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Six insecticide active ingredients (AIs) and five commercial insecticide formulations were applied by topical application and onto filter paper strips to determine differential toxicity to Aedes aegypti (L.) and Apis mellifera (L.), and to evaluate their potential use in future insecticide resistance monitoring surveys. For topical application, 0.1 or 1 µl of the technical insecticide solution was applied to the Ae. aegypti and A. mellifera thorax, respectively. For insecticide-impregnated strips the insecticide amount varied, according with the commercial formulation. By topical application deltamethrin was the most toxic AI (LD 50 = 0.057 µg/g) to Ae. aegypti and prallethrin was least toxic (LD 50 = 19.42 µg/g). For A. mellifera, the most toxic AIs were deltamethrin (LD 50 = 0.013 µg/g) and bifenthrin (LD50 = 0.156 µg/g); and the least toxic was chlorpyrifos (LD 50 = 3.246 µg/g). When the insecticide-impregnated papers method was used, Mosquitomist Two (chlorpyrifos 24.6%) was the most toxic insecticide for Ae. aegypti (LC50 = 0.024 µg/cm2 ), and Aqualuer (permethrin 20.6%, PBO 20.6%) was least toxic (LC50 = 0.408 µg/cm2 ). For A. mellifera the most toxic commercial insecticide formulations were Talstar (bifenthrin 7.9%; LC50 = 0.288 µg/cm2 ) and Mosquitomist Two (LC50 = 0.299 µg/cm2 ), with no significant differences, and the least toxic commercial formulation was Deltagard (deltamethrin 2.0%; LC50 = 15.084 µg/cm2 ). By topical application, more than 28 times of chlorpyrifos was needed to obtain the same mortality in A. mellifera as in Ae. aegypti. When using the insecticide-impregnated paper method, more than 206 times of Deltagard was needed to obtain the same mortality in A. mellifera as in Ae. aegypti. Even though Mosquitomist Two was the most toxic insecticide for both insect species, the honey bees were >12 times more tolerant to this insecticide, compared with the mosquitoes.

Aedes albopictus and Apis mellifera were exposed to six insecticide active ingredients and five commercial insecticide formulations by topical application and insecticide-impregnated paper strips respectively to determine the differential toxicity and the potential use of the two methods in insecticide resistance monitoring surveys. By topical application deltamethrin was the most toxic active ingredient (LD 50 = 0.018 µg/g) for Ae. albopictus whereas chlorpyrifos was the least toxic (LD 50 = 0.499 µg/g). For Apis mellifera, the most toxic active ingredients were bifenthrin (LD 50 = 0.047 µg/g) and deltamethrin (LD 50 = 0.055 µg/g) while chlorpyrifos (LD 50 = 0.215 µg/g) and permethrin (LD 50 = 0.287 µg/g) had comparatively low toxicity. When the insecticide-impregnated method was used, Mosquito Mist (a.i. chlorpyrifos) was the most toxic commercial formulation for both Ae. albopictus (LC50 = 0.028 µg/cm2 ) and A. mellifera (LC50 = 0.059 µg/ cm2 ). Duet and DeltaGard showed the least toxicity (LC50 = 2.429 µg/cm 2 and LC50 = 0.491 µg/cm 2 respectively) for Ae. albopictus and DeltaGard was the least toxic to A. mellifera (LC50 = 18.09 µg/cm2 ). When using the topical application method with insecticide active ingredients, more than 3 times permethrin and deltamethrin were required to obtain the same mortality rate in A. mellifera as in Ae. albopictus. However, chlorpyrifos was more toxic for A. mellifera than for Ae. albopictus. In the insecticide-impregnated paper-strip method with commercial insecticide formulations, more than 36 times of DeltaGard was required to obtain the same mortality rate in A. mellifera as in Ae. albopictus. Even though the Mosquito Mist is the most toxic commercial formulation for both insect species, A. mellifera were more than 2 times tolerant to this insecticide compared to Ae. albopictus. The study concludes the active ingredient deltamethrin or its commercial formulation DeltaGard is the best among tested insecticides to control Ae. albopictus with minimal effects to A. mellifera.

