Adwa ABDOU ALI’s thesis has just been formally accepted by the university! Her research, culminating in her thesis titled Insects of the date palm in traditional and modern orchards of Djibouti, compared the abundance of several potential insect pests of date palms in modern, monocultural orchards, and in older, traditional, and polycultural orchards, the kind one might find growing around oases. Both orchard types harbored potential pests, but the modern ones had more pests specialist of date palm, whereas the traditional orchards had a greater abundance of generalist pests.
Here’s the abstract:
In recent years, food insecurity and poverty, especially among the rural populations of Djibouti, have been increasing due to population growth and rising world food prices.
As a result, the government of Djibouti seeks to develop sustainable agriculture through date farming. The cultivation of date palms adapts well to the difficult pedoclimatic conditions of the Republic of Djibouti. Massive introductions of date palm have taken place in recent years to restore the older traditional palm groves (polycultures) and to create and/or extend new palm groves oriented towards monoculture.
However, the country faces major phytosanitary challenges: poor infrastructure, insufficient knowledge and a lack of research on the pests of this crop.
With the ultimate aim of protecting and increasing Djibouti’s date yields, this present work seeks to assess the susceptibility of palm groves to insect pests. To achieve this objective, a comparison of the insect fauna of the two types of palm groves was carried out using composite traps placed within the crown of the date palm. The experiment was carried out from 20 June to 2 September 2018, in six orchards on three sites.
The samples documented the existence and diversity of insects in these palm groves, as well as the presence and abundance of specialist date palm pests in monocultural palm groves. Natural enemies were also particularly abundant in the traditional palm groves, but species-level diversity did not show any correlations with type of palm grove.
This study contributes to the knowledge of insect diversity and potential pest species in the palm groves of Djibouti. These pests can have an important impact on date yields depending on the type of palm grove and this study thus underlines the needs to develop adequate means of pest control.
We have published a new article in the journal PLOS ONE. This publication is the first one based on the research of doctoral student Élisée Emmanuel DABRÉ.
The use of beneficial microorganisms, such as arbuscular mycorrhizal fungi and plant growth promoting rhizobacteria as biofertilizers in agricultural systems, has gained particular interest in recent years due to their positive effects on plant growth and crop yield. While many studies have focused on the indirect effects of these inoculants on insects associated with plants in controlled and semi-controlled environments, very few field investigations have been done.
We carried out an inventory of phytophagous insects and their natural enemies in soybean fields inoculated with spores of the mycorrhizal fungus Rhizophagus irregularis, the rhizobial bacterium Bradyrhizobium japonicum, and a bacteria promoting plant growth, Bacillus pumilus.
We showed in this study that inoculants reduced the abundance of soybean aphid (Aphis glycines) only in the presence of potassium. We also noted a decrease in the number of leafhoppers in the presence of potassium alone, indicating its probable role in the nutrition of these insects. Finally, we detected a negative correlation between the rate of mycorrhizal colonization of the roots and the abundance of piercing-sucking insects. Given that such insects are major vectors of plant disease, it seems that increased mycorrhizal fungal colonization can help protect crop plants.
The Ouellet-Robert Collection has a wonderful set of dragonfly and damselfly specimens (insect order Odonata) thanks in large part to the efforts of its eponymous founder, Adrien Robert. Indeed, the Odonata collection is so good that we chose a damselfly, the superb jewelwing (Calopteryx amata), as the emblem for the collection.
Before I arrived at the University of Montreal, seed funding for Canadensys from the Canada Foundation for Innovation had paid for the digitization of the specimen data associated with the collection’s Odonata. As a first tentative to better integrate the activities of the various insect collections in Quebec, and possibly to federate a more ambitious collaboration, with funding from the Quebec Centre for Biodiversity Science, colleagues and I visited six other Quebec collections and added their Odonata specimen data to the mix. The result is an impressive dataset including 37,000 occurrence records, from 616 different locations, for 137 species. This dataset, whose description is published in the Biodiversity Data Journal, is free to download and use for species distribution modeling, analyzing changes across time, and any number of other research topics. Given that many Odonata species in Quebec are at the northern limits of their geographic range, their possible range expansions northward may be good indicators for measuring the effects of climate change.
This publication represents the second one in less than a year focusing on the activities in the Ouellet-Robert Collection. The first was an overview of three computerization initiatives, including the Odonata specimen digitization, whereas this second one focuses on the Odonata data themselves.
