Sugarcane Entomology
Sugarcane entomology section deals with research activities related to control of insect pests. Sugarcane borers, pyrilla, bugs, thrips, mites, grass hoppers, and army worm are dangerous pests during the growing season. In past, chemical control of the pest was in regular practice and it was recommended for tackling these pests.
However, with the knowledge of harmful effects of pesticides on humans and animals, Integrated Pest Management technique and biological control has been developed in which the hazards of chemicals is either avoided or reduced to a minimum.
There’s an Entomology laboratory at the institute, which prepares Trichogramma and Chrysoperla cards bearing the eggs of these insects. These cards are then provided to farmers to use them in their sugarcane fields. After hatching of the eggs of these useful insects larvae and adults feed on eggs of harmful borers.
(Insect Control Methods for Farmers)
Major insect pests of sugarcane crop include Gordaspur, top, stem, root borers, pyrella, and termites..
Gordaspur borer Bissetia steniellus (Hampson) belongs to the family Pyralidae and order Lepidoptera. Its infestation was first noted in Naguman Area of Khyber Pakhtunkhwa province during 1980's. It's a devastating pest of sugarcane. It infests the crop during the grand growth period (July to September) of sugarcane. According to Mahela et al. (2002), females lay about 90-300 scale like eggs in clusters on the leaves along the midrib in 3-4 rows. These hatch in 4-9 days. Young larvae enter top portion of the cane through a single hole just above the node. They feed in groups by making spiral galleries which run upwards. After a week or ten days they attack the adjacent canes. The larval duration is 21-27 days and it pupates inside the cane. The complete life cycle is 35-40 days. Dry sugarcane tops are produced due to the attack of Goraspur borer during July to September and large patches of dried canes appear due to its attack (Faqir Gul et al. 2010).
Sugarcane top borer Scirpophaga novella (Fabricius) also belong to family Pyralidae and order Lepidoptera. It is one of the most destructive and major pest of sugarcane in Pakistan, India and China. Its active season is from March to November and after hatching, the young larvae bores into the leaf through midrib and consequently the main shoot or cane stalk. It hibernates in larval form when it has attained full growth. Pupation occurs through making a chamber with special type of emergence hole at a position just above the node. Maximum damage is realized from April to July as it feeds on sugarcane. The top borer infests the top portion of the sugarcane plants. It completes some 4-5 numbers of generation in a year and all of them damage the crop. In earlier stages (first two generations) the young sugarcane plants have reddish streaks together with small holes in the plants due to its attack. If it attacks in later stage of sugarcane plant development, it causes a special symptom called 'bunchy top'. It not only lowers yield of the crop but also deteriorates the quality and quantity of the juice.
Scientific name of sugarcane stem borer is Chilo infuscatellus (Snellen) with family Crambidae and order Lepidptera. It is also a serious problem of sugarcane crop and causes losses up to 36.5%. In years of severe infestation the damage may reach to 30-70%. Its caterpillers destroy about 20% of the young shoots during April to June annually. After hatching, the larvae attack the base of the plant and start feeding on them. The central whorl of the leaves in the stem (growing point) is cut by the caterpillars which result in wilting and drying. The central dead shoot is also called the 'dead-heart'. These plants though don't develop further but the dormant buds sprout and give side-shoots. After the cane development, the attack of the stem borer does not develop dead-hearts and the destruction is restricted only to a few internodes only. Even then, it causes a major yield decline (Courtesy: Rahman and Walayati, 2013).
Root borer of sugarcane is known as Emmalocera depressella (Swinhoe) and belongs to the family Pyralidae and order Lepidoptera. Its distribution is in India, Pakistan and Bangladesh. This species was first recorded in 1885 in sugarcane in India. It is presently regarded as a major pest of sugarcane in parts of India and Pakistan. A reduction of up to 66.2% to 73% has been reported. Massive yield losses can result in what is known as a "root-borer-wilt complex" infestation. It infects sugarcane in all stages of development. In sub-tropical areas its infestation starts from May and continues untill harvest time and reaches a peak period in August to November. It has been concluded that temperature from 31-34 degrees Celcius coupled with higher humidity area favorable conditions for this pest. On the contrary, very high or very low temperatures coupled with low humidity disfavors its development. The number of generations have been recorded as ranging between 3-5. Larvae usually tunnel inside the stalk base or in the stubble. Mature larvae hibernate in stubble in mid November to early December. Freshly hatched larvae may make 1-7 tiny holes in the internodes below soil levels in attempt to enter the base of the stalk. Dead-hearts can start froming after 12-17 days of hatching coupled with general yellowing of the leaves. Infestation also results in poor tillering in the mature plants. (Courtesy: www.sugarresearch.com.au).
Fig. - Sugarcane Root Borer. From left: dead heart and yellowing of leaves, male and female adults mating, root borer eggs, and root borer damage (Images Courtesy: Dr. HR Sardana, NCIPM, India). http://www.sugarresearch.com.au/icms_docs/163504_Emmalocera_depressella_Dossier.pdf
The scientific name of sugarcane pyrilla (sugarcane leaf hopper) is Pyrilla perpusilla (Walker) of the family Lophopidae and order Homoptera. It is the most dangerous sap-sucking sugarcane pest but also has been recorded in maize, wheat, millet and other crops. The pest wreathes havoc in the sub-tropical areas every 5-6 years. It sucks phloem sap from leaves and excretes honeydew onto foliage, which results in fungal diseases. This damages sugar yield and quality both directly and indirectly. The nymphs are reported to migrate to other crops (e.g. wheat) after sugarcane harvest where they assume adult form a couple of months later. The adults then migrate back to sugarcane. The active stages of the life cycles favor the underside of the leaf blades, particularly near midrib as resting and feeding sites. They are inactive during early morning, evening and night, typically resting on the under side of the leaves. Between 10 to 3 pm they become very active and could be found on both sides of the leaf surfaces. They jump among plants easily. Poor yield is obtained due to poor growth of seed setts and difficulties in milling canes from affected plants. Nymphs and adults suck sap from the leaves and can decrease sucrose content by up to 50%.
Sugarcane Termites (Odontotermes and Microtermes spp.) is a big problem in some sugarcane fields in Khyber Pakhtunkhwa. It can deteriorate germination and also quality of sugarcane at harvest. Termites attack the planted sugarcane setts at the ends or eye buds but in severe attack, the internodes as well. After germination, they attack the roots, eat the content, and filling the galleries with soil. This results in leaf drying and ultimately the death of plants. Maximum activity of termites in sugarcane has been noted in July. According to Ahmad et al. (2002), the cumulative damage of termites reached up to 34.8% in sugarcane crop.