Diapause development and cold hardiness of Pectinophora gossypiella (Lepidoptera: Gelechiidae) larvae in Greece

Olga P Kaltsa,Panagiotis G Milonas,Matilda Savopoulou-Soultani

doi:10.14411/eje.2006.072

Abstract

Larval diapause development and termination and some characteristics of cold hardiness in Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) were studied under field conditions in northern Greece. P. gossypiella overwintering larvae were sampled at 20 to 30 day intervals and subjected to two photoperiodic regimes at 20°C. In larvae kept under a long-day photope- riod (16L : 8D) diapause development was accelerated compared to those kept under a short-day photoperiod (8L : 16D). There was no difference in response to the two photoperiods after February. Mean number of days to pupation of P. gossypiella overwintering larvae decreased progressively through the sampling period, from November to April. Chilling is not a prerequisite but does accel- erate diapause development. Supercooling points for P. gossypiella overwintering larvae ranged from -14 to -17°C with the majority dying after freezing.

Highlights

Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) is one of the most destructive insects attacking cotton fields world-wide
The duration in days to pupation of overwintering P. gossypiella larvae was significantly reduced within the sampling period, November to April, when they experienced either a long-day (F6,126 = 52.05; P < 0.05) or short-day photoperiod (F6,118 = 28.65; P < 0.05) (Table 1)
Overwintering P. gossypiella larvae pupated after 127 days when transferred to the laboratory on 24th November and maintained at a photoperiod of 16L : 8D, whereas those transferred on 1st April pupated after 37 days

Summary

Introduction

Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) is one of the most destructive insects attacking cotton fields world-wide. The feeding of the larvae may reduce lint yields by as much as 60% (Fry et al, 1978) and cause severe economic losses for cotton growers (Henneberry & Naranjo, 1998). The insect overwinters in diapause as full grown larvae within the seeds or in protected places in the soil. Adult emergence in the south-western United States occurs in late March and continues until late August (Henneberry & Naranjo, 1998). In Greece P. gossypiella completes 3 to 4 generations per year. Diapause induction is triggered by a combination of shortening photoperiod and low temperature (Henneberry & Naranjo, 1998; Venette et al, 2000)

Methods

Results

Conclusion