臭腹腺蝗(直翅目:锥头蝗科)胃盲囊的异速生长和功能特性(英文)

Allometric growth and performance of the gastric caeca of Zonocerus variegatus (L.) (Orthoptera: Pyrgomorphidae)

通过对臭腹腺蝗Zonocerusvariegatus (直翅目 :锥头蝗科 ) 6个若虫期及成虫期主消化道和胃盲囊分段进行解剖和测量 ,对其胃盲囊的异速生长和功能特性进行了研究。结果表明 ,胃盲囊和主消化道的生长是不同速的。胃盲囊前段较后段生长速率更高 ,但两者生长速率显著相关。消化道和胃盲囊的平均长度亦显著相关。随年龄增长 ,消化道的生长速率降低 ,而胃盲囊的生长速率上升。与胃盲囊前段功能相同 ,胃盲囊后段亦具有消化和吸收功能 。

The allometry, growth and activities of the gastric caeca of Zonocerus variegatus(L.) were determined to find out the functions of its posterior caeca which are unknown. This was done by dissecting out the gut and measuring the main gut regions and the gastric caeca in the six nymphal stages and adult. The gut consists of three main regions; the crop, ventriculus, with gastric caeca attached at anterior rim, and the hindgut. Each set of caeca consists of a long anteriorly pointed arm and a short posteriorly pointed arm. The growth of the caeca relative to the main gut was allometric. The anterior caeca had higher growth ratios than the posterior caeca and both were highly correlated. The relationship between gut and caeca mean length was highly significant. The mean gut length and age were significantly correlated with growth rate exponent <1 indicating a decreasing growth increment with age. The mean caeca length and age were highly correlated with growth exponent >1 indicating an increasing growth with age. Females had higher mean lengths than males and this was highly significant (P<0.05). Males had higher growth ratios than females except at growth centres. The growth patterns of the caeca for wet and dry seasons were similar with a single growth centre. But the mean length of the caeca was significantly different between wet and dry season’s insects from the fourth instar to adult. The posterior caeca was considered a complementary structure to the anterior caeca. They perform the same function of digestion and absorption of food. The posterior caeca is concluded additional device to increase the surface area of the ventriculus to cope with low nutrient status of herbivory.