Managing Spider Mites in corn: A review

Corn is one of the three most important cereal crops in the world. The mites that attack maize belong to the family Tetranychidae, and the species Tetranychus urticae. Koch TSM and Oligonychus pratensis BGM (primary pests of cereals) are particularly formidable. Although high populations of spider mites frequently cause significant damage to corn (grain, silage, and sweet), the level of economic loss varies from season to season. Several factors influence population dynamics from year to year, including temperature, humidity, precipitation, soil type, pesticide applications, proximity to the host, and natural enemies. High temperatures and drought stress usually accelerate the accumulation process of high mite populations. This is compounded by the application of neonicotinoid pesticides, dust accumulation on corn leaves, and sandy soils as these soils are typically drought stressed, even with irrigation. Mites are responsible for severe yield losses of up to 40% of dry matter for silage. With the extensive and unsustainable use of pesticides, including acaricides and insecticides, management of mites currently commercially available miticides has become increasingly difficult, as these arthropods have developed resistance to over 95 active ingredients. The use of drought-tolerant corn plants can help reduce spider mite outbreaks and losses associated with these pests. Natural enemies, including predatory mites of the phytoseiidae family (Phytoseiulus persimilis Athias, Neoseiulus californicus), thrips (Scolothrips sexmaculatus), the tiny pirate bug (Orius sp), and the small black lady beetle (Stethorus punctillum) can keep spider mite numbers below the economic damage threshold. However, the effectiveness of these natural enemies is reduced by hot, low humidity conditions, pesticide use and dust accumulation on leaves. Proper irrigation can help reduce the risk of plant drought and the environment in which spider mites thrive. Eliminating alternate hosts for grasses can reduce their population potential. These biological and cultural control practices can be beneficial but often unreliable, which is why spider mite management on corn relies heavily on synthetic chemicals. New active ingredients such as etoxazole, dimethoate and fenpyroximate have been recentlyintroduced in the market to control spider mites more effectively. Preventive treatments at the beginning of the season can bring significant economic advantage. This effectiveness is greatly enhanced by aerial treatments.  Electrostatic nozzles, for example, have been shown to be 3 times more effective than conventional hydraulic nozzles in controlling corn spider mites. Keywords: Phytophagous mites, maize, natural enemies, synthetic chemicals, aerial treatmen

Comparative efficacy of mass trapping and attract-and-kill technique in the control of medfly (Ceratitis capitata, Wiedemann) in Central Moroccan peach orchards

To develop eco-friendly alternative control strategies for medfly, mass trapping trials were conducted in the central Morocco during the crop season 2016. Two control methods, mass trapping and the attract-and-kill technique were compared for the control of medfly on two peach varieties ('Rome Star' and 'Ryan Sun') in Sefou district. For mass trapping, 62 traps/1.23 ha of MagnetTM Med type baited with ammonium acetate, trimethylamine, putrescine and 0.01 g of deltamethrin were installed on both varieties. In plots testing the attract-and-kill technique, treatments with malathion in mixture with protein hydrolyzate were applied to straw tuMs attached to branches of the same varieties whenever 1 fly was caught on a Trimedlure trap installed at the center of each plot. The results showed that the number of flies captured by mass trapping reached 508 and 489 adults on 'Rome Star' and 'Ryan Sun', respectively. The average number varied from 1 to 3 adults/trap/day, depending on the date of capture and the variety, and females accounted for 62-100% of total caught flies. In plots protected by the attract-and-kill technique, and taking into account the threshold adopted by the farm, 11 and 15 treatments were carried out respectively on the 'Ryan Sun' and 'Rome Star' varieties. Overall, infestation rates in plots did not exceed 0.3% before or at harvest with mass trapping versus 0.9% with the attract-and-kill technique. On fruit dropped on the ground, the infestation rate did not exceed 4% in mass trapping, compared to 11.5% in the chemically treated plots. Mass trapping was therefore proved to be an effective and eco-friendly tool for managing medfly on peach fruit

From soil to host: Discovering the tripartite interactions between entomopathogenic nematodes, symbiotic bacteria and insect pests and related challenges

peer reviewedEntomopathogenic nematodes (EPNs) are emerging as key agents in ecological networks, exhibiting a wide range of interactions with other biotic components, in particular their symbiotic relationships with the bacteria Xenorhabdus and Photorhabdus. This comprehensive study reveals their global distribution and local benefits and highlights their historical background and taxonomic grouping. The importance of the secreted compounds of EPNs in pest management is highlighted by an in-depth exploration of their potential as biocontrol agents. The complex interactions between nematodes and endosymbiotic bacteria are dissected to understand their mutualistic relationships and subsequent effects on host organisms. The strategies used by EPNs to locate, recognize, and invade hosts will be carefully analyzed to understand their pathogenic phase and the resulting immune responses elicited in insect hosts. Infection strategies employed by the EPN-bacteria complex will be examined to assess their efficacy and real-world challenges. The challenges associated with the effective use of EPNs, including environmental constraints and the need for improved efficacy, will be thoroughly investigated to propose viable solutions. This study paves the way for harnessing the biocontrol potential of EPNs and provides a robust framework for future research to improve the efficacy of EPNs in sustainable agriculture and pest management while addressing the challenges identified

