A laboratory bioassay was developed and used to test field populations of the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), for development of resistance to the neonicotinoid insecticides imidacloprid (Trimax®) and thiamethoxam (Centric®). The bioassay determined LC₅₀ values by feeding adult tarnished plant bugs known doses of the insecticides in a 10% solution (by weight) of honey in water. Field populations from 19 (imidacloprid) and nine (thiamethoxam) locations in the mid-South were tested in 2006 and their LC₅₀s were compared to LC₅₀ values determined in tarnished plant bug populations at the same locations in 2007. The LC₅₀ values were also compared to LC₅₀ values determined using imidacloprid and thiamethoxam on a susceptible population from Crossett, AR. Results of the comparisons showed that no resistance to thiamethoxam had developed in the nine populations tested. Some resistance to imidacloprid was found in most of the test populations, because their LC₅₀ values were significantly greater than the LC₅₀ value for the susceptible population from Crossett. Resistance to imidacloprid did not increase in populations at 10 locations from 2006 to 2007, and the LC₅₀ values were not significantly different between the two years. The LC₅₀ for imidacloprid in 2007 was significantly greater than the LC₅₀ in 2006 in populations at only four of the 19 test locations. These results showed that while some resistance to imidacloprid was present, the overall tendency was for the resistance to remain the same or decrease during the two years it was studied. The bioassay developed and used in the study is the only rapid method available for monitoring resistance in tarnished plant bug populations to neonicotinoid insecticides. The baseline data for both imidicloprid and thiamethoxam provide a basis for comparison to determine changes in resistance in future monitoring studies.

Tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), populations from 21 locations in the Mississippi River Delta of Arkansas and Mississippi were tested for resistance to permethrin in 2004 and 2005. Each population was tested using permethrin in a discriminating-dose bioassay to determine percent mortality, and with a glass-vial bioassay that used dose-response regression lines to determine LC₅₀ values for permethrin. Results from the two bioassays were compared by regression of percent mortalities with LC₅₀ values. The regression was significant with an R² value of 0.90 which showed that the two methods of determining resistance were closely correlated. The regression equation had a slope of −0.74 and an intercept of 72.06, which showed that the LC₅₀ value decreased by 7.4 μg/vial for every 10% increase in mortality in the discriminating-dose bioassay. Percent mortality in the discriminating-dose bioassay and LC₅₀ values were related to control of plant bugs in the field using four spray chamber and one field cage test. Plant bug populations in these tests were not controlled with four different pyrethroids applied at recommended field rates. Results indicated that either a LC₅₀ value of 24 μg/vial or greater of permethrin, or 60% or less mortality in the discriminating-dose bioassay with permethrin, could be used to predict field control problems with plant bugs and pyrethroid insecticides in cotton, Gossypium hirsutum L. The discriminating-dose bioassay is a much easier bioassay to use as compared to determining LC₅₀ values using dose-mortality curves. It could be easily used by researchers, consultants, or Cooperative Extension personnel in an insecticide resistance monitoring program for tarnished plant bugs.

Understanding tritrophic effects of resistant crops on natural enemies feeding on pests is important for developing resistant plants while conserving natural enemies. The effect on convergent lady beetles, Hippodamia convergens Guerin-Meneville, fed greenbugs, Schizaphis graminum (Rondani), reared on resistant sorghum, Sorghum bicolor (L.) Moench, was assessed. Convergent lady beetles from sorghum fields were paired and allowed to mate. F₁ progeny were reared at a photoperiod of 14:10 light:dark hours at 23 or 30°C and fed daily with a known number of biotype I greenbugs from resistant PI550607 or susceptible RTx430 sorghum. Lady beetle eggs hatched 1 day later at 23°C (3.0 days) than at 30°C. Larvae completed development in 0.75 more day and pupae developed in 6.0 versus 3.0 days at 23 than at 30°C. Lady beetles consumed similar numbers of greenbugs from either genotype of sorghum, but larvae and adults consumed 1.7 and 2.5 times more greenbugs at 23 than at 30°C, respectively. Each lady beetle adult at 23°C consumed an average of 17,124 greenbugs. Adult lady beetles were paired in four combinations depending on the sorghum source of greenbugs from which they had been fed. Most eggs were produced (2,893 eggs) and hatched (2,657 or 91.0%) per lady beetle fed greenbugs from susceptible sorghum at 23°C.

