The Effect on the Mexican Bean Beetle

Life Tables and Larval Dispersal of Mexican Bean Beetle (Coleoptera: Coccinellidae) on Dry Bean in the High Plains

“…This also increased the potential for a higher temperature and lower humidity, factors responsible for egg mortality. Howard (1931) suggested that low relative humidity reduced egg survival in the Þeld. A high reduction in egg survival when average daily maximum temperatures exceeded 38ЊC in the Þeld was observed by Sprenkel and Rabb (1981).…”

“…Across all temperatures, the optimum humidity was 73%. Howard (1931) suggested that ßuctuations in canopy microclimatological factors above or below (Tables 1Ð 6). In comparing the tables, it can be seen that there was a great difference in mortality between the two years.…”

“…Adult beetles emerge late in the spring after prolonged warm temperatures. Precipitation has a direct inßuence on beetle emergence, and the percentage emerging is directly inßuenced by the temperature during the period of rainfall (Douglass 1928), whereas dry weather delays emergence from hibernation sites (Howard 1931). Winters with high snowfall contribute to increased overwintering adult survival (Douglass 1933).…”

“…Although the biology and ecology of the Mexican bean beetle and the factors affecting its population dynamics have not been studied in the western high plains, there are many studies of beetle biology from other regions of the United States on soybean. Abiotic factors, such as drought, have long been recognized as important factors affecting Mexican bean beetle population dynamics and pest status (Marcovitch and Stanley 1930, Miller 1930, Howard 1931 and play an important role in geographic distribution (Sweetman 1932). Recent studies have established the sensitivity of Mexican bean beetle eggs and larvae to humidity and temperature (Kitayama et al 1979).…”

“…The list of natural enemies of the Mexican bean beetle is considerable, but early workers found little inßuence on Mexican bean beetle population dynamics (Howard andEnglish 1924, Howard andLandis 1936). Despite some positive results using the parasite Pediobius foveolatus (Crawford) (Angalet al 1968), the parasites could not survive the winter in the Þeld, and maintenance in laboratory was required during the winter (Stevens et al 1975).…”