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The establishment of the multicolored Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), in North America has resulted in negative impacts on fruit production. We investigated the overwintering survival of H. axyridis after feeding on four diets: injured wine grape berries, 25% sucrose solution, water, and a control containing no food or water. After being exposed to these diets for 6 days, live individuals were transferred to clean plastic Petri dishes, and held at 5 ± 1 °C in growth chambers throughout the winter. Survival was recorded every month. Adult lady beetles collected during the overwintering flight in mid-October had higher survival rates than beetles collected from soybean fields in mid-August. These results suggest that an adaptation period prior to diapause increases the chances of lady beetle survival over the winter. In addition, injured wine grape berries, sugar, and water decreased beetle mortality during the overwintering months. Our results also showed that under similar conditions, females have higher survival during the winter than males. The importance of sugar and water on winter survival may drive H. axyridis adults to vineyards for feeding on wine grapes. Finally, we tested if adults of H. axyridis and the European paper wasp, Polistes dominulus Christ (Hymenoptera: Vespidae), were able to break the grape skin. Harmonia axyridis adults and paper wasps were not able to cause the primary injury to berries of Frontenac grapes under laboratory conditions. These results suggest that control of paper wasps in vineyards may not affect H. axyridis aggregations, and that H. axyridis feeding on wine grapes depends on previous injury to grape berries.

The multicolored Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is a generalist predator of aphids and other soft-bodied insects and has been utilized in biological control programs around the world. Over the last two decades, this species has spread throughout much of the continental USA and southern Canada. Despite the benefits it offers as a biological control agent, H. axyridis is perhaps most well known for its adverse impacts. In this paper we provide a review of the North American experience with H. axyridis, focusing on these adverse impacts, which can be classified into three general categories: impacts on non-target arthropods, impacts on fruit production and impacts as a household invader. The impacts of H. axyridis on non-target arthropods and, to lesser extent, the impacts as a household invader possibly could have been anticipated, due to its generalist feeding preferences and overwintering behavior in Asia. However, it is unlikely that the impacts on fruit production could have been anticipated. Therefore, even in retrospect, it is difficult to predict the potential impacts that an introduced natural enemy might have in its adventive range.

The use of selective insecticides may improve conservation of natural enemies and therefore contribute to the success of integrated pest management (IPM) programs. In this study, the toxicity of two commonly used selective insecticides, indoxacarb and spinosad, to the multicolored Asian lady beetle, Harmonia axyridis (Pallas), was evaluated. Third instars and adults of H. axyridis were exposed to indoxacarb at 50 and 100% of the field rate (FR), to spinosad at 100% FR and to water (untreated check) under laboratory conditions via three routes of exposure. Treatments were applied directly on insects (i.e., topical application), on Petri dishes (i.e., residues), or on soybean aphids, Aphis glycines Matsumara (i.e., treated prey). Mortality of exposed individuals in each life stage was recorded 2 and 7 days after treatment. Logistic regression indicated that indoxacarb at 100% FR, followed by indoxacarb at 50% FR, was more insecticidal than spinosad to third instars. Mortality was higher when H. axyridis were exposed to both insecticides via residues followed by treated prey. Indoxacarb at 100 or 50% FR was insecticidal to adults. Adults were tolerant to spinosad via all routes of exposure. The present results suggest that indoxacarb may decrease H. axyridis field populations by causing mortality to larvae and adults via all routes of exposure. Implications of the toxicity of indoxacarb to H. axyridis within an IPM context and possible reasons for the differences in susceptibility of H. axyridis for each route of exposure are discussed.