The dominant paradigm is that the host plant distributions determine those of plant-feeding insects. However, climate is known to affect the distribution of other organisms, including plants, so who’s to say it doesn’t affect plant-feeding insects too? A group of colleagues sought to answer that very question. We geographically modeled climate variables and host plant and aphid distributions to measure the amount of overlap and how much one may affect the other. For example, perhaps it’s climate conditions that preclude the aphid from being co-located with its host in particular locations. To our North American dataset we added the Cinara aphid collection localities from French and Chinese colleagues, and we used publicly available climate and conifer tree distribution data.
In our paper in Ecology and Evolution, we showed that the distributions of most Cinara species overlap completely with those of their hosts. In those cases, we could not say that climate played a direct constraining role in the aphids’ distributions, but only insofar as it affected that of the host plants. However, almost a third of the Cinara species were present in a reduced portion of their hosts’ range. This result suggests that aphid geographic distribution is constrained by both host and climate factors, and not by host alone.
During my M.S. research, my advisor David Voegtlin gave me a set of medium-sized suction traps that he had developed and built for catching aphids. As I sorted hundreds of aphids, I was amazed at the diversity of other insects in the traps and vowed that I would one day take a closer look at it. One of the first things I did when I arrived at the University of Montreal, was to build my own set of “Voegtlin traps” and set them up along a 150 m transect in the forest of the University’s Laurentian Biological Research Laboratory. We sampled several summer weeks, with suction traps and small Malaise traps set up side by side to compare the efficacy of these two trapping methods.
Over the course of several subsequent years, a small army of undergraduate students sorted the insects in a single week’s worth of that material. One of them, Alexis Trépanier, spent two full semesters classifying the Hymenoptera into “Operational Taxonomic Units”, ending up with just shy of 200 OTUs! He, undergraduate Diptera-sorter Titouan Eon-Le Guern, master’s student computer analyst Vincent Lessard, PhD student Thomas Théry and I just published the results of this project in the journal Insect Conservation and Diversity.
Along with describing the Voegtlin suction trap in detail, we found that these traps were excellent at capturing tiny insects, especially small parasitoid wasps known as Microhymenoptera and the very diverse family Phoridae (true flies, Diptera). Not only are these traps great for species discovery generally, but we found that the ensemble of the insects that they caught was different for each trap along the transect, despite the fact that the traps were only 50 m apart. This suggests that there is a fair amount of insect community heterogeneity in the Laurentian forest.
This summer, we’ve placed three pairs of traps in similar habitat replicates. We’re hoping to find out if that community heterogeneity is more or less random throughout the forest, or if it is patchy, based perhaps on the surrounding vegetation. With any luck, there’ll be a follow-up post in a couple years.
During the past few years, the Ouellet-Robert Entomological Collection personnel have been working towards increasing the use and value of the Collection. Today, entomology researchers especially need electronic data. In a recent publication, we described three computerization initiatives.
First, we examined each drawer of pinned specimens and each vial rack of alcohol-preserved specimens, and we graded the conservation health of these units across eight criteria (for example, the condition of the specimens, or their labels, or their storage containers). With these data, for internal use only, we are better able to target certain parts of the collection with the greatest need.
Secondly, we created a list of the species in the Collection, the number of individuals of each species, and if at least one specimen was had been collected in Quebec or North America. These data, made available on line, are intended for researchers who want to know what material is the Collection so that they can pay us a visit or ask for a loan or more information. We counted 1.5 million specimens, of which a third are pinned, and 20,000 species, of which half are from Quebec.
Finally, we digitized the specimen label data of certain aquatic insect groups, most importantly the dragonflies and damselflies (Odonata) of which we have a lot of material thanks to the effort of our previous curators, Jean-Guy Pilon and Pierre-Paul Harper, but especially Adrien Robert. These data will be useful for, among others, estimating the geographic distribution of Odonata over time and evaluating the effects of environmental change. In fact, we have already added to this dataset by computerizing the specimen label data of other Quebec insect collections: an article describing the combined dataset is in preparation.
The combination of these three new data resources represent but a starting point for a new digital age in the Ouellet-Robert Collection.
In April 2018, Thomas Théry successfully defended his doctoral dissertation. Almost a year later, his erstwhile advisor publicly celebrates the completion of his first PhD student’s studies. Entitled “Molecular systematics of the genus Essigella (Hemiptera: Sternorrhyncha)“, Thomas’s dissertation presented three published chapters.
