Megalurothrips usitatus,a tiny and discreet pest,is a major threat to cowpea(Vigna unguiculata).It is the primary target of excessive chemical pesticide use among local cowpea growers.To accurately select safe,effective,and promising biocontrol agents,we investigated the population dynamics of M.usitatus in cowpea fields in Yazhou District,Sanya City.15 billion spores·g-1 of Beauveria bassiana WP,32 000 IU·mg-1 of Bacillus thuringiensis WP,8 000 IU·µL-1 of Bacillus thuringiensis SC,15 billion spores·mg-1 of Metarhizium anisopliae CQma421 OD,5 billion spores·mg-1 of Cordyceps javanica JS001 OD and 0.3％of martrine AS were used in field trials of cowpea.Results showed that the population density of M.usitatus during the flowering stage of cowpea was time-dependent,with the highest count at 18:00,reaching 22.40 thrips per flower.Comparing the effiicacy of different application times,the most effective treatment at 8:00 was 0.3％martrine AS,achieving a corrected efficacy of 59.63％after 7 days.At 13:00,all treatments showed no significant efficacy.At 18:00,C.javanica JS001 OD exhibited the highest efficacy,reaching 62.37％after 7 days,whereas martrine AS peaked on day 3 and subsequently declined.Application of the aforementioned biopesticides significantly reduced the occurrence of'black head and tail'in cowpea.In conclusion,strategic application of martrine AS,C.javanica JS001 OD,and M.anisopliae CQma421 OD enhances control efficacy against M.usitatus.These findings provide a basis for reducing pesticide use in cowpea cultivation.
Megalurothrips usitatusoccurrence dynamicsfield control efficiencybiological insecticides
维普
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