Pectinophora gossypiella (pink bollworm)

Pink bollworm causes failure of buds to open, fruit shedding, lint damage and seed loss.

Introduction

An account summarising the control methods most effective against P. gossypiella has been written by Graham (1980). A review of control in south-western USA was given by Hutchison (1999).

Biological Control

P. gossypiella has been a target for biological control, particularly in the USA. Parasitoids were introduced there from India, from the Indonesia-northern Australia region and from several other countries, but only Bracon kirkpatricki became established (Greathead, 1989). Biological control agents were first obtained from India, in the belief that it was the origin of the pest. When these failed later introductions were from Indonesia-Australia as opinion shifted in favour of an origin in this region. However, the matter is not settled and Ingram (1994) suggested that it may have come from the Indo-Pakistan area because of the number of species recorded by Cheema et al. (1980) (Greathead, 1989). More recently nematodes have been used as control agents in the USA (Henneberry et al., 1996; Gouge et al., 1999).

Integrated Pest Management

Combinations of biological and chemical controls have also proved successful. Tuhan et al. (1987) found that application of Trichogramma brasiliense in combination with chemical insecticides gave good control of pink bollworm in India, and Bacillus thuringiensis has been found to be effective in combination with chemical insecticides in Egypt (Hussein et al., 1990).

The Pectinophora gossypiella IPM project in California, USA, was reviewed by Walters et al. (1998). The project used the release of sterile insects, cultural controls, intensive monitoring with pheromone baited traps for adult males and boll sampling, pheromone applications for mating disruption, very limited use of pesticides and the widespread use of genetically engineered cotton.

In Pakistan, Ahmad et al. (2001) found a combination of Biological control and mating disruption techniques to be effective.

P. gossypiella is a worldwide pest of cotton and in some regions of the world, it is the key cotton pest. Oerke et al. (1994; modified from Frisbie, 1983) classify it as a key pest in North and South America and Asia, and an economically important pest in Africa, Europe and the former USSR, and Oceania. Based on trials from 1945 to 1980, Schwartz (1983) calculated that the potential loss, without control, was 61% due to P. gossypiella in the USA. Estimated losses of 9% were suggested where the pest was controlled. For 1987, King et al. (1988) estimated that the area affected by P. gossypiella was 237,330 ha of which 131,949 ha were treated. The cost of treatment was $22/ha. The estimated crop loss was 0.13% or 4150 t. Green and Lyon (1989) said that P. gossypiella infested over 200,000 ha in the western USA. Frisbie et al. (1989) indicated that economically damaging thresholds were reached if boll infestation rose above 5-15%.Agarwal and Katiyar (1979) calculated the crop loss due to P. gossypiella based on field trials in Delhi. According to their data, the crop loss in the 1970s was 20.2% or 234,000 t of cotton.In the Yangtze valley, China, Cai et al. (1985) reported that P. gossypiella reduced cotton yield by ca 10%. In the Wuhan region, it reduced fibre yield by 17-26% (Luo et al., 1986). Yuan and Lu (1986) estimated specific losses due to P. gossypiella of 0.0467 g/larvae due to direct injury and 0.0544 g of cotton due to indirect damage in the Shanghai region.In Sudan, Darling (1951) estimated that 10.7% of the potential cotton yield could be lost following infestation by P. gossypiella.In Egypt, in 1985, trial plots in the Nile Delta used a pheromone to control P. gossypiella. Losses of 2.2% were recorded, compared with 4.5% following insecticide treatments. The cotton yield from pheromone-protected crops was 3450 kg/ha while that from insecticide treated crops was 3100 kg/ha. Insect pests other than P. gossypiella were also controlled by these treatments (McVeigh et al., 1983; El-Adl et al., 1988).