Are there beneficial insects in cashew plantations?
All insects are not pests. There are beneficial insects performing different roles in an ecosystem providing several ecosystem services in nature. Some insects are predators, and some are parasitoids, which kill the crop pests. Few insects including bees, beetles, thrips, flies act as pollinators, some are productive insects like silk worm, lac insects and some are scavengers.
Which predatory insects are commonly seen in cashew plantations?
Praying mantids, reduviids, ants, coccinellids, green lace wings, syrphids, geocorid bugs, Eocanthecona (pentatomid) bugs, Anthocorid bugs are the common predatory insects seen in cashew plantations.
Are spiders helpful in reducing pest population of cashew?
Yes. Spiders are very good predators seen in large numbers in cashew plantations. They predate on different types of insect pests including tea mosquito bug, thereby bringing down their population. But observations at ICAR-DCR, Puttur indicated that spiders cannot reduce tea mosquito bug population to a greater extent under the field conditions.
What is the importance of pollinators in cashew?
Cashew is a cross-pollinated crop that requires insects for pollination. In cashew both male and bisexual flowers present in same inflorescence. In general, male flowers are abundant (>80-90 %) and bisexual flowers are less than 10 %. Due to arrangement of anthers and stigma at differential position in the same bisexual flower, self-pollination is difficult. Further, cashew pollen grains are heavy and sticky in nature, thus wind has no role in pollination. Thus, insects especially bees are considered important to transfer pollen grains from one flower to the other to effect pollination and fruit set.
Which are all the insects considered as pollinators of cashew?
Though several insects including bees, ants, wasps visit cashew flowers, bees are considered to be important pollinators of cashew flowers. Bees include both honey bees and wild bees.
When do the bees visit cashew flowers? What is the reward they get in turn from cashew flowers?
Bees generally visit cashew flowers during day time. Foraging time vary with different bee species. Foraging activity may start from 7.00 or 8.0 am in the morning depending on the sunshine and their activity can be seen till 5 or 5.30 pm in the evening. But, peak foraging activity of most of the bees occur between 11.00 am and 1.00 pm. Bees get nectar and the pollen grains from flowers, which they feed and also carry to their nests to feed their young ones.
How are wild bees important in cashew pollination? Where do they live?
Wild bees comprise several species, they are also called as native bees or solitary bees that live in nature, but generally unnoticed. They provide important pollination service / ecosystem service to any crop ecosystem and found more abundant in cashew ecosystem. Some bees are stem nesting bees or cavity nesting bees, hence they make nests in plant sticks having soft piths like lantana, Ixora, Caesalpinia, Mussanda etc, grasses, or hollow stems like bamboo. Even in dried cashew sticks and the pruned ends of stems, several wild bees make nests. Few bee species are ground nesting bees, for eg. Pseudapis oxybeloides makes nest in soil.
Is apiary (keeping bee colonies) helpful in enhancing cashew pollination and yield
Yes. We can expect marginal yield increase in cashew by keeping bee colonies. Research carried out in few cashew growing regions of Karnataka and Tamil Nadu has showed that keeping honey bee colonies in cashew plantations help to increase yield from 10-30 %. One must keep in mind that the bee species, ecological conditions, surrounding bee flora, crop management measures adopted etc are important factors that determine the bee visitation in cashew and the resultant yield increase.
Is there any insecticide safe for the bees?
No chemical insecticide is considered as safe to the bees and insecticidal sprays are not recommended during the flowering period on many bee dependent crops. The different group of insecticides especially of organo phosphorus, organo chlorines, carbamates, neonicotinoids are highly toxic to bees. Whenever spraying is taken up, the bee colonies should be protected by confining and feeding them with sugar syrup. Avoiding sprays during its peak foraging period helps to reduce direct contact with the bees.