Phillip E. Kaufman

Nicotinoid and pyrethroid insecticide resistance in houseflies (Diptera: Muscidae) collected from Florida dairies

BACKGROUND The housefly, Musca domestica L., continues to be a major pest of confined livestock operations. Houseflies have developed resistance to most chemical classes, and new chemistries for use in animal agriculture are increasingly slow to emerge. Five adult housefly strains from four Florida dairy farms were evaluated for resistance to four insecticides (beta-cyfluthrin, permethrin, imidacloprid and nithiazine). RESULTS Significant levels of tolerance were found in most field strains to all insecticides, and in some cases substantial resistance was apparent (as deduced from comparison with prior published results). At the LC(90) level, greater than 20-fold resistance was found in two of the fly strains for permethrin and one fly strain for imidacloprid. Beta-cyfluthrin LC(90) resistance ratios exceeded tenfold resistance in three fly strains. The relatively underutilized insecticide nithiazine had the lowest resistance ratios; however, fourfold LC(90) resistance was observed in one southern Florida fly strain. Farm insecticide use and its impact on resistance selection in Florida housefly populations are discussed. CONCLUSION Housefly resistance to pyrethroids is widespread in Florida. Imidacloprid resistance is emerging, and tolerance was observed to both imidacloprid and nithiazine. If these insecticides are to retain efficacy, producer use must be restrained.

Lutzomyia spp. (Diptera: Psychodidae) Response to Olfactory Attractant- and Light Emitting Diode-Modified Mosquito Magnet X (MM-X) Traps

ABSTRACT Mosquito Magnet-X traps were modified for use with blue, green, red, and blue-green-red light-emitting diodes and olfactory attractants to determine the response of Lutzomyia shannoni (Dyar) and Lutzomyia vexator (Coquillett) (Diptera: Psychodidae) field populations to these attractants. Red and blue-green-red-baited traps captured the highest numbers of Lu. shannoni and Lu. vexator, respectively, although, there were no significant differences between the colors. Baiting the traps with CO2 attracted significantly higher numbers of Lu. shannoni but showed no effect on Lu. vexator capture. In comparison with CO2 alone, Lu. shannoni preferred 1-octen-3-ol and 1-hexen-3-ol (0.05 g per trap) in combination with CO2.

Relationship between insecticide resistance and kdr mutations in the dengue vector Aedes aegypti in Southern China

BackgroundAedes aegypti is an important vector for dengue virus and thus has been targeted with pyrethroid insecticides in many areas of the world. As such, resistance has been detected to several of these insecticides, including in China, but the mechanisms of the resistance are not well understood in this country.MethodsUsing the World Health Organization larval mosquito bioassay, five field populations of Aedes aegypti from Southern China were characterized for their resistance to cypermethrin and cyhalothrin. RNA extraction with PCR amplification, cloning and sequencing of the sodium channel gene was followed by comparisons of susceptible and wild mosquito strains Additionally, genomic DNA was used for Allele-specific PCR (AS-PCR) genotyping of the sodium channel genes to detect S989P, V1016G and F1534C mutations and allow for correlation analysis of resistance expression for the different mutations.ResultsAll wild strains expressed resistance to cypermethrin and cyhalothrin and the resistance expression between the two insecticides was highly correlated suggesting cross-resistance between these two pyrethroids. The AS-PCR technique effectively distinguished individual genotypes for all three mutations. Among the five wild strains tested, two strains carried all three mutations. Although the S989P and V1016G mutations were positively correlated to resistance expression of both pyrethroids, the F1534C mutation was negatively correlated.ConclusionsOur methodology proved highly reliable and will aid future detection of kdr mutations. The three sodium channel mutations were common in the Ae. aegypti strains sampled from Southern China. The V1016G mutation appears to be the most important kdr mutation in Ae. aegypti strains in Southern China.

