Acute lethal and behavioral sublethal responses of two stored-product psocids to surface insecticides.
BACKGROUND
The psocids Liposcelis bostrychophila Badonnel and L. entomophila (Enderlein) (Liposcelididae) are emerging pests of stored products. Although their behavior, particularly their high mobility, may contribute to the reported relatively low efficacy of insecticides against them, studies to investigate this have not been conducted. The present study aimed to assess the label rate efficacy of three commercial insecticides (beta-cyfluthrin, chlorfenapyr and pyrethrins) applied on concrete surfaces against L. bostrychophila and L. entomophila, and also their sublethal effect on the mobility of these species.


RESULTS
The synthetic insecticides beta-cyfluthrin and chlorfenapyr showed high short-term efficacy (LT(95)<or=15 h) against both psocid species, unlike the natural pyrethrins (LT(95) >or= 4 days). Liposcelis bostrychophila was slightly more tolerant (>or=1.2x) than L. entomophila to all three insecticides. Behavioral assays with fully sprayed and half-sprayed concrete arenas indicated that the insecticides reduced the mobility of both species. Pyrethrins seem to elicit weak repellence in L. bostrychophila.


CONCLUSIONS
beta-Cyfluthrin and chlorfenapyr were effective against both psocid species, but not pyrethrins. The mobility of both species does not seem to play a major role in the differential selectivity observed, but the lower mobility of L. bostrychophila may be a contributing factor to its higher insecticide tolerance.
Guedes
Raul Narciso C
RN
USDA-ARS, Grain Marketing and Production Research Center, Manhattan, KS 66502, USA. guedes@ufv.br
Campbell
James F
JF
Arthur
Frank H
FH
Opit
George P
GP
Zhu
Kun Yan
KY
Throne
James E
JE
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D007313:Insecta / Q000187:drug effects*; D007306:Insecticides / Q000494:pharmacology*; D008124:Locomotion / Q000187:drug effects*; D009570:Nitriles / Q000494:pharmacology; D011722:Pyrethrins / Q000494:pharmacology; D013997:Time Factors
D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C436643:chlorfenapyr; C052570:cyfluthrin