness of control programs based on Btk insecticide applications.The volume of areas annually exposed to defoliation depends on forest homogeneity, as infestations are more frequent in cork oak areas with a lower than 25% canopy cover rate. The microbiological control programme efficiently protected cork oaks from lepidopteran defoliators and caused an overall annual mean mortality of over 60%, with maximum rates of 89.9 and 98.0% for L. dispar and M. neustrium, respectively. To date, approximately 180,000 hectares of cork oak forests have been protected by spraying Btk-based insecticides

Sustainable management of the vine mealybug in organic vineyards

The vine mealybug (VMB), Planococcus ficus, is a major grapevine pest worldwide, whose chemical control is often unsatisfactory due to its cryptic behavior, insecticide resistance and high fecundity rate. Recently, increasing restrictions have been applied to insecticides used for managing VMB. This review discusses sustainable VMB management strategies in organic viticulture. Pheromone-mediated mating disruption has been proved to be effective in both organic wine and table-grape vineyards. Biocontrol projects carried out through the release of parasitoids and/or predators have often provided inconclusive results, ranging from effective reduction of mealybug infestation to a marginal impact of parasitoids on VMB density. The latter outcome is likely due to constraints affecting the parasitoid activity, such as the disrupting activity of mealybug-tending ants and broad-spectrum insecticides, or untimely release of parasitoids. Ant suppression should be associated with the release of beneficial organisms, as mealybug-tending ants can severely affect the parasitoid activity. Cultural and physical control and the employment of entomopathogens and natural products mitigate the buildup of VMB populations, but they are not widely applied. VMB control in organic viticulture requires the integration of different strategies, as application of single control tools as a stand-alone treatment may not be effective, especially for high pest infestation. Future research to determine the density action threshold below which sustainable methods are effective and calibrate efforts in relation with pest infestation is needed. A multi-disciplinary approach is required to define the most appropriate sustainable control protocols in different environmental conditions and promote a further spread of organic viticulture

Osservazioni preliminari sul comportamento riproduttivo di Planococcus ficus e Planococcus citri (Hemiptera: Pseudococcidae)

No abstract availablePlanococcus citri (Risso) ha una modalit? di riproduzione tipicamente anfigonica e un sistema di determinazione del sesso basato sulla condensazione dell?assetto cromosomico di origine paterna nella linea maschile (Brown, 1966). Le osservazioni condotte su P. citri per verificare la possibilit? di riproduzione per partenogenesi sono contrastanti (Myers, 1932; Bodenheimer, 1951; Gray, 1954; Panis, 1969), mentre non risultano in letteratura indagini specifiche sulle modalit? di riproduzione di Planococcus ficus (Signoret). Queste informazioni assumono un?importanza fondamentale quando si intendono sperimentare tecniche di lotta, come la confusione sessuale o le catture massali di maschi, che possono risultare efficaci solo se la specie bersaglio si riproduce per via anfigonica. Viste anche le recenti sperimentazioni sulla lotta a P. ficus con la tecnica della confusione sessuale (Walton et al., 2006), si ? ritenuto utile condurre osservazioni sulla possibilit? di riproduzione partenogenetica delle due cocciniglie. A tal fine, per ciascuna specie, 300 neanidi di I-II et? sono state allevate singolarmente all?interno di contenitori in Plexiglas trasparente contenenti tre acini d?uva. I contenitori sono stati chiusi superiormente con tulle a maglie sufficientemente fitte da impedire l?ingresso dei maschi. Dalle neanidi di P. citri sono stati ottenuti 37 maschi e 40 femmine. Queste ultime, in assenza di accoppiamento, nel corso della loro vita adulta non hanno ovideposto; solo un individuo ha prodotto un abbozzo di ovisacco senza uova. Dalle neanidi di P. ficus sono stati ottenuti 86 maschi e 39 femmine. Questa specie ha mostrato la capacit? di riprodursi per partenogenesi. Infatti, pur non accoppiandosi, 9 femmine hanno deposto uova da cui sono sgusciate neanidi; altri 6 individui hanno formato solo ovisacchi privi di uova. Ulteriori studi sono in corso per verificare l?assenza di partenogenesi in P. citri e valutare il potenziale biotico di femmine partenogenetiche e fecondate in P. ficus