Use of selective insecticides, such as spinosad and indoxacarb, that are more toxic to lepidopteran pests than to Harmonia axyridis (Pallas), could facilitate conservation of this predator in sweet corn integrated pest management (IPM). We examined the effects of spinosad and indoxacarb on survival, development, and reproduction of H. axyridis by spraying first instars and adult females. Treatments for the first instar assay were spinosad at 10, 25, and 50% of the field rate (FR), indoxacarb at 10% FR, and water (untreated check). We recorded survival of each life stage, developmental time to adults, and adult weight. Treatments for the adult female assay were spinosad at 50 and 100% FR, indoxacarb at 50% FR, and water (control). Each day, we recorded female survival and reproductive capacity. Indoxacarb decreased survival of first instars and adults, extended the developmental time for first instars to become adults, and reduced the fecundity of H. axyridis females. Spinosad decreased survival of first instars, extended the time for first instars to become adults, decreased weight gain, and reduced the fertility of H. axyridis females. Our results suggest that spinosad and indoxacarb may reduce H. axyridis population growth by affecting its survival, development, and reproduction. We also conclude that indoxacarb, when applied at 10% FR, has more lethal and sublethal effects on H. axyridis than spinosad applied at 10, 25 or 50% FR. The importance of sublethal effects of insecticides, as well as acute toxicity, in toxicological studies with natural enemies is discussed within the context of biological control and IPM.

Late-season plantings of sweet corn in Minnesota result in an abundant supply of silking corn, Zea mays L., throughout August to early September that is highly attractive to the corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae). During a 10-yr period, 1997-2006, insecticide efficacy trials were conducted in late-planted sweet corn in Minnesota for management of H. zea. These data were used to develop a logistic regression model to identify the variables and interactions that most influenced efficacy (proportion control) of late-instar H. zea. The pyrethroid lambdacyhalothrin (0.028 kg [AI]/ha) is a commonly used insecticide in sweet corn and was therefore chosen for use in parameter evaluation. Three variables were found to be significant (alpha = 0.05), the percentage of plants silking at the time of the first insecticide application, the interval between the first and second insecticide applications, and the interval between the last insecticide application and harvest. Odds ratio estimates indicated that as the percentage of plants silking at the time of first application increased, control of H. zea increased. As the interval between the first and second insecticide application increased, control of H. zea decreased. Finally, as the interval between the last insecticide application and harvest increased, control of H. zea increased. An additional timing trial was conducted in 2007 by using lambda-cyhalothrin, to evaluate the impact of the percentage of plants silking at the first application. The results indicated no significant differences in efficacy against late-instar H. zea at 0, 50, 90, and 100% of plants silking at the first application (regimes of five or more sprays). The implications of these effects are discussed within the context of current integrated pest management programs for late-planted sweet corn in the upper midwestern United States.

Use of insecticides with low toxicity to natural enemies is an important component of conservation biological control. In this study, we evaluated the toxicity of insecticides used in sweet corn, Zea mays L., and soybean, Glycine max (L.) Merr., to the multicolored Asian lady beetle, Harmonia axyridis (Pallas), under laboratory and field conditions. Field experiments conducted in sweet corn in 2003 and 2004 and in soybean in 2003, showed that H. axyridis was the most abundant predator. In sweet corn, densities of H. axyridis larvae in plots treated with spinosad or indoxacarb were generally higher than in plots treated with chlorpyrifos, carbaryl, bifenthrin, and A-cyhalothrin. In soybean, densities of H. axyridis larvae in plots treated with chlorpyrifos were higher than in plots treated with lambda-cyhalothrin. Laboratory experiments were conducted to evaluate the acute toxicity of insecticides to eggs, first and third instars, pupae, and adults. Spinosad, followed by indoxacarb, were the least toxic insecticides for all life stages of H. axyridis. Conventional insecticides showed high toxicity to H. axyridis when applied at field rates under laboratory conditions. Overall, first instars were most susceptible to the insecticides tested, followed by third instars and adults, eggs, and pupae. Our results suggest that spinosad, and to a lesser extent indoxacarb, offer reduced toxicity to H. axyridis and would be beneficial for conservation biological control in agricultural systems where H. axyridis is abundant.