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Reservoir host plants can play a critical role in the maintenance and spread of invasive agricultural insect pests, particularly when the pest species attacks a wide range of host plants, is ecologically plastic and demonstrates high reproductive fitness. The tomato leafminer, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), fits well within this category of alien pests. Indeed, this moth has become, in a very short period, the main phytosanitary factor limiting tomato production in the world. In addition, it is becoming a potential pest of potato crops. Among reported host weeds of this insect, Solanum nigrum L., Datura stramonium L. and Datura ferox L. are widely distributed in both T. absoluta's original geographical range and in newly infested areas. In this paper, we assess the suitability of these three plants as alternate hosts for T. absoluta. Development time of juvenile instars, adult longevity and female fecundity of the pest reared on these weeds were compared with those observed on tomato and potato plants under laboratory conditions. The study revealed that T. absoluta did not oviposit and develop on either D. stramonium or D. ferox. Conversely, tomato leafminers reared on S. nigrum (black nightshade) exhibited a reproductive fitness comparable with that seen on potato. All the investigated parameters confirmed that tomato is the most suitable host plant for the pest. These findings highlight the potential of the black nightshade to act as a reservoir host for T. absoluta and the carryover of its populations in periods when neither tomato nor potato crops are available. [ABSTRACT FROM AUTHOR]

For control of the Mediterranean fruit fly Ceratitis capitata ( Diptera: Tephritidae), the attract-and-kill or attracticide technique is an alternative to the spraying of traditional organophosphate pesticides. In this study, the effectiveness of Ceranock and AAL& K attract-and-kill bait stations was assessed for control of C. capitata in Tunisian peach ( Prunus persica) orchards. Our results showed that, in orchards with early-ripening varieties, the numbers of C. capitata males and fruit damage were significantly lower in plots treated with Ceranock and AAL& K bait stations than in plots treated with conventional organophosphate and pyrethroid insecticides. In addition, the abundances of non-target insects in the Chrysopidae, Coccinellidae and Miridae were significantly greater in plots treated with the bait stations than in plots treated with the conventional pesticides; that is, the use of attract-and-kill bait stations had fewer negative effects than the application of conventional pesticides on the biological diversity in Tunisian peach orchards. Overall, the results indicate that Ceranock and AAL& K attract-and-kill bait stations are useful alternatives for the control of C. capitata in Tunisian peach orchards planted with early-ripening varieties. [ABSTRACT FROM AUTHOR]

An experimental trial of integrated pest management against Tuta absoluta (Meyrick) based on mass trapping with a density of 32 traps per hectare was conducted in a 5 ha open-field tomato crop. During this trial, the efficiency of three brands of sex pheromone dispenser commercialized in Tunisia was tested. The 'superdosed' pheromone lure type TUA-Optima® (Russell IPM, Deeside, Flintshire, CH5 2LA, United Kingdom) loaded with 0.8 mg of synthetic pheromone was more attractive to males of T. absoluta, and these lures should be used with high populations. Standard lures Pherodis® and TUA-500® containing 0.5 mg of pheromone were less attractive, and can be used in open-field tomato crops with lower populations of T. absoluta. An assessment of the susceptibility of crop borders to T. absoluta, based on data collected from traps, revealed that levels of adult T. absoluta were similar between borders with either tomato or cereal crops. Particular attention should thus be paid to crop borders even when not adjacent to other tomato crops. [ABSTRACT FROM AUTHOR]

