1. Growth Response of Melonworm, Diaphania hyalinata Linnaeus (Insecta: Lepidoptera: Pyralidae) on three cultivars of cucurbit grown in South Florida.
Babu Panthi and Daksnina Seal
University of Florida
Tropical Research and Education Center
Homestead, Florida
Today I am going to talk about the growth response of Melonworm on three different cultivars of cucurbits (Summer Squash, Cucumber and Zucchini) grown in South Florida.

2. Introduction Melonworm (Diaphania hyalinata L.)
Serious tropical pest of cucurbitaceae
Major Hosts:
Summer Squash, Cucumber, Zucchini
Minor Hosts:
Watermelon, Pumpkin, Cantaloupe
Melonworm is the most important tropical pest of cucurbitaceae in South Florida which cause serious damage. Cucurbits such as Summer squash, cucumber and Zucchini are mainly grown in Florida in large number. These are the major host of Melonworm causing serious damage. The other minor hosts are watermelon, pumpkin, cantaloupe etc.

3. Introduction Melonworm (Diaphania hyalinata L.)
The first picture is of Melonworm adult moth. It has shiny white wings with narrow brown band around the wing margin and has white abdomen and brown head.
The second picture is of Pickleworm which is similar to Melonworm and has almost similar host range. Though they are not abundance in South Florida but is considered as a potential pest of cucurbits. The morphology of adult moth is quite similar with Melonworm. Whereas its abdomen is brown in color. The wings are also brown in color with specks of yellow spot in the center of wing.
en.wikipedia.org
Melonworm (Diaphania hyalinata L.)
Pickleworm (Diaphania nitidalis L.)

4. Geographic Distribution
Southeastern United States
Overwinter in South Florida
Disperse throughout Southern and Gulf coast state in summer
Also migrate to Carolinas and Northern states during summer
Can also be found in Oklahoma and Nebraska (Zehnder 2011)
Melonworm is found mostly in southeastern parts of United States. They generally overwinters in South Florida and then disperse throughout the Southern and Gulf coast in summer. They are also found to be migrated towards Carolinas and further northern states during summer and even in Oklahoma and Nebraska in the west.

5. Biology Larva (1.64mm HC) Egg (0.7mm) Adult (25mm) Pupa (18.15mm)
Melonworm completes its lifecycle in about 30 days completing its four life stages. Egg which is tiny oval yellow colored is either laid singly or in cluster underside of leaf. Egg hatches in about 3-5 days. Larva- there are 5 larval instars of Melonworm with last for about days. Pupa- it lasts for 5-7 days and adult emerges and live for 4-5 days.
Adult (25mm)
Pupa (18.15mm)

6. Mean (± SE) number of survival of larvae
Mean number of Melonworm larvae survived at different instars on four hosts. Initial culture was on Squash hosts.
Developmental Stage
Mean (± SE) number of survival of larvae
Cucumber
Yellow Squash
Water Melon
Zucchini
First instar
18.4±0.50a
19.2±0.37a
15.4±0.81b
15.8±0.37b
Second instar
17.6±0.24a
15.6±0.68b
15.2±0.58b
Third instar
17.8±0.37a
16.8±0.58ab
15.8±0.86ab
15.0±0.70b
Fourth instar
15.6±0.68a
15.8±0.58a
14.2±0.97a
14.0±0.70a
Fifth instar
17.4±0.68a
17.2±0.58a
15.8±0.66a
16.8±0.58a
Pupa
18.8±0.58a
18.8±0.37a
18.8±0.49a
17.6±0.51a
Means within a row for each field followed by the same letter do not differ significantly (P>0.05, DMRT)
(1st instar: F = 11.82, df = 3, 16, P = ; 2nd instar: F = 8.52, df = 3, 16, P = ; 3rd instar: F = 3.43, df = 3, 16, P = ; 4th instar: F = 1.55, df = 3, 16, P = ; 5th instar: F = 1.28, df = 3, 16, P = ; Pupa: F = 1.47, df = 3, 16, P = )

7. Mean (± SE) number of survival of larvae
Mean Number of Melonworm larvae survived at different instars raised on single host.
Developmental Stage
Mean (± SE) number of survival of larvae
Cucumber
Yellow Squash
Water Melon
Zucchini
First instar
16.2±0.20ab
17.2±1.02ab
14.4±0.51b
15.2±0.58ab
Second instar
15.0±0.32a
16.2±0.73a
13.0±0.45b
15.0±0.63a
Third instar
14.0±0.55a
15.4±0.81a
10.0±0.95b
11.6±0.51b
Fourth instar
12.8±0.49a
13.8±0.66a
8.6±1.17b
8.0±0.45b
Fifth instar
12.0±0.32a
13.4±1.29a
6.0±0.63b
5.0±0.55b
Pupa
11.0±0.63b
14.4±1.50a
5.4±0.81c
4.6±0.51c
Means within a row for each field followed by the same letter do not differ significantly (P>0.05, DMRT)
(1st instar: F = 3.52, df = 3, 16, P = ; 2nd instar: F = 5.68, df = 3, 16, P = ; 3rd instar: F = 10.99, df = 3, 16, P = ; 4th instar: F = 15.29, df = 3, 16, P < ; 5th instar: F = 28.90, df = 3, 16, P < ; Pupa: F = 24.35, df = 3, 16, P < )

8. Duration of each instar on four different hosts.
Developmental Stage
Mean (± SE) number of survival of larvae
Cucumber
Yellow Squash
Water Melon
Zucchini
Egg
2.2±0.37
3.1±0.24
2.7±0.43
First instar
2.1±0.40
2.4±0.29
3.3±0.54
2.9±0.33
Second instar
2.5±0.27
1.9±0.19
2.8±0.37
3.5±0.45
Third instar
2.5±0.32
2.2±0.46
3.4±0.40
Fourth instar
2.5±0.50
2.7±0.30
Fifth instar
5.6±0.93
4.7±0.62
5.2±0.66
5.3±0.83
Pupa
9.0±0.55
8.2±0.37
8.2±1.16
9.4±0.68
Means within a row for each field followed by the same letter do not differ significantly (P>0.05, DMRT)