Liriomyza trifoliearum Spencer

Eiseman, Charles S. & Lonsdale, Owen, 2018, New state and host records for Agromyzidae (Diptera) in the United States, with the description of thirty new species, Zootaxa 4479 (1), pp. 1-156 : 56

Liriomyza trifoliearum Spencer

Material examined. CALIFORNIA: Lake Co., McLaughlin Natural Reserve , 18.iv.2016, em. 1–4.v.2016, E. LoPresti, ex Trichostema laxum , #CSE2437, CNC654495 , CNC654496 (2♂) ; San Diego Co., Hawk Canyon , 11.iii.2017, em. 21.iii.2017, C.S. Eiseman, ex Eremalche rotundifolia , #CSE3257, CNC940065 (1♂) .

Hosts. Cleomaceae : Cleome L. ( Scheffer & Lonsdale 2018); Fabaceae : Lupinus polyphyllus Lindl. ( Lonsdale 2017) , Medicago sativa L., Pisum sativum L., Securigera varia (L.) Lassen, Trifolium incarnatum L., T. repens L. ( Spencer & Stegmaier 1973; Spencer 1981); * Lamiaceae : Trichostema laxum A. Gray ; * Malvaceae : Eremalche rotundifolia (A. Gray) Greene ; Solanaceae : Solanum physalifolium Rusby ( Spencer & Steyskal 1986) . Hendrickson & Keller (1983) noted that Liriomyza trifoliearum “can be abundantly reared on snap beans, Phaseolus vulgaris L.” in the laboratory, but they did not indicate whether larvae were ever found on this host in the field. They reported that three other legumes, Phaseolus lunatus L., Trifolium pratense L., and Vicia faba L., were acceptable host plants in the laboratory but less productive, and when these three species were grown for a summer next to a lightly infested alfalfa field, no mining took place on them.

Leaf mine. Whitish, entirely linear, with frass in strips or discrete grains. Spencer & Stegmaier (1973) describe it as an upper surface mine; Hendrickson & Keller (1983) state: “Oviposition may take place on either the upper or lower epidermis of an alfalfa leaflet, but the lower is preferred. Eggs are positioned between the leaflet epidermis and the mesophyll. Larvae mine in these same layers until shortly before pupation when they frequently cross over to the opposite epidermis.” The mines on Trichostema from which adults were reared were on the upper surface but crossed to the lower surface at the end. An empty mine found a year earlier at the same site was entirely on the upper surface, including a semicircular emergence slit.

Puparium. According to Spencer & Stegmaier (1973) the puparium is “dark orange yellow” and is normally formed externally, rarely in the leaf. Hendrickson & Keller (1983) state that it is cream colored initially, darkening to various shades of brown, and is formed within the leaf; the adult may emerge through either epidermis, apparently at random. Both of the puparia on Trichostema were formed within the leaf, adjacent to the lower epidermis, through which the adults later emerged.

Distribution. USA: AZ, CA, DE, FL, MA, MD, NM, NY, OH, OR, PA, UT, VA, WA, WI, WV; Canada: AB, BC, NB, NS, ON, PE, QC, SK.

Comments. These are the first records of an agromyzid (or any other leafminer) from Eremalche or Trichostema , and (after Lupinus ) represent only the second and third native plants from which Liriomyza trifoliearum has been reared. E. LoPresti (in litt.) reported that the mines were very scarce on Trichostema .