Evidence of an embryonic diapause in a tropical Phaneropterinae (Insecta Ensifera Tettigonioidea)

Abstract

Eggs of Stictophaula armata lngrisch 1994 from Chiang Mai, Thailand ( 18°4 7'N, 98°55'E), were incubated at 25 °C in the laboratory. Under constantly humid conditions, favourable for development, about half of the eggs hatched within 60 days after oviposition (peak 20-36 days), the other half hatched between 120 and 350 days after oviposition, most!) between 180-260 days. In the late hatching eggs, embryonic development ceased temporarily at mesentrepses. Eggs laid by females that themselves had hatched from early or from late hatching eggs gave similar results. When newly laid eggs were incuhated at 60% RH, no hatching occurred, but if the eggs were first incubated for a period varying between 2 and 12 months at 60% RH and then allowed to absorb water, hatching occurred with a unimodal distribution between 23 and 72 days after moistening of the eggs (peak 24-40 days). Hatching success was not reduced by a desiccation period of up to 6 months. The results are interpreted as the occurrence of an egg diapause that is eliminated by the incidence of drought.

Forest litter crickets prefer higher substrate moisture for oviposition: Evidence from field and lab experiments

“…Low moisture level may also induce diapause, which is the interruption of embryogenesis due to unfavorable environmental periods [ 69 , 70 ]. In katydids, moisture level is one of the factors that induces (during unfavorable conditions) and ends (when conditions become favorable) the physiological process of diapause [ 71 ]. Diapause is an important evolutionary strategy that allows populations to persist in partially unfavorable environments [ 31 ], increasing species geographic distribution [ 72 ].…”

Diapause termination in two species of tropical butterfly, Euploea core (Cramer) and Euploea sylvester (Fabricius) (Lepidoptera: Nymphalidae)

“…Termination of diapause by rainfall and high relative humidity is being shown in an ever‐increasing array of tropical species. Species of Lepidoptera (Jones 1987; Jones & Rienks 1987; Scheermeyer 1987; Braby 1995; Kemp 2001; Pieloor & Seymour 2001), Hymenoptera (Seymour 1991; Seymour & Jones 2000), Orthoptera (Tanaka 1987; Ingrisch 1996) and Coleoptera (Tanaka et al . 1987a,b) have the end of their diapause correlated with rainfall.…”