Reproductive diapause in Hippodamia convergens (Coleoptera: Coccinellidae) and its life history consequences

Repellency of conspecific and heterospecific larval residues to Hippodamia convergens (Coleoptera: Coccinellidae) ovipositing on sorghum plants

“…The insects were transferred to clean dishes on the days that pollen was provided, and sunflower petioles were replaced every third day when the insects were fed. On this feeding cycle, individual females become reproductive one by one over an extended period (Michaud & Qureshi, 2006). The first 25 H. convergens females to become reproductive were labeled with a number on the dish, and then fed Ephestia eggs daily to sustain oviposition for production of larvae to be used in experiments.…”

Non-target effects of chlorantraniliprole and thiamethoxam on Chrysoperla carnea when employed as sunflower seed treatments

“…The effects on reproductive parameters observed in the present work suggest that populations of C. carnea might be reduced in sunflower fields when seed is treated with chlorantraniliprole or thiamethoxam. This is a significant agroecological finding because sunflower extrafloral nectar is an important source of hydration and nutrition for a wide range of beneficial insects during the hot, dry summers on the Great Plains when little free moisture is available (Michaud and Qureshi 2006). For example, the presence of sunflowers has been shown to improve the area-wide survival of natural enemy species important in the biological control of key pests in neighboring crops such as wheat, i.e.…”

Larval Food Supply Constrains Female Reproductive Schedules inHippodamia convergens(Coleoptera: Coccinellidae)

“…However, there are additional advantages when progeny must complete development on a time-limited resource. The time frame for oviposition in an aphid outbreak is short (Kindlmann and Dixon 1993) and selects for triangular fecundity functions that skew a larger proportion of RE earlier in adult life (Dixon andAgarwala 2002, Michaud andQureshi 2006). The large females in our study appeared better able to achieve this pattern of Ôfront-loadedÕ RE than medium females, whereas small females were physiologically constrained and unable to do so, supporting our second hypothesis that larval food restriction would negatively impact reproductive schedules.…”

“…Thus, females exploiting an aphid outbreak face a predictable trajectory of change in habitat quality for their offspring; over a time frame as short as 2 or 3 wk; initially abundant prey become increasingly scarce and competition and intraguild predation intensify. Consequently, aphidophagous coccinellids typically exhibit a triangular fecundity function (Dixon andAgarwala 2002, Michaud andQureshi 2006) and lay as many eggs as possible early in adult life. The current study used the convergent lady beetle, Hippodamia convergens GuerinÐMeneville, to explore whether this trajectory of reproductive effort (RE) is constrained by female body size, and whether any changes in egg size are associated with changes in clutch size.…”

“…convergens is a widely distributed Nearctic coccinellid that occurs in wide-ranging habitats from temperate to fully tropical regions. High Plains populations of H. convergens in the United States typically have two generations per year with intervening periods of aestivation in summer and hibernation in winter, unless cool summer weather permits additional aphid outbreaks (Michaud and Qureshi 2006). The Þrst generation matures in spring, feeding on cereal aphids that bloom on ßushing cool-season grasses and cereals such as winter wheat, and the second in fall when lower temperatures permit another bloom of aphids on maturing warm-season grasses and senescing broad leaf plants.…”