Application of permethrin products by ultra-low volume (ULV) spraying against the container-inhabiting mosquito Aedes albopictus (Skuse) has been used for many years, but the impact of the insecticides on domesticated honey bees, Apis mellifera (Linnaeus) is still lacking. The present study was carried out to evaluate the impact of the permethrin product, Aqualuer® 20-20 (active ingredient: 20.6% permethrin+20.6% Piperonyl butoxide) ULV sprays on caged Ae. albopictus and A. mellifera in open semi-field conditions with cages spaced at 3 m, 22.8 m, and 45.7 m downwind of the spray-truck path. The results indicated that ULV spray of Aqualuer 20-20 is highly effective against Ae. albopictus achieving 94% mortality at 22.8 m and 82% mortality up to 45.7 m downwind distance. The highest mortality of A. mellifera was only 72% at 3 m downwind distance, but the spray killed 42% of the exposed bees up to 45.7 m down the spray path. This semi-field study conducted during the day time indicates the high effectiveness of the ULV spray of permethrin against Ae. albopictus and its comparatively low impact on the direct exposed non-target honey bee, A. mellifera. Further studies designed to be conducted in the natural environment during its real-time operations following label instructions of the insecticide will help establish spraying guidelines to minimize any unfavorable impact on domesticated A. mellifera while having expected mortality effects on Ae. albopictus.

The presence of thrips in vegetable crops has become an important phytosanitary issue in Mexico. Their direct injuries to plants are the result of the feeding by their immature and adult stages, whereas their indirect injuries are caused by the transmission of various viruses. The objective of this study was to identify the species of thrips associated with 6 vegetable crops in order to determine their population fluctuations and to ascertain the effects of temperature and rainfall on their populations. Samples were collected from zucchini, onion, pepper, cucumber, tomato, and tomatillo in Puebla and Morelos from Feb 2010 to Feb 2011. Three species were identified: Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) on all vegetables, Frankliniella fortissima (Priesner) on zucchini and cucumber, and Thrips tabaci (Lindeman) (Thysanoptera: Thripidae) on onion and pepper. The highest population level for thrips coincided with the presence of flowers on the crops, except in the case of o...

Solenopsis invicta virus 1 (SINV-1) was found regularly and prevalently in S. invicta. In sampled locations where S. invicta and S. geminata are sympatric (specifically, Gainesville, FL and Travis, TX), SINV-1 was detected in S. geminata. Conversely, in areas in which S. geminata and S. invicta are allopatric, SINV-1 was not detected in S. geminata; these locations included north Australia (n=12), southern Mexico (n=107), Hawaii (n=48), Taiwan (n=12), and the Johnston Atoll (n=6). A similar relationship was observed for S. richteri. In areas in which S. invicta and S. richteri were sympatric, SINV-1 was detected in the S. richteri population, but in areas in which S. invicta and S. richteri were allopatric, SINV-1 was not detected. These occurrences suggest that S. invicta is the host of predilection, or preferred host for SINV-1, and that the congenerics, S. geminata and S. richteri serve as either accidental, reservoir, or transfer hosts. The minus genome strand of SINV-1 was detected in S. geminata and S. richteri indicating that these species may serve as functional hosts capable of supporting SINV-1 replication. SINV-1 was not detected in S. xyloni regardless of its proximity to S. invicta. These results suggest that SINV-1 may be an example of pathogen spillover or pollution.

Kneallhazia solenopsae is a pathogenic microsporidium that infects the fire ants Solenopsis invicta and Solenopsis richteri in South America and the USA. In this study, we analyzed the prevalence and molecular diversity of K. solenopsae in fire ants from North and South America. We report the first empirical evidence of K. solenopsae infections in the tropical fire ant, Solenopsis geminata, and S. geminata × Solenopsis xyloni hybrids, revealing an expanded host range for this microsporidium. We also analyzed the molecular diversity at the 16S ribosomal RNA gene in K. solenopsae from the ant hosts S. invicta, S. richteri, S. geminata and S. geminata × S. xyloni hybrids from North America, Argentina and Brazil. We found 22 16S haplotypes. One of these haplotypes (WD_1) appears to be widely distributed, and is found in S. invicta from the USA and S. geminata from southern Mexico. Phylogenetic analyses of 16S sequences revealed that K. solenopsae haplotypes fall into one of two major clades that are differentiated by 2–3%. In some cases, multiple K. solenopsae haplotypes per colony were found, suggesting either an incomplete homogenization among gene copies within the 16S gene cluster or multiple K. solenopsae variants simultaneously infecting host colonies.

