Although behavioral resistance remains enigmatic, an examination of the literature firmly supports the existence of behavioral resistance in both the presence and absence of the better understood and accepted physiological and biochemical mechanisms. Studies of pyrethroid resistance in the horn fly and the tobacco budworm have identified several resistance mechanisms, including behavioral adaptations, in addition to target‐site insensitivity and enhanced detoxification. The coexistence of physiological and behavioral responses neither precludes a common mechanism nor requires one. Even if a common mechanism such as knockdown resistance or enhanced detoxification is involved, this does not negate the survival benefit of either avoiding the toxicant or reducing movement to avoid exposure. Thus, behavioral resistance may be much more ubiquitous and important than previous interpretation of the literature suggests.

In Louisiana during the last decade, the redbanded stink bug, Piezodorus guildinii (Westwood), has become a significant and yield-limiting pest of soybean. The redbanded stink bug was previously reported in the United States in 1892, but was never considered an economically important pest until recently. Soybeans representing four maturity groups (MG) III, IV, V, and VI were sampled weekly from beginning bloom (R1) to physiological maturity (R8) during 2008-2010 at five locations across Louisiana to determine the Pentatomidae composition. In total, 13,146 stink bugs were captured and subsequently identified to species. The predominant species included the redbanded stink bug (54.2%); southern green stink bug (27.1%), Nezara viridula L.; brown stink bug (6.6%), Euschistus servus (Say); and green stink bug (5.5%), Acrosternum hilare (Say). Redbanded stink bug comprised the largest percentage of the complex collected at four of the five survey sites. Numbers exceeding action thresholds of this stink bug complex were only detected during R4 to R7 growth stages. Redbanded stink bug accounted for the largest percentage of the stink bug complex in early maturing soybean varieties (MG III [86%] and IV [60%]) and declined in later maturing soybeans (MG V [54%] and VI [50%]). The redbanded stink bug was initially identified in southern Louisiana during 2000 and had been reported in all soybean producing regions in Louisiana by 2006. This survey is the first to report the redbanded stink bug as a predominant pest of soybeans from locations within the United States.

The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is an important pest of cotton, Gossypium hirsutum L., in the mid-southern United States. It is exclusively controlled with foliar insecticide applications, and sampling methods and thresholds need to be revisited. The current experiment was designed to establish a plant-based threshold during the flowering period of cotton development. Experiments were conducted in MisSissippi in 2005 and 2006, Arkansas in 2005, and Louisiana in 2005 through 2008. Treatments consisted of various combinations of thresholds based on the percentage of dirty squares that were compared with the current threshold with a drop cloth or automatic weekly applications. Dirty squares were characterized as those with yellow staining on the developing bud resulting from tarnished plant bug excrement. Treatments consisted of 5, 10, 20, and 30% dirty squares. Each plot was sampled weekly, and insecticides were applied when the mean of all replications of a particular treatment reached the designated threshold. At the end of the season, plots were harvested and lint yields were recorded. Differences were observed in the number of applications and yields among the different treatments. The 10% dirty squares threshold resulted in a similar economic return compared with the drop cloth. A threshold of 10% dirty squares resulted in a similar number of insecticide applications, yields, and economic returns compared with that observed with the drop cloth. These results suggest that a threshold of 10% dirty squares could be used to trigger insecticide applications targeting tarnished plant bugs in flowering cotton.

Limited information exists on the insecticide susceptibility of redbanded stink bug, Piezodorus guildinii (Westwood) (Heteroptera: Pentatomidae), despite its impact on soybean, Glycine max (L.) Merr., production in Brazil and the United States. Therefore, this study set out to 1) determine baseline levels of susceptibility to currently recommended pesticides using topical and vial bioassays, 2) determine the levels of esterase activity in populations in the United States and Brazil, and 3) compare control among products in field trials. In topical bioassays conducted in the United States using technical grade materials, the LC50 values of lambda-cyhalothrin, acephate, and methamidophos were 4-25, 141-295, and 40-151 ng per insect, respectively. The LC50 values of imidacloprid and thiamethoxam were 11 and 27 ng per insect, respectively. In vial bioassays conducted in the United States using technical grade materials, the LC50 values of cypermethrin, acephate, and methamidophos were 0.4-0.9, 3.8, and 1.6 microg per vial, respectively. In topical bioassays conducted in Brazil by using commercially formulated products, the LC50 values of acephate, methamidophos, endosulfan, and imidacloprid were 0.90-1.9, 0.4-0.6, 1.5-6.6, and 0.2-0.3 microg per insect, respectively. In vial bioassays conducted in Brazil using commercially formulated products, the LC50 values of endosulfan, methamidophos, and lambda-cyhalothrin were 4-32 and 2-24 microg/cm2 for thiamethoxam and imidacloprid. Esterase activity in Louisiana (United States) populations ranged from 251 to 658 nmol alpha-naphthol formed/min/mg protein. Esterase activity levels in Londrina (Brazil) populations averaged 163 nmol/min/mg. In field tests, P. guildinii in Louisiana were controlled by organophosphates thiamethoxam and imidacloprid and in Brazil, with combinations of neonicotinoids and pyrethroids.

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Florida Entomological Society is collaborating with JSTOR to digitize, preserve and extend access to The Florida Entomologist. ABSTRACTEfficacy of conventional and experimental insecticides against the fall armyworm, Spodoptera frugiperda (J. E. Smith), was evaluated in laboratory bioassays. In a laboratory diet bioassay, third instars of a laboratory-strain were more susceptible to novel insecticides, including chlorfenapyr, methoxyfenozide, spinosad, and tebufenozide, than to a recommended insecticide, thiodicarb. In other laboratory bioassays, fall armyworms were fed field grown cotton leaves, white flowers, or bolls treated with one of two recommended insecticides, L-cyhalothrin or thiodicarb, or one of four experimental insecticides, chlorfenapyr, emamectin benzoate, methoxyfenozide, or spinosad. First instar mortality was significantly greater on leaves treated with chlorfenapyr, L-cyhalothrin, or thiodicarb than for the untreated control at 24 h after infestation (HAI). First instar mortality was significantly greater on leaves treated with all insecticides, with the exception of methoxyfenozide, than for the untreated control at 48 HAI. Likewise, first instar mortality was significantly greater on white flowers treated with all insecticides, with the exception of methoxyfenozide, than for the untreated control at 24 HAI. First instar mortality on white flowers treated with all insecticides was significantly greater than the untreated control at 48 HAI. Fifth instar mortality on bolls was not significantly different among treatments at 1 day after infestation (DAI). At 3 and 5 DAI, fifth instar mortality was significantly greater on bolls treated with all insecticides, with the exception of methoxyfenozide and spinosad, than for the untreated control. At 7 DAI, fifth instar mortality was significantly greater on bolls treated with all insecticides, with the exception of spinosad, than for the untreated control. These data indicate that these recommended and experimental insecticides are effective in controlling early fall armyworm instars on cotton if larvae come in contact with these insecticides.