Comparative development and reproduction of <i>Planococcus ficus</i> and <i>Planococcus citri</i> (Hemiptera: Pseudococcidae) on grapevine under field conditions

1. Mealybugs are major pests in grape-growing areas worldwide, causing direct and indirect crop damage. The vine mealybug Planococcus ficus (Signoret) is a key pest in most of grape-producing countries, whereas the citrus mealybug Planococcus citri (Risso) is reported as being destructive in Brazilian and Spanish vineyards. 2. We examined the adaptation of the citrus mealybug to grapevine by investigating its development, reproduction and life-history parameters under Mediterranean field conditions in comparison with those of P. ficus. 3. Both mealybug species developed and reproduced successfully on grapevine. However, P. ficus showed a shorter development time, larger female body size, and higher fecundity, fertility and survival than P. citri. 4. The life-history parameters further highlighted the different growth potential of vine and citrus mealybug populations because P. ficus exhibited a net reproductive rate and an intrinsic rate of increase two- to four-fold higher than that of P. citri. Furthermore, the vine mealybug population doubled its number in approximately half time with respect to the citrus mealybug. 5. Overall, the results of the present study show a better development and reproductive performance and a higher population growth potential of P. ficus compared with P. citri, indicating a higher capacity of the vine mealybug to develop on grapevine in Mediterranean vineyards

Laboratory evaluation of the suitability of vine mealybug, <i>Planococcus ficus</i>, as a host for <i>Leptomastix dactylopii</i>

Planococcus ficus (Signoret) is a key pest of grapevines and can cause severe crop losses in table and wine grape cultivars. In order to explore the potential of annual inoculative releases of Leptomastix dactylopii Howard against the vine mealybug, laboratory experiments were conducted to evaluate the suitability of P. ficus as a host for the parasitoid. The biological performance of L. dactylopii on P. ficus was examined in choice and no-choice tests, and compared with its performance on the primary host, Planococcus citri (Risso). Planococcus ficus supported complete development of the parasitoid with higher than 86% survival rates and a lower than 5% effective encapsulation. The low rates of encapsulation and host-feeding and high survivorship make P. ficus a suitable host for L. dactylopii in mass rearing facilities. In the choice test, parasitoids reared on P. ficus, or with prior oviposition experience on this species, preferred it over P. citri. Unexpectedly, parasitoids reared on P. citri, or with prior oviposition experience on this species, did not show any preference for either mealybug species. Our findings highlight a potential innate preference of L. dactylopii for the vine mealybug and indicate that this innate preference can be modified by the rearing host and early oviposition experiences. Thus, mass rearing of L. dactylopii on P. ficus would increase its preference for the target pest, with a positive impact on biological control programs against the vine mealybug

Spatial distribution and sequential sampling plans for Tuta absoluta (Lepidoptera: Gelechiidae) in greenhouse tomato crops

BACKGROUNG: This work investigated the within- and between-plant distribution of the tomato leafminer, Tuta absoluta (Meyrick), in order to define action thresholds based on leaf infestation and propose enumerative and binomial sequential sampling plans for pest management applications in protected crops. RESULTS: The pest spatial distribution was aggregated between plants, and median leaves were the most suitable sample to evaluate its density. Action thresholds of 36 and 48%, 43 and 56%, 60 and 73% of infested leaves, corresponding to economic thresholds of 1 and 3% of damaged fruits, were defined for tomato cultivars with big, medium and small fruits, respectively. Green's method was a more suitable enumerative sampling plan as it required a lower sampling effort. Binomial sampling plans needed lower average sample sizes than enumerative plans to make a treatment decision, with probabilities of error &lt; 0.10. CONCLUSIONS: Enumerative sampling plan required 87 or 343 leaves to estimate the population density in extensive or intensive ecological studies, respectively. Binomial plans would be more practical and efficient for control purposes, needing average sample sizes of 17, 20 and 14 leaves to take a pest management decision in order to avoid fruit damage higher than 1% in cultivars with big, medium and small fruits, respectively

