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ABSTRACTBiological invasions by alien agricultural insect pests represent nowadays a major threat to the durability of agricultural systems. In this study, we report for the first time the presence of an invasive economic pest of ornamental and solanaceous crops in Tunisia: the cotton mealybug, Phenacoccus solenopsisTinsley (Hemiptera: Pseudococcidae). It is native to America and has been spreading in Asia and the Mediterranean Basin. It was found in autumn 2021 forming dense colonies on Lantana camaraL. (Verbenaceae) used for ornamental purposes in urban parks in the governorate of Tunis and on tomato Lycopersicon esculentumMill. (Solanaceae) protected crops in the governorate of Sousse. Phenacoccus solenopsiswas identified using an integrative approach based on morphological features and molecular analysis. Phylogenetic analysis using the mitochondrial Cytochrome Oxidase I (mtCOI) sequences of P. solenopsispopulations from native and invaded areas retrieved in GenBank showed that Tunisian specimens might derive from an Asian population. We found that Nephus quadrimaculatusHerbst (Coleoptera: Coccinellidae: Scymninae) is the only natural enemy associated with this newly introduced pest so far. This is the first report of P. solenopsisattacking Lantana and tomato plants in Tunisia, and it should be considered as a potential threat to associated crops.

Exploiting plant defense mechanisms is a promising tool for pest management in modern agriculture. Plant Essential Oils (EOs) are used for the sustainable control of agricultural pests; however, their impact on plant defense has been scarcely investigated. In this work, we study for the first time whether the spraying of EOs can activate plant defense mechanisms in sweet pepper. The olfactory capacity of Encarsia formosa (Hymenoptera: Aphelinidae) to respond to defense-activated plants was used to select garlic and peppermint EOs among nine EOs sprayed on sweet peppers. The expression level of defense-related genes in plant tissues and the phytotoxicity were measured in response to EO foliar applications. Moreover, the olfactory responses of the herbivores, Bemisia tabaci (Hemiptera: Aleyrodidae) and Frankliniella occidentalis (Thysanoptera: Thripidae), and their natural enemies, Orius laevigatus (Hemiptera: Anthocoridae) and Nesidiocoris tenuis (Hemiptera: Miridae), to EO induced plant volatiles were also investigated. The gene expression analysis revealed activated jasmonic and salicylic acid defense signaling pathways in EO-sprayed sweet pepper plants and a negligible phytotoxic effect was recorded. Choice tests revealed varying behavioral responses in selected insect models when plants were treated with garlic and peppermint EOs in different concentrations. Our results suggest that garlic and peppermint EO spray applications can enhance the defense mechanisms of sweet peppers and have a cascading bottom-up effects on the associated food chain. These initial findings provide a foundation for the future development of Integrated Pest Management strategies to protect solanaceous crops.

Tomato has an economic relevance worldwide but its production is threatened by several biotic factors, including the invasive South American tomato pinworm Tuta absoluta. The control of this pest mainly relies on the repeated applications of synthetic insecticides that can have considerable non-target effects; therefore, new sustainable control approaches are required. The biocidal activity of garlic has been recognized and no risks for consumers and the environment are expected in its use. However, the practical implementation of garlic extracts is hampered by several drawbacks that could be overcome by nanotechnologies. We developed and characterized a new garlic essential oil-based nanoemulsion (GEO-NE) and laboratory trials were carried out to investigate its insecticidal activity against T. absoluta involving different instars and exposure routes. GEO-NE side effects on the mirid predator Nesidiocoris tenuis and tomato plants were also assessed in the laboratory. The nanoformulation had dimensions belonging to the nanometric scale and good stability over time. GEO-NE showed significant toxicity towards T. absoluta eggs and larvae and repellence for ovipositing females. No lethal effect on N. tenuis adults was recorded but its progeny was significantly reduced on GEO-NE treated plants. By contrast, GEO-NE had no phytotoxic effects on sprayed tomato plants. Our findings suggested that GEO-NE can successfully control T. absoluta and its application deserves to be considered as a potential tool for tomato Integrated Pest Management.

