Do defensive chemicals facilitate intraguild predation and influence invasion success in ladybird beetles?

Egg predation and cannibalism are believed to be common phenomena among many species of aphidophagous predatory ladybird beetles despite the presence of alkaloid based defensive chemicals in all life stages. We identified defensive chemicals from eggs of three congeneric species, one introduced into North America (Coccinella septempunctata L.), and two native (C.

A population genetic signature of human releases in an invasive ladybeetle.

Biological invasions have been accelerated by a variety of human activities. Propagule pressure, the number of introduced individuals and independent introductions, is probably to be influenced by these human activities and may be an important factor for successful range expansion in new environments. We tested whether the current distribution of the predatory ladybeetle Coccinella septempunctata in the introduced range (USA) is the result of multiple historical human introductions or natural range expansion from the first established populations in the USA.

Intraspecific alkaloid variation in ladybird eggs and its effects on con- and hetero-specific intraguild predators.

Egg predation and cannibalism are common phenomena in predatory ladybirds despite the presence of defensive alkaloids. Consumption of heterospecific eggs negatively affects survivorship and development; however, intraspecific variation in quantities of alkaloids and post-ingestion responses to con- and hetero-specific alkaloids, are not well understood. We examined variation in the quantity of alkaloids in eggs of Harmonia axyridis (Pallas), Coccinella septempunctata L.

Asymmetric larval interactions between introduced and indigenous ladybirds in North America.

Understanding the mechanisms that result in the success of introduced species will contribute to predicting future invasions and managing invaded systems. We examined interactions between larvae of two predatory ladybird species recently introduced to North America, Coccinella septempunctata (CS) and Harmonia axyridis (HA), and two indigenous ladybirds, Coccinella transversoguttata (CT) and Hippodamia convergens (HC). By pairing young and old larvae in the laboratory at low and high levels of aphid availability, we assessed the degree of asymmetry in intraguild predation (IGP), the strength of competitive effects on growth and development of larvae escaping predation, and the nature of attack and escape behavior among the species.

Effect of conspecific and heterospecific feces on foraging and oviposition of two predatory ladybirds: role of fecal cues in predator avoidance.

Growing evidence suggests a flow of chemical information from higher to lower trophic levels that affects foraging and oviposition of 'prey' in response to potential risks from predators. This was investigated in two species of ladybird predators of aphid, Harmonia axyridis and Propylea japonica. H.