Diagnostic markers for <i>Planococcus ficus</i> (Signoret) and <i>Planococcus citri</i> (Risso) by random amplification of polymorphic DNA-polymerase chain reaction and species-specific mitochondrial DNA primers

Planococcus ficus (Signoret) and Planococcus citri (Risso) (Hom., Pseudococcidae) are important phytophagous components in different agroecosystems. The two species may coexist in the same environment and are most difficult to distinguish by morphological features. The aim of this study was to find genetic markers suitable for distinguishing P. ficus from P. citri, to assist in the rapid identification of field specimens. By using synthetic sex pheromone-baited traps, pure male populations of both species were collected from a vineyard and from a citrus orchard in northern Sardinia, Italy. Individual males of citrus and vine mealybugs were preliminarily examined by the random amplification of polymorphic DNA (RAPD) technique. Among twelve 10-mer random primers, the oligonucleotide OPL-12 generated several markers suitable for distinguishing between the two species. This primer was then used to characterize individual males and females of both mealybug species collected near pheromone-baited traps in vineyards and orange orchards from different geographic areas. Reference samples from other regions of southern Italy were also included. A clear differentiation of the two species was accomplished according to their pattern of amplification, thus confirming a high level of intra-specific genetic homogeneity. Consequently, two fragments of the cytochrome c oxidase I gene from P. citri and P. ficus were compared and two pairs of species-specific polymerase chain reaction (PCR) primers were developed based on diverging sequences. These primers allowed sensitive and reliable PCR identification of both males and females of P. citri and of P. ficus of different geographic origin

Variation of life-history parameters of <i>Planococcus ficus</i> (Hemiptera: Pseudococcidae) in response to grapevine nitrogen fertilization

The effects of different nitrogen fertilization regimes on body size and selected life-history parameters (development time, survival, fecundity and fertility) of the vine mealybug, Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae), were investigated on potted grapevines under laboratory and screenhouse conditions. In both trials, five groups of four grapevines each were supplied with 0, 0.25, 0.5, 1.0 or 2.0 g/l of ammonium nitrate fertilizer for a month and then artificially infested with 200 first-instar vine mealybugs (24 h of age). The concentration of nitrogen on grape leaves was measured during both experiments by a SPAD chlorophyll metre, showing statistical differences among treatments. The nitrogen fertilization significantly affected the investigated P. ficus parameters, providing consistent results in both laboratory and screenhouse trials. The vine mealybug females exhibited higher survival and fecundity, larger body size and lower development time on plants supplied with higher nitrogen fertilization rates. Survival, body size and fecundity of P. ficus were positively correlated with the leaf nitrogen concentration, whereas the development time was negatively correlated. Fertility did not vary significantly among treatments. Our results show that high nitrogen regimes increase the reproductive performance of P. ficus on grapevines and point out the importance of implementing balanced fertilization plans in grapevine IPM programs to reduce population densities and prevent insect outbreaks

Multiple Effects of Nitrogen Fertilization on Grape Vegetative Growth, Berry Quality and Pest Development in Mediterranean Vineyards

Nitrogen is a key macronutrient for the quantitative and qualitative yield of grapes; in addition, it influences the development and reproduction of grape pests. The multiple effects of different nitrogen rates were investigated on the red berry cultivar ‘Carignano’ and the grape pest Planococcus ficus in a two-year field trial. Different amounts of ammonium nitrate were compared: 0, 80 and 160 Units ha−1 for mineral nitrogen. The amount of nitrogen fertilization supplied influenced the nitrogen status of vines and increased the pruning weight and leaf area, as well as the overall grape yield, by increasing the cluster weight. However, doubling the nitrogen rate did not generally increase the vegetative and productive parameters of grapevines. At harvest, nitrogen supply did not influence the anthocyanin content, tritatable acidity, and soluble solids, although the latter parameter showed a clear, yet not significant, decreasing trend. Planococcus ficus exhibited higher fecundity, survival and shorter development time on grapevines provided with nitrogen, whereas its fertility was unaffected by nitrogen fertilization. Ultimately, nitrogen had a direct and positive effect on grape yield and vine mealybug development, highlighting the importance of integrated cultural and pest control practices to promote grape production