** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** BY CONSUMING CROP PLANTS, HERBIVORES (WHICH ARE ANIMALS THAT FEED ON PLANT TISSUES) CAUSE MAJOR LOSSES IN CROP YIELDS, WHICH IN TURN NEGATIVELY IMPACTS FARMERS AND HUMAN WELFARE MORE GENERALLY. HERBIVORES ARE DIVERSE AND INCLUDE INSECTS LIKE CATERPILLARS AND APHIDS THAT DAMAGE A RANGE OF DICOT CROP PLANTS (LIKE SOYBEAN AND TOMATO) AS WELL AS CEREAL CROP PLANTS (LIKE MAIZE, WHEAT, BARLEY, AND SORGHUM). WHILE MANY INSECT HERBIVORES HAVE BEEN EXTENSIVELY STUDIED, LESS IS KNOWN ABOUT SPIDER MITE PESTS OF CROPS PLANTS. SPIDER MITES ARE ONLY DISTANTLY RELATED TO INSECTS AND ARE PESTS OF CEREAL CROPS INCLUDING MAIZE AND SORGHUM, ESPECIALLY UNDER CONDITIONS OF HIGH HEAT, ARIDITY, AND DROUGHT. IN FACT, DURING SUCH CONDITIONS, THE GENERALIST TWO-SPOTTED SPIDER MITE TETRANYCHUS URTICAE (WHICH FEEDS ON DIVERSE DICOT AND CEREAL CROP PLANTS) AND THE GRASS SPECIALIST BANKS GRASS MITE OLIGONYCHUS PRATENSIS (WHICH FEEDS MAINLY ON CEREALS SUCH AS MAIZE, SORGHUM AND WHEAT) CAN BECOME SIGNIFICANT PESTS OF CEREAL CROPS IN MANY AGRICULTURAL REGIONS. THIS PROJECT WILL INVESTIGATE THE GENOMIC, GENETIC, AND MOLECULAR BASES OF BOTH MITE SPECIES' ABILITY TO INTERACT WITH AND DAMAGE MAIZE, SORGHUM, AND BARLEY. WHILE BOTH THE TWO-SPOTTED SPIDER MITE AND THE BANKS GRASS MITE ARE MORPHOLOGICALLY SIMILAR AND FEED ON PLANTS IN A SIMILAR WAY, BECAUSE THEY DIFFER IN THE RANGE OF HOST PLANTS THEY FEED UPON, THEY MAY THEREFORE INTERACT DIFFERENTLY WITH THE CEREAL SPECIES ON WHICH THEY ARE CROP PESTS. HENCE, THE PROJECT WILL ASSESS SIMILARITIES AND DIFFERENCES IN THE TWO MITE SPECIES' MOLECULAR RESPONSES TO CEREAL HOSTS AND TEST THE ROLES OF SPECIFIC MITE GENES IN MEDIATING THE HERBIVORE-PLANT INTERACTIONS. TO ACCOMPLISH THE PROJECT OBJECTIVES THE GENOME OF THE BANKS GRASS MITE WILL BE SEQUENCED AND COMPARED TO THAT OF THE ALREADY EXISTING GENOME OF THE TWO-SPOTTED SPIDER MITE, AND THE TRANSCRIPTIONAL RESPONSES (WHICH GENES ARE TURNED ON OR OFF) OF BOTH MITE SPECIES TO MULTIPLE CEREAL PLANT HOSTS (MAIZE, SORGHUM, AND BARLEY) WILL ALSO BE ASSESSED. THE COMPARATIVE GENOMIC AND GENE EXPRESSION STUDIES WILL IDENTIFY SHARED GENES IN BOTH SPECIES THAT MAY BE IMPORTANT FOR MEDIATING THEIR ABILITY TO FEED ON CEREAL HOSTS, AS WELL AS GENES IN EACH SPECIES THAT MAY HAVE MORE SPECIES-SPECIFIC ROLES. FURTHER, SPECIFIC GENES IDENTIFIED AS CANDIDATES FOR ALLOWING SPIDER MITES TO COLONIZE, FEED UPON, AND DAMAGE CEREAL CROPS WILL BE FUNCTIONALLY TESTED USING CRISPR-CAS9 BASED GENE EDITING TECHNIQUES THAT HAVE RECENTLY BEEN DEVELOPED FOR SPIDER MITES. THE KNOWLEDGE AND GENETIC AND GENOMIC RESOURCES TO BE GENERATED BY THE PROJECT WILL INFORM GENOME-ENABLED APPROACHES TO CONTROL THESE TWO DESTRUCTIVE PESTS OF CEREAL CROPS FOR WHICH ECONOMICALLY IMPORTANT OUTBREAKS TYPICALLY OCCUR DURING CONDITIONS OF DROUGHT WHEN PLANTS ARE ALREADY EXPERIENCING A MAJOR STRESS THAT REDUCES CROP YIELDS. ADDITIONALLY, EDUCATIONAL MATERIALS TO BE DEVELOPED AND RELEASED VIA THE LEARN.GENETICS WEB RESOURCE WILL INFOR,M A DIVERSE AUDIENCE INCLUDING K-12 AND UNDERGRADUATE STUDENTS AND EDUCATORS, AND THE PUBLIC, ON THE IMPORTANCE OF HEAT AND DROUGHT STRESS ON CROPS IN THE CONTEXT OF HERBIVORES AND HERBIVORE-INDUCED IMPACTS ON CROP YIELDS. FINALLY, UNDERGRADUATE AND GRADUATE STUDENTS WILL BE TRAINED IN MOLECULAR, GENETIC, GENOMIC, AND BIOINFORMATIC METHODS OF IMPORTANCE FOR DEVELOPING MODERN AND SUSTAINABLE AGRICULTURAL PRACTICES.