Pompeo Suma

Management strategies of mealybug pests of citrus in mediterranean countries

Six mealybug species have been reported as citrus pests in the Mediterranean Basin: the citrus mealybugPlanococcus citri (Risso), the citriculus mealybugPseudococcus cryptus Hempel, the longtailed mealybugPseudococcus longispinus (Targioni-Tozzetti), the citrophilus mealybugPseudococcus calceolariae (Maskell), the obscure mealybugPseudococcus viburni (Signoret) and the spherical mealybugNipaecoccus viridis (Newstead). Some of these species,e.g. N. viridis, have recently been introduced into the region and are still spreading. Mealybugs are usually occasional or minor pests of citrus, but some species can reach key pest status. Mealybug management strategies in citrus have been based mostly on classical biological control and, to a lesser extent, on augmentative releases. However, chemical control is widely used, mainly because of the poor adaptation of the principal natural enemies to the climatic conditions of the Mediterranean. The application of pheromones is still restricted to monitoring the citrus mealybug, whose sex pheromone is commercially available. Mass trapping and mating disruption should be considered for possible use in IPM programs as an alternative method to supplementary chemical treatments. Enhancement of biological control through management of ant populations is another promising tactic for control of mealybugs. Strategies for managing mealybug pests of citrus, and possible levels of integration of different tactics according to the pest status, are discussed.

Chapter 9 – Biological Control of Stored-Product Pests

Previous reviews on biological control of stored-product pests published during the last 30 years reported results of laboratory experiments, collected examples for practical application in grain stores and in processing companies, and summarized the literature on the relevant control agents dating back to the beginning of the last century.

Encapsulation rates of the parasitoid Anagyrus sp. nr. pseudococci, by three mealybug species (Hemiptera: Pseudococcidae)

Laboratory studies assessing the degree of suitability of the mealybugs Planococcus ficus (Signoret), Planococcus citri (Risso) and Pseudococcus calceolariae (Maskell), towards the Sicilian ecotype of the encyrtid parasitoid Anagyrus sp. nr. pseudococci were carried out. All three species of mealybugs were shown to encapsulate the eggs of the encyrtid; however, significant differences were revealed among them in rates of encapsulation and/or superparasitism. The level of aggregate encapsulation and effective encapsulation of the parasitoid eggs by P. citri (74.95 ± 0.87 and 60.19 ± 1.70, respectively) was significantly higher than that recorded for P. ficus (aggregate encapsulation = 58.43 ± 0.83 and effective encapsulation = 31.31 ± 1.55) and significantly lower than the values found in Ps. calceolariae (93.99 ± 0.97 and 88.61 ± 2.03, respectively). As such, rates of parasitism were significantly lower for P. ficus compared with both P. citri and Ps. calceolariae. The two latter species of mealybugs showed similar rates of parasitism by A. sp. nr. pseudococci. Moreover, a significantly higher rate of superparasitism was found for Ps. calceolariae compared with both P. citri and P. ficus, whereas no significant differences were found between the two species of Planococcus for this parameter.

Developmental time, longevity, reproductive capacity and sex ratio of the mealybug parasitoid Anagyrus sp. nr. pseudococci (Girault) (Hymenoptera: Encyrtidae)

Abstract Key biological parameters of Anagyrus sp. nr. pseudococci reared on the citrus mealybug Planococcus citri (Risso) were determined. The mean longevity of female wasps was 21.1 days, the median lethal time (LT50) was 22 days, the mean number of offspring per female was 30.2 wasps and the sex ratio of the progeny was slightly male biased (1.1 males per female). Wasps fed with water showed a significantly lower longevity compared to that recorded for wasps fed with syrup for bee nutrition mixed with water. The longevity of female wasps was significantly higher compared to males when the syrup-water solution was provided as food. Longevity was significantly higher for female wasps fed with syrup and water in comparison with those exposed to host mealybugs. The mean development time of female and male wasps was 14.7±0.1 and 14.5±0.1 days, respectively.

Commercial and wild Sicilian Origanum vulgare essential oils: chemical composition, antimicrobial activity and repellent effects

Abstract The composition of two different Origanum vulgare essential oils (EOs) was analysed by gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS); their repellent and antimicrobial effects were evaluated against adults and late-instar larvae of Tribolium confusum and adults of Sitophilus oryzae (Insecta: Coleoptera), Gram-negative and -positive bacteria Pseudomonas fluorescens, Escherichia coli, Staphylococcus aureus, Bacillus cereus and the pathogenic fungi, Penicillium digitatum and Aspergillus flavus. The main constituents of the essential oil from the first sample (obtained by hydrodistillation of inflorescences of wild Sicilian O. vulgare) were thymol and γ-terpinene wherein main component of the second one (a commercial essential oil) was carvacrol. The two tested oils showed relevant antimicrobial and repellent activity, with variable efficacy depending on chemical composition, concentration, targeted species and exposure time. Based on the obtained results, the study extends knowledge on oregano EOs for their potential use as food protectants during storage.

Bethylids attacking stored-product pests: an overview

Bethylidae is a family belonging to the insect order Hymenoptera and contains about 2 200 described species. Bethylids typically parasitize larvae of Lepidoptera and Coleoptera, including species that are serious pests of stored products. Here, we review the main characteristics of each of the bethylids reported as biological control agent of these pests. The biological characteristics and peculiarities are reported for each species, and the potential for their practical application is discussed.

