Thermal response in adult codling moth

Abstract

Abstract. The thermoregulation behaviour of the adult codling moth, Cydia pomonella, is investigated in the laboratory using temperature gradient experiments. Unmated males and females are tested at dawn when moths typically move to resting sites. Mated females are tested during oviposition over a complete diurnal cycle. Temperature strongly affects microhabitat selection in adult moths. Unmated males and females prefer to rest at the low‐temperature ends of temperature gradients between 15 and 32 °C. Relative humidity does not influence the thermal response in unmated females, whereas males show a less distinct temperature selection under high humidity. By contrast to unmated moths, ovipositing females prove to be highly thermophilous (i.e. they deposit the highest proportions of their eggs in the zones of highest temperatures of gradients between 15 and 36 °C). This striking discrepancy in thermal response of females between their premating and oviposition period is likely to reflect an adaptation to different selection pressures from the thermal environment. Unmated moths may benefit from low temperatures by a longer lifespan and crypsis within the tree canopy, whereas the choice of warmer oviposition sites by mated females will favour a faster development of eggs.

Relationship Between Behavior and Physiology in an Invasive Pest Species: Oviposition Site Selection and Temperature-Dependent Development of the Oriental Fruit Moth (Lepidoptera: Tortricidae)

“…Each ring tunnel (with an outer diameter of 32.6 cm and an inner diameter of 27.0 cm) was a hollow ring of aluminum, 2 mm thick, where the horizontal portion of the ring was 20 mm wide and the tunnel height was 20 mm. The ring tunnel was tightly covered with a 2-mm-thick lid (Kü hrt et al 2006). A constant temperature gradient was generated with a single IRlamp per ring (R125 IR R, 250 W; Philips, Roosendaal, The Netherlands), heating the ring horizontally at an angle of 0Њ (Fig.…”

“…Similarly, infestation by the Þrst generation of the codling moth Cydia pomonella L. (Lepidoptera: Tortricidae) was lower at the north-facing tree side compared with the south-or east-facing side (Stoeckli et al 2008). Laboratory experiments documented that this species deposits its eggs on the warmest site, whereas egg survival decreases rapidly with rising temperatures (Kü hrt et al 2006). Hence, performance of preimaginal stages and microhabitat selection by the adult female were, contrary to expectations, not correlated in these cases.…”

“…In lepidopteran herbivores, several species were observed to oviposit on the sunny side of plants, even in the absence of differences in leaf quality potentially affecting larval development (Bernays and Chapman 1994). Among the microclimatic factors, temperature has a crucial inßuence on the behavior of adult herbivores (Kü hrt et al 2006) and their interactions with plants (Shreeve 1986, Alonso 1999, as well as on the performance of their offspring (Hughes et al 2004, Manrique et al 2008). Temperature at the oviposition site may provide reliable cues for thermal conditions optimal for embryonic and larval development, given that the larvae are relatively sedentary and develop close to the oviposition site.…”

“…Studies on the response of the oriental fruit moth to changing abiotic conditions (Hughes et al 2004) indicate a high potential for adaptation. However, in contrast to the codling moth C. pomonella (Kü hrt et al 2005(Kü hrt et al , 2006, little is known on the thermal response of the oriental fruit moth, despite its high economic signiÞcance (Natale et al 2003, IlÕichev et al 2004, Evenden and McClaughlin 2005.…”

“…Thermal preference of females during oviposition was assessed using a circular temperature gradient arena, which prevents any edge effects (Kü hrt et al 2006). Performance of the offspring was studied under controlled conditions (Summers et al 1984, Kü hrt et al 2005 at different constant temperatures, thus potentially providing comparable insight into population dynamics of particular species.…”