Haider Karar

Seasonal Abundance of Aphids and Aphidophagous Insects in Pecan.

Seasonal occurrence of aphids and aphidophagous insects was monitored for six years (2006–2011) from full leaf expansion in May to leaf fall in October in “Desirable” variety pecan trees that were not treated with insecticides. Aphid outbreaks occurred two times per season, once in the spring and again in the late summer. Yellow pecan and blackmargined aphids exceeded the recommended treatment thresholds one time and black pecan aphids exceeded the recommended treatment levels three times over the six seasons. Increases in aphidophagous insect abundance coincided with aphid outbreaks in five of the six seasons. Among aphidophagous insects Harmonia axyridis and Olla v-nigrum were frequently collected in both the tree canopy and at the ground level, whereas, Coccinella septempunctata, Hippodamia convergens were rarely found in the tree canopy and commonly found at the ground level. Green lacewing abundance was higher in the ground level than in the tree canopy. Brown lacewings were more abundant in the tree canopy than at the ground level. Dolichopodid and syrphid fly abundance, at the ground level increased during peak aphid abundance in the tree canopy. Application of an aqueous solution of fermenting molasses to the pecan foliage during an aphid outbreak significantly increased the abundance of ladybeetles and lacewings and significantly reduced the abundance of yellow pecan, blackmargined and black pecan aphids.

Integration of cultural and mechanical practices for management of the mango mealybug Drosicha mangiferae

Mango (Mangifera indica L.) is one of the most economically important trees which has been cultivated for several centuries. The tree is susceptible to insect damage and is attacked by leaf eaters, termites, root grubs, sapsuckers, gall formers, stem borers, pod borers and fruit borers. The mango mealybug Drosicha mangiferae Green (Hemiptera: Monophlebidae) is one of the most destructive pests in the Indo-Pak subcontinent, sometimes causing premature fruit drop. A combination of several management strategies such as use of entomopathogens, chemical insecticides and burning of adult females has been used to control D. mangiferae. Overreliance on insecticides has eliminated natural enemies, and we were therefore interested in investigating the impact of alternative insect pest management strategies such as cultural and mechanical techniques on D. mangiferae. The results of our studies suggested that different bands significantly stopped the upward movement of overwintering and surviving populations of D. mangiferae. To augment the bands’ results, mounding the tree with debris on a plastic sheet once a year was the most effective technique and resulted in maximum reduction of the nymphal population of D. mangiferae. The newly developed Haider band—designed in our laboratory in the present studies—was very successful in the field in controlling the upward movement of newly hatched nymphs on trees: only 0.8% of the nymphs crossed the band. Only 7% to 10% of the nymphs crossed plastic sheets, polyethylene sheets and funnel bands. The cotton and gunny bag (jute) bands were the least effective: 42% of the nymphs managed to cross them. The results suggested that employing cultural practices and bands together could reduce the need for insecticide treatments and offer a sustainable method for D. mangiferae control.