Diurnal activity and territorial behavior of the tiger beetle, Pseudoxycheila tarsalis Bates (Carabidae: Cicindelinae), were studied in San Vito, Costa Rica, by marking the beetles, observing their behavior and distribution, and timing their activities. We tested hypotheses that: 1) beetles were randomly distributed in the study area, 2) male and female beetles moved equally throughout the study area in one day, and 3) males and females moved the same distance over successive days. Beetle activity increased with increasing temperature and decreased with cool, rainy, or cloudy conditions. The beetles preferred open areas with no vegetation. Males drove away other males that entered their “territory” where they rested and attempted to copulate with passing females. Both sexes of P. tarsalis showed some fidelity to an area, but males ranged only about half as far as females. Males may derive a reproductive advantage by restricting their range and waiting for receptive females, even those ovipositing. Individuals of both sexes returned to approximately the same general area after their daily foraging, ovipositing, and other activities. Individuals were normally (Poisson) distributed throughout the study area, with about eight beetles per 4 × 5-m plot at any one time.

Survival, emergence, and branch girdling by Oncideres pustulata LeConte on huisache, Acacia farnesiana (L.) Willd., and leucaena, Leucaena leucocephala (Lam.) de Wit, the preferred host plants, were compared in field studies in northeastern Mexico during 2003–2005. Most mortality of medium- to large-sized larvae was attributed to predation by birds, while small larvae were killed by cold temperatures (<4 °C) during the winter of 2004. Birds observed preying upon O. pustulata were the bronzed cowbird, Molothrus aeneus (Wagler), and red-winged blackbird, Agelaius phoeniceus L. Predation by birds was two to three times greater on leucaena than huisache, probably because of the softer wood of leucaena. Consequently, emergence of adults from huisache was 50–80% greater than from leucaena. The relationship between cumulative emergence rate and time was sigmoidal (r² = 0.99), with 50% emerging during early October, irrespective of host plant or year. The sex ratio of emerging adults throughout the study was skewed toward females (1.6:1) regardless of host plant or year. The relationship between cumulative rates of branch girdling and time was also sigmoidal (r² ≥ 0.98) with no significant difference between host plants. The number of branches girdled per tree ranged from 4.6 in 2003 to 0.1 in 2005 as a consequence of the impact of subfreezing temperatures during the previous winter. Although the number of branches girdled by O. pustulata was similar in both host plants, the average diameter of girdled twigs was significantly greater in leucaena (2.8 cm) than huisache (2.2 cm), probably because of the softer wood of leucaena. O. pustulata successfully utilized both huisache and leucaena as host plants. However, our results suggested that more O. pustulata survived and emerged on huisache. This probably is because of less predation by birds on larvae in huisache because of its harder wood, as compared to leucaena.

Thirty-nine species of mosquito (Diptera: Culicidae) have been reported from the Mexican State of Coahuila, however, no systematic survey by county has been done. Many mosquito species vector diseases that affect humans, including dengue fever vectored by Aedes albopictus (Skuse). Better knowledge of the distribution of mosquitoes will aid public health program planning. Mosquito adults and larvae were collected from 28 counties in Coahuila; 592 larval slide mounts were prepared from different aquatic habitats, and 1447 adults were pinned. Twenty-two species, two of which were not reported before, were identified by county. Mosquito abundance, diversity and habitat information also are provided.

The black fly Greniera michiganensis Taber is described from the western Lower Peninsula of Michigan. Larvae were found in a cold, shallow, narrow, ephemeral rill, on the lower surface of barely submerged leaves of black oak, Quercus velutina Lamarck, and on a few barely submerged leaves of quaking aspen, Populus tremuloides Michaux. The species is most similar to Greniera denaria (Davies, Peterson and Wood) but differs in larval, pupal, and adult morphology. According to the standard reference on North American Simuliidae, this is the first record of the genus from Michigan.