Here, we report on the first state and county record of Euschistus quadrator Rolston (Hemiptera: Pentatomidae) in Washington County, Mississippi. The species has been documented from Honduras to Virginia primarily on soybean, cotton, various row crops, fruit, and non-crop hosts. The local impact on agricultural crops in the area is unknown. The lack of E. quadrator sightings in Mississippi compared with the frequency of occurrence in literature from Louisiana is of interest. Weather patterns may have contributed to the range expansion. Future efforts to educate growers and consultants on identifying key characteristics of the various Euschistus species common in the southeastern United States may reveal an even larger distribution of E. quadrator in the state and region.
Euschistus quadrator Rolston (Hemiptera: Pentatomidae) is a polyphagous stink bug that is recognized as a pest of soybean (Glycine max [L.] Merrill; Fabaceae) and cotton (Gossypium hirsutum L; Malvaceae ) (McPherson et al. 1982; Drees & Rice 1990; Baur et al. 2000; Bundy & McPherson 2000a; Willrich et al. 2003; Esquivel et al. 2009; Ruberson et al. 2009; Temple et al. 2011, 2013; Parker 2012; Suh et al. 2013; Tillman et al. 2015). The species was first identified in 1974 with specimens collected in northern Mexico, the Yucatan Peninsula, Texas, and Louisiana (Rolston 1974). Since the initial description, the insect host range records have grown to include Honduras (Arismendi & Thomas 2003) to the south and additional states in the southeastern United States including: Alabama (Ray et al. 2012), Florida (Brennan et al. 2015), Georgia (Tillman 2008), North Carolina (Owens et al. 2013), South Carolina (Reay-Jones 2014), and Virginia (Kamminga et al. 2009). Euschistus quadrator is considered to be part of the lesser brown stink bug complex, which consists of E. obscurus (Palisot), E. ictericus (L.), and E. crassus Dallas (Hopkins et al. 2005).
In addition to cotton and soybean, E. quadrator is found on various other crops associated with E. servus (Say) including: corn (Zea mays L.; Poaceae) (Tillman 2010), peanuts (Arachis hypogaea L.; Fabaceae) (Tillman 2008), sorghum (Sorghum bicolor [L.] Moench; Poaceae) (Tillman 2013a), wheat (Triticum spp.; Poaceae) (Dees & Rice 1990; Bundy & McPherson 2000a; Tillman 2010; Reay-Jones 2014), and alfalfa (Medicago sativa L.; Fabaceae) (Tillman 2013b). Additional host plants mentioned in the literature include blackberry (Rubus spp.; Rosaceae) (Brennan et al. 2013) and tropical soda apple (Solanum viarum Dunal; Solanaceae) (Diaz et al. 2012).
Members of the genus Euschistus and the predatory stink bug Podisus maculiventris (Say) share physical characteristics and host ranges with E. quadrator, which may lead to mixtures of 2 or more of these species during field sampling (McPherson 1982; Tillman 2013b; Tillman et al. 2015). Some individuals of E. servus display spiny projections on the pronotum that commonly are seen in E. quadrator and P. maculiventris, and each species shares a similar brown dorsal coloring. One morphological feature for separating P. maculiventris from species of Euschistus is to compare the width of the mouthparts and antennae. A 1:1 width ratio of the mouthparts and an antenna denote a plant-feeding stink bug, whereas a 2:1 ratio would distinguish a predatory stink bug (Knutson & Ruberson 1997). Among members of the brown stink bug complex, E. quadrator is distinguished by a lack of pigment on the hemelytra (Esquivel et al. 2009). Eggs of E. quadrator have also been described alongside those of other stink bugs found in soybeans, which resulted in a useful guide for early detection of these highly mobile pests (Bundy & McPherson 2000b). Although E. quadrator and other members of the lesser brown stink bug complex are found on crop host plants commonly associated with E. servus, the population density of the lesser brown stink bug complex is typically lower than that of E. servus (Parker 2012; Temple et al. 2013; Tillman 2013a). South Texas is an exception, and E. quadrator is more abundant in cotton than all other species of Euschistus in that region of the state (Hopkins et al. 2005).
Plant injury occurs when E. quadrator inserts its stylet into the developing pod wall or boll and extracts plant fluids from the developing fruit. Stink bug feeding can result in seed discoloration, reduced seed size and weight, irregular seed, reduction in seeds per pod, lower oilseed content, increased protein, and decreased percentage of germination in soybean (Miner 1961; Daugherty et al. 1964). Cotton boll feeding of E. quadrator is similar to that of E. servus and can result in reductions in yield and fiber quality (Hopkins et al. 2009).
The 2 primary crop hosts for E. quadrator, soybean and cotton, were planted on approximately 2 million and 440,000 acres (809,371 and 178,062 ha), respectively, in Mississippi in 2016 (USDA-NASS 2016). In 2014, more insecticides were applied for stink bug control in soybean than for any other category of insects in Arkansas, Alabama, Louisiana, Mississippi, North Carolina, Tennessee, and Virginia (Musser et al. 2015). Effective control of E. quadrator in soybean and cotton has been accomplished in other states with products recommended for E. servus (Willrich et al. 2003; Hopkins et al. 2009).
Euschistus quadrator adults (Fig. 1) were first observed in Mississippi among sweep net samples from R6-stage (i.e., full seed) soybean in Washington County (33.4303°N, 90.9232°W) on 25 Aug 2016. Further in-depth surveys should be undertaken to determine the level of establishment in soybean and cotton in Mississippi. The origins of E. quadrator at this location are unknown at this time, but others have suggested the reduced use of insecticides in Bacillus thuringiensis (Berliner) corn and soybean has contributed to increased populations and range of stink bugs in the southern USA (Hopkins et al. 2005). Sustained populations of E. quadrator have consistently been found on soybean and cotton in Winnsboro, Louisiana, which is approximately 160 km from Washington County, Mississippi. Northeast Louisiana would be a likely source for insects transported by westerly winds across the Mississippi River. Further efforts to train growers and consultants in identification of this relatively new species will contribute to more appropriate use of insect control methods in soybean and cotton in Mississippi.
Fig. 1.
Euschistus quadrator dorsal view (left) showing spines on the pronotum and ventral view (right). Specimen photographed by Michael Grodowitz and confirmed as Euschistus quadrator Rolston by Joseph Eger, Tampa, Florida.
A collected specimen was deposited in the Mississippi Entomological Museum at Mississippi State University.
The authors would like to thank Gordon “Lou” Andrews, Donny Adams, Richard Evans, Desari Wright, Megan Clark, Chris Johnson, and Arnel Patterson, for their technical assistance.
