Agatino Russo

Can alternative host plant and prey affect phytophagy and biological control by the zoophytophagous mirid Nesidiocoris tenuis

Nesidiocoristenuis (Reuter) (Hemiptera: Miridae) is an important natural enemy of several key arthropod pests. However, in tomato crop this predator can cause economic damage owing to its zoophytophagous behavior. We investigated in laboratory conditions the influence of two alternative plants, Dittrichiaviscosa L. (Asteraceae) and Sesamumindicum (L.) (Pedaliaceae), with or without prey, on N. tenuis damage and its biological control services on Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) eggs. Both D. viscosa and S. indicum, as companion plants in dual-choice bioassays, significantly reduced the damage of the mirid on tomato. S. indicum was more attractive than D. viscosa for feeding and oviposition and its presence did not interfere with the predation on T. absoluta eggs. We also studied the potential of the three plants as preyless rearing substrate for the mirid, and only S. indicum showed to be a suitable host plant for N. tenuis development and oviposition. The potential applications of S. indicum in N. tenuis field management and mass rearing 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.

Combined Non-Target Effects of Insecticide and High Temperature on the Parasitoid Bracon nigricans.

We studied the acute toxicity and the sublethal effects, on reproduction and host-killing activity, of four widely used insecticides on the generalist parasitoid Bracon nigricans (Hymenoptera: Braconidae), a natural enemy of the invasive tomato pest, Tuta absoluta (Lepidoptera: Gelechiidae). Laboratory bioassays were conducted applying maximum insecticide label rates at three constant temperatures, 25, 35 and 40°C, considered as regular, high and very high, respectively. Data on female survival and offspring production were used to calculate population growth indexes as a measure of population recovery after pesticide exposure. Spinetoram caused 80% mortality at 25°C and 100% at higher temperatures, while spinosad caused 100% mortality under all temperature regimes. Cyantraniliprole was slightly toxic to B. nigricans adults in terms of acute toxicity at the three temperatures, while it did not cause any sublethal effects in egg-laying and host-killing activities. The interaction between the two tested factors (insecticide and temperature) significantly influenced the number of eggs laid by the parasitoid, which was the lowest in the case of females exposed to chlorantraniliprole at 35°C. Furthermore, significantly lower B. nigricans demographic growth indexes were estimated for all the insecticides under all temperature conditions, with the exception of chlorantraniliprole at 25°C. Our findings highlight an interaction between high temperatures and insecticide exposure, which suggests a need for including natural stressors, such as temperature, in pesticide risk assessments procedures.

Life tables of Xylocoris flavipes (Hemiptera: Anthocoridae) feeding on Tribolium castaneum (Coleoptera: Tenebrionidae)

Abstract Effects of four constant temperatures (19°C, 21°C, 24°C, and 32°C) on the development and reproduction of Xylocoris flavipes (Reuter) (Heteroptera: Anthocoridae) and on its predatory activity against the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) were investigated. Survival of eggs and larvae was high at 24°C and 32°C. At 19°C none of the larvae survived longer than the first instar, whereas at 21°C the number of the larvae completing the immature stage was extremely low. Developmental time was significantly shorter at 32°C. Females lived longer at 21°C, but no differences were observed at 24°C and 32°C. Fecundity was greatly reduced at 21°C and was higher at 32°C. At 21°C, the intrinsic rate of increase (rm) reached the minimum (0.0004), and gradually increased with temperature (0.054 at 24°C and 0.137 at 32°C). At 24°C larvae consumed more prey during their development, but at 32°C the predation rate per day was higher. For adults both total predation rate and predation rate per day were higher at 32°C. The performance of the anthocorid at the various temperatures is discussed in relation to its practical use as a control agent for stored product insects.

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.

Life Fertility Tables of Piophila casei L. (Diptera: Piophilidae) Reared at Five Different Temperatures

Abstract Piophila casei L. or cheese skipper is a well-known fly with a controversial role: it is considered harmful in the food industries but important in nature as a detritivore and useful for studies in forensic entomology. The temperature response of P. casei was studied at five constant temperatures: 15, 19, 25, 28, and 32°C. The lowest mortality percentage of eggs was recorded at 15°C and the highest at 32°C. Conversely, less mortality was observed for maggots at higher temperatures. The developmental time from first instar to adult decreased with temperature reaching the lowest value at 32°C (13.7 d). Adult longevity was strongly affected by temperature, decreasing from 20.5 d at 15°C to 6.6 d at 32°C. Mean total fecundity per female was higher at 25°C and lower at 15 and 19°C, whereas the best performance in mean daily total fecundity per female was recorded at 32°C. Male longevity followed a similar trend to the one observed for females. The net reproductive rate (R0) was greatest at 25°C, whereas the highest rm was recorded at 32°C. At this latter temperature, the highest mean generation time (T) and doubling time (D) were also observed. The finite rate of increase (λ) was augmented slightly with higher temperatures.