Species of the aphid genus Essigella are found natively only in North America, feeding along the lengths of pine needles. The taxonomy of the genus was last treated by John Sorensen in 1994. He used difficult, time-consuming, but effective multi-variate morphometric methods to delineate the species. Thomas sought to corroborate or challenge Sorensen’s taxon concepts using molecular methods. In his first chapter, published in Insect Systematics and Diversity, Thomas used genes from the aphids’ nucleus, mitochondrion, and obligate nutritional symbiont Buchnera aphidicola and several molecular species delimitation methods. It was indeed a relief and a pleasure to find that, by and large, his results corroborated Sorensen’s.
Thomas did find a few additional species, however, and he proceeded to describe and name them formally in his follow-up publication in ZooKeys. Thomas’s species descriptions were innovative in that he used actual genetic nucleotide differences as diagnostic characters for his new species, something rarely done in animal taxonomy and never done before with aphids. Not to court too much controversy, Thomas made certain to include morphological diagnoses as well! The third chapter of Thomas’s dissertation was actually the first one published. We’ve already described that work on the Monterey pine needle aphid colonizing new geographic regions.
Thomas landed a full-time employment at the Insectarium of Montreal, just next door to the Biodiversity Centre, so we are pleased to see him regularly as he comes to work on his beetles at the Ouellet-Robert collection. Yes, that means that despite having worked on aphids for his PhD, we were unsuccessful at taking the histerid out of this coleopterist. We’re proud of you anyway, Dr Théry, congratulations!
Théry T, Kanturski M, Favret C. 2018. Molecular phylogenetic analysis and species delimitation in the pine needle-feeding aphid genus Essigella(Hemiptera, Sternorrhyncha, Aphididae). Insect Systematics and Diversity, 2(4):1;1-15. DOI: 10.1093/isd/ixy006
Théry T, Kanturski M, Favret C. 2018. Molecular data and species diagnosis in Essigella Del Guercio, 1909 (Sternorrhyncha, Aphididae, Lachninae). ZooKeys, 765: 103-122. DOI: 10.3897/zookeys.765.24144
Théry T, Brockerhoff EG, Carnegie AJ, Chen Rui, Elms SR, Hullé M, Glatz R, Ortego J, Qiao Gexia, Turpeau É, Favret C. 2017. EF-1α DNA sequences indicate multiple origins of introduced populations of Essigella californica(Hemiptera, Aphididae). Journal of Economic Entomology, 110(3): 1269-1274. DOI: 10.1093/jee/tox026
Aphis lugentis is an aphid species relatively common in North America, feeding primarily on Senecio, a genus of the daisy family. This aphid species had recently been found in southern France and in a new publication, we document its presence across the Mediterranean in Tunisia, as well as in South America, namely Argentina, Chile, and Peru. In order to confirm the identity of our samples, we examined them under the microscope and sequenced their barcode gene. Publication of the note in the Proceedings of the Entomological Society of Washington implicated eight co-authors from four countries, including two undergraduate interns in the Favret Lab.
Ortego J, Ayadi M, Ben Halima Kamel M, Juteau V, Marullo-Masson D, Nieto Nafría JM, Bel Khadi MS, Favret C. 2019. The spread of the North American Aphis lugentis Williams (Hemiptera: Aphididae) to Africa and South America. Proceedings of the Entomological Society of Washington, 121(1): 128-134. DOI: 10.4289/0013-87126.96.36.199
The recreational use of marijuana becomes legal across Canada today. Of course increased cultivation of Cannabis sativa will accelerate research on this species, as was highlighted in the scientific journal Nature. It will also mean the need to protect the crop against insects and other injurious organisms. One such insect is the Cannabis aphid, Phorodon cannabis. This Eurasian species was recently introduced to North America. In a recent publication, my colleagues and I brought attention to the presence of this insect in the United States and Canada, in fields and greenhouses. We also discussed its biology and taxonomy. The aphid has already caused crop damage but its full economic impact remains to be seen.
Cranshaw WS, Halbert SE, Favret C, Britt KE, Miller GL. 2018. Phorodon cannabis Passerini (Hemiptera: Aphididae), a newly recognized pest in North America found on industrial hemp. Insecta Mundi, 662: 1-12. URL: http://journals.fcla.edu/mundi/article/view/107029