Stink bug identification on sunflower

The area cultivated with sunflower (Helianthus annuus) has expanded in Brazil, with the grains being used in the production of edible oil, biodiesel, ornamentation, animal feed, among others (SOUZA et al., 2015). The occurrence of the stink bug on sunflower plants Xyonysius spp. It has been recorded by researchers since the 1980s, although considered a pest of minor importance but with great potential to cause damage to the productivity of sunflower grains. Little is known about the biology and ecology of Xyonysius spp. Aguiar (2002), found that the number of achenes/chapter and the percentage of damaged achenes were significantly affected by different population levels of X.major.

In August 2019, under a central pivot, sunflowers were cultivated in an area of ​​the Federal Institute of Education, Science and Technology of Brasília – campus Planaltina (IFB – campus Planaltina), for teaching purposes. When the sunflower was in the v5 phenological stage, leaves were observed with symptoms characteristic of stink bug “attack”, noting the presence of insects of the genus Xyonysius spp. on leaves and plant tips. During pre-flowering, the presence of the aforementioned stink bugs was again observed in a high population in the flower heads that had not yet opened (Figure 1). In the face of outbreaks of this pest in sunflower crops, species identification studies using some structural characteristics are of great value.

 Exclusive

The genus bed bugs Xyonysius spp. were collected from sunflower grown at IFB – campus Planaltina, packed in bottles containing 70% alcohol and taken to the Biology laboratory of the Technology in Agroecology course.

The insects were compared using structural characteristics described in table 1, with the species X. californicus e X. major. A stereoscopic microscope coupled to a micro computer was used to capture the images.

Table 1. Structural characteristics of X. californicus e X. californicus collected in sunflower.

Structural features	X. californicus	X.major
Comp. (mm)	3,8 ≤ 5,0	5,0 ≤ 5,6
Cor	Brown	Dark
Face	behind thigh on metasternum	behind thigh on metasternum
External costal margin of the chorion	slightly curved	direct
Comp. antenna (mm)	1 <4	1 <4
ventral edge of male genital capsule	Less Rounded	widely rounded
Parameter Blade	Slightly elongated	slightly shortened

Structural features

            X. californicus           

X.major

Comp. (mm)

3,8 ≤ 5,0

5,0 ≤ 5,6

Cor

Brown

Dark

Face

behind thigh on metasternum

behind thigh on metasternum

External costal margin of the chorion

slightly curved

direct

Comp. antenna (mm)

1 <4

1 <4

ventral edge of

male genital capsule

Less

Rounded

widely

rounded

Parameter Blade

Slightly

elongated

slightly

shortened

SOURCE: Adapted from Schaefer (1998)

 

Results and discussion

It was found that the average length of the insects was 5,0 mm, their thoracic and abdominal belly is black, the rostrum ends behind the thighs at the metasternum, the external costal margin of the chorion is slightly curved, the average length of the antenna is 1<4 mm, Ventral edge of the male genital capsule rounded and lamina paramere shortened. In figure 2, structural characteristics of the insects collected in the IFB area – Planaltina campus can be seen, used to identify the species of Xyonysius spp. 

Conclusion

According to the methodology used, it was found that the species Xyonysius major was present in the IFB sunflower plants – campus Planaltina.