Assessing Permethrin Resistance in the Stable Fly (Diptera: Muscidae) in Florida by Using Laboratory Selections and Field Evaluations

ABSTRACT Insecticide resistance in the stable fly, Stomoxys calcitrans (L.) (Diptera: Muscidae), has been demonstrated previously, but mostly with insecticides that are no longer used, such as the organochlorines. Resistance to commonly used pyrethroids has been evaluated twice, but only in the midwestern United States. Stable fly susceptibility to a commonly used pyrethroid, permethrin, was determined in Florida to assess the possibility of resistance development. Diagnostic concentration evaluations of three stable fly field strains demonstrated a maximum of 57 and 21% survival to permethrin residues of 3× and 10× the LC99 of a susceptible strain, respectively. Stable flies from an equine facility with no reported insecticide use demonstrated ≈20% survival with a 3× diagnostic concentration. Despite a distance of 91-km between field collection sites, survival profiles of field-collected stable fly strains were similar. Although an established stable fly colony collected from a local dairy previously expressed low level resistance to permethrin residues, five generations of laboratory permethrin selection increased resistance 15-fold.

Resistance to cyfluthrin and tetrachlorvinphos in the lesser mealworm, Alphitobius diaperinus, collected from the eastern United States.

Abstract The lesser mealworm, Alphitobius diaperinus (Panzer), is an important pest in poultry facilities. The toxicity of cyfluthrin and tetrachlorvinphos to five strains of the lesser mealworm was compared with the toxicity to a susceptible laboratory strain. Bioassays were carried out with both larvae and adults. For the susceptible strain, cyfluthrin and tetrachlorvinphos had similar toxicity to adults, but cyfluthrin was 5 times more toxic to larvae when compared with tetrachlorvinphos. High levels of resistance to tetrachlorvinphos in two beetle strains were detected in both larvae and adults, although these strains were heterogeneous and still contained susceptible individuals. Resistance to cyfluthrin ranged from 1.7‐ to 9.5‐fold for adults and from 0.5‐ to 29‐fold for larvae at the LC95. Overall, the patterns of resistance did not mirror the insecticide use patterns reported at these facilities. The implications of these results to management of the lesser mealworms are discussed. Copyright

Detection of and Monitoring for Aedes albopictus (Diptera: Culicidae) in Suburban and Sylvatic Habitats in North Central Florida Using Four Sampling Techniques

ABSTRACT A sampling study using a BG-Sentinel trap baited with CO2, a gravid trap baited with an oak-pine infusion, a human subject, and a vegetative aspirator was conducted to compare their reliability at detecting Aedes albopictus Skuse in suburban and sylvatic habitats. We collected 73,849 mosquitoes, representing 29 species from 11 genera over a 20-wk period. The BG-Sentinel trap accounted for over 85% of all Ae. albopictus captured and was significantly more effective at detecting the presence of Ae. albopictus compared with the other three techniques. Landing counts provided the fewest mosquito species (n = 10), yet provided a quick and effective weekly assessment of the major biting species and were the most effective method for sampling Ae. albopictus within a 10-min period. Fewer Ae. albopictus were sampled from sylvatic habitats compared with suburban ones. Sampling criteria advantageous for surveying Ae. albopictus and other mosquito species are discussed.

Selection for Resistance to Imidacloprid in the House Fly (Diptera: Muscidae)

ABSTRACT The house fly, Musca domestica L. (Diptera: Muscidae), continues to be a primary pest of livestock facilities worldwide. This pest also has shown a propensity for pesticide resistance development when under high selection pressures. In this study the house fly strain FDm was created by a 20% contribution from each of five colonies collected from dairies in Florida with known imidacloprid resistance. The FDm strain was used to evaluate the level of imidacloprid resistance after five selections near the LC70 value of each selected generation. Overall, the mean selection mortality was 72.7, with males being considerably more susceptible than females. The unselected (F0) FDm strain showed considerable susceptibility to imidacloprid after its creation, compared with the five parental strains. Between 9,500 and 14,000 virgin house flies were used in each selection. After the fifth and final selection, a 331-fold increase in imidacloprid resistance at the LC70 was observed over the parental FDm strain. In parallel studies, the FDm strain showed increasing tolerance of the commercial imidacloprid product QuickBayt. These results suggest that livestock producers should use caution when choosing pesticides and consider rotating fly baits, as is encouraged with other pesticide treatment regimes on farms.