To assess the potential of Asobara japonica Belokobylskij (Hymenoptera: Braconidae) as a biological control agent for the invasive Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), key biological traits were evaluated: preference and suitability of different host ages, relative performance on two host species (D. suzukii and Drosophila melanogaster Meigen), female life-time fecundity and egg maturation on the two host species, and parasitism levels on D. suzukii larvae infesting different host fruits (blackberry, cherry and strawberry). Asobara japonica preferred young over old hosts, and although host age did not affect offspring survival, parasitoid offspring developed faster in older than younger hosts but had a reduced body size. There was higher A. japonica offspring survival, longer developmental time, and larger body when reared from D. suzukii than D. melanogaster. Female wasps emerged with around one third of their lifetime egg load and matured eggs rapidly with mature egg load reaching a peak 2–3 d post-emergence. Large females (typically reared from D. suzukii) contained more mature eggs than small females (typically from D. melanogaster). During their lifetime, A. japonica females produced 117.4 and 92.5 progeny on D. suzukii and D. melanogaster, respectively, with a corresponding intrinsic rate of increase of 0.217 and 0.210, respectively. Progeny were strongly female-biased (> 90% females), regardless of host age or species. This larval parasitoid was able to develop from D. suzukii infesting cherry, blackberry or strawberry. This information may help improve protocols for the rearing and future evaluations of this parasitoid for a potential biological control program against D. suzukii.

Since its first detection in Tunisia in 2008, the tomato pinworm, Tuta absoluta,has become a serious problem to tomato crops by causing heavy yield losses. The aim of this work was to evaluate the efficacy of some actives ingredients, commonly used by Tunisian farmers, under laboratory and greenhouse conditions in controlling T. absolutalarvae. We also tested the role of mass trapping as control method for T. absolutawhile performing two greenhouse trials: one to test the most effective number of pheromone traps to be used and the second evaluating the combination of insecticides and pheromone traps. Our study demonstrated that the product combining abamectin and chlorantraniliprole was the most effective 2 h after the treatment in laboratory trials. Moreover, this study indicated that the dose of two sex pheromone traps/greenhouse was the most effective compared to the other tested dose. Also, mass trapping alone (2 sex pheromone traps/greenhouse) was not effective in reducing larval populations: flubendiamid and cyromazin caused 96 and 77% larval mortality, respectively.

SummaryThe results of a trial conducted in Southern Italy to evaluate the effectiveness of Apiguard® treatments against Varroa destructorAnderson and Trueman are reported. Twenty one colonies of Apis melliferaL. in Dadant-Blatt hives were used. Two groups of seven colonies each were treated and one group was left as untreated controls. Two aluminium trays of Apiguard® were installed in the hives with a two week interval between treatments. The trays of one of the treatments (group 1) were covered with a plastic mesh which only allowed the bees' legs and mouthparts to contact the product. The plastic mesh allowed evaporation but reduced bee contact and product removal. The other Apiguard® treated group (group 2) received uncovered trays as recommended by the manufacturer. Apiguard® trays were present in the hives for 30 days. Two methods were used to evaluate the treatment efficacy: the percent effectiveness (E%) and the degree of efficacy (DE%). Mean E% (± s.e.) was significantly higher in the uncovered trays (93.34 ± 1.18%) than in the covered trays (87.23 ± 1.80%) (F= 8.80, d.f.= 1, P= 0.012). Similarly DE% also was significantly different between the 2 groups (Covered trays = 84.24 ± 2.23%; Uncovered trays = 91.78 ± 1.45%) (F= 8.781, d.f.= 1, P = 0.012).

During the years after the invasion of Western Palaearctic tomato crops by the South American tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), several indigenous generalist parasitoids have been recorded on this new host. Among these, Bracon nigricans Szépligeti (Hymenoptera: Braconidae) is widely distributed in the Palaearctic region, and has been frequently recovered from South American tomato leafminer. However, most of the available data on this species deal with taxonomic aspects and its recovery in faunistic surveys. The current study documents the biology of B. nigricans on South American tomato leafminer, and provides a scientific basis for its inclusion in South American tomato leafminer management programs in Afro-Eurasia. We studied several B. nigricans life-history traits relevant to juvenile development and reproduction by females. B. nigricans proved to be an idiobiont and a synovigenic ectoparasitoid of mature South American tomato leafminer larvae. Several B. nigricans reproductive traits were influenced by the age of the mothers; on average, the progeny had a slightly male-biased sex ratio (60% males) and a low rate of successful development (≈37%). Adult females lived 42.8 d and produced an average of 29.8 offspring. These biological parameters yielded an intrinsic rate of increase of 0.052. Females showed behavioral plasticity in host use, as initial host paralysis was followed by host-feeding, oviposition, or host rejection, with a consequent high mortality rate among hosts exposed to parasitism. Although further field studies are needed, these data, obtained in laboratory conditions, suggest that B. nigricans should be considered as a potential biological control agent of in newly invaded areas of the Palaearctic region.