Salinity and shade preferences result in ovipositional differences between sympatric tiger beetle species

Abstract

Summary 1. Adult tiger beetles of the genus Cicindela often co‐occur within a habitat but larvae do not. Larvae are sedentary and form usually permanent burrows at the site of oviposition where they require 1–3 years for development. 2. To test niche partitioning based on ovipositional preference, the behaviour of two sympatric salt marsh tiger beetles, Cicindela circumpicta and C. togata (Coleoptera: Cicindelidae), were examined. 3. In laboratory studies, female C. circumpicta and C. togata distinguished between experimental salinities, with the former preferring 4 parts per thousand (ppt) and the latter preferring 12 ppt. In the field, C. circumpicta larvae were associated with lower salinities (1–3 ppt) and vegetation along the edges of salt flats while C. togata larvae were found on open salt flats often near halophytes (average salinity = 7.8 ppt). 4. In the field, females chose sites for oviposition in response to shade but not vertical landmarks. In a direct test, 53 of 56 new larval burrows occurred in shaded treatments, three in nonshaded controls. 5. Compared with nonshaded controls, shade increased survival of eggs that were collected in the laboratory and placed in the field. For C. circumpicta eggs, 78% placed in shaded treatments hatched, while significantly fewer (22%) hatched in exposed treatments. For C. togata, 43% of eggs placed in the shade hatched, while no eggs placed in exposed treatments hatched. 6. These results support the hypothesis of niche partitioning between C. circumpicta and C. togata based on ovipositional choice and resulting larval habitat.

Biology, Habitat Preference, and Larval Description of Cicindela cursitans Leconte (Coleoptera: Carabidae: Cicindelinae)

“…It is likely that oviposition near plants is unrelated to the plant species, but perhaps does relate to plant morphology. Microhabitat selection occurs for other species, and the use of shade as an oviposition cue has been previously recorded in salt flat species (Hoback et al 2000).…”

Movement of Cicindela hirticollis Say Larvae in Response to Moisture and Flooding

“…This suggests that larvae respond to flooding by escaping flooded areas, perhaps to compensate for low immersion survival (Brust et al, 2005). Other species which inhabit salt flats exposed to static water (Hoback et al, 1998) survive immersion in hypoxic water by switching to anaerobic metabolism (Hoback et al, 2000a). Tropical species which inhabit the Amazon River basin exhibit alternative adaptations to survive long periods of immersion including aquatic respiration, extreme tolerance of anoxia, and rapid development to the adult stage (Zerm and Adis, 2002;2004;.…”

Ecomorphology and Mating Behavior of Two Species of Night-stalking Tiger Beetles, Omus audouini and O. dejeanii

“…Oviposition behavior of tiger beetles is highly substrate specific to accommodate the burrowing behavior of the larvae (Willis 1967, Leffler 1979, Knisley 1987, Shivashankar & Pearson 1994, Hoback et al 2000, Cornelisse & Hafernik 2009) and may be expected to influence post-copulatory behavior of the female. Considering the possibility of female control over sperm use, an experimental manipulation was done to evaluate whether female Omus are capable of ejecting speminal products.…”

“…Eggs are laid singly in individually prepared sites, rather than en masse, and generally on the order of 10-50 eggs per day depending on the species (Knisley & Schultz 1997, Hoback et al 2000, Pearson & Vogler 2001. The oviposition site is critical for egg and larval success.…”

“…The oviposition site is critical for egg and larval success. Individual species have their own preference in oviposition site selection, based on salinity, exposure, soil particulate size, and even slope (Leffler 1979, Knisley & Schultz 1997, Hoback et al 2000, Cornelisse & Hafernik 2009, Willis 1967. Oviposition site is of particular importance not only for egg development (moisture apparently being the dominant factor in determining eclosion/hatching, Knisley & Schultz 1997) but also for the ecology of the larva.…”