1 host and harm

Holochlora bilobata (Karny) can cause harm to a great variety of fruit trees and garden- flowers. On one hand, they mostly feed on hosts' leaves, plumule or petal etc., as regarding food behavior of adults and larvae. Low-instar larvae can engender into pinhole on leaf. From the third instar to adulthood, the insect engenders indention on leaves, and when seriously, even eat up leaves, just remaining midrib. It also eat petal engendering bloom fragmentary which makes a bad impact on the view value. Now it discovers that injured plants include 10 family 14 species, some important tropical or subtropical fruit tree, such as Mangifera indica, Mangifera persiciformis, Litchi chinensis, Dimocarpus longana, Psidium guajava, Averrhola caramabola, Punica granatum, Syzygium jambos, and some flowers, Rosa chinensis, Lagerstroemia indica, Osmanthus fragrans, Ligustrum quihoui, Michelia alba etc. It feeds on young leaves of fruit trees, for example, Mangifera indica, Mangifera persiciformis, Litchi chinensis, Dimocarpus longana, Averrhola caramabola etc. Usually the leaves which is case-hardened or whose color has turned dark green are lightly suffered injury.

On the other hand, adults lay eggs in tissue of vegetal wattle, which makes host suffer severe mechanical damage. Concerning the wattle which has eggs, not only its cortices are corroded, but also deep oviposition orifice beyond vimineous medullae causes long and deep wound. Water and nutrition conduction of host plant is strongly effected, which results in growing languishingly, leaves’ yellowing and even dying. In the next year, with emergence of an insect larva from an egg the tissue which has eggs usually be infected fungal disease, or severely mildewed. Wind-breakage easily happens, because wound is becoming increasingly large and has no means of concrescence.

In Nanning, Holochlora bilobata (Karny) has one generation per year and overwinters in the tissue of host plant branches by means of eggs. The period of egg is more than 210 days. Hibernated egg is hatched out in the following year from last ten days of April to mid-May. Larvae commonly live for 60~68d or even 74d or till mid-August. From last ten days of June to last ten-day of August is a period of adult eclosion. From the first ten days of July to mid-August is the major period for adult emergence. Oviposition period commonly lasts 45~60d. Adult oviposition period is from last ten days of August to mid-October.

The adults usually lay eggs in plant tissue at 8:00~10:00 p.m.. When adult oviposits, it selects host plants according to thickness of branches and quantity of tissue fluid. Commonly diameter of branch which is most suitable for oviposition is 7.5~8.9mm, and branches whose diameters exceed 11.0mm or are less than 6.6mm are hard to find eggs. The branch which has little or moderate tissue fluid is better for ovipositing. Such plants as banyan, jackfruit and etc., of which there are more sap in the bark, haven't been found eggs. Using ovipositor to file a rabbet through to medullae, adults lay eggs in the flute. They repeated filing and laying eggs, over which they use mucus to ahere wood pieces to cover. Length of flute is 91.8~126.6mm, the longest flute is 162.2mm and the shortest one is 61.5mm. Its width is 1.1~2.1mm, and depth is 6.3mm. Eggs staggerly line in the flute. The width of pile of wood pieces is 3.4~5.7mm. The adults often select those branches, which lie below the middle or lower part of tree-crown, and are crosswise or breadthwise to oviposit. The rabbets usually incline downwards. Per female adult can oviposit in 3~4 flutes and there’s about 24~74 eggs in each flute. The number of eggs which each female adult lays is 128 ~183, sometimes even 228.

Field investigation shows that the plants which adult females select for oviposition mostly are Lagerstroemia indica ,Psidium guajava, Averrhola caramabola, Ligustrum quihoui, Mangifera persiciformis, Cleidiocarpon cavaleriei, Syzygium jambos, Osmanthus fragrans, Chinnamomum buramnni, and Carmona microphylla.

Adults have eclosion at night and eat food at following night. Adults are hidden during the day, and eat food, copulate, oviposit from dusk to midnight. On the thirtieth to thirty-fifth day after eclosion, adults begin to copulate. In the next 15~25 days, they begin to oviposit, and then die in the following 8~16 days. Longevity of adult can reach to 85~102 days and even 112 days. Adults have certain abilities to fly, can shift between different hosts, and cause harm or oviposit. Female adults have no phototaxis, while male adults have feeble phototaxis. Ratio between male and female approaches 1:1.

Larvae have eclosion from mid-night to 7:00 a.m. and then move to tip of host branches to harm young leaves or petals. Larvae have five instars. Low-instar larvae can move about and eat food at day and night. After the third instar, their appetite markedly increase, and the fourth or fifth instars are glutton. Larvae eat exuvium, and they will kill each other short of food. The 3rd~5th larvae usually gather round to harm without interference.

According to our observation each instar of Holochlora bilobata (Karny) suffers from natural enemies. The natural enemy of eggs is a sort of parasitic wasp which were not identified. Parasitism rate usually is 12%~25%, and parasitism mostly occurs during from mid-September to mid-October. Concerning sole parasitism, parasitised eggs die in later period and can't be hatched. The natural enemies of larvae are mostly Hierodula patellifera (Serville), spiders and birds. Per adult of Hierodula patellifera can prey on the 1st~3rd larvae of Holochlora bilobata (Karny) on Ligustrum quihoui. The natural enemies of adults are birds and Hierodula patellifera, which can control the population number of Holochlora bilobata (Karny).