Genetic Variability of Two Leaffooted Bugs, Leptoglossus clypealis and Leptoglossus zonatus (Hemiptera: Coreidae) in the Central Valley of California

Abstract

Leaffooted plant bugs (LFPBs) (Leptoglossus spp., Guérin-Méneville) (Hemiptera: Coreidae) are large seed-feeding bugs native to the Western Hemisphere. In California, several Leptoglossus spp. feed on almonds, pistachios, and pomegranate and are occasional pests. The objective of this study was to survey the different species of Leptoglossus present in almond, pistachio, and pomegranate orchards in the Central Valley of California. We used two molecular markers, amplified fragment length polymorphisms (AFLPs) and mitochondrial DNA COI, to determine the number of species or strains of each species, and to infer whether individuals of each species move and possibly interbreed with populations from the other host plants. Two species of leaffooted bugs were abundant, Leptoglossus clypealis Heidemann, and Leptoglossus zonatus (Dallas). L. clypealis was collected in almond and pistachio, while L. zonatus was found on all three host plants, but was the dominant species in pomegranate. The AFLP results indicated that L. clypealis consisted of one species, which suggests it moves between almonds and pistachios during the growing season. Mitochondrial DNA COI for L. clypealis found 1-2% divergence between sequences, and a high haplotype diversity of 0.979 with 17 haplotypes. The AFLP results for L. zonatus found two genetically divergent populations which were morphologically similar. The mtDNA COI sequences for L. zonatus were used for haplotype analysis; three haplotypes were found in California, with one haplotype shared with collections from Brazil. The importance of genetic variability and cryptic species for pest management are discussed.

Comparing the Feeding Damage of the Invasive Brown Marmorated Stink Bug to a Native Stink Bug and Leaffooted Bug on California Pistachios

“…However, whether H. halys will become a serious threat to Californian pistachio production will depend on its presence and abundance in the respective counties. Despite its highly invasive behavior in other parts of the country and the world [ 18 ], H. halys abundance in California has so far been surprisingly low, and some have suggested an impact of hot dry climate in the interior valleys may reduce its densities [ 16 ], whereas L. zonatus populations appear to be increasing in population density or survival [ 15 , 54 ]. Further studies looking into H. halys survival and potential limiting factors to its abundance in California are, therefore, necessary to make more informative predictions.…”

Seasonal Dynamics of the Leaffooted Bug Leptoglossus zonatus and Its Implications for Control in Almonds and Pistachios

“…Leptoglossus zonatus has a wide geographic range across its presumptive origins in the Western Hemisphere [27,28] and an equally broad range of crops that it can damage (e.g., [29,30,31,32,33]). Here, we report that in California’s San Joaquin Valley, L. zonatus has three distinct generations per year (Figure 2) with the adult stage being the principle overwintering stage (Figure 3).…”

“…One of the more important findings was that adults are the overwintering stage (Figure 2). In California’s Central Valley, there has been an apparent shift from L. clypealis as the primary coreid pest of pistachio and almonds [39] to L. zonatus [33]. The shift may be due to a natural expansion of L. zonatus range or the increased planting of almond, pistachio, and pomegranates in California.…”

“…Pomegranates in particular provide an excellent fall host where the third generation nymphs can develop to overwintering adults that will then move to sheltered areas from about December to March and then into nut crops from March to May [5]. As mentioned, a broad range of host plants is recorded for L. zonatus with variable developmental success [25,26,33,36,37]. Because the overwintering adult population is the principle population damaging the new and most susceptible almonds and pistachio crop [10], a late fall host that supports the development from nymph to overwintered adults may be the key element in the development of large and potentially damaging winter populations.…”

Optimizing Trap Characteristics to Monitor the Leaffooted Bug Leptoglossus zonatus (Heteroptera: Coreidae) in Orchards

“…Early reports first documented L. clypealis feeding on pistachio, which led to nut drop and epicarp lesion [ 16 , 17 ]. While historically L. clypealis has been the dominant species found on California tree nuts [ 18 ], recent surveys have noted a shift towards L. zonatus , which is now considered the primary species attacking these crops [ 15 , 19 , 20 ].…”