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Obligate endosymbiont bacteria associated with insects are naturally providing their hosts with essential nutrients such as vitamins and amino acids and biological services including protection from pathogens. In this study, we aimed to investigate the presence of Wolbachia infection among males and females of the parasitic apricot seed wasp (ASW) Eurytoma samsonowi Vassiliev (Vassiliev Petrograd 11: 1-15, 1915) (Hymenoptera: Eurytomidae), a very harmful pest of apricot (Prunus armeniaca), in the oasis of Gafsa, Southern-West of Tunisia. The detection of Wolbachia infection was assessed based on the amplification of the Wolbachia surface protein (wsp) gene and a multilocus sequence typing (MLST) as a universal genotyping tool for Wolbachia involving the analyses of genes gatB, coxA, hcpA, fbpA, and ftsz. Confirming the screening results, Wolbachia was detected in the natural apricot wasp for the first time, with a significant difference between males (5%) and females (59%) based on wsp gene. All Wolbachia strains identified in E. samsonowi were clustered among supergroups B of Wolbachia., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Phenacoccus solenopsis Tinsley (Hemiptera: Coccomorpha: Pseudococcidae), the cotton mealybug, is an invasive polyphagous species that has been extending its geographic range, posing a conspicuous threat to many Mediterranean crops of economic importance. These include three species of Solanaceae, namely Solanum lycopersicum L. (tomato), Solanum tuberosum L. (potato) and Solanum melongena L. (eggplant) all of which are economically important worldwide. In this study, we used age-stage two-sex life tables to investigate the suitability of these three plant species as hosts for P. solenopsis and to calculate pest fitness, life history parameters and population projection parameters. All tested host plants that were suitable for the pest and eggplant host plant induced a higher fecundity (276.50 ± 10.78 eggs/female), net reproductive rate ( R 0 ) (243.32 ± 15.83 offspring/female) and finite rate of increase ( λ ) (1.18 ± 0.0043 day -1 ) and more extended adult longevity (males: 6.50 ± 0.34 days and females: 24.15 ± 0.50 days). Population growth predictions over a period of 90 days of infestation, commencing with an initial population of 10 eggs showed that adult population size was 674,551 on tomato, 826,717 on potato and 355,139 on eggplant. Our data on plant host preference of P. solenopsis will aid the development of appropriate management strategies and achieve successful control of this invasive pest in key Mediterranean crop systems.

The parasitoid Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae) is increasingly being used in integrated pest management (IPM) programs as a biological control agent in order to suppress tephritid fruit flies of economic importance. Innate and acquired behavioral responses-such as pest host fruit preference-of parasitoids can modulate their efficiency in the field and should be taken into consideration prior to parasitoid species' selection for mass-rearing. We have assessed the influence of medfly-infested (two infestation ages, 1 and 4-d-old) and uninfested fruit species on host preference and efficiency of D. longicaudata by using a multistep assay including olfactory, laboratory and semi-field trials. We found that D. longicaudata was significantly more attracted to medfly-infested apples for both infestation ages, with the oldest being the most preferred. D. longicaudata exhibited a significant preference among the four fruits tested. The implications of these behavioral responses of D. longicaudata to medfly host fruits and infestation age are discussed in relationship to its use in IPM programs in the Mediterranean basin area.

Laboratory and field investigations to identify and evaluate plant co-attractants of the aggregation pheromone of the date palm pest Oryctes agamemnon are reported. Volatiles emitted by freshly cut palm core and palm core with feeding males, were collected, analyzed by gas chromatography coupled to mass spectrometry and evaluated in olfactometers alone or combined with synthetic pheromone. A collection of palm odor without male effluvia was attractive alone and enhanced attraction to synthetic pheromone in an olfactometer similar to that to a collection of palm odor emitted with feeding males and containing natural pheromone. Behavioral responses to collections of palm volatiles were correlated to the amount of volatiles material in them. Enhancement of the attractiveness of the pheromone was not correlated to chemicals specific to beetle feeding. The chemicals common to the active collections extracts were benzoate esters, mostly ethyl benzoate, anisole derivatives and sesquiterpenes. Blends of the most abundant components of the extracts were evaluated for enhancement of the attractiveness of pheromone (1 μg) in olfactometers at 1 or 10 μg doses. The mixtures were further evaluated by field trapping in Tunisia at 3-10 mg/day using reference (6 mg/day) or experimental pheromone formulations. A mixture of ethyl benzoate, 4-methylanisole and farnesol (1:1:1 w/w at 6.5 mg/day) enhanced captures in pheromone baited traps in 2014 and 2015 and this mixture was as active as the natural palm bait. The practical prospect of the result for the management for O. agamemnon, and other palm beetles is discussed.

