Farmers rely mostly on chemical pesticides for pest control. But, as okra is harvested on alternate days, the dependence on chemical pesticides results in several ecological and spraying problems, as well as re-entry for harvest problems.

The need to identify alternate methods to manage pests is evident. Among the eco-friendly methods, several authors have reported the effectiveness of biocontrol agents and neem. Hence, studies were conducted on okra to find out the effectiveness of biocontrol agents and neem in reducing the damage, and the economic feasibility of using these in a pest management program.

A field trial on okra was conducted to study the effects of Bt (Bacillus thuringiensis), the predator C. carnea (Chrysoperla carnea), and neem (Econeem 0.3 percent), along with monocrotophos for comparison, on the major pests.

The treatments (see Table 1 below) were released/applied three times at intervals of 15 days, starting from 45 days after sowing (DAS). The eggs of C. carnea were mixed with sawdust. Immediately after hatching, they were dusted randomly on the plants/leaves during the evening hours. Halt (Bacillus thuringiensis var Kurstaki) was used as bacterial pesticide. The spray fluid for the different treatments was applied at a rate of 500 l/ha with a backpack hydraulic sprayer equipped with a hollow-cone nozzle.

Observations on the incidence of leafhoppers, whiteflies, and aphids were visually recorded before treatment and at 3 and 7 days after treatment (DAT) on six leaves per plant, two each from top, middle, and bottom regions, from ten tagged plants in each plot. The mean population was determined for each treatment. The larval population of H. armigera in ten tagged plants per plots was recorded on 0, 3, and 7 DAT. The fruit damage at the time of each harvest was recorded. The mean larval population and mean percent fruit damage were worked out. The additional yields obtained in treated plots over control were calculated, and total income derived for each treatment was determined. The cost-benefit ratio (CBR) was arrived at for all treatments, taking into account the total cost of cultivation, cost of treatment, and total income from each treatment.

The observations on leafhoppers, whiteflies, and aphids revealed that the treatments with monocrotophos (0.75 l/ha), C. carnea (50,000 larvae/ha), Econeem 0.3% (1.01 l/ha), and C. carnea (25,000 larvae/ha) + Econeem 0.3% (0.5 l/ha) were effective, and all were equal in controlling the sucking pests.

All treatments were found to be effective in reducing larval population of H. armigera. At the end of the first spray/release, all treatments recorded lower larval populations as compared to the untreated check.

In the second round of spray/release, the lowest population of 0.33 larva per five plants was recorded in plots released/sprayed with C. carnea + Econeem 0.3% on seven days after treatment, and the same trend was observed after the third spray.

The observations on fruit damage by H. armigera revealed that it was the lowest in C. carnea + Econeem 0.3% (8.61%) released/sprayed plots, followed by monocrotophos (9.81%). C. carnea, apart from feeding on sucking pests, also feeds on the eggs and early instar larvae of lepidopterans. Econeem 0.3% combined with C. carnea (or) Bt, effectively controlled H. armigera and E. vitella, indicating that these plant products can be successfully integrated with biocontrol agents.

The results on the fruit damage by E. vitella indicated that the lowest fruit damage (7.71%) was recorded in plots treated with monocrotophos followed by Bt + Econeem 0.3% at half of the dose (9.21%).

The highest fruit yield (11,426 kg/ha) was recorded in monocrotophos-treated plots with a higher CBR (1:2.98) and was on par with C. carnea + Econeem 0.3% (10,326 kg/ha and 1:2.60 respectively), followed by release of C. carnea alone and application of Econeem alone, whereas treatments in combination with Bt recorded lower yields than other treatments. This might be due to the effectiveness of the other treatments against both the sucking pests and fruit borers. Hence, the harmful effects of chemical pesticides can be mitigated by using biopesticides and plant derivatives instead of solely relying on chemical pesticides, since these are found to be eco-friendly.

It was concluded that release/application of the predator, Chrysoperla carnea (25,000 larvae/ha/release) plus Econeem 0.3% (0.5 l/ha) thrice at 15-day intervals, starting from 45 days after sowing, could effectively check the population of sucking pests as well as fruit borers. The percent fruit damage by the fruit borers H. armigera and E. vitella was also reduced.