20-9-2024 MONTE CORONA, VALENCIA - LEAFHOPPER ASSASSIN BUG (Zelus renardii)

Zelus renardii, commonly known as the leaf hopper assassin bug, is a predacious insect contained within tribe Harpactorini.[3] Diurnal and found on both wild and crop plants, Z. renardii has spread from its native habitats in western North and Central America into three other biogeographic regions across the globe.

Zelus 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.

The native range of Z. renardii extends over various climatic zones throughout mainland North and Central America at altitudes between 8m to 2000m above sea level. Native ranges include tropical, dry, semi-arid, arid, and Mediterranean climates. Additionally, Z. renardii also appears well suited to urban and disturbed areas, as it has been observed in suburban areas on both native and non-native herbaceous and woody plants, as well as common garden plants. Egg masses can frequently be found on vegetable plants. Z. renardii is also sympatric with Z. tetracantus over a large part of its range in western USA, Mexico, Guatemala, Jamaica, and other parts of Central America.

The adaptability to multiple habitat conditions may have facilitated its spread in non-native regions as they have preadaptations to diverse climatic condition. To date, Z. renardii has expanded to Hawaii, where they preyed mainly on invasive sugarcane leafhopper (Perkinsiella saccharicida) and other tropical areas within the Pacific, such as Johnston Atoll, Samoa, and the Philippines. Z. renardii has also been reported in Mediterranean-type environments within Chile and Argentina.

Expansion of Z. renardii throughout Europe began in Mediterranean regions, namely Greece and Spain. However, expansion has continued and Z. renardii is now known in multiple countries in the Mediterranean basin, such as France, Italy, Turkey and Albania. The majority of these observations have been from urban areas. Eight years post-introduction in Spain, Z. renardii had a limited expansion in Mediterranean-type habitats, and was mainly limited to coastal regions of the Iberian east and south from the city of Valencia to Malaga. Additionally, Z. renardii has been observed as far southeast as the Kfar Masaryk region of northern Israel.

Given the abundance of Z. renardii in anthropogenic environments, humans are likely the main vectors of transport into non-native habitats. Since eggs, which are typically glued to plants, take 8–12 days to hatch and both the 1st and 2nd instars typically remain in the areas around their hatching site, shipping of nursery plants or plant products is thought to be a major avenue of distribution into non-native locations. Disturbed and agricultural areas are suitable for Z. renardii and may also contribute to its spread throughout native and non-native regions once established.

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.

Zelus 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.

Zelus renardii is a medium to large hemipteran with an average total length between 10.57 and 14.25 mm. It is generally greenish-yellow ventrally and yellow-brown dorsally, with the corium distinctly reddish with paler venation. It also has a long, robust body with a cylindrical head, small reddish eyes, and a thick curved rostrum. The front tibia are covered posteriorly by glandular setae which secrete a sticky substance. Distinguishing it from other Zelus species, the scutellum is long and bears no projections and the last ventral abdominal segment is slender with a hooked median process apically.

Females are similar to male except larger in total length 12.14-14.25 mm (versus 10.57 – 12.98 mm in males), and the hemelytron extend slightly beyond the tip of the abdomen.

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

During mating, pairs of Z. renardii can copulate between 1 and 3 times per day. The female may exhibit defensive behaviour at any stage, resulting in failure of the males mating attempt. Precopulatory behaviour begins with antennal movement by both sexes. When the male is ready to mate, he approaches the female from either the front or the back; likelihood of rejection depends on the approach and mounting position. If the male approaches and tries to mount from the front, the female is more likely to exhibit defensive behaviour like foreleg raising or striking. But if the male approaches from the front and female is receptive, there is a short precopulatory period where both sexes stridulate by rubbing their rostra against prosternal grooves. Alternatively, females are less likely to exhibit defensive behaviour when the male approaches from behind; and, if the female is receptive, only the female exhibits rostral stridulation.