Studies were conducted to examine the phenology, geographic distribution, and host specificity of the Solenopsis invicta virus-1 (SINV-1). Two genotypes examined, SINV-1 and -1A, exhibited similar seasonal prevalence patterns. Infection rates among colonies of S. invicta in Gainesville, Florida, were lowest from early winter (December) to early spring (April) increasing rapidly in late spring (May) and remaining high through August before declining again in the fall (September/October). Correlation analysis revealed a significant relationship between mean monthly temperature and SINV-1 (p0.0005, r=0.82) and SINV-1A (p0.0001, r=0.86) infection rates in S. invicta colonies. SINV-1 was widely distributed among S. invicta populations. The virus was detected in S. invicta from Argentina and from all U.S. states examined, with the exception of New Mexico. SINV-1 and -1A were also detected in other Solenopsis species. SINV-1 was detected in Solenopsis richteri and the S. invicta/richteri hybrid collected from northern Alabama and Solenopsis geminata from Florida. SINV-1A was detected in S. geminata and Solenopsis carolinensis in Florida and the S. invicta/richteri hybrid in Alabama. Of the 1989 arthropods collected from 6 pitfall trap experiments from Gainesville and Williston, Florida, none except S. invicta tested positive for SINV-1 or SINV-1A. SINV-1 did not appear to infect or replicate within Sf9 or Dm-2 cells in vitro. The number of SINV-1 genome copies did not significantly increase over the course of the experiment, nor were any cytopathic effects observed. Phylogenetic analyses of SINV-1/-1A nucleotide sequences indicated significant divergence between viruses collected from Argentina and the U.S.

Effects of the synergists piperonyl butoxide (PBO) and S,S,S-tributyl phosphorotrithioate (DEF) on propoxur pharmacokinetics were examined in the German cockroach, Blattella germanica (L.). Treatment of adult male German cockroaches with the cytochrome P450 monooxygenase inhibitor, PBO, or the esterase inhibitor, DEF, increased propoxur toxicity by 2- and 6.8-fold, respectively, implicating hydrolysis as a major detoxification route of propoxur in the German cockroach. However, significant hydrolytic metabolism could not be demonstrated conclusively in vitro resulting in a conflict between in situ bioassay data and in vitro metabolic studies. In vitro propoxur metabolism with NADPH-fortified microsomes produced at least nine metabolites. Formation of metabolites was NADPH-dependent; no quantifiable metabolism was detected with cytosolic fractions. However, microsomal fractions lacking an NADPH source did produce a low, but detectable, quantity of metabolites (1.6 pmol). PBO inhibited NADPH-dependent propoxur metabolism in a dose-dependent fashion, implicating cytochrome P450 monooxygenases as the enzyme system responsible for the metabolism. Interestingly, DEF also inhibited the NADPH-dependent metabolism of propoxur, albeit to a lower extent. Treatment with PBO or DEF also caused a significant reduction in the cuticular penetration rate of propoxur. The data demonstrate that unanticipated effects are possible with synergists and that caution must be exercised when interpreting synergist results.

Pre- and post-treatment temperature effects on -cyhalothrin toxicity were determined in insecticide-susceptible and resistant German cockroach, Blattella germanica (L.), strains. Acclimation at 19, 26, or 31C for 10 days before insecticide treatment had no effect on l- cyhalothrin toxicity in either strain. No differences were observed in aldrin epoxidase and glutathione S-transferase activities when “Orlando” (susceptible) cockroaches were incubated for 10 days at 19, 26, and 31C. When temperature treatment followed insecticide application, a negative temperature coefficient of toxicity (greater toxicity at lower temperature) toward l- cyhalothrin was observed for the Orlando but not the kdr-type resistant “Village Green” cockroaches. Piperonyl butoxide synergized l- cyhalothrin in “Orlando” cockroaches 3 and 5-fold at 26 and 31C, respectively. Conversely, piperonyl butoxide pre-treatment did not cause a significant reduction in the LD 50 value in the “Village Green” strain regardless of temperature.