First interception of the asiatic Bamboo longhorn, Chlorophorus annularis (F., 1787) (Coleoptera, Cerambycidae) in Italy

This study provide information on the first occurrence in Italy of the Coleoptera Cerambycidae Chlorophorus annularis (Fabricius, 1787). It is a species naturally and widely distributed in Asia and in oriental tropical and subtropical areas. This cerambyx is a post-harvest pest of bamboo belonging to several genera as Bambusa, Dendrocalamus, Phyllostachys, Sinocalamus, but it can also infest cultivated plants as Citrus spp., Gossypium, Liquidambar spp., Saccharum officinarum L., Vitis spp., and Zea mays L.

Potential for management of Protopulvinaria pyriformis (Cockerell) (Hemiptera: Coccidae) in organic avocado in eastern Sicily, Italy

Organic avocado (Persea americana Mill. (Lauraceae) farming is a growing industry in eastern Sicily, and in this environment Protopulvinaria pyriformis (Cockerell) (Hemiptera: Coccidae) is a key pest. Biological control strategies against this invasive scale are thus crucial for the sustainability of this cropping system. A field trial was performed to record the natural enemy complex in early autumn, and for comparing the efficacy of a paraffinic oil application (Biolid E® at 2L/ha), of the release of adults (1/m2) of the predator Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae), and of their combined application, i. e. oil spray and after one week predator release. In the pretreatment sampling a high proportion of ovipositing female, 38. 64% of the entire population, was recorded. The natural parasitoid community of P. pyriformis consisted of two primary parasitoids and one facultative hyperparasitoid species. Metaphycus helvolus (Compere) (Hymenoptera: Encyrtidae) accounted for 81% of the parasitoids recovered; Microterys nietneri (Motschulski) (Hymenoptera: Encyrtidae) for 8%, and the secondary parasitoid Pachyneuron muscarum (L. ) (Hymenoptera: Pteromalidae) for 11%. The mean percentage of parasitism recorded was 2. 45%, however, an encapsulation rate of 1. 78% was also observed. Adults and larvae of generalist predators belonging to the genera Scymnus spp, Exochomus spp. (Coleoptera: Coccinellidae) and larvae of Chrysopa spp. (Neuroptera: Chrysopidae) were also noticed actively feeding on immature stages of the soft scale. The number of live scales (N2-oviposting females) was reduced by 54. 16, 55. 73 and 19. 58 % following the oil application, the oil plus predator release and predator alone, respectively. While, in the control plots the number of live scales increased by 23. 4%, and no changes in the presence of natural enemies was recorded in the sprayed plots. The recorded data suggest that any pesticide application should take into account and thus respect the activity of the rich natural enemy assemblage. In addition, artificial releases of C. montrouzieri were not able to effectively control the scale population.

Vine and citrus mealybug pest control based on synthetic chemicals. A review

Synthetic chemicals are extensively used to limit the substantial crop damage induced by two closely related scale insects, the vine mealybug Planococcus ficus (Signoret) and the citrus mealybug Planococcus citri Risso (Hemiptera: Pseudococcidae). Both organisms are economically important pests occurring in vineyards and/or in citrus orchards worldwide. Synthetic chemicals can be either incorporated in pesticides aimed at directly controlling these pests or used as semiochemicals (i.e., sex pheromones) for monitoring, mass trapping, mating disruption, and/or for kairomonal attraction to enhance parasitoid performances. Growing evidence of both an alarming bee decline and destruction of auxiliary fauna driven by pesticides have stimulated an urgent need for in-depth research clarifying the adverse side effects of pesticides on beneficial arthropods. We have reviewed the current knowledge on mealybug pest control based on insecticides and semiochemicals. We highlight the following major advances: (1) How the active substances of insecticides (four organophosphates, imidacloprid, buprofezin, and spirotetramat) affect target and non-target organisms, (2) in which contexts and how a semiochemical-based strategy could be applied to deal with serious mealybug infestations, and (3) the implications of the appropriate exploitation of these synthetic chemicals for sustainable development. Using selective insecticides with novel modes of action and long-lasting efficacy in combination with eco-friendly semiochemical-based tools is a promising strategy for developing sustainable integrated pest management programs. This would help to maintain biodiversity dynamics and vital ecosystem services, thereby sustaining crop yields.

First Records of Ceroplastes floridensis Comstock (Hemiptera: Coccidae) and Chrysomphalus pinnulifer (Maskell) (Hemiptera: Diaspididae) in Tunisia

2 New records are important for documenting new distributional data and for alerting researchers to a potential new pest. The scale insect fauna (Hemiptera: Coccoidea) of Tunisia has been little studied and is still poorly known. Additions are continuously reported resulting from faunistic studies including our report of Coccus pseudomagnoliarum (Kuwana) from the Cap Bon region (Jendoubi et al., 2008). Here we report two additional species of scale insects as new country records for Tunisia: Ceroplastes floridensis Comstock (Coccidae) and Chry som - phalus pinnulifer (Maskell) (Diaspididae). Brief comments on zoogeographical distribution and the pest status of each species are provided. Both species were collected during a survey in autumn 2009 listing species of scale insects in the main citrus-growing regions of Tunisia: Nabeul (northeast), and Beja and Jen - douba (northwest). All slide-mounted females were identified at the Univer sity of Catania, referring to the keys of Balachowsky (1956), McKenzie (1956), Hamon and Williams (1984) and Pellizzari and Camporese (1994).