Insights into food webs associated with the South American tomato pinworm: N. tenuis intraguild behaviour

BACKGROUND The complexity of both natural and managed ecosystems involves various forms of interaction among organisms. Two or more species that exploit the same resource can engage in competitive behaviours, usually referred to as intraguild interactions. These can be direct, i.e. one species feeds directly upon the competitor (intraguild predation) or indirect, e.g. when the dominant organism competes for a food source that another organism is feeding upon (kleptoparasitism). We investigated the potential for such interactions in a biological model composed by the South American tomato pinworm, Tuta absoluta, and three of its newly associated natural enemies: the zoophytophagous predator Nesidiocoris tenuis and the two idiobiont ectoparasitoids Bracon nigricans and Necremnus tutae. RESULTS N. tenuis was shown (i) to scavenge on parasitised T. absoluta larvae and (ii) directly to attack and feed upon larvae of both parasitoid species, although at a higher percentage in the case of N. tutae. In the presence of the host plant, the predator reduced the emergence of both B. nigricans and N. tutae adults significantly. CONCLUSION This study stresses the ecological success of a generalist predator over indigenous parasitoids attacking an invasive pest. Moreover, these findings provide potential elements for better design of biological control programmes against T. absoluta.

Citrus peel essential oil nanoformulations to control the tomato borer, Tuta absoluta: chemical properties and biological activity

The repeated use of conventional synthetic pesticides in crop protection leads to resistance development by pests along with a negative impact on the environment, particularly non-target arthropods. Plant-derived active compounds, such as essential oils (EOs), play a key role in sustainably controlling pests. The lethal and sublethal activity of citrus peel EOs as emulsions and included in polyethylene glycol (PEG) nanoparticles (EO-NPs) was determined against the invasive tomato pest Tuta absoluta. Their effects on the plants were also assessed. The results showed an overall good insecticidal activity of the compounds tested, with a higher mortality through contact on eggs and larvae by EO emulsions and through ingestion on larvae by EO-NPs. The nanoformulation also significantly reduced the visible toxic effects on the plants. The data collected suggest that these natural compounds, especially when nanoformulated, could be successfully used in integrated pest management programs for T. absoluta.

First record of the Persea Mite Oligonychus perseae (Acari: Tetranychidae) in Italy with a review of the literature

The Persea Mite Oligonychus perseae Tuttle, Baker and Abbatiello, is reported for the first time in Italy. The pest was found on avocado in Sicily (South Italy), in August 2014. The predatory mite Iphiseius degenerans (Berlese) was found in association with O. perseae colonies.

The scale insects (Hemiptera: Coccoidea) of the Maltese Archipelago

Past works on scale insects (Hemiptera: Coccoidea) from the Maltese Archipelago are reviewed. Based on the literature and contemporary collections, a total of 93 species of scale insects belonging to 12 scale insect families are here reported (Aclerdidae 1 species; Asterolecaniidae 4; Coccidae 17; Diaspididae 46; Eriococcidae 5; Kermesidae 1; Margarodidae 1; Micrococcidae 1; Monophlebidae 2; Pseudoccocidae 11; Putoidae 2 and Rhizoecidae 2). Of these, 17 species represent new distribution records. Ten species are excluded from the scale insect fauna of the Maltese Islands. Of the 93 species present, only 29 (31.18%) are probably indigenous and the rest (68.82%) represent established introductions from elsewhere. More than 65% of the indigenous species are typical Mediterranean in distribution, with a few species having a mainly European chorotype. A quarter of the established aliens originate from Eurasia, followed by an East Asian/ Oriental component (20.31%); European (14.06%); Neotropical (14.06%); cryptogenic (14.06%); African (7.81%) and Australasian (4.70%). Movement of live fruit trees and ornamental plants into the Maltese Archipelago from nearby countries is probably the main route for entry of alien scale insects into the country. Some possible future introductions are discussed.