Symptom Identification and Control Techniques for the Litchi Fruit Borer
The litchi fruit borer is a major pest of longan and litchi. Its larvae bore into tender shoots, flower clusters and fruits. Damage during the young fruit stage causes severe fruit drop, while damage at maturity leaves the fruit stalk filled with insect frass, affecting quality. When tender shoots and flower clusters are damaged, their tips wither, affecting new shoot growth and flowering and fruiting the following year. This pest occurs in southern Fujian...
The litchi fruit borer is a major pest of longan and litchi. Its larvae bore into tender shoots, flower clusters and fruits. Damage during the young fruit stage causes severe fruit drop, while damage at maturity leaves the fruit stalk filled with insect frass, affecting quality. When tender shoots and flower clusters are damaged, their tips wither, affecting new shoot growth and flowering and fruiting the following year.
In southern Fujian this pest has 10 generations per year with overlapping generations. It overwinters as larvae inside branch tips, begins pupating at the end of March, and starts damaging branch tips, flower clusters and fruits in early to mid-April. From June to July it mainly bores into fruits; from early August to early September it damages longan fruits and tender shoots; and from mid-September to early November it bores into new shoots of litchi and longan.
Control methods:
1. Combine with shoot-control pruning. Winter shoots are an important overwintering site for this pest, so autumn shoots should be encouraged, winter shoots pruned, and spring shoots with a high pest population removed.
2. From May to July, fallen leaves and fallen fruits should be promptly swept up, gathered and burned to eliminate the source of the pest.
3. Chemical control: generally spray 3 times a year, timed at the litchi and longan stages from flower drop to young fruit, 15-20 days before fruit maturity, and when autumn shoots sprout and unfold leaves, applying the pesticide from the initial hatching to the peak period of the larvae. It can also be controlled incidentally through the control of the litchi stink bug, the litchi leafminer, the longan gelechiid moth, and the longan psyllid. Pesticide options include 10% lambda-cyhalothrin 3000-fold solution, 4.5% Ludan emulsifiable concentrate 1000-fold solution, 2.5% Kung Fu 2500-fold solution, 40.8% Lorsban 1000-fold solution, 2.5% Decis 2500-fold solution, 20% Meisaoli 2000-fold plus 80% dichlorvos 600-fold, 5% Cascade 1500-fold, etc. To prevent the pest from developing resistance, the above pesticides should be used alternately.