Appearance And Management Of A New Devastating Pest Of Cotton, Phenacoccus solenopsis Tinsley, In Pakistan

Mealy bug started pestering cotton growers in 2005. The infestation spread in most of the cotton growing areas, within a year. During 2006-07, its attack damaged nearly 40% of the area under cotton (3 million ha), causing a loss of approx. 2.4 million bales. Infestation is even wider in 2007-08 crop season.

Belonging to the family Pseudococcidae and genus Phenacoccus, the identification of its species remain uncertain. Initially, it was considered as solani and later solenopsis, However, others have described it as a new species and named as gossypiphilous (unpublished; Abbas, M.A., Arif, J. and Saeed, S., 2008).

Baring the fact that mealy bugs have hydrophobic layer around its body, seek sheltered sites, have high fecundity rates, eggs are laid in cottony pouches, nymphs are protected by the adults, conventional application fails to reach the target pest. Although known as pest of cotton, as many as, 149 host plants – ranging from vegetables, orchards, ornamentals, as well as weeds, have been reported. Therefore, its management requires measures to target control on all crops around the year, besides the considerations of its complex biology. Because of the toxicity and the residue issues associated, OPs are not recommended for vegetables (which share the same cotton cropping areas). For this reason, mealy bug management requires use of soft insecticides that are relatively safe to the beneficial and are usable on vegetables and orchards.

This paper reports life cycle of cotton mealy bugs, population dynamics on cotton and a review of 3 years research program concluding to the discovery of using specific adjuvant, Ultra (alkyl ether sulfate sodium salt) along with a highly potent CNI, imidacloprid for the control of mealy bugs. It is concluded that when used with synergistic adjuvant, imidacloprid significantly enhanced penetration of the chemical in the waxy cuticle of the pest thereby improved performance against mealy bugs. More recently, a new chemistry presenting 2-way systemicity, spirotetramat in combination with imidacloprid was also evaluated with its efficacy along with a number of adjuvants. The premix combination of spirotetramat+imidacloprid (without the need for any external adjuvant) as foliar application, provided excellent control of mealy bugs, The studies further discovered that the spirotetramat+imidacloprid combination, as seed treatment could provid long residual control of mealy bugs, along with exceptional control of other cotton pests (jassid, whitefly and thrips), during the first 2 months of cotton crop; thus making the mixture an outstanding performer to provide early protection of cotton, as seed treatment and foliar application for the management of mealy bugs, in the later part of  the cotton and horticultural crops.