Leafhopper Assassin Bug

Naming

"Z. renardii" is considered a sister species to "Z. cervicalis", as they share two unique characters: the lateral margins of dorsal phallothecal sclerite are recurved and the medial process is strongly hooked apically.

Behavior

Adult and nymph "Z. renardii" are zoophagous generalist predators which feed on a wide range of prey, from herbivorous insects that feed on wild and crop plants to other insect predators, like lacewings. Nymphs mainly feed on herbivorous insects between 0.5 and 4mm in length, such as aphids, weevils, and thrips. Whereas adults feed on larger prey items between 1.5 and 19 mm in length from various orders, including Hemiptera, Lepidoptera, Coleoptera, Hymenoptera, Neuroptera, Blattodea, and Orthoptera. Since "Z. renardii" feeds on such a wide variety of prey, its diet may shift under different ecological conditions or between habitats which have different prey composition and abundance. Although "Z. renardii" is a predaceous insect, the 1st and 2nd instars may utilize some plant material, such as pollen or nectar from extrafloral nectaries on the bottom of leaves or fruiting structures, as a supplement to their regular zoophagous diet or to sustain them for short periods when more suitable prey is not available.

"Z. renardii" is also an important intraguild predator of lacewings and other insect predators. "Z. renardii" shows changes in prey preferences across developmental stages which influences the relevance of intraguild predation. The intensity of intraguild predation on other predators increases with the age of "Z. renardii", as adults fed on larger prey and on a greater proportion of predatory species than 2nd instars.Prey capture in the wild usually occurs on vegetation, and "Z. renardii" will remain relatively exposed during feeding. Therefore, a shorter predation and feeding time is hypothesized to be an ecological advantage that reduces predation risk. Prey detection is thought to be primarily based on movement, as moving prey are captured at a higher frequency, whereas more sessile prey, like cotton aphids, are subjected to less predation, even if they are present in high abundance. Smaller, more mobile prey are ambushed while less mobile prey are stalked. Generally, predatory behaviour of "Z. renardii" proceeds as follows: antennal movement in direction of prey, aiding in detection. Once "Z. renardii" detects prey, it slowly moves towards the prey with forelegs lifted and antennae projected forwards. A sticky substance, secreted by glands on the tibia, increase the success of prey capture and prevent its escape. The stylet is then inserted and pre-oral digestive agents are excreted into the prey, paralyzing and liquifying them.

The entire feeding period on medium to large prey items takes between 60 and 80 minutes. After feeding, intense rostral and antennal grooming occurs.

Habitat

There appears to be no pattern of host-plant preference in "Z. renardii" as it can be caught while beating and sweeping both flowering and non-flowering vegetation. "Z. renardii" is also common in agricultural and even urban and suburban environments.

"Z. renardii" also exhibits different vertical distributions depending on age. Nymphs occupied and foraged on lower parts of plants, whereas adults spent most of their time in the upper parts of plants, which may be a mechanism to avoid either competition between individuals or cannibalism. These differences in microhabitats may affect prey encounter rates.

Reproduction

"Z. renardii" eggs are small, kidney-shaped, and light brown in colour. They are generally laid in masses and glued to the surfaces of vegetation.

Food

Adult and nymph "Z. renardii" are zoophagous generalist predators which feed on a wide range of prey, from herbivorous insects that feed on wild and crop plants to other insect predators, like lacewings. Nymphs mainly feed on herbivorous insects between 0.5 and 4mm in length, such as aphids, weevils, and thrips. Whereas adults feed on larger prey items between 1.5 and 19 mm in length from various orders, including Hemiptera, Lepidoptera, Coleoptera, Hymenoptera, Neuroptera, Blattodea, and Orthoptera. Since "Z. renardii" feeds on such a wide variety of prey, its diet may shift under different ecological conditions or between habitats which have different prey composition and abundance. Although "Z. renardii" is a predaceous insect, the 1st and 2nd instars may utilize some plant material, such as pollen or nectar from extrafloral nectaries on the bottom of leaves or fruiting structures, as a supplement to their regular zoophagous diet or to sustain them for short periods when more suitable prey is not available.

"Z. renardii" is also an important intraguild predator of lacewings and other insect predators. "Z. renardii" shows changes in prey preferences across developmental stages which influences the relevance of intraguild predation. The intensity of intraguild predation on other predators increases with the age of "Z. renardii", as adults fed on larger prey and on a greater proportion of predatory species than 2nd instars.

Cultural

As "Z. renardii" feeds on many herbivorous pest species of cotton, maize, soybean, alfalfa, and fruit tree crops, it can be considered a biological control agent. However, even though prey items of "Z. renardii" are often considered pests in an agricultural context, some beneficial species that are also used as biological control in agricultural systems are preyed upon. Due to its generalist diet, "Z. renardii" can function as an important intraguild predator on arthropods, such as the lacewing "Chrysoperla carnea", which is commonly used to control cotton aphids. As it consumes herbivorous pests and other predators of that pest, it can disrupt the trophic cascades that the biological control agent is being used to impose in anthropogenic systems, and can indirectly cause the abundance of the pest to rise. This affect may be prevented if "Z. renardii's" preference for the other predator is low relative to its preference for the shared prey.