Etude de l'effet de l'augmentation du CO2 atmosphérique sur l'interaction plante-phytophage : cas particulier du système haricot / piqueurs-suceurs

Doctorat en sciences - UCL, 199

Étude prospective de la fondation, de l’immigration et des facteurs de mortalité des colonies de pucerons noirs de l’oranger Toxoptera aurantii Boyer de Fonscolombe (Hemiptera : Aphididae) au nord du Gharb

Four hundred and eighty brown citrus aphid T. aurantii colonies from ten cohorts were followed and referred from middle of April to end of May in several citrus orchards in the Gharb area during 2006 et 2007 years. This pest would prefer to colonize the S1 and S2 citrus leaves stages but all other studied stages would be predisposed to be also colonized. The colonies of indeterminate foundation were the most important, followed by those founded by the apterous ones (e. g. summer colonies) and also those resulting from alatae one (e. g. spring colonies). Immigration of alates is also discussed. T. aurantii regulation factors are multiple (17 sources) and may act individually or combined. A significante difference of mortality level of T. aurantii colonies was noted and discussed between regulation's origins. Coccinellidae is the most efficient predators of T. aurantii, with A. decempunctata and i (Coleoptera : Coccinellidae). Impact of beneficial such as A. decempunctata, C. septempunctata, A. decempunctata in association with C. septempunctata on aphid regulation is respectively from 5 to 48.33% ; 5 to 16.7%, and 5 to 18.33%. Impact of other regulation’s origins such as temperature and old leaves on aphid mortality is respectively from 8 to 55% and 3.33 to 40%. Others predators such as Aphidoletes Aphidimyza Rond. (Diptera : Cecidomyiidae), Chrysoperla carnea Stephens (Neuroptera : chrysopidae) and Episyrphus balteatus DeGeer (Diptera : Syrphidae), affect also T. aurantii colonies. The impact of theses indigenous beneficial species, acting individually or with ladybird on colony survival is low, except for A. decempunctata in association with E. balteatus with a maximum of 10%.Quatre cent quatre-vingts colonies de pucerons noirs de l’oranger T. aurantii de dix cohortes ont été suivies, référencées et dénombrées de miavril à fin mai dans 10 vergers d’agrumes (Citrus spp.) de la région du Gharb durant les années 2006 et 2007. L’origine des colonies de ce ravageur qui colonise principalement certains stades des feuilles est la plupart du temps indéterminée. Cependant ces colonies peuvent être également formées par des individus aptères (surtout colonies d’été) et ailées (surtout colonies printanières). L’immigration des individus ailés a été discutée ainsi que les facteurs de régulation qui sont au nombre de 17 et agissent individuellement ou de façon conjuguée. Une différence significative du taux de régulation des colonies de T. aurantii a été notée et discutée entre les différentes origines de régulation. Les coccinelles Adalia decempunctata L. et Coccinella septempunctata L. (Coleoptera : Coccinellidae) sont les prédateurs les plus efficaces contre T. aurantii. L’impact de A. decempunctata représente 5 à 48,33% de l’ensemble de la régulation, il est de 5 à 16,7% pour C. septempunctata, de 5 à 18,33% pour le couple A. decempunctata + C. septempunctata. La température et l’âge des pousses sont aussi des facteurs importants de régulation, et représentent respectivement de 8 à 55% et de 3,33 à 40% dans la limitation des colonies de T. aurantii. D’autres prédateurs affectent également les colonies de T. aurantii, tels que Aphidoletes Aphidimyza Rond. (Diptera : Cecidomyiidae), Chrysoperla carnea Stephens (Neuroptera : chrysopidae) et Episyrphus balteatus DeGeer (Diptera : Syrphidae). L’effet de ces espèces indigènes, qui agissent individuellement ou avec les coccinelles, reste faible, excepté pour le couple A. decempunctata + E. balteatus avec un maximum de 10 %.Smaili Moulay Chrif, Blenzar Abdelali, Boutaleb Abdelmalek Joutei. Étude prospective de la fondation, de l’immigration et des facteurs de mortalité des colonies de pucerons noirs de l’oranger Toxoptera aurantii Boyer de Fonscolombe (Hemiptera : Aphididae) au nord du Gharb. In: Ecologia mediterranea, tome 35,2009. pp. 5-18

The false tiger of almond, Monosteira unicostata (Hemiptera: Tingidae): Biology, ecology, and control methods