Impact of Exposure Length and Pupal Source on Muscidifurax raptorellus and Nasonia vitripennis (Hymenoptera: Pteromalidae) Parasitism in a New York Poultry Facility

Abstract Commercially obtained Nasonia vitripennis Walker and Muscidifurax raptorellus Kogan & Legner were released weekly for 12 wk into a high-rise, caged-layer poultry house. After the release period, parasitoids were sampled using sentinel house fly (Musca domestica L.) pupae that were either laboratory-reared or field-collected as larvae and exposed for 2, 4, 7, and 14 d. Parasitoid-induced mortality was observed in 31% of laboratory colony pupae and in 26% of field-collected pupae, whereas successful parasitism rates of 48 and 51% were observed from these pupal sources, respectively. Parasitism was primarily by M. raptorellus (88%), and Muscidifurax raptor Girault & Sanders (11%), while N. vitripennis accounted for <1%. Percent female progeny ranged from 43% in M. raptorellus to 76% in N. vitripennis. Parasitoid emergence from 2-d exposed sentinel pupae was the lowest of all treatments. Parasitoid emergence from 7-d exposed sentinel pupae was the highest of all treatments. We found no differences between pupal source, suggesting that when sampling for M. raptor, M. raptorellus, and N. vitripennis, in poultry facilities, pupal source is not a confounding factor.

Parasitism Rates of Muscidifurax raptorellus and Nasonia vitripennis (Hymenoptera: Pteromalidae) After Individual and Paired Releases in New York Poultry Facilities

Abstract Commercially reared parasitoids were released into three high-rise, caged-layer poultry houses; one house received only N. vitripennis Walker, the second house received only M. raptorellus Kogan & Legner, and the third house received an equal ratio of both species. Overall, house fly parasitism by M. raptorellus was never higher than 7% in any house. Most parasitism in the M. raptorellus release house was attributed to N. vitripennis. Parasitism of house fly pupae by M. raptorellus did not significantly increase during or after the 6-wk release period in the house that received both parasitoids. However, a depression in total parasitism was not detected when releases of the two species were made in this house.

The importance of agricultural tire habitats for mosquitoes of public health importance in New York State.

ABSTRACT The presence of mosquito species breeding in agricultural “bunker tires” on dairy farms in New York state was evaluated. Twelve species of mosquitoes (Aedes vexans, Anopheles barberi, An. punctipennis, An. perplexens, Culex pipiens pipiens, Cx. restuans, Cx. salinarius, Cx. territans, Toxorhynchites rutilus septentrionalis, Ochlerotatus atropalpus, Oc. japonicus japonicus, and Oc. triseriatus) were collected from 8 New York state dairy farms in 2001 and from 17 dairy farms in 2002. All but 2 of these species have been found naturally infected with arboviruses and could be important vectors affecting human and animal health. Because of the potential public and animal health importance of the invasive species Oc. j. japonicus, active surveillance to identify breeding sites and distribution of this mosquito is essential. In 2001, Oc. j. japonicus was recovered from 5 of 8 central New York dairy farms surveyed. In 2002, Oc. j. japonicus was recovered from 4 of the same dairy farms plus an additional dairy out of 5 surveyed. This species appears to be established on dairy farms in the south, central, and eastern regions of New York state, with greatest abundance in the southeastern region. A single Oc. j. japonicus larva was collected from the northern region on the final sampling date in September 2002. Our data demonstrate that agricultural tire habitats can be productive breeding sites for arbovirus vectors. As a consequence, these habitats should not be ignored in vector control and surveillance programs.