Search

Since insects are ectothermic, they are highly vulnerable to the sudden increase of temperature. Indeed, it has been hypothesized that the survival, development, fecundity, and even population expansion of insects are all affected significantly by extremely high temperature. We studied the effect of short-term high temperature stress on the survival and development of different stages, adult longevity and fecundity of Ophraella communa (Coleoptera: Chrysomelidae), a biological control agent of the invasive plant, the common ragweed, Ambrosia artemisiifolia (Asterales: Asteraceae) in the laboratory. The results showed that egg, larval, pupal and adult survival rates were significantly affected after 2 hour-short-stress at high temperatures (35 to 47°C) when compared to the 28°C control. With the exceptions of the control and 35°C stress, survival rate of females was significantly higher than that of males after short-stress at any high temperature. Short-term high temperature stress also significantly impacted longevity and fecundity of adult beetles. Except for control, female longevity was significantly longer than male's after short-stress at any high temperature. The survival rates of different stages, and adult longevity and fecundity of the beetle decreased significantly with the increase of short-term stress temperature. Based on the results of the present study, we conclude that the development and population expansion of O. communa may be significantly affected when they are exposed to a high temperature stage in a summer day in the areas invaded by common ragweed, in southern China. [ABSTRACT FROM AUTHOR]

Ambrosia artemisiifoliaL. is native to North America, and was unintentionally introduced into China in the 1930s, where it has become invasive. The two insect speciesEpiblema strenuanaandOphraella communahave been considered as biological control agents ofA. artemisiifoliain China. The purpose of this study was to examine the control effect ofO. communa+E. strenuanaonA. artemisiifoliain the field. The mortality ofA. artemisiifoliaplants increased with time and increasing initial release densities ofO. communaand/orE. strenuanain 2008 and 2009. The treatments of 0.53O. communa+ 0.53E. strenuanaper plant and 12O. communa+ 16E. strenuanaper plant at early (60–70 cm tall) and later (90–100 cm tall) growth stages could subsequently kill all plants prior to seed production in both 2008 and 2009. Thus, the two initial densities of the two insect species may be recommended when they are jointly used for biological control ofA. artemisiifoliaat the two growth stages. However, all or some plants could survive and bear seeds in any other treatment and in the non-treated control plots. This implies that biological control ofA. artemisiifoliawith the two biological control agents will be recommended in the areas invaded byA. artemisiifoliain China. [ABSTRACT FROM AUTHOR]