The almond tree, following the olive tree, holds the distinction of being the fruit species occupying the largest area in Morocco, spanning 128,000 ha and hosting 16 million trees. This sector holds immense socio-economic significance both nationally and globally. Despite its prominence, the almond tree faces severe phytosanitary challenges, prominently among them, the False tiger bug of the almond tree, Monosteira unicostata (Mulsant & Rey [Hemiptera: Tingidae]). This polyphagous, sedentary, and gregarious hemipteran, boasting five larval instars and typically generating four generations annually, exhibits a life cycle duration ranging from 2 to 3 months contingent on the season. This pest inflicts notable harm on almond tree leaves by extracting their chlorophyll content through its piercing mouthparts and depositing excrement, impeding respiratory function and adversely impacting fruit development, maturation, and overall production. Diverse control strategies have been implemented to tackle this issue, commencing with prophylaxis involving resistant varieties and sound agricultural practices. Subsequently, biological control methods leveraging natural enemies such as Piocoris luridus and species from families including Coccinellidae, Anthocoridae, Lygaeidae, Miridae, and Nabidae have been employed. Plant-based biopesticides such as azadirachtin (Azadirachta indica), thyme oil (Thymus zygis), Jatropha oil (Jatropha curcas), and concentrated extracts of Artemisia absinthium, as well as mineral-based approaches involving treated kaolin sprays through particle film technology, contribute to the arsenal of control measures. In cases of severe infestations, synthetic active ingredients such as organophosphates, pyrethroids, carbamates, abamectin, and deltamethrin, among others, have proven efficacy in managing this pest

Elaboration of a strategy to control the peach twig borer Anarsia lineatella Zeller in the Sefrou region in Morocco

Trapping by specific sex pheromones initiated in 2009 to monitor three pests, peach twig borer (Anarsia lineatella), oriental fruit moth (Cydia molesta) and plum fruit moth (Grapholita funebrana) revealed the greater importance of peach twig borer in comparison to the others. The results of monitoring the development of larval stages over time and the accumulated degree-days from biofix show that the pest develops five generations per year, one of which undergoes a diapause. In 2009 and 2010 chemical control based on tolerance threshold of 10 males/trap/2 weeks showed unsatisfactory results. With this method, the percentage of affected fruits increased from 6.8% in 2009 to 18.6% in 2010 despite the application of four treatments of organophosphate-based insecticides in 2009 and the application of four treatments in 2010 using active ingredients from different chemical families (pyrethroid, organophosphate and chlorinicotinyl). On the other hand, management of the peach twig borer by the degree-days method tested and planned on the basis of a bifenthrin treatment between 150 to 204 degree-days accumulated from biofix, gave interesting results where the percentage of affected fruits hardly exceeded 0.5% over the four years of stud

Assessing <i>Panonychus ulmi</i> (Acari: Tetranychidae) Infestations and Their Key Predators on <i>Malus domestica</i> Borkh in Varied Ecological Settings

This study investigates the infestation dynamics of Panonychus ulmi McGregor 1916 and its associated predators in Malus domestica borkh orchards across three towns in Morocco: Midelt, Ait Sebaa, and Imouzzer-Kender, situated in the Fez-Meknes and Draa-Tafilalt regions. Ait Sebaa (Fez-Meknes region), characterized by high temperatures and a lower altitude, exhibited a substantial increase in P. ulmi and its predators. In contrast, Midelt (Draa-Tafilalt region), with the highest altitude, demonstrated lower mite counts. Imouzzer-Kender (Fez-Meknes region), at an intermediate altitude, showed moderate mite levels. Detailed findings reveal a positive correlation between P. ulmi and temperature, as well as with phytoseiid mites. Conversely, a negative correlation exists between P. ulmi and altitude. Additionally, a positive correlation between phytoseiid mites and temperature is identified. Overall, this study provides valuable information on the ecological interactions between mites, temperature, altitude and humidity in distinct Moroccan regions, highlighting the need to take regional specificities into account in pest management strategies

Evaluation of the impact of two citrus plants on the variation of Panonychus citri (Acari: Tetranychidae) and beneficial phytoseiid mites

The abundance of Panonychus citri McGregor 1916 (Acari: Tetranychidae) and its associated enemies (Euseius stipulatus Athias-Henriot, 1960; Typhlodromus sp.; Phytoseiulus persimilis Athias-Henriot, 1957) was studied on two 12-year-old citrus cultivars, specifically Clementine “Nules” (Citrus Clementina) and Valencia (Citrus sinensis), in the Gharb region of Morocco. Throughout the entire monitoring period in the Valencia late cultivar, the density of the spider mite P. citri on leaves was notably higher at 38.0% (n = 1,212 mobile forms). Predator P. persimilis exhibited a leaf occupancy of 25.0% (n = 812), followed by Typhlodromus sp. at 20.0% (n = 643). Conversely, the abundance of E. stipulatus was lower at 17.0% (n = 538). In the Nules variety, P. citri abundance recorded a higher percentage at 48.0% (n = 1,922). E. stipulatus emerged as the most abundant predator at 23.0% (n = 898), followed by P. persimilis with 16.0% (n = 639). Meanwhile, the population of Typlodromus sp. remained notably low at 13.0% (n = 498). Regarding the fluctuation of the different mites studied on the two cultivars across monitoring dates, the period from May 4 to June 1 was characterized by low temperatures and a diminished presence of mite populations (P. citri, E. stipulatus, Typhlodromus sp., and P. persimilis). However, from June 7 to June 19, characterized by high temperatures, a notable increase in the presence of mite populations was observed. As regards the effect of the variety on the different mites studied, the varietal impact was significant