Background: Phytophagous insects differ in their degree of specialisation on host plants, and range from strictly monophagous species that can develop on only one host plant to extremely polyphagous species that can develop on hundreds of plant species in many families. Nutritional compounds in host fruits affect several larval traits that may be related to adult fitness. In this study, we determined the relationship between fruit nutrient composition and the degree of host specialisation of seven of the eight tephritid species present in La Réunion; these species are known to have very different host ranges in natura. In the laboratory, larval survival, larval developmental time, and pupal weight were assessed on 22 fruit species occurring in La Réunion. In addition, data on fruit nutritional composition were obtained from existing databases., Results: For each tephritid, the three larval traits were significantly affected by fruit species and the effects of fruits on larval traits differed among tephritids. As expected, the polyphagous species Bactrocera zonata, Ceratitis catoirii, C. rosa, and C. capitata were able to survive on a larger range of fruits than the oligophagous species Zeugodacus cucurbitae, Dacus demmerezi, and Neoceratitis cyanescens. Pupal weight was positively correlated with larval survival and was negatively correlated with developmental time for polyphagous species. Canonical correspondence analysis of the relationship between fruit nutrient composition and tephritid survival showed that polyphagous species survived better than oligophagous ones in fruits containing higher concentrations of carbohydrate, fibre, and lipid., Conclusion: Nutrient composition of host fruit at least partly explains the suitability of host fruits for larvae. Completed with female preferences experiments these results will increase our understanding of factors affecting tephritid host range.

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.

The mosquito Culex pipiens has been involved as vector of the West Nile virus in Tunisia. Its bio-ecological characteristics in combination with some environmental factors have favoured the emergence of this virus in a West-Nile free zone. This leads to question about the potential risk of introducing another arbovirus, the Rift Valley fever (RVF) virus, in Tunisia from neighbouring countries where RVF circulates. In this study, we have evaluated the vector competence of different populations of Cx. pipiens towards two strains of RVF virus, the virulent ZH548 and the avirulent Clone 13 by experimental infections and the genetic differentiation of these populations of Cx. pipiens using four microsatellite loci. We found disseminated infection rates ranging from 0% to 14.7% and a high genetic differentiation among populations without any geographical pattern (no isolation by distance). Thus, although Cx. pipiens is able to sustain an amplification of RVF virus, viral dissemination through mosquito dispersal would be unlikely. However, as RVF is an emerging disease transmitted by several other potential mosquito species (e.g. Ochlerotatus caspius), attention should be maintained to survey livestock and mosquitoes in Tunisia.

The date palm mite, Oligonychus afrasiaticus (McGregor) (Acari: Tetranychidae), is a serious pest of palm date fruits. Life cycle, fecundity, and longevity of this mite were studied on fruits of four date palms, Phoenix dactylifera L. (Arecales: Arecaceae)(varieties: Deglet Noor, Alig, Kentichi, and Besser), under laboratory conditions at 27 = 1 °C, 60 ± 10% RH. Total development time of immature female was shorter on Deglet Noor fruits than on the other cultivars. O. afrasiaticus on Deglet Noor had the highest total fecundity per female, while low fecundity values occurred on Besser. The comparison of intrinsic rates of natural increase (r(m)), net reproductive rates (R(o)), and the survival rates of immature stage of O. afrasiaticus on the host plants suggests that O. afrasiaticus performs better on Deglet Noor fruits. The mite feeding on Alig showed the lowest intrinsic rate of natural population increase (r(m) = 0.103 day (-1)). The estimation of difference in susceptibility of cultivars to O. afrasiaticus is crucial for developing efficient pest control programs. Indeed, less susceptible cultivars can either be left unsprayed or sprayed at low threshold.